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

Abstract

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 850 mg l−1 Cr6+ and 1000 mg l−1 PCP concentration and concomitantly reduced 69% Cr6+ and degraded 72% PCP within 168 h at pH 7.5, 35 ± 1°C temperature, was selected and identified as Brevibacterium casei. At 168 h of growth, bacterium showed maximum PCP utilization of 720 mg l−1 and released 900 mg l−1 chloride ion. The bacterium exhibited remarkable ability to significantly reduce Cr6+ and degrade PCP in presence of other metals, between 100–120 rpm aeration and over broad pH (6.5–10.0) and temperature (30–40°C) range. Maximum 78% Cr6+ reduction and 82% PCP degradation was observed at pH 8.0, 35 ± 1°C within 168 h of incubation, 120 rpm and initial concentration of 850 mg l−1 Cr6+ and 1000 mg l−1 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.

Biodegradation of petroleum hydrocarbons in the presence of nickel and cobalt

“…Interestingly, 82% degradation of the organic compound with simultaneous Cr 6+ reduction was reported, unlike in the present study where about 50% of the PHs were degraded along with sequestration the Ni 2+ and Co 2+ within the same time frame. It is noteworthy that PHs are more hydrophobic and recalcitrant than phenolic compounds, and this might be responsible for the lower degradation observed in the bacterial strains than the findings of Verma and Singh . Apparently, 5.0 mM is not toxic enough to impede metabolic potential of the strains investigated, and thus incapable of retarding degradation of the PHs.…”

“… demonstrated that low concentrations of Zn 2+ and Mn 2+ (1–10 mg l −1 ) stimulated biomass growth of Ochrobactrum cytisi on tert ‐butyl ether, unlike Ni 2+ (1–4 mg l −1 ) that retarded the growth. Moreover, Brevibacterium casei was reportedly reduced 78% Cr 6+ along with 82% degradation of pentachlorophenol simultaneously . In the contrary, Ni has been found to inhibit bacterial utilization of PHs in contaminated soils .…”

Simultaneous Bioremediation of Phenol and Cr (VI) from Tannery Wastewater Using Bacterial Consortium

“…Similarly at 200 rpm, complete phenol removal and up to 78% removal of Cr (VI) were detected at 96 h of treatment. Verma and Singh (2013) have observed increased reduction of pentachlorophenol and Cr (VI) with increased in agitation speed up to 120 rpm using Brevibacterium casei. However, the authors reported lower reduction of contaminants with further increase in agitation speed which is contrary to our findings.…”

Isolation and Identification of Biosurfactant Producing Chromate Resistant Bacteria Isolated From Chromium Contaminated Site.

“…have been earlier used for the treatment of metal contaminated waste. However, these treatments are very expensive, require large amount of chemical and energy, produce secondary waste into the environment and affect soil texture (Szpyrkowicz et al, 2001;Verma and Singh, 2013). Bacteria show potential approach in this regard as they could adapt and inhabit such polluted environments and remediate the toxic metals by converting them into less toxic and easily disposable forms.…”