Exhibit 24

                                 POWER OF ATTORNEY

    The undersigned, as a Section 16 reporting person of Pfenex Inc. (the
"Company"), hereby constitutes and appoints Evert Schimmelpennink, Marilyn Bock,
Shawn Scranton, Daniel Koeppen, Zachary Myers and Bridget Balisy the
undersigned's true and lawful attorneys-in-fact to:

    1.  complete and execute Forms 3, 4 and 5 and other forms and all amendments
        thereto as such attorneys-in-fact shall in their discretion determine to
        be required or advisable pursuant to Section 16 of the Securities
        Exchange Act of 1934 (as amended) and the rules and regulations
        promulgated thereunder, or any successor laws and regulations, as a
        consequence of the undersigned's ownership, acquisition or disposition
        of securities of the Company; and

    2.  do all acts necessary in order to file such forms with the Securities
        and Exchange Commission, any securities exchange or national
        association, the Company and such other person or agency as the
        attorneys-in-fact shall deem appropriate.

    The undersigned, as a Section 16 reporting person of the Company, hereby
revokes any and all prior powers of attorney previously signed by the
undersigned.

    The undersigned hereby ratifies and confirms all that said attorneys-in-fact
and agent shall do or cause to be done by virtue hereof.  The undersigned
acknowledges that the foregoing attorneys-in-fact, in serving in such capacity
at the request of the undersigned, is not assuming, nor is the Company assuming,
any of the undersigned's responsibilities to comply with Section 16 of the
Securities Exchange Act of 1934 (as amended).

    This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4 and 5 with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier revoked by the undersigned in a signed writing delivered to the
Company and the foregoing attorneys-in-fact.

    IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of this 16th day of April, 2020.



                                      Signature:  /s/ Magda Marquet, Ph.D.
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                                      Print Name:  Magda Marquet, Ph.D.
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