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: Table 2 shows alpha diversity information and sequencing depth for each sample. A total of 808 near full-length Sanger and a total of ∼ 54 000 pyrotag 16S amplicon sequences were completed. Microbial diversity coverage estimates based on alpha diversity were bracketed on the low end by the Chao1 estimator and on the high end by the CatchAll estimate. Chao1 and abundance-based coverage estimator (ACE) metrics of samples rarified to the same sequencing depth showed that the influent and acidogenic basin had the lowest levels of diversity, while the majority of operational taxonomic units (OTUs) in this study were found from both the UASB bioreactor and the aerobic basin of the brewery wastewater treatment plant (WWTP). Figure 2 describes phylum-level diversity from all samples arranged by unweighted pair group method with arithmetic mean (UPGMA) cladogram based on the unweighted UniFrac distance, which shows that samples clustered primarily because of unit process type (jackknife sensitivity analysis of sequencing depth in Supporting Information Fig. S1). Samples tended to primarily cluster by treatment regime, except the pilot reactor mixed liquor samples clustered closely to the corresponding time point of the final dried SCP product. The four main dominant phyla found from pyrotags in this study were the Bacteroidetes, Firmicutes, Actinobacteria and Proteobacteria (from the alpha, beta and gamma classes), and were consistent with previous research on wastewater aerobic treatment (Seviour and Nielsen, 2010) and process wastewater specifically (Manz et al., 1994). The candidate divisions of SR1 and RF3, seen previously in methanogenesis bioreactor surveys (Chouari et al., 2005; Riviere et al., 2009), comprised 2.8% and 2.3% of sequences respectively from the methanogenesis UASB process. TM7 (Hugenholtz et al., 2001) and BD1-5 (Li et al., 1999) accounted for 5.2% and 5.1% of sequences detected in the treatment plant wet well. Krona hierarchical pie charts (Supplemental Information, http://inside.mines.edu/~jspear/resources.html) showed the relative abundance of OTUs across lower taxonomic levels. The influent was dominated by several groups of Firmicutes from the Lactobacillus and Enterococcus families. Acidogenic basin pyrotag sequences were dominated by the genus Prevotella, a saccharolytic fermenter. The remaining stages showed no highly dominant clades across time, although several clades of closely related enriched OTUs (from Bacteroidetes, Firmicutes and Proteobacteria) appear to dominate in the pilot bioreactor and SCP product. In addition, approximately 14.3% of all OTUs (representing 4% of total sequences) remained unclassified beyond the domain level (5.9% of pilot plant OTUs, 5.2% of methanogenesis OTUs and 4.0% of aerobic basin OTUs).
Affiliation: Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, USA.