Exhibit 31.3
CERTIFICATION OF PRINCIPAL EXECUTIVE OFFICER
PURSUANT TO RULE 13a-14 AND 15d-14
UNDER THE SECURITIES EXCHANGE ACT OF 1934, AS AMENDED
I, Mark A. Emalfarb, certify that:
| 1. | I have reviewed this Amendment No. 1 to the Annual Report on Form 10-K/A of Dyadic International Inc.; and | |
| 2. | Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report. |
Date: April 30, 2026
| /s/ Mark A. Emalfarb | |
Mark A. Emalfarb | |
| Chief Executive Officer | |
| (Principal Executive Officer) |