US 12,338,428 B2
Materials and methods for managing aerobic gas fermentation
Gary J. Smith, North Yorkshire (GB); Paul S. Pearlman, Thornton, PA (US); and Gregory S. Kirby, Avondale, PA (US)
Assigned to INV NYLON CHEMICALS AMERICAS, LLC
Filed by INV NYLON CHEMICALS AMERICAS, LLC, Wilmington, DE (US)
Filed on Apr. 1, 2019, as Appl. No. 16/372,092.
Claims priority of provisional application 62/650,575, filed on Mar. 30, 2018.
Prior Publication US 2019/0300838 A1, Oct. 3, 2019
Int. Cl. C12N 1/20 (2006.01); C12M 1/00 (2006.01); C12M 1/04 (2006.01); C12M 1/107 (2006.01); C12M 1/34 (2006.01); C12M 1/36 (2006.01); C12P 1/00 (2006.01); C12P 5/00 (2006.01)
CPC C12M 41/34 (2013.01) [C12M 1/04 (2013.01); C12M 21/04 (2013.01); C12M 23/58 (2013.01); C12M 29/24 (2013.01); C12M 41/48 (2013.01); C12P 1/00 (2013.01); C12P 5/00 (2013.01)] 10 Claims
 
1. A method for controlling dissolved oxygen concentration in a continuous aerobic gas fermentation process, the method comprising:
a. providing a microorganism to a fermenter connected in series to a second fermenter;
b. introducing at least three feed streams to the fermenter of a., wherein at least two separate feed streams comprises gaseous oxygen and wherein at least one feed stream comprises a flammable gas and optionally oxygen at an oxygen concentration below the limiting oxygen concentration (LOC);
c. continuously measuring the dissolved oxygen concentration in at least one location in the fermenter of b to determine wherein the dissolved oxygen concentration must be increased or decreased;
d. measuring the gaseous oxygen concentration in a headspace in the fermenter of b.; and
e. controlling the dissolved oxygen concentration in the fermenter to be greater than a minimum dissolved oxygen concentration required for the microorganism to function and less than the dissolved oxygen concentration above which the gaseous oxygen concentration in the headspace exceeds the limiting oxygen concentration (LOC), wherein the microorganism is considered to function if the microorganism has a specific oxygen uptake rate of at least 1 mmol oxygen/(g dry cell weight)/hour, wherein controlling the dissolved oxygen concentration comprises regulating a gas bubble size within the fermenter to be equal to or less than 200 microns,
f. measuring gaseous oxygen concentration in a headspace of the fermenter following e; and
g. controlling the gaseous oxygen concentration in the headspace to be less than 75% of the limiting oxygen concentration (LOC) of the gaseous mixture in the headspace of the fermenter, wherein
the fermenter is operated such that fermentation occurs at a pressure in a range of from 3.5 bar to 7.3 bar;
a maximum oxygen uptake rate occurs at a dissolved oxygen concentration less than or equal to about 2% saturation,
at least two control loops are used, wherein at least one control loop measures and controls dissolved oxygen content in the fermentation liquid and wherein at least one control loop measures and controls gaseous oxygen concentration in the headspace of the fermenter,
the fermenter is a gas-lift external fermenter that is neither a stirred fermenter nor a mechanically agitated fermenter, and comprises an external loop for circulating the fermentation liquid and said microorganism is Cupriavidus necator (C. necator) or Cupriavidus metalliduruns(C. metalliduruns).