Ownership Submission
FORM 3
 UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940
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(Print or Type Responses)
1. Name and Address of Reporting Person *
  KIRK RANDAL J
 2. Date of Event Requiring Statement (Month/Day/Year)
10/16/2012		 3. Issuer Name and Ticker or Trading Symbol
Synthetic Biologics, Inc. [SYN]
(Last)
(First)
(Middle)
C/O THIRD SECURITY, LLC, 1881 GROVE AVENUE		 4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
_____ Director __X__ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
5. If Amendment, Date Original Filed(Month/Day/Year)
(Street)

RADFORD, VA 24141		 6. Individual or Joint/Group Filing(Check Applicable Line)
___ Form filed by One Reporting Person
_X_ Form filed by More than One Reporting Person
(City)
(State)
(Zip)
Table I - Non-Derivative Securities Beneficially Owned
1.Title of Security
(Instr. 4)		 2. Amount of Securities Beneficially Owned
(Instr. 4)		 3. Ownership Form: Direct (D) or Indirect (I)
(Instr. 5)		 4. Nature of Indirect Beneficial Ownership
(Instr. 5)
Common Stock 6,675,768 (1)
I
by Intrexon (2)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly. SEC 1473 (7-02)
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Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security
(Instr. 4)		 2. Date Exercisable and Expiration Date
(Month/Day/Year)		 3. Title and Amount of Securities Underlying Derivative Security
(Instr. 4)		 4. Conversion or Exercise Price of Derivative Security 5. Ownership Form of Derivative Security: Direct (D) or Indirect (I)
(Instr. 5)		 6. Nature of Indirect Beneficial Ownership
(Instr. 5)
Date Exercisable Expiration Date Title Amount or Number of Shares

Reporting Owners

Reporting Owner Name / Address Relationships
Director 10% Owner Officer Other
KIRK RANDAL J
C/O THIRD SECURITY, LLC
1881 GROVE AVENUE
RADFORD, VA 24141		     X    
INTREXON CORP
C/O LEGAL DEPARTMENT
20358 SENECA MEADOWS PARKWAY
GERMANTOWN, MD 20876		     X    

Signatures

/s/ Randal J. Kirk 10/19/2012
**Signature of Reporting Person Date
/s/ Randal J. Kirk, CEO Intrexon Corporation 10/19/2012
**Signature of Reporting Person Date

Explanation of Responses:

* If the form is filed by more than one reporting person, see Instruction 5(b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1) Pursuant to an Exclusive Channel Collaboration Agreement entered into between Intrexon Corporation ("Intrexon") and Synthetic Biologics, Inc. ("Synthetic Biologics") on November 18, 2011 ("Channel Agreement #1"), Synthetic Biologics agreed to issue to Intrexon 3,123,558 shares of common stock of the issuer as partial consideration for the execution and delivery of Channel Agreement #1. The closing date of Channel Agreement #1 was December 7, 2011. In connection with a subsequent Exclusive Channel Collaboration Agreement between Intrexon and Synthetic Biologics on August 6, 2012 ("Channel Agreement #2"), Synthetic Biologics agreed to issue to Intrexon 3,552,210 shares of common stock of the issuer as partial consideration for the execution and delivery of Channel Agreement #2. The closing date of Channel Agreement #2 was October 16, 2012.
(2) Randal J. Kirk, directly and through certain affiliates, has voting and dispositive power over a majority of the outstanding capital stock of Intrexon. Mr. Kirk may therefore be deemed to have voting and dispositive power over the shares of the issuer owned by Intrexon. Shares held by Intrexon may be deemed to be indirectly beneficially owned (as defined under Rule 13d-3 promulgated under the Securities Exchange Act of 1934, as amended) by Mr. Kirk. Mr. Kirk disclaims beneficial ownership of such shares, except to the extent of any pecuniary interest therein.

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