Statement of Changes in Beneficial Ownership (4)

FORM 4 [ ] Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).
UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP OF SECURITIES
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Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940

1. Name and Address of Reporting Person ^* EMALFARB MARK A	2. Issuer Name and Ticker or Trading Symbol DYADIC INTERNATIONAL INC [ DYAI ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director __X__ 10% Owner __X__ Officer (give title below) _____ Other (specify below) President and CEO
(Last) (First) (Middle) C/O DYADIC INTERNATIONAL, INC., 140 INTRACOASTAL POINTE DRIVE SUITE 404	3. Date of Earliest Transaction (MM/DD/YYYY) 6/7/2021
(Street) JUPITER, FL 33477-5094 (City) (State) (Zip)	4. If Amendment, Date Original Filed (MM/DD/YYYY)	6. Individual or Joint/Group Filing (Check Applicable Line) _X _ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	3. Trans. Code (Instr. 8)		4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
1.Title of Security (Instr. 3)	2. Trans. Date	2A. Deemed Execution Date, if any	Code	V	Amount	(A) or (D)	Price		6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
Common Stock	6/7/2021		S		44000 ⁽¹⁾	D	$3.95 ⁽²⁾	4287917	I	Through Mark A. Emalfarb Trust U/A DTD 10/1/1987
Common Stock	6/8/2021		S		30000 ⁽¹⁾	D	$3.82 ⁽²⁾	4257917	I	Through Mark A Emalfarb Trust U/A/DTD 10/1/1987
Common Stock	6/9/2021		S		23000 ⁽¹⁾	D	$3.72 ⁽²⁾	4234917	I	Through Mark A. Emalfarb Trust U/A/ DTD 10/1/1987
Common Stock	6/9/2021		M		100000	A	$1.67	4334917	I	Through Mark A. Emalfarb Trust U/A DTD 10/1/1987

*Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)*
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	4. Trans. Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
1. Title of Derivate Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Trans. Date	3A. Deemed Execution Date, if any	Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares	8. Price of Derivative Security (Instr. 5)			11. Nature of Indirect Beneficial Ownership (Instr. 4)
Stock Option	$1.67	6/9/2021		M			100000 ⁽³⁾	6/21/2016	6/21/2021	Common Stock	100000	$0	0	D

Explanation of Responses:
(1)	These shares were sold to satisfy exercise price and tax withholding obligations to be funded for options expiring on June 21, 2021. As a result of the option exercises and sale transactions reported on this Form 4 together with the Form 4 filed on June 4, 2021, the reporting person's net share ownership increased by an aggregate of 167,930 shares, from 4,166,987 to 4,334,917 shares of Common Stock.
(2)	The price reported in Column 4 is a weighted average price. These sold in multiple transactions at prices ranging from $4.01 to $3.92, inclusive, on June 7, 2021, $3.96 to $3.80, inclusive, on June 8, 2021, and $3.85 to $3.68, inclusive, on June 9, 2021. The reporting person undertakes to provide to Dyadic International, Inc., any security holder of Dyadic International, Inc., or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of footnote (2) to this Form 4.
(3)	Exercise of reporting person's stock options that would otherwise expire June 21, 2021.

Reporting Owners
Reporting Owner Name / Address	Relationships
Reporting Owner Name / Address	Director	10% Owner	Officer	Other
EMALFARB MARK A C/O DYADIC INTERNATIONAL, INC. 140 INTRACOASTAL POINTE DRIVE SUITE 404 JUPITER, FL 33477-5094	X	X	President and CEO