Materials and methods for controlling PHA biosynthesis in PHA-generating species of the genera Ralstonia or Cupriavidus and organisms related thereto

A method for producing a biomass in a continuous fermentation system;

• the method comprising:
• providing an organism belonging to a genus selected from the group consisting of Cupriavidus and Ralstonia;
• culturing a population of the organism to produce a biomass comprising polyhydroxyalkanoate, in the fermentation system;
• independently controlling a concentration of each of one or more selected limiting nutrients in at least one reactor of the fermentation system, wherein the selected limiting nutrients comprise nitrogen;
• phosphorous;
• or a combination thereof;
• and
• operating the fermentation system under continuous fermentation conditions comprising a limiting nitrogen concentration of 0.6 mM to 2.9 mM in at least one reactor of the fermentation system and/or a limiting phosphorous concentration of 0.12 mM to 1.7 mM in the at least one reactor;
• and
• maintaining a population biomass production rate of at least 0.5 g/L/h in the at least one reactor and measuring a concentration of polyhydroxyalkanoate, wherein the population biomass comprises a targeted concentration of between 5 wt % and 25 wt % polyhydroxyalkanoate, wherein a relative difference between the targeted concentration of polyhydroxyalkanoate in the population biomass and an average concentration of polyhydroxyalkanoate in the population biomass as measured during a 1 hour period during operation of the fermentation system is less than 20%.