You are here:
Interacting effects of sunlight, agriculturally derived dissolved organic matter and reactive oxygen species on fecal indicator bacteria growth dynamics
Citation:
Oladeinde, A., E. Lipp, AND M. Molina. Interacting effects of sunlight, agriculturally derived dissolved organic matter and reactive oxygen species on fecal indicator bacteria growth dynamics. ISME-International Society for Microbial Ecology 2016 Annual Meeting, Montreal, CANADA, August 21 - 26, 2016.
Impact/Purpose:
Presented at the 16th International Symposium on Microbial Ecology.
Description:
Bacterial survival in agriculturally impacted surface waters is dependent on resource availability and also on potential resource transformations, mediated by biotic and abiotic processes. In this study, we focused on the effect of sunlight irradiated cattle fecal extract (CFE) as a source of dissolved organic matter(DOM; (31-45 mg L-1 C), on the growth dynamics of two fecal indicator bacteria (FIB) strains of Escherichia coli and Enterococcus faecalis incubated individually and in co-culture. We employed RNA-Seq and RT-qPCR to compare the expression of oxidative stress genes in FIB incubated in irradiated and non-irradiated CFE. Overall, irradiation of CFE for 12 h resulted in the production of labile nutrients and reactive oxygen species (ROS,) and had differential effects on the survival of FIB in mono-culture versus co-culture. Sunlight irradiation resulted in significantly lower growth in E. faecalis (1-log10 reduction) and limited expression in genes with peroxidase and catalase activity (95% reduction in exogenous H2O2. As a co-culture in irradiated CFE, the growth rate of E. faecalis doubled, suggesting E. faecalis benefited from E. coli’s H2O2 removal efficiency. However, in non-irradiated CFE, E. faecalis showed a ~3-log10 die-off within 3 h of incubation, suggesting an antagonistic interaction in the presence of E. coli. Our study provides valuable insights on the interacting effects of sunlight, agriculturally derived DOM, and ROS on bacterial survival dynamics.
