Publications
Influence of 3-chloroaniline on the biofilm lifestyle of Comamonas testosteroni and its implications on bioaugmentation
Reference: Applied and Environmental Microbiology (2016) 82: 4401-4409

Bioaugmentation has been frequently proposed in wastewater and soil treatment to remove toxic aromatic compounds. The performance of bioaugmentation is affected by a number of biological and environmental factors including the interaction between the target pollutant and the augmented bacterial cells. In this study, using Comamonas testosteroni and 3-chloroaniline (3-CA) as the model organism and target pollutant, we explored the influence of toxic aromatic pollutant on the biofilm lifestyle of bacteria capable of degrading aromatic compounds toward a better understanding of cell-pollutant interaction in bioaugmentation. Our results showed that the exposure to 3-CA greatly reduced the retention of C. testosteroni cells in packed-bed bioreactors (from 22% to 15% after three pore volumes), which could be attributed to the altered bacterial motility and cell surface hydrophobicity. To further understand the molecular mechanisms, we employed an integrated genomic and transcriptomic analysis to examine the influence of 3-CA on the expression of genes important to the biofilm lifestyle of C. testosteroni. We found that the exposure to 3-CA reduced the intracellular c-di-GMP level by downregulating the expression of genes encoding c-di-GMP synthases and induced massive cell dispersal from the biofilms. Our findings provide novel environmental implications on bioaugmentation, in particular, in biofilm reactors, for the treatment of wastewater containing recalcitrant industrial pollutants. Importance: Bioaugmentation is a bioremediation approach that has been often described in literature but has been hardly to no successfully applied in practice. Many biological and environmental factors influence the overall performance of bioaugmentation. Among which, the interaction between the target pollutant and the augmented bacterial cells is one of the most important factors. In this study, we revealed the influence of toxic aromatic pollutant on the biofilm lifestyle of bacteria capable of degrading aromatic compounds toward a better understanding of cell-pollutant interaction in bioaugmentation. Our findings provide novel environmental implications on bioaugmentation for the treatment of wastewater containing recalcitrant industrial pollutants; in particular, the exposure to toxic pollutants may reduce the retention of augmented organisms in biofilm reactors by reducing the c-di-GMP level and the approaches to elevating or maintaining a high c-di-GMP level may be promising to establish and maintain a sustainable bioaugmentation activity.

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Published By
Wu Y., Mohanty A., Chia S.S., Cao B.