Utilization of Textile Wastewater as A Substrate for Polyhydroxyalkanoate (PHA) and Enhanced Production by Mutant Enterobacter

In our previous study, we found that Enterobacter strain TS3 is able to decolorize of textile wastewater (TW) through a fermentative polyhydroxyalkanoate (PHA) production process. This current study aimed to enhance the ability of strain TS3 to produce PHA using TW by a UV-light radiation-based mutagenesis system, and to enhanced PHA by multiple-round UV-light radiation. The highest PHA-production mutant was obtained in the second rounds of UV-light radiation. The radiation time was optimized to 40 s in the first round followed by 20 s at a distance of 60 cm of plates. The mutant strain TS3-UV2 yielded PHA production at 84.96 ± 1.32% cell dry mass (CDM). The highest PHA concentration (88.66 ± 1.00% CDM) is achieved at pH 7, 150 rpm and 35 °C for 60 h of incubation. Under optimal condition, the mutant yielded 0.53 times more production of PHA than the parent strain. Moreover, the decolorization efficiency of TW was observed to be 72.32% under optimal PHA conditions. Interestingly, the mutant strain could synthesize the medium- co -long-chain-length PHA (mcl- co -lcl PHA), while short- co -medium-chain-length PHA (scl- co -mcl PHA) was observed in the wild type using TW as substrate. Therefore, the mutation and optimization strategy appear to be suitable for producing high-density PHA.