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Biosynthesis of poly(3-hydroxybutyrate) (PHB) by Cupriavidus necator from various pretreated molasses as carbon source

Sen, Khok Yong, Hussin, M. Hazwan, Baidurah, Siti
Biocatalysis and agricultural biotechnology 2019 v.17 pp. 51-59
Cupriavidus necator, bacteria, biomass, biosynthesis, carbon, economic sustainability, feedstocks, fermentation, fructose, glucose, industrial applications, molasses, oils, ovens, polyhydroxybutyrate, sucrose, sugar content
The high production cost of polyhydroxybutyrate (PHB) particularly substrate cost limits its industrial applications. Reduced substrate cost by utilizing cheaper carbon source enables to improve its economic viability. Cane final molasses are considered potential feedstock due to its abundance, low cost, and high sugar content. However, sucrose in molasses required to convert to its monomers: fructose and glucose by pretreatments for the bacteria consumption during the fermentation process. In this study, the main components of molasses and sugar content in various pretreated molasses were analyzed. The PHB content and cell dry weight of C. necator biomass fermented utilizing glucose, untreated molasses and pretreated molasses as carbon sources are compared. The molasses consist of 34.49 ± 0.13% sucrose, 5.93 ± 0.07% glucose and 5.00 ± 0.04% fructose respectively. The hydrothermal acid pretreated molasses (oil bath) contains the highest fructose and glucose content which are 21.31 ± 0.04% and 20.32 ± 0.06% respectively. Although the hydrothermal acid pretreated molasses (oil bath) contains the highest fructose and glucose content, the cell dry weight and PHB produced by C. necator using hydrothermal acid pretreated molasses (oven) is the highest which are 2.86 ± 0.82 g and 27% respectively.