Harnessing enterobacter cloacae SAW-2 for environmental cleanup: a dual approach to molybdenum and phenolic pollution

Millions of tonnes of heavy metals and organic pollutants are produced or used annually through industrial activities, and a large share of these substances pollute the environment. In the long term, bioremediation is the most affordable method for removing them, especially at low concentrations where other approaches like physical or chemical methods are less effective. The study explores how a molybdenum-reducing bacterium from polluted soil can decolorize different phenolics, separate from its molybdenum reduction function. Based on biochemical analysis, the bacterium was preliminarily identified as Enterobacter cloacae strain Saw-2. Optimal reduction of molybdate to Mo-blue by the bacterium occurs at a pH of 6.3 to 6.8 and a temperature of 34 to 37°C. Glucose exhibited as the most preferred electron donor for the reduction up to 30 mM of molybdate concentration with a phosphate concentration of 5.0 mM. Cd2+, Hg2+, Cu2+, and Ag2+ at 2 ppm inhibited molybdenum reduction around 20 to 45% of enzymatic activity. Phenol and catechol served as growth substrates for the bacterium.