Biopolymer generation from sweet sorghum juice: screening, isolation, identification, and fermentative polyhydroxyalkanoate production by Bacillus aryabhattai

Authors: VARAVUT TANAMOOL, TSUYOSHI IMAI, PAIBOON DANVIRUTAI, PAKAWADEE KAEWKANNETRA

Abstract: This study aims to use sweet sorghum juice (SSJ) to produce an environmentally friendly biopolymer of polyhydroxyalkanoates (PHAs) by bacteria isolated from soil. Among 18 isolates, only 3 isolates, coded as S4, S6, and S11, were chosen to produce PHA via batch fermentation compared to 3 strains of Alcaligenes eutrophus, A. latus, and Hydrogenophaga sp., respectively, under controlled conditions at pH 7, 35 °C, and 20 g/L of initial total sugar in the SSJ. The results clearly showed that the isolate S4 can produce maximum PHAs of 1.74 g/L with 57.62% dry cell weight and yield maximum hourly productivity at 0.097 g/L. S4 was further identified by full-length 16S rDNA gene sequence homology, and the findings showed that it was closely related to Bacillus aryabhattai (99.70% similarity). Interestingly, there has been as of yet no report on the use of this strain to produce an added-value biopolymer of PHA.

Keywords: Biopolymer, polyhydroxyalkanoates, sweet sorghum juice, fermentation, Bacillus aryabhattai

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