Biobutanol Production Using Non-grain Biomass Sorghum saccharatum as a Substrate

The global energy challenge has recently prompted biotechnological research to explore new non-food substrates of plant origin for obtaining liquid biofuels. One of the important areas of research is the process of pretreatment and further use of non-grain biomass (lignocellulose) as a substrate for bioconversion to higher alcohols.

The aim of this work was to determine the macrocomponent composition and biochemical characteristics of sweet sorghum [Sorghum saccharatum (L.) Moench], select an effective bacterial culture for fermentation of the non-grain part of sorghum biomass as a substrate for obtaining biobutanol, and elaborate the best protective medium and storage temperature for lyophilization of the producer.

This work was conducted using butanol producing strains Clostridium sp. UCM B-7570, Clostridium acetobutylicum UCM B-7407, and C. tyrobutylicum IFBG C4B from the “Collection of Microorganism Strains and Plant Lines for Agricultural and Industrial Biotechnology” of the Institute of Food Biotechnology and Genomics of the National Academy of Sciences of Ukraine. The bacterial cultures were cultivated on the sweet sorghum biomass provided by the National Botanical Garden named after M. M. Gryshko of the National Academy of Sciences of Ukraine. A gas chromatograph was used to determine the presence of ethanol, acetone, and butanol in the cultural liquid.

It has been established that the proposed improvement of the biobutanol production process made it possible to obtain 8 g/dm³ of the target product from 60 g of dry green biomass of sweet sorghum of the Energodar variety. The composition of the protective medium for drying the Clostridium sp. UCM B-7570 culture and its storage period in the lyophilic form have been optimized.

The obtained results demonstrate the possibility of using the biomass of different varieties of sweet sorghum as a substrate for obtaining biobutanol, and the optimized storage conditions of the Clostridium sp. UCM B-7570 culture can minimize the possibility of its degradation.