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Microbial community analysis of anaerobic reactors treating soft drink wastewater.

Narihiro T, Kim NK, Mei R, Nobu MK, Liu WT - PLoS ONE (2015)

Bottom Line: In particular, KSB3, GN04, Bacteroidetes, and Chloroflexi are consistently associated with the organic loading rate (OLR) increase to 1.5 g COD/L-d.Interestingly, KSB3 and GN04 dramatically decrease in both reactors after further OLR increase to 2.0 g COD/L-d.These results indicate that OLR strongly influences microbial community composition.

View Article: PubMed Central - PubMed

Affiliation: Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205 North Mathews Ave, Urbana, IL 61801, United States of America; Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 6, Higashi, Tsukuba, Ibaraki 305-8566, Japan.

ABSTRACT
The anaerobic packed-bed (AP) and hybrid packed-bed (HP) reactors containing methanogenic microbial consortia were applied to treat synthetic soft drink wastewater, which contains polyethylene glycol (PEG) and fructose as the primary constituents. The AP and HP reactors achieved high COD removal efficiency (>95%) after 80 and 33 days of the operation, respectively, and operated stably over 2 years. 16S rRNA gene pyrotag analyses on a total of 25 biofilm samples generated 98,057 reads, which were clustered into 2,882 operational taxonomic units (OTUs). Both AP and HP communities were predominated by Bacteroidetes, Chloroflexi, Firmicutes, and candidate phylum KSB3 that may degrade organic compound in wastewater treatment processes. Other OTUs related to uncharacterized Geobacter and Spirochaetes clades and candidate phylum GN04 were also detected at high abundance; however, their relationship to wastewater treatment has remained unclear. In particular, KSB3, GN04, Bacteroidetes, and Chloroflexi are consistently associated with the organic loading rate (OLR) increase to 1.5 g COD/L-d. Interestingly, KSB3 and GN04 dramatically decrease in both reactors after further OLR increase to 2.0 g COD/L-d. These results indicate that OLR strongly influences microbial community composition. This suggests that specific uncultivated taxa may take central roles in COD removal from soft drink wastewater depending on OLR.

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Principal coordinate analysis based on the abundances of 16S rRNA gene OTUs (unweighted UniFrac).For this analysis, observed 16S rRNA gene OTUs were normalized to 1,400 reads per sample. A and H indicate the samples taken from the anaerobic packed-bed (AP) and hybrid packed-bed (HP) reactors. The numbers following A and H indicate days of the operation for biomass sampling.
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pone.0119131.g003: Principal coordinate analysis based on the abundances of 16S rRNA gene OTUs (unweighted UniFrac).For this analysis, observed 16S rRNA gene OTUs were normalized to 1,400 reads per sample. A and H indicate the samples taken from the anaerobic packed-bed (AP) and hybrid packed-bed (HP) reactors. The numbers following A and H indicate days of the operation for biomass sampling.

Mentions: 16S rRNA gene pyrotag libraries were constructed for twelve AP and HP biofilm samples each and their seed sludge. A total of 98,057 16S rRNA gene pyrotag reads were retrieved and further classified into 2,882 OTUs using a 97% sequence identity cut-off (S1 Table). Although the rarefaction curves of most samples were insufficient to achieve the plateau (S1 Fig.), the high Good’s coverage values (>93%) suggested that obtained OTUs adequately estimated the microbial diversity of the reactors. According to the Chao1 indexes, the biofilm may contain approximately 1.53–2.23-fold more OTUs than detected. Comparing microbial community composition between samples, unweighted UniFrac-based principal coordinate analysis (PCoA) clearly showed that the community composition varied with time (Fig. 3). Specifically, the microbial constituents continuously change over 321 days and reached stable structure only after 462 days, based on Jackknife clustering analysis, weighted UniFrac-based PCoA and correspondence analysis (CA) (S2, S3, and S4 Figs.). Despite the dynamic community structure, the steady COD removal indicates that the enriched microbial consortia at all stages were suitable for soft drink wastewater treatment at the respective operation conditions (Fig. 2). Using OTU-level phylogenetic analyses, we identify dominant organisms (Fig. 4) and discuss their potential ecological roles below.


Microbial community analysis of anaerobic reactors treating soft drink wastewater.

Narihiro T, Kim NK, Mei R, Nobu MK, Liu WT - PLoS ONE (2015)

Principal coordinate analysis based on the abundances of 16S rRNA gene OTUs (unweighted UniFrac).For this analysis, observed 16S rRNA gene OTUs were normalized to 1,400 reads per sample. A and H indicate the samples taken from the anaerobic packed-bed (AP) and hybrid packed-bed (HP) reactors. The numbers following A and H indicate days of the operation for biomass sampling.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4352018&req=5

pone.0119131.g003: Principal coordinate analysis based on the abundances of 16S rRNA gene OTUs (unweighted UniFrac).For this analysis, observed 16S rRNA gene OTUs were normalized to 1,400 reads per sample. A and H indicate the samples taken from the anaerobic packed-bed (AP) and hybrid packed-bed (HP) reactors. The numbers following A and H indicate days of the operation for biomass sampling.
Mentions: 16S rRNA gene pyrotag libraries were constructed for twelve AP and HP biofilm samples each and their seed sludge. A total of 98,057 16S rRNA gene pyrotag reads were retrieved and further classified into 2,882 OTUs using a 97% sequence identity cut-off (S1 Table). Although the rarefaction curves of most samples were insufficient to achieve the plateau (S1 Fig.), the high Good’s coverage values (>93%) suggested that obtained OTUs adequately estimated the microbial diversity of the reactors. According to the Chao1 indexes, the biofilm may contain approximately 1.53–2.23-fold more OTUs than detected. Comparing microbial community composition between samples, unweighted UniFrac-based principal coordinate analysis (PCoA) clearly showed that the community composition varied with time (Fig. 3). Specifically, the microbial constituents continuously change over 321 days and reached stable structure only after 462 days, based on Jackknife clustering analysis, weighted UniFrac-based PCoA and correspondence analysis (CA) (S2, S3, and S4 Figs.). Despite the dynamic community structure, the steady COD removal indicates that the enriched microbial consortia at all stages were suitable for soft drink wastewater treatment at the respective operation conditions (Fig. 2). Using OTU-level phylogenetic analyses, we identify dominant organisms (Fig. 4) and discuss their potential ecological roles below.

Bottom Line: In particular, KSB3, GN04, Bacteroidetes, and Chloroflexi are consistently associated with the organic loading rate (OLR) increase to 1.5 g COD/L-d.Interestingly, KSB3 and GN04 dramatically decrease in both reactors after further OLR increase to 2.0 g COD/L-d.These results indicate that OLR strongly influences microbial community composition.

View Article: PubMed Central - PubMed

Affiliation: Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, 205 North Mathews Ave, Urbana, IL 61801, United States of America; Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 6, Higashi, Tsukuba, Ibaraki 305-8566, Japan.

ABSTRACT
The anaerobic packed-bed (AP) and hybrid packed-bed (HP) reactors containing methanogenic microbial consortia were applied to treat synthetic soft drink wastewater, which contains polyethylene glycol (PEG) and fructose as the primary constituents. The AP and HP reactors achieved high COD removal efficiency (>95%) after 80 and 33 days of the operation, respectively, and operated stably over 2 years. 16S rRNA gene pyrotag analyses on a total of 25 biofilm samples generated 98,057 reads, which were clustered into 2,882 operational taxonomic units (OTUs). Both AP and HP communities were predominated by Bacteroidetes, Chloroflexi, Firmicutes, and candidate phylum KSB3 that may degrade organic compound in wastewater treatment processes. Other OTUs related to uncharacterized Geobacter and Spirochaetes clades and candidate phylum GN04 were also detected at high abundance; however, their relationship to wastewater treatment has remained unclear. In particular, KSB3, GN04, Bacteroidetes, and Chloroflexi are consistently associated with the organic loading rate (OLR) increase to 1.5 g COD/L-d. Interestingly, KSB3 and GN04 dramatically decrease in both reactors after further OLR increase to 2.0 g COD/L-d. These results indicate that OLR strongly influences microbial community composition. This suggests that specific uncultivated taxa may take central roles in COD removal from soft drink wastewater depending on OLR.

Show MeSH