Enhanced Biogas Production from Glucose and Glycerol by Artificial Consortia of Anaerobic Sludge with Immobilized Yeast

Today, there is considerable interest in creating artificial microbial consortia to solve various biotechnological problems. The use of such consortia allows for the improvement of process indicators, namely, increasing the rate of accumulation of target products and enhancing the conversion efficiency of the original substrates. In this work, the prospects for creating artificial consortia based on anaerobic sludge (AS) with cells of different yeasts were confirmed to increase the efficiency of methanogenesis in glucose- and glycerol-containing media and obtain biogas with an increased methane content. Yeasts of the genera Saccharomyces, Candida, Kluyveromyces, and Pachysolen were used to create the artificial consortia. Their concentration in the biomass of consortium cells was 1.5%. Yeast cells were used in an immobilized form, which was obtained by incorporating cells into a cryogel of polyvinyl alcohol. The possibility of increasing the efficiency of methanogenesis by 1.5 times in relation to the control (AS without the addition of yeast cells) was demonstrated. Using a consortium composed of methanogenic sludge and yeast cells of the genus Pachysolen, known for their ability to convert glycerol into ethanol under aerobic conditions, the possibility of highly efficient anaerobic conversion of glycerol into biogas was shown for the first time. Analysis of the metabolic activity of the consortia not only for the main components of the gas phase (CH4, CO2, and H2) and metabolites in the cell culture medium, but also for the concentration of intracellular adenosine triphosphate (ATP), controlled by the method of bioluminescent ATP-metry, showed a high level of functionality and thus, prospects for using such consortia in methanogenesis processes. The advantages and the prospect of using the developed consortia instead of individual AS for the treatment of methanogenic wastewater were confirmed during static tests conducted with several samples of real and model waste.