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The Microbiota and Abundance of the Class 1 Integron-Integrase Gene in Tropical Sewage Treatment Plant Influent and Activated Sludge.

Paiva MC, Ávila MP, Reis MP, Costa PS, Nardi RM, Nascimento AM - PLoS ONE (2015)

Bottom Line: Among the 25 phyla, Proteobacteria, Bacteroidetes and Firmicutes represented 85% (AS) and 92% (RS) of all reads.Increased relative abundance of Micrococcales, Myxococcales, and Sphingobacteriales and reduced pathogen abundance were noted in AS.At the genus level, differences were observed for the dominant genera Simplicispira and Diaphorobacter (AS) as well as for Enhydrobacter (RS).

View Article: PubMed Central - PubMed

Affiliation: Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; Campus Dona Lindu, Universidade Federal de São João del Rei, Divinópolis, Minas Gerais, Brazil.

ABSTRACT
Bacteria are assumed to efficiently remove organic pollutants from sewage in sewage treatment plants, where antibiotic-resistance genes can move between species via mobile genetic elements known as integrons. Nevertheless, few studies have addressed bacterial diversity and class 1 integron abundance in tropical sewage. Here, we describe the extant microbiota, using V6 tag sequencing, and quantify the class 1 integron-integrase gene (intI1) in raw sewage (RS) and activated sludge (AS). The analysis of 1,174,486 quality-filtered reads obtained from RS and AS samples revealed complex and distinct bacterial diversity in these samples. The RS sample, with 3,074 operational taxonomic units, exhibited the highest alpha-diversity indices. Among the 25 phyla, Proteobacteria, Bacteroidetes and Firmicutes represented 85% (AS) and 92% (RS) of all reads. Increased relative abundance of Micrococcales, Myxococcales, and Sphingobacteriales and reduced pathogen abundance were noted in AS. At the genus level, differences were observed for the dominant genera Simplicispira and Diaphorobacter (AS) as well as for Enhydrobacter (RS). The activated sludge process decreased (55%) the amount of bacteria harboring the intI1 gene in the RS sample. Altogether, our results emphasize the importance of biological treatment for diminishing pathogenic bacteria and those bearing the intI1 gene that arrive at a sewage treatment plant.

No MeSH data available.


Cumulative relative frequency of the OTUs of raw sewage (RS) and activated sludge (AS).
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pone.0131532.g001: Cumulative relative frequency of the OTUs of raw sewage (RS) and activated sludge (AS).

Mentions: To estimate the relative diversity captured in each sample, the normalized libraries (with the lowest number of reads, 587,243) were used to calculate the cumulative relative frequency curve, OTU richness, ChaoI and ACE richness estimators, as well as the Shannon and Simpson diversity indices. Good’s coverage values were similar in both samples (RS, 99.85%; AS, 99.9%). As illustrated in Fig 1, the bacterial communities from RS and AS were dominated by a few OTUs. The long tails of the taxon rank distribution curves indicated that the diversity in these environments mostly arose from rare taxa. Although both communities exhibited a high number of rare OTUs, the read distribution of dominant OTUs in each sample was relatively equitable, as shown by the high Simpson index values (RS, 0.93; AS, 0.95). Altogether, Good’s coverage and the cumulative relative frequency curve suggested that most of the diversity was captured. The Shannon index (RS, 3.96; AS, 3.9) revealed considerable bacterial diversity in the samples. Moreover, the Chao1 (RS, 3677.6; AS, 2346.2) and ACE (RS, 3843.4; AS, 2441.0) values also predicted higher bacterial diversity in the RS sample (S2 Table).


The Microbiota and Abundance of the Class 1 Integron-Integrase Gene in Tropical Sewage Treatment Plant Influent and Activated Sludge.

Paiva MC, Ávila MP, Reis MP, Costa PS, Nardi RM, Nascimento AM - PLoS ONE (2015)

Cumulative relative frequency of the OTUs of raw sewage (RS) and activated sludge (AS).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4482650&req=5

pone.0131532.g001: Cumulative relative frequency of the OTUs of raw sewage (RS) and activated sludge (AS).
Mentions: To estimate the relative diversity captured in each sample, the normalized libraries (with the lowest number of reads, 587,243) were used to calculate the cumulative relative frequency curve, OTU richness, ChaoI and ACE richness estimators, as well as the Shannon and Simpson diversity indices. Good’s coverage values were similar in both samples (RS, 99.85%; AS, 99.9%). As illustrated in Fig 1, the bacterial communities from RS and AS were dominated by a few OTUs. The long tails of the taxon rank distribution curves indicated that the diversity in these environments mostly arose from rare taxa. Although both communities exhibited a high number of rare OTUs, the read distribution of dominant OTUs in each sample was relatively equitable, as shown by the high Simpson index values (RS, 0.93; AS, 0.95). Altogether, Good’s coverage and the cumulative relative frequency curve suggested that most of the diversity was captured. The Shannon index (RS, 3.96; AS, 3.9) revealed considerable bacterial diversity in the samples. Moreover, the Chao1 (RS, 3677.6; AS, 2346.2) and ACE (RS, 3843.4; AS, 2441.0) values also predicted higher bacterial diversity in the RS sample (S2 Table).

Bottom Line: Among the 25 phyla, Proteobacteria, Bacteroidetes and Firmicutes represented 85% (AS) and 92% (RS) of all reads.Increased relative abundance of Micrococcales, Myxococcales, and Sphingobacteriales and reduced pathogen abundance were noted in AS.At the genus level, differences were observed for the dominant genera Simplicispira and Diaphorobacter (AS) as well as for Enhydrobacter (RS).

View Article: PubMed Central - PubMed

Affiliation: Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil; Campus Dona Lindu, Universidade Federal de São João del Rei, Divinópolis, Minas Gerais, Brazil.

ABSTRACT
Bacteria are assumed to efficiently remove organic pollutants from sewage in sewage treatment plants, where antibiotic-resistance genes can move between species via mobile genetic elements known as integrons. Nevertheless, few studies have addressed bacterial diversity and class 1 integron abundance in tropical sewage. Here, we describe the extant microbiota, using V6 tag sequencing, and quantify the class 1 integron-integrase gene (intI1) in raw sewage (RS) and activated sludge (AS). The analysis of 1,174,486 quality-filtered reads obtained from RS and AS samples revealed complex and distinct bacterial diversity in these samples. The RS sample, with 3,074 operational taxonomic units, exhibited the highest alpha-diversity indices. Among the 25 phyla, Proteobacteria, Bacteroidetes and Firmicutes represented 85% (AS) and 92% (RS) of all reads. Increased relative abundance of Micrococcales, Myxococcales, and Sphingobacteriales and reduced pathogen abundance were noted in AS. At the genus level, differences were observed for the dominant genera Simplicispira and Diaphorobacter (AS) as well as for Enhydrobacter (RS). The activated sludge process decreased (55%) the amount of bacteria harboring the intI1 gene in the RS sample. Altogether, our results emphasize the importance of biological treatment for diminishing pathogenic bacteria and those bearing the intI1 gene that arrive at a sewage treatment plant.

No MeSH data available.