Pollution shapes the bacterial community of a river: a case study

Abstract

Bacteria are involved in many vital biogeochemical functions in aquatic ecosystems. Owing to their small size and high growth rates, they tend to be highly responsive to any changes in their environment. This potential to reflect any kind of environmental change makes them sensitive indicators towards the effect of pollutants in aquatic systems. The present study focused on investigation of change in the bacterial community structure of Hindon River in Ghaziabad in North India, in relation to the river’s pollution levels. Both spatial and temporal variation in the resident as well as active bacterial community was determined using 16S rRNA gene and transcript as molecular markers through denaturing gradient gel electrophoresis. Sequence analysis of eluted bands showed that Bacteroidetes followed by γ-proteobacteria, Actinobacteria, β-proteobacteria, δ-proteobacteria, e-proteobacteria and Nitrospirae, represented the dominant phyla. Moreover, the effect of pollutants on the bacterial diversity was more conspicuous at RNA level. In addition, when assessing the diversity of culturables, 8 bacterial strains, having minimum inhibitory concentrations in the range of 200–250 mg l−1 for Ni, 75–200 mg l−1 for Co and 75–200 mg l−1 for Cd, were isolated and characterized. The identified bacteria have the potential to be used as sensitive biomarkers for the development of bioremediation strategies and their monitoring.