exhibit 10. 6 intrexon 20374 seneca meadows pkwy germantown, md 20376 ( + 1 ) 301 # # # - # # # - # # # # dna. com intrexon 20374 seneca meadows pkwy germantown, md 20376 ( + 1 ) 301 # # # - # # # - # # # # dna. com intrexon intrexon 20374 seneca meadows pkwy germantown, md 20376 ( + 1 ) 301 # # # - # # # - # # # # dna. com 20374 seneca meadows pkwy germantown, md 20376 ( + 1 ) 301 # # # - # # # - # # # # dna. com better dna december 23, 2019 oragenics, inc. 4902 eisenhower blvd., suite 125 tampa, fl 33634 attention : chief executive officer re : letter providing notice of assignment ( “ notice ” ) regarding the stock issuance agreement and the exclusive channel collaboration agreement ( as amended ), each dated 6 / 5 / 2012 ( collectively, the “ agreement ( s ) ” ) by and between oragenics, inc. and intrexon corporation ( “ intrexon ” ) re : letter providing notice of assignment ( “ notice ” ) regarding the stock issuance agreement and the exclusive channel collaboration agreement ( as amended ), each dated 6 / 5 / 2012 ( collectively, the “ agreement ( s ) ” ) by and between oragenics, inc. and intrexon corporation ( “ intrexon ” ) re : letter providing notice of assignment ( “ notice ” ) regarding the stock issuance agreement and the exclusive channel collaboration agreement ( as amended ), each dated 6 / 5 / 2012 ( collectively, the “ agreement ( s ) ” ) by and between oragenics, inc. and intrexon corporation ( “ intrexon ” ) dear sir or madam : intrexon has recently executed an agreement to sell several of its business units, including its api fermentation business, in a transaction expected to close in early 2020 ( the “ transaction ” ). for details regarding the transaction, see the press release located on intrexon ’ s website at https : / / investors. dna. com / press. in preparation for the transaction closing, intrexon has reorganized the entirety of its ongoing api fermentation operations and assets into il