Abstract
The phylogenetic diversity of bacterial communities in response to environmental disturbances such as organic pollution has been well studied, but little is known about the way in which organic contaminants influence the acclimation of functional bacteria. In the present study, tolerance assays for bacterial communities from the sediment in the Pearl River Estuary were conducted with the isolation of functional bacteria using pyrene and different estrogens as environmental stressors. Molecular ecological networks and phylogenetic trees were constructed using both 16S rRNA gene sequences of cultured bacterial strains and 16S rRNA gene-based pyrosequencing data to illustrate the successions of bacterial communities and their acclimations to the different organic compounds. A total of 111 bacterial strains exhibiting degradation and endurance capabilities in response to the pyrene estrogen-induced stress were successfully isolated and were mainly affiliated with three orders, Pseudomonadales, Vibrionales, and Rhodobacterales. Molecular ecological networks and phylogenetic trees showed various adaptive abilities of bacteria to the different organic compounds. For instance, some bacterial OTUs could be found only in particular organic compound-treated groups while some other OTUs could tolerate stresses from different organic compounds. Furthermore, the results indicated that some new phylotypes were emerged under stresses of different organic pollutions and these new phylotypes could adapt to the contaminated environments and contribute significantly to the microbial community shifts. Overall, this study demonstrated a crucial role of the community succession and the acclimation of functional bacteria in the adaptive responses to various environmental disturbances.
Highlights
Bacteria can adapt to a range of different habitats, including contaminated and extreme environments, and they can perform a wide diversity of physiological activities (Dash et al, 2013)
We aimed to investigate the changes of bacterial communities and their acclimation to the different organic compounds as environmental stressors
A total of 148 strains (63, 48, and 37 from pyrene, estrogen supplemented MSM, and normal 2116E medium, respectively) were characterized by 16S rRNA gene sequencing and aligned with the National Center for Biotechnology Information (NCBI) website to yield the top BLAST hits corresponding to almost the full length of the 16S rRNA gene sequences
Summary
Bacteria can adapt to a range of different habitats, including contaminated and extreme environments, and they can perform a wide diversity of physiological activities (Dash et al, 2013). Bacteria can play both positive and negative roles in an ecosystem, first by degrading organic waste and by spreading the resultant dangerous contaminants. They have been well acknowledged as central players in the health of all organisms and ecosystems (Layeghifard et al, 2016). It was observed that these stresses could lead to a rise in disease-associated bacterial populations in the coral environment In another example of adaptation, microbial strains under high-stress environments [polycyclic aromatic hydrocarbon (PAH) and steroid contamination] began growing, and were able to use these stress-producing substances as energy and carbon sources (Haritash and Kaushik, 2009)
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