Isolation and process parameter optimization of Brevibacterium casei for simultaneous bioremediation of hexavalent chromium and pentachlorophenol

Chromate and pentachlorophenol are major pollutants discharged through tanneries. Three bacteria resistant to high Cr6+ and PCP concentrations simultaneously were isolated. The TVS-3 strain was tolerant to highest 850mg l1 Cr6+ and 1000mg l1 PCP concentration and concomitantly reduced 69% Cr6+ and degraded 72% PCP within 168h at pH 7.5, 35 +/- 1 degrees C temperature, was selected and identified as Brevibacterium casei. At 168h of growth, bacterium showed maximum PCP utilization of 720mg l1 and released 900mg l1 chloride ion. The bacterium exhibited remarkable ability to significantly reduce Cr6+ and degrade PCP in presence of other metals, between 100120rpm aeration and over broad pH (6.510.0) and temperature (3040 degrees C) range. Maximum 78% Cr6+ reduction and 82% PCP degradation was observed at pH 8.0, 35 +/- 1 degrees C within 168h of incubation, 120rpm and initial concentration of 850mg l1 Cr6+ and 1000mg l1 PCP. This is the first study reporting 78% Cr6+ reduction and 82% PCP degradation simultaneously by single native bacteria under wide growth conditions utilizing PCP as sole carbon source. This bacterium may potentially be useful for simultaneous bioremediation of Cr6+ and PCP containing wastes in the environment.