Polycyclic aromatic hydrocarbons (PAHs) at the Gulf of Kutch, Gujarat, India: Occurrence, source apportionment, and toxicity of PAHs as an emerging issue.

The present study extrapolates the assessment and characterization of a barely studied region, the Gulf of Kutch, (near Jamnagar), Gujarat, India, in terms of PAH exposure, adverse effects caused by them, and various toxicological indices showing the catastrophic effects of their elevated concentrations. ΣPAH concentration in the site ranged from 118,280 to 1,099,410ngg-1 dw, with a predominance of 2-3-ring PAHs (79.09%) as compared to 4-5- and 6-ring PAHs (20.91%). The concentrations of carcinogenic PAHs were found to be between 8120 and 160,000ngg-1 dw, with a mean of 63,810ngg-1 dw, which is much higher than normal acceptable values. The toxic equivalent quotient for 6CPAHs ranged from 150.47 to 26,330ngg-1 BaPeq, encompassing 50.63% of ΣPAH toxicity. This toxicological profile of the present study site would be of paramount importance as it offers fresh information regarding the load of legacy pollutants such as PAHs and the inputs and methods to cope with their extremely high concentrations in less explored marine habitats.

Distribution, sources and ecological risk assessment of PAHs in historically contaminated surface sediments at Bhavnagar coast, Gujarat, India.

The concentration, distribution and ecological risk of polycyclic aromatic hydrocarbons (PAHs) have been investigated in surface sediments near Bhavnagar coast. The concentration of ∑PAHs ranged from 5.02 to 981.18 µg g(-1) dry weight, indicating heavy pollution compared to other historically polluted study sites. It was found to be introduced via mixed origins such as burning of gas, oil, coal, production of petrochemicals, cement, and rubber tires. Domestic fuel burning and motor vehicles are also culprits for air pollution. Industrial effluents and accidental oil spillage can also be considered. PAHs can be exposed through air, water, soil and food sources including ingestion, inhalation, and dermal content in both occupational and non-occupational levels by single or sometimes multiple exposures routes concomitantly. Furthermore, diagnostic ratios, statistical principal component analysis (PCA) and hierarchical cluster analysis (HCA) models have confirmed that the sources of PAHs were both - petrogenic and pyrogenic. For both the sites, assessment of ecological risk of the elevated levels of these pollutants has been exercised based on toxic equivalency factors (TEFs) and risk quotient (RQ) methods. The composite results indicated accurately that both the sites, bears potentially acute and chronic health hazards such as decreased immune functionality, genotoxicity, malignancy and developmental malfunctions in humans. The sites studied here and the workers have been exposed to hazardous pollutants for a longer period of time. Evidences indicate that mixtures of PAHs are carcinogenic to humans, based on occupational studies on workers, exposed to these pollutants. Hence, the present study and statistical approaches applied herein clearly indicate the historic mix routes of PAHs that resulted in magnified concentrations leading to high ecosystem risk. Thus, the scientific communities are urged to develop strategies to minimize the concentrations of PAHs from the historically impacted coastlines, thereby concerning for the future investigations and restoration of these sites.

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.

Polyhydroxyalkanoate from marine Bacillus megaterium using CSMCRI's Dry Sea Mix as a novel growth medium.

Oceans have significant potential to empower mankind and thus marine organisms are believed to be an enormous source for useful biomolecules. Polyhydroxyalkanoates (PHAs) are biological macromolecules that can be applied in nearly all fields. In the present study, Bacillus megaterium strain JK4h has been exploited for maximum PHB production using novel Dry Sea Mix (DSM) via Central Composite Design (CCD) of Response Surface Methodology (RSM) approach. The isolate was found to be producing 56.77% Cell Dry Weight (CDW) of PHAs within 24h, with optimized combinations of peptone, yeast extract and glucose. The PHB yield had been increased 2.61 fold compared to un-optimized experiments. The obtained PHA/PHB had been chemically characterized through Nuclear Magnetic Resonance (NMR), Fourier Transform Infrared Spectroscopy (FTIR), Thermo Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC). The results indicate the successful optimization for maximum production of biological macromolecule and it was found to be highly pure polyhydroxybutyrate (PHB). Thus, DSM can be served as a novel and cost effective medium for PHA production offering the use of marine resources as a "green" sustainable alternative.

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.