Anaerobic microbial community enriched with amino acids

Amino acids are important monomers that are ubiquitously present in anaerobic environments after protein hydrolysis. Anaerobic digester sludge from two sources was used to inoculate batch cultures, which were fed with twenty individual amino acids. Five successive enrichments were performed with 10% v/v transfer. 16S rRNA and rRNA gene were extracted and amplified from enrichment cultures. Amplicons were sequenced using Illumina Miseq platform. Distinct community structures were observed between the first enrichment and later enrichments. Such trajectory of community evolution indicated enrichment of specific amino acids degraders that were not abundant in the early enrichments. Based on known knowledge of fermenters, syntrophs, and methanogens, four types of communities were observed.