Shift of low to high nucleic acid bacteria as a potential bioindicator for the screening of anthropogenic effects in a receiving river due to palm oil mill effluent final discharge

•The changes of the microbiological status of a water body were affected by the POME final discharge.•The increased HNA cells in the affected river with originally high LNA cells at the upstream point could be an indicative of the effects of effluent.•The shift of HNA/LNA ratios could be used as a potential bioindicator for the screening of anthropogenic effects due to effluent.•The quantification of HNA/LNA ratio in assessing the effects of effluent could be applied to complement the use of specific bacterial indicators.