title: The Microbiota and Abundance of the Class 1 Integron-Integrase Gene in Tropical Sewage Treatment Plant Influent and Activated Sludge.
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.
authors.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.
authors.forename: Magna C
authors.initials: MC
authors.lastname: Paiva
authors.affiliation: Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Marcelo P
authors.initials: MP
authors.lastname: Ávila
authors.affiliation: Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Mariana P
authors.initials: MP
authors.lastname: Reis
authors.affiliation: Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Patrícia S
authors.initials: PS
authors.lastname: Costa
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Regina M D
authors.initials: RM
authors.lastname: Nardi
authors.affiliation: Departamento de Biologia Geral, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Andréa M A
authors.initials: AM
authors.lastname: Nascimento
mesh_terms: D001419:Bacteria / Q000145:classification / Q000201:enzymology / Q000235:genetics; D001938:Brazil; D014644:Genetic Variation; D006801:Humans; D019426:Integrases / Q000032:analysis / Q000235:genetics*; D064307:Microbiota / Q000235:genetics*; D012722:Sewage / Q000382:microbiology*; D014329:Tropical Climate; D062065:Wastewater / Q000032:analysis / Q000382:microbiology; D018508:Water Purification
chemical_list: D019426:Integrases; D012722:Sewage; D062065:Wastewater; C115006:integron integrase IntI1