Microbial response to single-cell protein production and brewery wastewater treatment.
Bottom Line: A pyrosequencing survey of the brewery treatment plant showed that each unit process selected for a unique microbial community.Notably, flow equalization basins were dominated by Prevotella, methanogenesis effluent had the highest levels of diversity, and clarifier wet-well samples were sources of sequences for the candidate bacterial phyla of TM7 and BD1-5.These diazotrophs are potentially useful as the basis of a SCP product for commercial feed production.
Affiliation: Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, USA.Show MeSH
Mentions: To address the question of which OTUs might be biotechnologically relevant, the variations of OTU abundances in the pilot reactor and SCP product samples over time were used to generate Bray–Curtis distances (a generalized distance metric) between repeatedly occurring OTUs. These data were clustered using UPGMA (Supporting Information Fig. S3) and identified that a small number of recurrent OTUs with high abundance (6.2% of OTUs and 67.6% of sequences) contributed to a deep clade within the clustergram. For these OTUs to be responsible for SCP formation, they should have a distribution that was enriched within the pilot bioreactor and SCP product when compared with the community of the acidogenic basin (which served as the influent community to the pilot bioreactor). When the MetaStats statistic was used to compare these OTUs with the pilot bioreactor influent distribution of OTUs, about 44.7% of the sequences (from the combined set of SCP and pilot bioreactor OTUs) were significantly enriched over the influent, and 29.6% of the sequences from the combined set were from OTUs that were significantly depleted compared with the influent (Supporting Information Fig. S4). When a phylogenetic tree was constructed from representative pyrotags of these OTUs, a phylogenetically coherent trend was observed. As shown in Fig. 4, when sequences from enriched or depleted OTUs were cross-referenced with the known microbial lifestyle of the taxonomic classification of the sequence, the depleted OTUs tended to be more from saccharolytic fermenters, primarily Prevotellaceae. Enriched OTUs tended to be from genera consisting of rhizospheric diazotrophs such as Azospirillum, Azonexus and Telmatospirillum, and a smaller fraction of saccharolytic fermenters. OTUs identified as having a rhizospheric diazotroph lifestyle were absent from both the pilot bioreactor influent and from depleted OTUs, but accounted for 39.4% of sequences from enriched OTUs in the pilot bioreactor and 73.0% of sequences from enriched OTUs in the final product.
Affiliation: Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, USA.