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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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Distance matrix tree of 16S rRNA gene sequences assigned to the Geobacter retrieved from anaerobic reactors based on the neighbor-joining method.Boldface indicates the sequences obtained in this study. The 16S rRNA gene sequences of Thermodesulfobacterium commune DSM 2178 (AF418169), Thermodesulfobacterium hveragerdense DSM 12571 (NR_029311), and Thermodesulfobacterium hydrogeniphilum DSM 14290 (NR_025146) were used as outgroup. The bar indicates 10% base substitution. Branching points supported probabilities >95%, >75%, and >50% by bootstrap analyses (based on 1,000 replicates) are indicated by solid circle, open circles, and open square, respectively.
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pone.0119131.g006: Distance matrix tree of 16S rRNA gene sequences assigned to the Geobacter retrieved from anaerobic reactors based on the neighbor-joining method.Boldface indicates the sequences obtained in this study. The 16S rRNA gene sequences of Thermodesulfobacterium commune DSM 2178 (AF418169), Thermodesulfobacterium hveragerdense DSM 12571 (NR_029311), and Thermodesulfobacterium hydrogeniphilum DSM 14290 (NR_025146) were used as outgroup. The bar indicates 10% base substitution. Branching points supported probabilities >95%, >75%, and >50% by bootstrap analyses (based on 1,000 replicates) are indicated by solid circle, open circles, and open square, respectively.

Mentions: Besides such phyla widely associated with anaerobic digestion, we also observed populations of candidate phyla KSB3 and GN04 during later stages of operation (Fig. 4). After 600 days, KSB3 (OTU389) predominated up to 38.3% and 4.8% in AP and HP respectively. This KSB3 closely relates to a clone (99.2% similarity to clone SwB25fl, accession no. AB266941) associated with a mesophilic UASB reactors treating sugar-containing wastewater (Fig. 5) [35]. Further, KSB3 was also previously observed to degrade carbohydrates (i.e., glucose and maltose), especially in association with increase in influent sugar concentration [46, 47]. Thus, KSB3 likely participates in fructose degradation in both AP and HP reactors. The GN04-related OTU3172 was detected in the AP (2.6–5.6%) and HP (1.5–8.1%) reactors after 530 days operation (Fig. 4). Like KSB3, this GN04 OTU is related to a lineage (specifically MSB-5A5) associated with mesophilic UASB reactors treating sugar-containing wastewater (e.g., 99.5% identity with clone N2B95fl; accession no. AB266976) (Fig. 6) [35]. However, in both cases, their physiology and in situ functions remains largely unknown. The RDA plot indicated that GN04 and KSB3 populations are positioned close to the origin of the axes, indicating that their appearance could not be explained by the environmental factors tested. Further study on metagenomic and single-cell genomic analyses would provide more useful information to elucidate the ecophysiological traits of these functionally unknown microbes.


Microbial community analysis of anaerobic reactors treating soft drink wastewater.

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

Distance matrix tree of 16S rRNA gene sequences assigned to the Geobacter retrieved from anaerobic reactors based on the neighbor-joining method.Boldface indicates the sequences obtained in this study. The 16S rRNA gene sequences of Thermodesulfobacterium commune DSM 2178 (AF418169), Thermodesulfobacterium hveragerdense DSM 12571 (NR_029311), and Thermodesulfobacterium hydrogeniphilum DSM 14290 (NR_025146) were used as outgroup. The bar indicates 10% base substitution. Branching points supported probabilities >95%, >75%, and >50% by bootstrap analyses (based on 1,000 replicates) are indicated by solid circle, open circles, and open square, respectively.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0119131.g006: Distance matrix tree of 16S rRNA gene sequences assigned to the Geobacter retrieved from anaerobic reactors based on the neighbor-joining method.Boldface indicates the sequences obtained in this study. The 16S rRNA gene sequences of Thermodesulfobacterium commune DSM 2178 (AF418169), Thermodesulfobacterium hveragerdense DSM 12571 (NR_029311), and Thermodesulfobacterium hydrogeniphilum DSM 14290 (NR_025146) were used as outgroup. The bar indicates 10% base substitution. Branching points supported probabilities >95%, >75%, and >50% by bootstrap analyses (based on 1,000 replicates) are indicated by solid circle, open circles, and open square, respectively.
Mentions: Besides such phyla widely associated with anaerobic digestion, we also observed populations of candidate phyla KSB3 and GN04 during later stages of operation (Fig. 4). After 600 days, KSB3 (OTU389) predominated up to 38.3% and 4.8% in AP and HP respectively. This KSB3 closely relates to a clone (99.2% similarity to clone SwB25fl, accession no. AB266941) associated with a mesophilic UASB reactors treating sugar-containing wastewater (Fig. 5) [35]. Further, KSB3 was also previously observed to degrade carbohydrates (i.e., glucose and maltose), especially in association with increase in influent sugar concentration [46, 47]. Thus, KSB3 likely participates in fructose degradation in both AP and HP reactors. The GN04-related OTU3172 was detected in the AP (2.6–5.6%) and HP (1.5–8.1%) reactors after 530 days operation (Fig. 4). Like KSB3, this GN04 OTU is related to a lineage (specifically MSB-5A5) associated with mesophilic UASB reactors treating sugar-containing wastewater (e.g., 99.5% identity with clone N2B95fl; accession no. AB266976) (Fig. 6) [35]. However, in both cases, their physiology and in situ functions remains largely unknown. The RDA plot indicated that GN04 and KSB3 populations are positioned close to the origin of the axes, indicating that their appearance could not be explained by the environmental factors tested. Further study on metagenomic and single-cell genomic analyses would provide more useful information to elucidate the ecophysiological traits of these functionally unknown microbes.

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