Journal Article

Metabolic and microbial community dynamics during the anaerobic digestion of maize silage in a two-phase process

Lucas, Rico, Sträuber, Heike, Kleinsteuber, Sabine

2016

Overview

Two-phasic anaerobic digestion processes (hydrolysis/acidogenesis separated from acetogenesis/methanogenesis) can be used for biogas production on demand or a combined chemicals/bioenergy production. For an effective process control, detailed knowledge about the microbial catalysts and their correlation to process conditions is crucial. In this study, maize silage was digested in a two-phase process and interrelationships between process parameters and microbial communities were revealed. In the first-phase reactor, alternating metabolic periods were observed which emerged independently from the feeding frequency. During the L-period, up to 11.8 g L⁻¹ lactic acid was produced which significantly correlated to lactic acid bacteria of the genus Lactobacillus as the most abundant community members. During the alternating G-period, the production of volatile fatty acids (up to 5.3, 4.0 and 3.1 g L⁻¹ for propionic, n-butyric and n-caproic acid, respectively) dominated accompanied by a high gas production containing up to 28 % hydrogen. The relative abundance of various Clostridiales increased during this metabolic period. In the second-phase reactor, the metabolic fluctuations of the first phase were smoothed out resulting in a stable biogas production as well as stable bacterial and methanogenic communities. However, the biogas composition followed the metabolic dynamics of the first phase: the hydrogen content increased during the L-period whereas highest CH₄/CO₂ ratios (up to 2.8) were reached during the G-period. Aceticlastic Methanosaeta as well as hydrogenotrophic Methanoculleus and Methanobacteriaceae were identified as dominant methanogens. Consequently, a directed control of the first-phase stabilizing desired metabolic states can lead to an enhanced productivity regarding chemicals and bioenergy.

• Publisher: Springer Berlin Heidelberg,Springer,Springer Nature B.V
• Subject: Agricultural biotechnology / Alternative energy sources / Anaerobic digestion / Anaerobiosis / Archaea - growth & development / Archaea - metabolism / Bacteria / Bacteria - growth & development / Bacteria - metabolism / Bioenergy and Biofuels / Biofuels / Biogas / Biomass / Biomass energy / Biomedical and Life Sciences / Biota / Biotechnology / Carbon dioxide / catalysts / Chemical properties / Chemical reactions / Clostridiales / Corn / Corn silage / Fatty acids / feeding frequency / Fermentation / hexanoic acid / hydrogen / hydrolysis / Identification and classification / Laboratories / lactic acid / Lactic Acid - metabolism / lactic acid bacteria / Lactobacillus / Life Sciences / Metabolism / Methane / Methane - metabolism / methane production / Methanobacteriaceae / Methanoculleus / Methanogenesis / methanogens / Methanosaeta / Microbial activity / Microbial colonies / microbial communities / Microbial Genetics and Genomics / Microbiology / Observations / Oil and gas production / Process control / Process controls / Properties / Reactors / Relative abundance / Retention / Silage / Studies / volatile fatty acids / Volatile Organic Compounds - metabolism / Zea mays / Zea mays - metabolism