title: Investigation of bacterial diversity in membrane bioreactor and conventional activated sludge processes from petroleum refineries using phylogenetic and statistical approaches.
abstract: Bacterial diversity of two distinct wastewater treatment systems, conventional activated sludge (CAS) and membrane bioreactor (MBR), of petroleum refineries were investigated through 16S rRNA gene libraries. Sequencing and phylogenetic analysis showed that the bacterial community composition of sludge samples was distinct between the two wastewater treatment systems. MBR clones belonged predominantly to Class Betaproteobacteria, represented mainly by genera Thiobacillus and Thauera, whereas CAS clones were mostly related to Class Alphaproteobacteria, represented by uncultured bacteria related to Order Parvularculales. Richness estimators ACE and Chao revealed that the diversity observed in both libraries at the species level is an underestimate of the total bacterial diversity present in the environment and further sampling would yield an increased observed diversity. Shannon and Simpson diversity indices were different between the libraries and revealed greater bacterial diversity for the MBR library, considering an evolutionary distance of 0.03. LIBSHUFF analyses revealed that MBR and CAS communities were significantly different at the 95% confidence level (P< or =0.05) for distances 0< or =D< or =0.20. This work described, qualitatively and quantitatively, the structure of bacterial communities in industrial-scale MBR and CAS processes of the wastewater treatment system from petroleum refineries and demonstrated clearly differentiated communities responsible for the stable performance of wastewater treatment plants.
authors.affiliation: Division of Microbial Resources, Research Center for Chemistry, Biology and Agriculture (CPQBA), Campinas University - UNICAMP, CP 6171, CEP 13081-970, Campinas, SP, Brazil.
authors.forename: Cynthia C
authors.initials: CC
authors.lastname: Silva
authors.forename: Ederson C
authors.initials: EC
authors.lastname: Jesus
authors.forename: Ana P R
authors.initials: AP
authors.lastname: Torres
authors.forename: Maira P
authors.initials: MP
authors.lastname: Sousa
authors.forename: Vânia M J
authors.initials: VM
authors.lastname: Santiago
authors.forename: Valéria M
authors.initials: VM
authors.lastname: Oliveira
mesh_terms: D001483:Base Sequence; D001673:Biodegradation, Environmental; D019149:Bioreactors / Q000382:microbiology*; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D019652:Extraction and Processing Industry; D014644:Genetic Variation; D007220:Industrial Waste; D008969:Molecular Sequence Data; D010578:Petroleum; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D020560:Proteobacteria / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D012336:RNA, Ribosomal, 16S / Q000737:chemistry / Q000235:genetics; D016415:Sequence Alignment; D012722:Sewage / Q000382:microbiology*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014874:Water Pollutants, Chemical / Q000378:metabolism*
chemical_list: D004269:DNA, Bacterial; D007220:Industrial Waste; D010578:Petroleum; D012336:RNA, Ribosomal, 16S; D012722:Sewage; D014874:Water Pollutants, Chemical