Enhanced chrysene degradation by a mixed culture Biorem-CGBD using response surface design.

Degradation of chrysene, a four ringed highly carcinogenic polycyclic aromatic hydrocarbon (PAH) has been demonstrated by bacterial mixed culture Biorem-CGBD comprising Achromobacter xylosoxidans, Pseudomonas sp. and Sphingomonas sp., isolated from crude oil polluted saline sites at Bhavnagar coast, Gujarat, India. A full factorial Central Composite Design (CCD) using Response Surface Methodology (RSM) was applied to construct response surfaces, predicting 41.93% of maximum chrysene degradation with an experimental validation of 66.45% chrysene degradation on 15th day, using a combination of 0.175, 0.175 and 0.385 mL of OD600 = 1 inoculum of A. xylosoxidans, Pseudomonas sp. and Sphingomonas sp., respectively and a regression coefficient (R2) of 0.9485 indicating reproducibility of the experiment. It was observed that chrysene degradation can be successfully enhanced using RSM, making mixed culture Biorem-CGBD a potential bioremediation target for PAH contaminated saline sites.

Application of response surface methodology for rapid chrysene biodegradation by newly isolated marine-derived fungus Cochliobolus lunatus strain CHR4D.

For the first time, Cochliobolus lunatus strain CHR4D, a marine-derived ascomycete fungus isolated from historically contaminated crude oil polluted shoreline of Alang-Sosiya ship-breaking yard, at Bhavnagar coast, Gujarat has been reported showing the rapid and enhanced biodegradation of chrysene, a four ringed high molecular weight (HMW) polycyclic aromatic hydrocarbon (PAH). Mineral Salt Broth (MSB) components such as ammonium tartrate and glucose along with chrysene, pH and trace metal solution have been successfully optimized by Response Surface Methodology (RSM) using central composite design (CCD). A validated, two-step optimization protocol has yielded a substantial 93.10% chrysene degradation on the 4(th) day, against unoptimized 56.37% degradation on the 14(th) day. The results depict 1.65 fold increase in chrysene degradation and 1.40 fold increase in biomass with a considerable decrement in time. Based on the successful laboratory experiments, C. lunatus strain CHR4D can thus be predicted as a potential candidate for mycoremediation of HMW PAHs impacted environments.

Enhanced biodegradation of total polycyclic aromatic hydrocarbons (TPAHs) by marine halotolerant Achromobacter xylosoxidans using Triton X-100 and ß-cyclodextrin--a microcosm approach.

Ability of Achromobacter xylosoxidans, a chrysene degrading marine halotolerant bacterium to degrade polycyclic aromatic hydrocarbons (PAHs) using a cost effective laboratory microcosm approach, was investigated. Effect of variables as chrysene, glucose as a co-substrate, Triton X-100 as a non-ionic surfactant and ß-cyclodextrin as a PAHs solubilizer was examined on degradation of low molecular weight (LMW) and high molecular weight (HMW) PAHs. A total of eleven PAHs detected from polluted saline soil were found to be degraded. Glucose, in combination with Triton X-100 and ß-cyclodextrin resulted in 2.8 and 1.4-fold increase in degradation of LMW PAHs and 7.59 and 2.23-fold increase in degradation of HMW PAHs, respectively. Enhanced biodegradation of total PAHs (TPAHs) by amendments with Triton X-100 and ß-cyclodextrin using Achromobacter xylosoxidans can prove to be promising approach for in situ bioremediation of marine sites contaminated with PAHs.

Enhanced chrysene degradation by halotolerant Achromobacter xylosoxidans using Response Surface Methodology.

Degradation of chrysene, a four ring High Molecular Weight (HMW) Polycyclic Aromatic Hydrocarbon (PAH) is of intense environmental interest, being carcinogenic, teratogenic and mutagenic. Multiple PAH degrading halotolerant Achromobacter xylosoxidans was isolated from crude oil polluted saline site. Response Surface Methodology (RSM) using Central Composite Design (CCD) of Bushnell-Haas medium components was successfully employed for optimization resulting 40.79% chrysene degradation on 4th day. The interactions between variables as chrysene and glucose concentrations, pH and inoculum size on degradation were examined by RSM. Under optimum conditions, A. xylosoxidans exhibited 85.96% chrysene degradation on 5th day. The optimum values predicted by RSM were confirmed through confirmatory experiments. It was also noted that pH and glucose as co-substrate play a dynamic role in enhancement of chrysene degradation. Hence, A. xylosoxidans can be further used for subsequent microcosm and in situ experiments for its potential to remediate PAH contaminated saline and non-saline soils.