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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>As filed with the Securities and Exchange Commission on March&nbsp;29, 2023 </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="right"><B>Registration <FONT STYLE="white-space:nowrap">No.&nbsp;333-&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</FONT>
</B></P> <P STYLE="font-size:4pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P> <P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:0pt;border-bottom:1px solid #000000">&nbsp;</P>
<P STYLE="line-height:3.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1px solid #000000">&nbsp;</P> <P STYLE="margin-top:4pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>UNITED STATES </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>SECURITIES AND EXCHANGE COMMISSION </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B>Washington, D.C. 20549 </B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center>
<P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>FORM <FONT
STYLE="white-space:nowrap">S-8</FONT></B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:18pt; font-family:Times New Roman" ALIGN="center"><B>REGISTRATION STATEMENT </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B><I>UNDER </I></B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:12pt; font-family:Times New Roman" ALIGN="center"><B><I>THE
SECURITIES ACT OF 1933 </I></B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center> <P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:24pt; font-family:Times New Roman" ALIGN="center"><B>Synlogic, Inc. </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>(Exact
name of registrant as specified in its charter) </B></P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center>
<P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD VALIGN="top" ALIGN="center"><B>Delaware</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" ALIGN="center"><B><FONT STYLE="white-space:nowrap">26-1824804</FONT></B></TD></TR>
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<TD VALIGN="top" ALIGN="center"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(State or other jurisdiction of</B></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>incorporation or organization)</B></P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" ALIGN="center"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(I.R.S. Employer</B></P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Identification Number)</B></P></TD></TR>
</TABLE> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>301 Binney Street, Suite 402 </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Cambridge, MA 02142 </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>(617) <FONT STYLE="white-space:nowrap">401-9975</FONT></B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Address, including zip code, and telephone number, including area code, of registrant&#146;s principal executive offices) </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>2015 Equity Incentive Award Plan </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Full Title of the Plan) </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Aoife Brennan </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>President
and Chief Executive Officer </B></P> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Synlogic, Inc. </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>301 Binney Street, Suite 402 </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Cambridge, MA 02142 </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>(617) <FONT STYLE="white-space:nowrap">401-9975</FONT></B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>(Name, address, including zip code, and telephone number, including area code, of agent for service) </B></P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><center> <P STYLE="line-height:6.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1.00pt solid #000000;width:21%">&nbsp;</P></center>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a <FONT STYLE="white-space:nowrap">non-accelerated</FONT>
filer, a smaller reporting company or an emerging growth company. See the definitions of &#147;large accelerated filer,&#148; &#147;accelerated filer,&#148; &#147;smaller reporting company,&#148; and &#147;emerging growth company&#148; in Rule <FONT
STYLE="white-space:nowrap">12b-2</FONT> of the Exchange Act. </P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD VALIGN="bottom">Large&nbsp;accelerated&nbsp;filer</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&#9744;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">Accelerated&nbsp;filer</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&#9744;</TD></TR>
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<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
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<TD VALIGN="bottom">Non-accelerated filer</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&#9746;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">Smaller&nbsp;reporting&nbsp;company</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&#9746;</TD></TR>
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<TD HEIGHT="8" COLSPAN="2"></TD>
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<TD VALIGN="bottom">&nbsp;</TD>
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<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">Emerging&nbsp;growth&nbsp;company</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&#9744;</TD></TR>
</TABLE> <P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period
for complying with any new or revised financial accounting standards provided pursuant to Section&nbsp;7(a)(2)(B) of the Securities Act.&nbsp;&nbsp;&#9744; </P> <P STYLE="font-size:10pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<P STYLE="line-height:1.0pt;margin-top:0pt;margin-bottom:0pt;border-bottom:1px solid #000000">&nbsp;</P> <P STYLE="line-height:3.0pt;margin-top:0pt;margin-bottom:2pt;border-bottom:1px solid #000000">&nbsp;</P>
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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>EXPLANATORY NOTE </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">This Registration Statement on Form <FONT STYLE="white-space:nowrap">S-8</FONT> is being filed for the purpose of registering an additional 3,336,812 shares
of the Registrant&#146;s common stock issuable under the Registrant&#146;s 2015 Equity Incentive Award Plan, for which a Registration Statement of the Registrant on Form <FONT STYLE="white-space:nowrap">S-8</FONT> (File No.&nbsp;
<A HREF="http://www.sec.gov/Archives/edgar/data/1527599/000119312517304682/d471033ds8.htm"><FONT STYLE="white-space:nowrap">333-220841</FONT></A>) is effective, as a result of the operation of an automatic annual increase provision therein, which
added 3,336,812 shares of Common Stock. This Registration Statement registers additional securities of the same class as other securities for which registration statements filed on Form <FONT STYLE="white-space:nowrap">S-8</FONT> of the Registrant
relating to one or more employee benefit plans is effective (File Nos. <A HREF="http://www.sec.gov/Archives/edgar/data/1527599/000110465915069371/a15-14644_9s8.htm"><FONT STYLE="white-space:nowrap">333-207299</FONT></A>, <A HREF="http://www.sec.gov/Archives/edgar/data/1527599/000110465916108376/a16-7287_1s8.htm">
<FONT STYLE="white-space:nowrap">333-210466</FONT></A>, <A HREF="http://www.sec.gov/Archives/edgar/data/1527599/000119312517304682/d471033ds8.htm"><FONT STYLE="white-space:nowrap">333-220841</FONT></A>, <A HREF="http://www.sec.gov/Archives/edgar/data/1527599/000119312518089307/d553208ds8.htm">
<FONT STYLE="white-space:nowrap">333-223798</FONT></A>, <A HREF="http://www.sec.gov/Archives/edgar/data/1527599/000119312519071992/d720964ds8.htm"><FONT STYLE="white-space:nowrap">333-230224</FONT></A>, <A HREF="http://www.sec.gov/Archives/edgar/data/1527599/000119312520071058/d824729ds8.htm">
<FONT STYLE="white-space:nowrap">333-237104</FONT></A>, <A HREF="http://www.sec.gov/Archives/edgar/data/1527599/000119312521093470/d171240ds8.htm"><FONT STYLE="white-space:nowrap">333-254688</FONT></A> and <A HREF="http://www.sec.gov/Archives/edgar/data/1527599/000119312522077901/d320640ds8.htm">
<FONT STYLE="white-space:nowrap">333-263630</FONT></A>).</P> <P STYLE="margin-top:24pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>INCORPORATION BY REFERENCE OF CONTENTS OF </B></P>
<P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>REGISTRATION STATEMENT ON FORM <FONT STYLE="white-space:nowrap">S-8</FONT> </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Pursuant to Instruction E of Form <FONT STYLE="white-space:nowrap">S-8,</FONT> the contents of the Registration Statement on <A HREF="http://www.sec.gov/Archives/edgar/data/1527599/000119312517304682/d471033ds8.htm">Form
 <FONT STYLE="white-space:nowrap">S-8</FONT></A> filed with the Securities and Exchange Commission on October&nbsp;5, 2017 (File No.&nbsp;<A HREF="http://www.sec.gov/Archives/edgar/data/1527599/000119312517304682/d471033ds8.htm"><FONT
STYLE="white-space:nowrap">333-220841</FONT></A>) are incorporated by reference herein. </P>
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 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Exhibit Index </B></P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
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<TD VALIGN="bottom" ROWSPAN="2" NOWRAP ALIGN="center" STYLE="border-bottom:1.00pt solid #000000"><B>Exhibit<BR>Number</B></TD>
<TD VALIGN="bottom" ROWSPAN="2">&nbsp;</TD>
<TD VALIGN="bottom" ROWSPAN="2" ALIGN="center" STYLE="border-bottom:1.00pt solid #000000"> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:8pt; font-family:Times New Roman" ALIGN="center"><B>Exhibit Description</B></P></TD>
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<TD VALIGN="bottom" COLSPAN="10" ALIGN="center" STYLE="border-bottom:1.00pt solid #000000"><B>Incorporated by Reference</B></TD>
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<TD VALIGN="bottom" COLSPAN="2" ROWSPAN="2" ALIGN="center" STYLE="border-bottom:1.00pt solid #000000"><B>Filed<BR>Herewith</B></TD>
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<TD VALIGN="bottom" COLSPAN="2" ALIGN="center" STYLE="border-bottom:1.00pt solid #000000"><B>Form</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
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<TD VALIGN="bottom" COLSPAN="2" ALIGN="center" STYLE="border-bottom:1.00pt solid #000000"><B>Date</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" COLSPAN="2" ALIGN="center" STYLE="border-bottom:1.00pt solid #000000"><B>Number</B></TD>
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<TD VALIGN="top" NOWRAP>&nbsp;&nbsp;&nbsp;&nbsp;4.1</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top"><A HREF="http://www.sec.gov/Archives/edgar/data/1527599/000110465915069368/a15-14644_8ex3d1.htm">Amended and Restated Certificate of Incorporation. </A></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="white-space:nowrap">8-K</FONT></TD>
<TD NOWRAP VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10/6/2015</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;</TD>
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<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">3.1</TD>
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<TD VALIGN="top" NOWRAP>&nbsp;&nbsp;&nbsp;&nbsp;4.2</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top"><A HREF="http://www.sec.gov/Archives/edgar/data/1527599/000119312517270395/d431294dex31.htm">Certificate of Amendment to Amended and Restated Certificate of Incorporation. </A></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="white-space:nowrap">8-K</FONT></TD>
<TD NOWRAP VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">8/28/2017</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">3.1</TD>
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<TD VALIGN="top" NOWRAP>&nbsp;&nbsp;&nbsp;&nbsp;4.3</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top"><A HREF="http://www.sec.gov/Archives/edgar/data/1527599/000119312517270395/d431294dex32.htm">Certificate of Amendment to Amended and Restated Certificate of Incorporation. </A></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="white-space:nowrap">8-K</FONT></TD>
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<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">8/28/2017</TD>
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<TD VALIGN="bottom" ALIGN="right">3.2</TD>
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<TD VALIGN="top" NOWRAP>&nbsp;&nbsp;&nbsp;&nbsp;4.4</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top"><A HREF="http://www.sec.gov/Archives/edgar/data/1527599/000110465915069368/a15-14644_8ex3d2.htm">Amended and Restated Bylaws. </A></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="white-space:nowrap">8-K</FONT></TD>
<TD NOWRAP VALIGN="bottom">&nbsp;</TD>
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<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10/6/2015</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">3.2</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;</TD>
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<TD VALIGN="top" NOWRAP>&nbsp;&nbsp;&nbsp;&nbsp;4.5</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top"><A HREF="http://www.sec.gov/Archives/edgar/data/1527599/000119312517309912/d471035dex45.htm">Form of Common Stock Certificate. </A></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="white-space:nowrap">S-3</FONT></TD>
<TD NOWRAP VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10/13/2017</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">4.5</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP>&nbsp;&nbsp;&nbsp;&nbsp;5.1</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top"><A HREF="d490480dex51.htm">Opinion of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C. </A></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">X</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP>&nbsp;&nbsp;23.1</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top"><A HREF="d490480dex231.htm">Consent of KPMG LLP, independent registered public accounting firm. </A></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">X</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP>&nbsp;&nbsp;23.2</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top"><A HREF="d490480dex51.htm">Consent of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C. (included in Exhibit 5.1). </A></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">X</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP>&nbsp;&nbsp;24.1</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top"><A HREF="d490480ds8.htm#sig">Power of Attorney. Reference is made to the signature page to the Registration Statement. </A></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">X</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP>&nbsp;&nbsp;99.1(A)#</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top"><A HREF="http://www.sec.gov/Archives/edgar/data/1527599/000156459018006323/sybx-ex101_397.htm">2015 Equity Incentive Award Plan. </A></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="white-space:nowrap">10-K</FONT></TD>
<TD NOWRAP VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">3/20/2018</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10.1</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP>&nbsp;&nbsp;99.1(B)#</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top"><A HREF="http://www.sec.gov/Archives/edgar/data/1527599/000104746915007251/a2225898zex-10_9b.htm">Form of Stock Option Grant Notice and Stock Option Agreement under the 2015 Equity Incentive Award Plan. </A></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="white-space:nowrap">S-1/A</FONT></TD>
<TD NOWRAP VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">9/11/2015</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10.9</TD>
<TD NOWRAP VALIGN="bottom">(B)&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP>&nbsp;&nbsp;99.1(C)#</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top"><A HREF="http://www.sec.gov/Archives/edgar/data/1527599/000104746915007251/a2225898zex-10_9c.htm">Form of Restricted Stock Award Grant Notice and Agreement and Form of Restricted Stock Unit Award Grant Notice and Agreement under the 2015
Equity Incentive Award Plan. </A></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right"><FONT STYLE="white-space:nowrap">S-1/A</FONT></TD>
<TD NOWRAP VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">9/11/2015</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">10.9</TD>
<TD NOWRAP VALIGN="bottom">(C)&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="8"></TD>
<TD HEIGHT="8" COLSPAN="2"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD>
<TD HEIGHT="8" COLSPAN="4"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" NOWRAP>107</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top"><A HREF="d490480dexfilingfees.htm">Calculation of Filing Fee Table </A></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="right">X</TD>
<TD NOWRAP VALIGN="bottom">&nbsp;</TD></TR>
</TABLE> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt" BORDER="0" CELLPADDING="0" CELLSPACING="0" WIDTH="100%">
<TR style = "page-break-inside:avoid">
<TD WIDTH="2%" VALIGN="top" ALIGN="left">#</TD>
<TD ALIGN="left" VALIGN="top"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman; " ALIGN="left">Indicates management contract or compensatory plan. </P></TD></TR></TABLE>
</DIV></Center>


<p style="margin-top:1em; margin-bottom:0em; page-break-before:always">
<HR SIZE="3" style="COLOR:#999999" WIDTH="100%" ALIGN="CENTER">


<Center><DIV STYLE="width:8.5in" align="left">
 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B><A NAME="sig"></A>Signatures </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant has duly caused this Registration Statement on Form <FONT
STYLE="white-space:nowrap">S-8</FONT> to be signed on its behalf by the undersigned, thereunto duly authorized, in Cambridge, Massachusetts on March&nbsp;29, 2023. </P>
<P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P><DIV ALIGN="right">
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="40%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt">


<TR>

<TD WIDTH="7%"></TD>

<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="92%"></TD></TR>


<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top" COLSPAN="3"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman"><B>SYNLOGIC, INC.</B></P></TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">By:</P></TD>
<TD VALIGN="bottom" STYLE=" BORDER-BOTTOM:1px solid #000000">&nbsp;</TD>
<TD VALIGN="bottom" STYLE="BORDER-BOTTOM:1px solid #000000"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">/s/ Aoife Brennan</P></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman">Aoife Brennan</P></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="bottom"></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom"> <P STYLE=" margin-top:0pt ; margin-bottom:0pt; margin-left:1.00em; text-indent:-1.00em; font-size:10pt; font-family:Times New Roman"><I>President and Chief Executive Officer</I></P></TD></TR>
</TABLE></DIV> <P STYLE="margin-top:24pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Power of Attorney </B></P>
<P STYLE="margin-top:12pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below hereby constitutes and appoints Aoife Brennan and Michael Jensen, and each
of them acting individually, as his or her true and lawful <FONT STYLE="white-space:nowrap"><FONT STYLE="white-space:nowrap">attorneys-in-fact</FONT></FONT> and agents, each with full power of substitution, for him or her in any and all capacities,
to sign any and all amendments to this Registration Statement, including post-effective amendments or any abbreviated registration statement and any amendments thereto filed pursuant to Rule 462(b) increasing the number of securities for which
registration is sought, and to file the same, with all exhibits thereto and other documents in connection therewith, with the SEC, granting unto said <FONT STYLE="white-space:nowrap"><FONT STYLE="white-space:nowrap">attorneys-in-fact</FONT></FONT>
and agents, with full power of each to act alone, full power and authority to do and perform each and every act and thing requisite and necessary to be done in connection therewith, as fully for all intents and purposes as he or she might or could
do in person, hereby ratifying and confirming all that said <FONT STYLE="white-space:nowrap"><FONT STYLE="white-space:nowrap">attorneys-in-fact</FONT></FONT> and agents, or his, her or their substitute or substitutes, may lawfully do or cause to be
done by virtue hereof. </P>
</DIV></Center>


<p style="margin-top:1em; margin-bottom:0em; page-break-before:always">
<HR SIZE="3" style="COLOR:#999999" WIDTH="100%" ALIGN="CENTER">


<Center><DIV STYLE="width:8.5in" align="left">
 <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Pursuant to the requirements of the Securities Act, this Registration Statement has been signed by the
following persons in the capacities and on the dates indicated. </P> <P STYLE="font-size:12pt;margin-top:0pt;margin-bottom:0pt">&nbsp;</P>
<TABLE CELLSPACING="0" CELLPADDING="0" WIDTH="100%" BORDER="0" STYLE="BORDER-COLLAPSE:COLLAPSE; font-family:Times New Roman; font-size:10pt">


<TR>

<TD WIDTH="38%"></TD>

<TD VALIGN="bottom"></TD>
<TD WIDTH="44%"></TD>

<TD VALIGN="bottom" WIDTH="1%"></TD>
<TD WIDTH="16%"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:8pt">
<TD VALIGN="bottom" ALIGN="center"><B>Name</B></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>Title</B></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="bottom" ALIGN="center"><B>Date</B></TD></TR>


<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman" ALIGN="center">/s/ Aoife Brennan</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Aoife Brennan</B></P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">President, Chief Executive Officer, and Director<BR><I>(Principal Executive Officer)</I></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP>March&nbsp;29, 2023</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman" ALIGN="center">/s/ Michael Jensen</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Michael Jensen</B></P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; font-size:10pt; font-family:Times New Roman">Chief Financial Officer</P> <P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman"><I>(Principal Financial
Officer and Principal Accounting Officer)</I></P></TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP>March&nbsp;29, 2023</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman" ALIGN="center">/s/ Peter Barrett</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Peter Barrett</B></P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">Chairman of the Board</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP>March&nbsp;29, 2023</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman" ALIGN="center">/s/ Michael Burgess</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Michael Burgess</B></P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">Director</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP>March&nbsp;29, 2023</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman" ALIGN="center">/s/ Michael Heffernan</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Michael Heffernan</B></P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">Director</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP>March&nbsp;29, 2023</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman" ALIGN="center">/s/ Patricia Hurter</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Patricia Hurter</B></P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">Director</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP>March&nbsp;29, 2023</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman" ALIGN="center">/s/ Lisa Kelly-Croswell</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Lisa Kelly-Croswell</B></P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">Director</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP>March&nbsp;29, 2023</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman" ALIGN="center">/s/ Nick Leschly</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Nick Leschly</B></P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">Director</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP>March&nbsp;29, 2023</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman" ALIGN="center">/s/ Edward Mathers</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Edward Mathers</B></P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">Director</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP>March&nbsp;29, 2023</TD></TR>
<TR STYLE="font-size:1pt">
<TD HEIGHT="16"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD>
<TD HEIGHT="16" COLSPAN="2"></TD></TR>
<TR STYLE="page-break-inside:avoid ; font-family:Times New Roman; font-size:10pt">
<TD VALIGN="top"> <P STYLE="margin-top:0pt; margin-bottom:0pt; border-bottom:1px solid #000000; font-size:10pt; font-family:Times New Roman" ALIGN="center">/s/ Richard P. Shea</P>
<P STYLE="margin-top:0pt; margin-bottom:1pt; font-size:10pt; font-family:Times New Roman" ALIGN="center"><B>Richard P. Shea</B></P></TD>
<TD VALIGN="bottom">&nbsp;&nbsp;</TD>
<TD VALIGN="top">Director</TD>
<TD VALIGN="bottom">&nbsp;</TD>
<TD VALIGN="top" NOWRAP>March&nbsp;29, 2023</TD></TR>
</TABLE>
</DIV></Center>

</BODY></HTML>
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{"company-data": {"conformed-name": "SYNLOGIC, INC.", "cik": "0001527599", "assigned-sic": "2834", "irs-number": "261824804", "state-of-incorporation": "DE", "fiscal-year-end": "1231"}, "filing-values": {"form-type": "S-8", "act": "33", "file-number": "333-270925", "film-number": "23771875"}, "business-address": {"street1": "301 BINNEY STREET", "street2": "SUITE 402", "city": "CAMBRIDGE", "state": "MA", "zip": "02142", "phone": "617-401-9975"}, "mail-address": {"street1": "301 BINNEY STREET", "street2": "SUITE 402", "city": "CAMBRIDGE", "state": "MA", "zip": "02142"}, "former-company": {"former-conformed-name": "Mirna Therapeutics, Inc.", "date-changed": "20110809"}}
S-8
As filed with the Securities and Exchange Commission on March 29, 2023
Registration
No. 333-
UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM
S-8
REGISTRATION STATEMENT
UNDER
THE
SECURITIES ACT OF 1933
Synlogic, Inc.
(Exact
name of registrant as specified in its charter)
Delaware
26-1824804
(State or other jurisdiction of
incorporation or organization)
(I.R.S. Employer
Identification Number)
301 Binney Street, Suite 402
Cambridge, MA 02142
(617)
401-9975
(Address, including zip code, and telephone number, including area code, of registrant's principal executive offices)
2015 Equity Incentive Award Plan
(Full Title of the Plan)
Aoife Brennan
President
and Chief Executive Officer
Synlogic, Inc.
301 Binney Street, Suite 402
Cambridge, MA 02142
(617)
401-9975
(Name, address, including zip code, and telephone number, including area code, of agent for service)
Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a
non-accelerated
filer, a smaller reporting company or an emerging growth company. See the definitions of "large accelerated filer," "accelerated filer," "smaller reporting company," and "emerging growth company" in Rule
12b-2
of the Exchange Act.
Large accelerated filer
☐
Accelerated filer
☐
Non-accelerated filer
☒
Smaller reporting company
☒
Emerging growth company
☐
If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period
for complying with any new or revised financial accounting standards provided pursuant to Section 7(a)(2)(B) of the Securities Act.  ☐
EXPLANATORY NOTE
This Registration Statement on Form
S-8
is being filed for the purpose of registering an additional 3,336,812 shares
of the Registrant's common stock issuable under the Registrant's 2015 Equity Incentive Award Plan, for which a Registration Statement of the Registrant on Form
S-8
(File No.
333-220841
) is effective, as a result of the operation of an automatic annual increase provision therein, which
added 3,336,812 shares of Common Stock. This Registration Statement registers additional securities of the same class as other securities for which registration statements filed on Form
S-8
of the Registrant
relating to one or more employee benefit plans is effective (File Nos.
333-207299
,
333-210466
,
333-220841
,
333-223798
,
333-230224
,
333-237104
,
333-254688
and
333-263630
).
INCORPORATION BY REFERENCE OF CONTENTS OF
REGISTRATION STATEMENT ON FORM
S-8
Pursuant to Instruction E of Form
S-8,
the contents of the Registration Statement on
Form
S-8
filed with the Securities and Exchange Commission on October 5, 2017 (File No.
333-220841
) are incorporated by reference herein.
Exhibit Index
Exhibit
Number
Exhibit Description
Incorporated by Reference
Filed
Herewith
Form
Date
Number
4.1
Amended and Restated Certificate of Incorporation.
8-K
10/6/2015
3.1
4.2
Certificate of Amendment to Amended and Restated Certificate of Incorporation.
8-K
8/28/2017
3.1
4.3
Certificate of Amendment to Amended and Restated Certificate of Incorporation.
8-K
8/28/2017
3.2
4.4
Amended and Restated Bylaws.
8-K
10/6/2015
3.2
4.5
Form of Common Stock Certificate.
S-3
10/13/2017
4.5
5.1
Opinion of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C.
X
23.1
Consent of KPMG LLP, independent registered public accounting firm.
X
23.2
Consent of Mintz, Levin, Cohn, Ferris, Glovsky and Popeo, P.C. (included in Exhibit 5.1).
X
24.1
Power of Attorney. Reference is made to the signature page to the Registration Statement.
X
99.1(A)#
2015 Equity Incentive Award Plan.
10-K
3/20/2018
10.1
99.1(B)#
Form of Stock Option Grant Notice and Stock Option Agreement under the 2015 Equity Incentive Award Plan.
S-1/A
9/11/2015
10.9
(B)
99.1(C)#
Form of Restricted Stock Award Grant Notice and Agreement and Form of Restricted Stock Unit Award Grant Notice and Agreement under the 2015
Equity Incentive Award Plan.
S-1/A
9/11/2015
10.9
(C)
107
Calculation of Filing Fee Table
X
#
Indicates management contract or compensatory plan.
Signatures
Pursuant to the requirements of the Securities Act of 1933, as amended, the Registrant has duly caused this Registration Statement on Form
S-8
to be signed on its behalf by the undersigned, thereunto duly authorized, in Cambridge, Massachusetts on March 29, 2023.
SYNLOGIC, INC.
By:
/s/ Aoife Brennan
Aoife Brennan
President and Chief Executive Officer
Power of Attorney
KNOW ALL PERSONS BY THESE PRESENTS, that each person whose signature appears below hereby constitutes and appoints Aoife Brennan and Michael Jensen, and each
of them acting individually, as his or her true and lawful
attorneys-in-fact
and agents, each with full power of substitution, for him or her in any and all capacities,
to sign any and all amendments to this Registration Statement, including post-effective amendments or any abbreviated registration statement and any amendments thereto filed pursuant to Rule 462(b) increasing the number of securities for which
registration is sought, and to file the same, with all exhibits thereto and other documents in connection therewith, with the SEC, granting unto said
attorneys-in-fact
and agents, with full power of each to act alone, full power and authority to do and perform each and every act and thing requisite and necessary to be done in connection therewith, as fully for all intents and purposes as he or she might or could
do in person, hereby ratifying and confirming all that said
attorneys-in-fact
and agents, or his, her or their substitute or substitutes, may lawfully do or cause to be
done by virtue hereof.
Pursuant to the requirements of the Securities Act, this Registration Statement has been signed by the
following persons in the capacities and on the dates indicated.
Name
Title
Date
/s/ Aoife Brennan
Aoife Brennan
President, Chief Executive Officer, and Director
(Principal Executive Officer)
March 29, 2023
/s/ Michael Jensen
Michael Jensen
Chief Financial Officer
(Principal Financial
Officer and Principal Accounting Officer)
March 29, 2023
/s/ Peter Barrett
Peter Barrett
Chairman of the Board
March 29, 2023
/s/ Michael Burgess
Michael Burgess
Director
March 29, 2023
/s/ Michael Heffernan
Michael Heffernan
Director
March 29, 2023
/s/ Patricia Hurter
Patricia Hurter
Director
March 29, 2023
/s/ Lisa Kelly-Croswell
Lisa Kelly-Croswell
Director
March 29, 2023
/s/ Nick Leschly
Nick Leschly
Director
March 29, 2023
/s/ Edward Mathers
Edward Mathers
Director
March 29, 2023
/s/ Richard P. Shea
Richard P. Shea
Director
March 29, 2023