Introduction:

Bacterial communities can be used as indicators of the ecological status of freshwater ecosystems in the evaluation of water quality. The objective of this research was to determine the relationship between the structure and function of bacterial communities and the chemical and microbiological quality of the Almendares and San Juan rivers.

Methods:

They were taken samples from three sampling stations of both rivers in the period 2014-2017. It was determined the structure and composition of the bacterial communities by denaturing gradient gel electrophoresis (DGGE) and 454 pyrosequencing. It was determined the extracellular proteolytic activity and acid phosphatase activity in the waters of both ecosystems and they were isolated and characterized bacteria from the waters and rhizosediments of aquatic plants of the Almendares River.

Results:

The structure and composition of the bacterial communities allowed to establish significant differences between the two rivers. It was shown that faecal contamination is the factor that most contributes to the variability of the bacterial communities composition of the Almendares River. On the other hand, the high concentrations of dissolved oxygen and low concentrations of nutrients are the factors that most influence the bacterial communities of the San Juan River. The highest proteolytic activity was detected in the San Juan River compared to the Almendares River. Nevertheless, it was detected the highest acid phosphatase activity in Almendares River. Bacteria belonging to the genus Bacillus sp. predominated in the Amendares River and produced proteases, amylases, phosphatases, esterases, aminopeptidases and glucanases. Conclusions: It was demonstrated the feasibility of using bacterial communities as indicators of the ecological status of freshwater ecosystems to evaluate the impact of chemical and microbiological contamination on the environment and human health.

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