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Yields of Polyhydroxyalkanoates (PHAs) during Batch Fermentation of Sugar Cane Juice by Alcaligenes latus and Alcaligenes eutrophus



Author(s)

Waranya Suwannasing, Samart Moonamart and Pakawadee Kaewkannetra

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DOI:10.17265/1934-7391/2011.11.012

In this work, sugar cane juice was fermented to produce polyhydroxyalkanoates (PHAs) by Alcaligenes latus TISTR 1403 and A. eutrophus TISTR 1095. The juice was characterized and composed of total sugars 105.5 g·L^-1 (sucrose 36.6 g·L^-1, fructose 26.0 g·L^-1, glucose 21.8 g·L^-1 and other sugars 21.1 g·L^-1). Each inoculums (10%, v/v) was separately cultivated in the medium containing 20 g·L^-1 total sugars under condition (30ºC, 200 rpm, pH 6.5-7). It was found that the A. eutrophus can be grown better than the A. latus. Only the A. eutrophus was further cultured under different total sugar concentrations (20, 30, 40 and 50 g·L^-1). The optimal contents of total sugar, dry cell mass (DCM) and maximum PHAs were obtained at 50 g·L^-1, 6.013 g·L^-1 and 1.84 g·L^-1, respectively after 60 h fermentation which were converted to biomass yield (Y_x/s), product yield (Y_p/s), specific product yield (Y_p/x) and productivity of 0.163, 0.05, 0.306 and 0.031 g·L^-1h^-1. Large scale of PHAs production was conducted in 5 L fermentor using the optimal condition obtained under 30% dissolved oxygen. The DCM and the maximum PHAs were 5.881 g·L^-1and 1.281 g·L^-1 which were calculated to values of Y_x/s, Y_p/s, Y_p/x and productivity at 0.19, 0.04, 0.218 and 0.021 g·L^-1h^-1, respectively.

Alcaligenes latus, Alcaligenes eutrophus, fermentation, PHAs, sugar cane juice.