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.

Laccase production by Myrothecium gramineum and its optimization under solid state fermentation using cowpea pod as substrate

The present study highlights the utilization of wastes such as cowpea outer pod generated from agro industries forlaccase production using Myrothecium gramineum LCJ177 under solid-state fermentation. Conventional methodswere used to optimize the process parameters. The classical one-factor-at-a-time method showed that the optimalstarch concentration was 1 g/L, peptone concentration was 0.5 g/L, copper sulfate concentration was 0.6 mM, andpyrogallol concentration was 0.8 mM. Likewise, the suitable physical conditions were an initial pH of five of theculture medium, the temperature of 30°C and moisture content of 60%. Utilization of dried cowpea outer pod as asubstrate reduces the pollution levels by converting agro-wastes as useful by-products.

Optimization of an Activity Assay of Coprinus Cinereus Peroxidase

ABSTRACT To seek a simple, rapid and sensitive Coprinus cinereus Peroxidase (CIP) activity assay, a convenient one-factor-at-a-time (OFAT) method and a response surface methodology (RSM) were used. The recombinant CIP expressed in Pichia pastoris was purified with the Ni-NTA spin column. Based on the results of catalytic efficiency (kcat/Km) analysis, 2,2'-azinobis (ethylbenzthiazoline -6-sulfonate) (ABTS) was selected as the optimal enzyme substrate. Results of the OFAT method showed that enzymatic reaction performed in 0.1 mol/L sodium acetate (pH 5.0) buffer in a 200-µl reaction mixture containing 0.5 mmol/L ABTS, 10 mmol/L hydrogen peroxide (H2O2), 49.7 ng CIP at 25°C gave an average CIP activity of 88 U/mL. The ABTS and H2O2 concentrations were then further optimized to improve the sensitivity of the assay. To do that, RSM was conducted through central composite design, and a reduced quadratic model with good fit regression equation was generated. ANOVA analysis of this model indicated that the concentrations of ABTS and H2O2 and their interaction had significant impact on the assay sensitivity. The optimal reaction mixture was determined to include an initial ABTS concentration of 0.82 mmol/L 49.7 ng CIP and 16.36 mmol/L H2O2, and the activity under this condition was determined to be 138.89 U/mL.