Optimisation of biodegradation conditions for waste canola oil by cold-adapted Rhodococcus sp. AQ5-07 from Antarctica

BACKGROUND: The potential waste canola oil-degrading ability of the cold-adapted Antarctic bacterial strain Rhodococcus sp. AQ5-07 was evaluated. Globally, increasing waste from food industries generates serious anthropogenic environmental risks that can threaten terrestrial and aquatic organisms and communities. The removal of oils such as canola oil from the environment and wastewater using biological approaches is desirable as the thermal process of oil degradation is expensive and ineffective. RESULTS: Rhodococcus sp. AQ5-07 was found to have high canola oil-degrading ability. Physico-cultural conditions influencing its activity were studied using one-factor-at-a-time (OFAT) and statistical optimisation approaches. Considerable degradation (78.60%) of 3% oil was achieved by this bacterium when incubated with 1.0 g/L ammonium sulphate, 0.3 g/L yeast extract, pH 7.5 and 10% inoculum at 10°C over a 72-h incubation period. Optimisation of the medium conditions using response surface methodology (RSM) resulted in a 9.01% increase in oil degradation (87.61%) when supplemented with 3.5% canola oil, 1.05 g/L ammonium sulphate, 0.28g/L yeast extract, pH 7.5 and 10% inoculum at 12.5°C over the same incubation period. The bacterium was able to tolerate an oil concentration of up to 4.0%, after which decreased bacterial growth and oil degradation were observed. CONCLUSIONS: These features make this strain worthy of examination for practical bioremediation of lipid-rich contaminated sites. This is the first report of any waste catering oil degradation by bacteria originating from Antarctica.

Nutrients and culture conditions requirements for the degradation of phenol by Rhodococcus UKMP-5M.

The capability of Rhodococcus UKMP-5M, isolated from petroleum contaminated soil, in the degradation of phenol was studied using shake flask culture. The effect of nutrients and cultivation conditions on growth of this bacterium and phenol degradation was investigated. Among the different types of medium tested (M1, M2, M3 and M4), M1 was found to be the preferred medium for growth of this bacterium and phenol degradation. The optimized cultivation conditions for growth of Rhodococcus UKMP-5M and phenol degradation were; 30oC, initial pH 7.5 and buffer concentration ranged from 5 to 50 mM. Improvement of growth and phenol degradation was achieved in medium supplemented with 2 g l-1 glucose. In addition, NaCl at a concentration of 0.1 g l-1 was required to enhance growth and phenol degradation. The addition of 0.4 g l-1 (NH4)2SO4 into the culture medium greatly enhanced phenol degradation. At optimal medium composition and cultivation condition, Rhodococcus UKMP-5M was able to utilize phenol at concentration up to 900 mg l-1. Results of this study showed that Rhodococcus UKMP-5M has potential to be used in the degradation of phenol.