Exploring the microcystin-LR degrading potential of a bacterial consortium obtained from abattoir effluents

The occurrence of microcystins in freshwater bodies is a global concern as they pose possible health effects on aquatic life, humans, wildlife and livestock. In a continued drive to find technologies for their safe removal from water, biodegradation has been identified as one of the effective, low cost and safe technologies. Using classic batch culture experiments, this work identified a bacterial consortium obtained from abattoir effluents, that could metabolize microcystin-LR (MC-LR) as the sole source of carbon. After 21 days of incubation the MC-LR concentrations (3 mg L^- 1) were reduced by 57% due to biological activities. The composition of the bacterial consortium was determined from 16 S rRNA gene sequencing and 20 dominant genera were identified. Among the 20 dominant genera identified, five (Stenotrophomonas, Aeromonas, Alcaligenes, Morganella and Citrobacter) are known MC-LR degraders. The remaining genera have not previously been reported to degrade MC-LR. These taxa may represent novel MC-LR-degrading bacteria, or alternatively, they may play supportive roles in the consortium without directly participating in MC-LR degradation. Hence their exact role needs to be established. Compared to the indigenous abattoir effluent bacterial communities, the MC-LR degrading consortium exhibited improved metabolic potentials as measured by their ability to metabolize a set of 31 different carbon substrates. Overall, these results confirm the ubiquitous distribution of microcystin degraders and further highlight industrial effluents as potential sinks for biotechnological tools for environmental bioremediation. Nonetheless, further work to optimize the degradation reaction, identify the role and pathogenicity of each individual bacterium as well as identify the genes involved remain crucial to cement possible future applications of this bacterial assemblage.