Patent ID: 8030021

Claim:
A method for producing PHA polymers, the method comprising: performing in a bioreactor aerobic microbial biosynthesis of PHA polymers from a feedstock using mixed bacterial cultures in non-sterile conditions, wherein the feedstock comprises anaerobic degradation products; extracting the biosynthesized PHA polymers to obtain PHA granules; and repeatedly cycling the bioreactor through a first period and a second period; wherein the first period comprises maintaining in the bioreactor excess feedstock and limited nutrients; wherein the second period comprises maintaining in the bioreactor nutrients but limited feedstock and one of the following methods: (a) wherein the anaerobic degradation products comprise methane; or (b) wherein repeatedly cycling the bioreactor through the first period and the second period selects for organisms that stored PHAs in the first period while selecting against organisms that did not store PHA in the first period; or (c) wherein the anaerobic degradation products comprise methane and wherein repeatedly cycling the bioreactor through the first period and the second period selects for organisms that stored PHAs in the first period while selecting against organisms that did not store PHA in the first period.