engleski

Paenibacillus polymyxa DSM 742 – the future of sustainable production of 2,3-butanediol

Paenivacillus polymyxa is a gram-positive GRAS bacterium which produces wide range of useful biochemicals such as ethanol, lactate, 2, 3-butanediol, phytohormones, polysaccharides, antibiotics and enzymes. The most interesting product of P. polymyxa metabolism is 2, 3-butanediol due to its wide application in cosmetic industry, in food industry as aroma compound or in pharmaceutical industry as an antiseptic. The focus of this research was the cultivation of P. polymyxa DSM 742 strain and process optimization for enhanced production of 2, 3-butanediol. Carbon source for our cultivations were sugars stemming from pre-treated lignocellulosic biomass like glucose and xylose. The highest 2, 3-butanediol concentration of 18, 61gL-1 was achieved during cultivation in medium with 70 g L-1 of glucose during 40 h of fermentation. However, during bacterium cultivation in only xylose containing medium 2, 3-butanediol production was considerably diminished. In order to make our 2, 3-butanediol production economically and ecologically sustainable, the pre-treated brewers' spent grains (BSG) with diluted sulphuric acid were used as a substrate. Non-detoxified and detoxified liquid part of pre-treated BSG was used for bacterial cultivation as well as the enzymatically hydrolysed solid part of pre-treated BSG. Liquid part of pre-treated BSG was detoxified with activated carbon to remove inhibitory compounds. Our results showed very low concentrations of 2, 3-butanediol and ethanol after cultivation on non-detoxified liquid part of pre-treated BSG. During bacterial cultivation on detoxified liquid part of pre-treated BSG relatively high lactate concentration was observed (30 g L-1), while 2, 3-butanediol concentration was negligible. Cultivation on the enzymatically hydrolysed solid part of pre-treated BSG gave 9, 8 g L-1 of 2, 3-butanediol and 3, 93 g L-1 of ethanol. On the basis of obtained results it can be concluded that different experimental set-ups give the possibility of directing the metabolism of P. polymyxa DSM 742 towards the production of either 2, 3-butanediol and ethanol or lactate.

Paenibacillus polymyxa ; 2, 3-butanediol ; sustainable production ; pre-treated brewers' spent grain

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