Biotransformation as a tool for remediation of polycyclic aromatic hydrocarbons from polluted environment - review on toxicity and treatment technologies.

Polycyclic aromatic hydrocarbons, a prominent family of persistent organic molecules produced by both anthropogenic and natural processes, are widespread in terrestrial and aquatic environments owing to their hydrophobicity, electrochemical stability and low aqueous solubility. Phenanthrene and naphthalene belong to the group of polycyclic aromatic hydrocarbons whose occurrence are reported to be relatively higher. The bioremediation mode of removing the toxicities of these two compounds has been reported to be promising than other methods. Most of the microbial classes of bacterial, fungal and algal origin are reported to degrade the target pollutants into non-toxic compounds effectively. The review aims to give an overview on toxicological studies, identification and enrichment techniques of phenanthrene and naphthalene degrading microbes and the bioremediation technologies (microbial assisted reactors, microbial fuel cells and microbial assisted constructed wetlands) reported by various researchers. All the three modes of bioremediation techniques were proved to be promising on different perspectives. In the treatment of phenanthrene, a maximum recovery of 96% and 98% was achieved in an aerobic membrane reactor with Bacillus species and single chamber air cathode microbial fuel cell with Acidovorax and Aquamicrobium respectively were reported. With the constructed wetland configuration, 95.5% of removal was attained with manganese oxide based microbial constructed wetland. The maximum degradation efficiency reported for naphthalene are 99% in a reverse membrane bioreactor, 98.5% in a marine sediment microbial fuel cell and 92.8% with a low-cost sandy soil constructed wetland.

Laccase production from Bacillus aestuarii KSK using Borassus flabellifer empty fruit bunch waste as a substrate and assessing their malachite green dye degradation.

AIMS: The lignocellulosic waste, Borassus flabellifer empty fruit bunch waste (BFEFBW), was employed to produce laccase using Bacillus aestuarii KSK under solid-state fermentation (SSF) conditions and to assess the efficiency of malachite green (MG) dye decolourization. METHODS AND RESULTS: Abiotic factors such as pH (5.0-9.0), temperature (25-45°C) and incubation time (24-96 h) were optimized using Response surface methodology-Box-Behenan Design (RSM-BBD) to exploit the laccase production. The anticipated model revealed that the highest laccase activity of 437 U/ml shows after 60 h of incubation at 35°C at pH 7.0. The bacterial laccase was used to remove 89% of the MG dye in less time. CONCLUSION: The laccase from B. aestuarii KSK decolorizes the MG and thereby making it a suitable choice for wastewater treatment from industrial effluents. SIGNIFICANCE AND IMPACT OF THE STUDY: This study is the first report on the production of laccase from B. flabellifer empty fruit bunch waste as a substrate. Bacillus aestuarii KSK was isolated from the soil sample and used to produce laccase under SSF conditions. The bacterial laccase has the potential for industrial application in textile waste dye treatment.

Enhanced photocatalytic activity of novel Canthium coromandelicum leaves based copper oxide nanoparticles for the degradation of textile dyes.

The present study focused to synthesize the copper oxide nanoparticles (CuONPs) using novel Canthium coromandelicum leaves in a cost-effective, easy, and sustainable approach. The obtained Canthium coromandelicum-copper oxide nanoparticles (CC-CuONPs) were characterized using UV-Visible spectroscopy, FT-IR analysis, FESEM, HR-TEM imaging, and XRD study. The XRD pattern verified the development of crystalline CC-CuONPs with an average size of 33 nm. The biosynthesized CC-CuONPs were roughly spherical, according to HR-TEM and FESEM analyses. FT-IR research verified the existence of functional groups involved in CC-CuONPs production. Cu and O2 have high-energy signals of 78.32% and 12.78%, respectively, according to data from EDX. The photocatalytic evaluation showed that synthesized CC-CuONPs have the efficiency of degrading methylene blue (MB) and methyl orange (MO) by 91.32%, 89.35% respectively. The findings showed that biosynthesized CC-CuONPs might effectively remove contaminants in an environmentally acceptable manner.

Impact of an organic formulation (panchakavya) on the bioleaching of copper and lead in contaminated mine soil.

The study was aimed to evaluate the potential of organic formulation, panchakavya, for enhancing the biological leaching of Pb and Cu in contaminated mine soil. Response surface methodology based Box-Behnken design was used to optimize the variables such as incubation time, panchakavya concentration, and agitation rate. The maximum bioleaching (Pb=64% and Cu=49%) was observed after 54 h of incubation with 10 mL panchakavya at 120 rpm. Statistics-based contour and three-dimensional plots were generated to understand the relationship between Pb and Cu bioleaching and variables. High-performance liquid chromatography analysis showed the presence of lactic (25.88 mg g(-1)), citric (0.14 mg g(-1)), succinic (0.14 mg g(-1)), malic (0.66 mg g(-1)), and acetic (0.44 mg g(-1)) acids in panchakavya, which may have a vital role in the removal of metals from the contaminated soil. Soil fraction studies indicate a significant increase of Pb (45%) in the exchangeable fraction of panchakavya-treated soil. XRD studies confirmed the role of panchakavya induced calcite and other minerals in the precipitation of metal ions. A significant increase in the enzyme activities of phosphatase, dehydrogenase, urease, amylase, invertase, and cellulase were observed in the panchakavya-treated soil.