Abstract 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.
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