Methanogenesis mediated by methylotrophic mixed culture

TLDR: Enrichment of methanogenic cultures on methanol from the microbial population in the anaerobic digesters operated on agricultural wastes revealed a high rate of biomethanation efficiency and signify metabolic partnerships in the methylotrophic biochemical mechanisms operative toward energy recovery.

Abstract: Enrichment of methanogenic cultures on methanol from the microbial population in the anaerobic digesters operated on agricultural wastes revealed a high rate of biomethanation efficiency. Routine maintenance of this enrichment in a minimal basal medium at room temperature resulted in maximal growth in 40–50 d, and indicated pigment production toward the end of the growth phase. The cultures grown in three different media, with different substrates under light and dark conditions, were analyzed for protein, pigment, and gaseous products, and morphological studies were carried out by light, phase-contrast, fluorescence, and electron microscopy. In different media with methanol as substrate, growth and pigment production were maximal for the light-grown cells, decreasing in the order: phototrophic (PS(m)) > mineral > basal medium. Methanation and phototrophic growth were inversely correlated under lightgrown conditions. In contrast, growth in the dark was predominently methanogenic in the decreasing order: mineral > basal > PS (m). Among other growth conditions tested, utilization of phototrophic substrates under light and dark conditions indicated the following: 1. Basal and mineral media were supportive of methanogenic growth under both light and dark conditions, although methane yields under light-grown conditions were low; 2. Among the different substrates tested, methanol-grown cells gave the highest methane yield in the dark and; 3. Phototrophic growth in PS medium with succinate, malate, and pyruvate was better than that with methanol.