Bioethanol Production from Miscanthus sinensis Cellulose by Bioconversion

Introduction. Cellulose-containing parts of herbs are an excellent source of alternative energy and can be used to produce biological ethanol. The present research aims at improving this fundamental and promising area of biotechnology. It introduces a new consortium of microorganisms that can saccharify while fermenting the substrate. Study objects and methods. The research featured technical cellulose obtained from Miscanthus sinensis using hydrotropic delignification and oxidation with pertrifluoroacetic acid. The ethanol content in the culture liquid was determined using an Agilent 7890B gas chromatograph with a flame ionization detector. The biocompatibility of the strains was studied by growing a direct co-culture in a dense nutrient medium. Results and discussion. The research objective was to create a new microbial consortium for the single-step production of bioethanol from Miscanthus sinensis cellulose. A set of biocompatibility experiments and cultivation conditions made it possible to select the optimal producers. The two developed microbial consortia required optimal compositions of culture media, which were determined by varying the ratio of components and measuring the yield of ethanol in the resulting culture liquid. Conclusion. The best consortium for Miscanthus sinensis cellulose consisted of Pichia stipites Y7124, Candida shehatae NCL3501, Kluyveromyces marxianus Y-4290, and Zymomonas mobilis 113 at a ratio of 1:1:1:1. The optimal parameters of bioethanol production included: temperature = 35 ± 1°C, pH = 5.2, time = 16 ± 1 h. The most efficient culture medium had the following composition (g/l): glucose – 5.0; peptone – 5.0; yeast extract – 0.4; K2HPO4 – 1.5; (NH)2 HPO4 – 1.5; MgSO4 – 0.5.