Rumen bacteria at work: bioaugmentation strategies to enhance biogas production from cow manure

Aims: To investigate the effects of different bioaugmentation strategies for enhancing the biogas production from cow manure and evaluate microbial community patterns. Methods and Results: Co-inoculation with cow rumen fluid and cow rumen-derived enriched microbial consortia was evaluated in anaerobic batch tests at 36°C and 41°C. Singular addition of both rumen fluid and enriched bioaugmentation culture had a promising enhancement on methane yields; however, the highest methane yield (311 ml CH₄ per gram VS at 41°C) was achieved when the anaerobic seed sludge was co-inoculated together with rumen fluid and enriched bioaugmentation culture. Bacterial community profiles were investigated by Ion PGM Platform, and specific lignocellulolytic bacteria dynamics in batch tests were assessed by qPCR. The temperature had minor effects on the abundance of bacterial community; in which Bacteroidetes and Firmicutes were the most abundant phyla in all digesters. Furthermore, Rikenellaceae, Clostridiaceae, Porphyromonadaceae, Bacteroidaceae and Ruminococcaceae played a crucial role during the anaerobic degradation of cow manure. There was an important impact of Firmicutes flavefaciens and Ruminococcus albus at 41°C, which in turn positively affected the methane production. Conclusion: The degree of enhancement in biogas production can be upgraded by the co-inoculation of rumen-derived bioaugmentation culture with anaerobic seed sludge with high methanogenic activity. Significance and Impact of the Study: A close look at the biotic interactions and their associations with abiotic factors might be valuable for evaluating rumen-related bioaugmentation applications.