TitleImpact of wastewater effluent on the structure
and antibiotic resistance of native microbial communities
NameHonarbakhsh, Maryam (author), Bini, Elisabetta (chair), Vetriani, Costantino (internal member), Kerkhof, Lee (internal member), Rutgers University, Graduate School - New Brunswick,
SubjectMicrobiology and Molecular Genetics,
Drug resistance in microorganisms,
Sewage disposal plants
DescriptionIn this work, we investigated the impact of antibiotic resistant bacteria from final effluents of a sewage discharge on the selection of antibiotic resistance in natural bacterial communities in sites downstream the treatment plant. Samples were collected from the final effluents of the wastewater treatment plant and from two sites along the receiving stream. A fourth site, upstream of the discharge, was used as control. Phylogenetic analysis of the 16S rRNA gene sequences was performed to derive the composition and structure of the four microbial communities. Clone library data and TRFLP profiles showed that the four communities were all dominated by Betaproteobacteria, which constituted approximately two thirds of the final effluent community. The diversity and abundance of other bacterial phylotypes varied across sites. Bacterial diversity included 9 phylotypes in the final effluent, 15 and 13 phylotypes respectively in the sites downstream the discharge. Furthermore, bacteria were isolated from the same samples using culture-dependent techniques, which allowed to link antibiotic resistance to particular bacterial species. While clone libraries were dominated by Betaproteobacteria, culturable isolates mainly belonged to the class of Gammaproteobacteria. Specifically, the analysis of the isolates from the final effluent showed the presence of Bacillus, Enterobacter, Acinetobacter, and Staphylococcus strains, while samples collected downstream from the plant were characterized by species belonging to the genera Brevibacterium, Chryseobacterium, Aeromonas and Delftia. All the isolates were resistant to amoxicillin, and most displayed resistance to multiple antibiotics. The distribution of β-lactamase genes across the four sites was also assessed. Phylogenetic analysis revealed that the distribution of the bla TEM4 gene is divided to two main clusters. The first cluster contains sequences that are exclusively detected at the plant and receiving water, but not at the upstream site, while sequences of the second cluster were present at all of the four sites.
NoteIncludes bibliographical references
Noteby Maryam Honarbakhsh
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.