New insights into the biodegradation of chlorpyrifos by a novel bacterial consortium: Process optimization using general factorial experimental design.

Himalayan mountains are subjected to the intensive and unjudicial application of chlorpyrifos (CP) in agricultural practices; hence it has spurred concerns over food safety and environmental consequences. These low-temperature mountainous regions are foremost ecosystems, representing the large-scale distribution of cold trapped CP residues. A bacterial consortium ECO-M was formed by isolating the CP degrading bacterial strains viz Agrobacterium tumefaciens strain ECO1, Cellulosimicrobium funkei strain ECO2, Shinella zoogloeoides strain ECO3 and Bacillus aryabhattai strain ECO4. At an initial concentration of 50 mg L-1, consortium ECO-M degraded 100% of CP within 6 days. Emergence and subsequent degradation of the two metabolites, 3, 5, 6-trichloro-2-pyridinol (TCP) and 2-hydroxypyridine were confirmed by GC-MS analysis. A degradation pathway of CP by isolated strains has been proposed. A general factorial experimental design was effectuated to prognosticate the optimum biodegradation by manifesting the optimal biological and physicochemical factors. Fitness of the experimental design was affirmed experimentally by employing optimized factors i.e., temperature 30 °C, CP concentration 50 mg L-1 and an inoculum size of 10% (v/v). The model appropriacy and the rationality of the optimization procedure were appraised by installing an in-situ microcosms experiment using the real contaminated soil collected from the Himalayan mountain ecosystem. The augmentation culture seems to be effectively conspicuous in stimulating maximum degradation up to 94.3% in the CP contaminated soil.

Technological advancement in electrochemical biosensor based detection of Organophosphate pesticide chlorpyrifos in the environment: A review of status and prospects.

Chlorpyrifos (CP), an organophosphate insecticide is broadly used in the agricultural and industrial sectors to control a broad-spectrum of insects of economically important crops. CP detection has been gaining prominence due to its widespread contamination in different environmental matrices, high acute toxicity, and potential to cause long-term environmental and ecological damage even at trace levels. Traditional chromatographic methods for CP detection are complex and require sample preparation and highly skilled personnel for their operation. Over the past decades, electrochemical biosensors have emerged as a promising technology for CP detection as these circumvent deficiencies associated with classical chromatographic techniques. The advantageous features such as appreciable detection limit, miniaturization, sensitivity, low-cost and onsite detection potential are the propulsive force towards sustainable growth of electrochemical biosensing platforms. Recent development in enzyme immobilization methods, novel surface modifications, nanotechnology and fabrication techniques signify a foremost possibility for the design of electrochemical biosensing platforms with improved sensitivity and selectivity. The prime objective of this review is to accentuate the recent advances in the design of biosensing platforms based on diverse biomolecules and biomimetic molecules with unique properties, which would potentially fascinate their applicability for detection of CP residues in real samples. The review also covers the sensing principle of the prime biomolecule and biomimetic molecule based electrochemical biosensors along with their analytical performance, advantages and shortcomings. Present challenges and future outlooks in the field of electrochemical biosensors based CP detection are also discussed. This deep analysis of electrochemical biosensors will provide research directions for further approaching towards commercial development of the broad range of organophosphorus compounds.

Isolation and Characterization of Fipronil Degrading Acinetobacter calcoaceticus and Acinetobacter oleivorans from Rhizospheric Zone of Zea mays.

An enrichment culture technique was used for the isolation of bacteria capable of utilizing fipronil as a sole source of carbon and energy. Based on morphological, biochemical characteristics and phylogenetic analysis of 16S rRNA sequence, the bacterial strains were identified as Acinetobacter calcoaceticus and Acinetobacter oleivorans. Biodegradation experiments were conducted in loamy sand soil samples fortified with fipronil (50 µg kg(-1)) and inoculated with Acinetobacter sp. cells (45 × 10(7) CFU mL(-1)) for 90 days. Soil samples were periodically analyzed by gas liquid chromatography equipped with electron capture detector. Biodegradation of fipronil fitted well with the pseudo first-order kinetics, with rate constant value between 0.041 and 0.051 days(-1). In pot experiments, fipronil and its metabolites fipronil sulfide, fipronil sulfone and fipronil amide were found below quantifiable limit in soil and root, shoot and leaves of Zea mays. These results demonstrated that A. calcoaceticus and A. oleivorans may serve as promising strains in the bioremediation of fipronil-contaminated soils.

Degradation of fipronil by Stenotrophomonas acidaminiphila isolated from rhizospheric soil of Zea mays.

Fipronil is a widely used insecticide in agriculture and can cause potential health hazards to non-target soil invertebrates and nearby aquatic systems. In the present study, a fipronil degrading bacterium was isolated from fipronil contaminated soil, i.e. rhizospheric zone of Zea mays. Morphological, biochemical and molecular characterization of strain indicated that it clearly belongs to Stenotrophomonas acidaminiphila (accession no. KJ396942). A three-factor Box-Behnken experimental design combined with response surface modeling was employed to predict the optimum conditions for fipronil degradation. The optimum pH, temperature and total inocula biomass for the degradation of fipronil were 7.5, 35 °C and 0.175 g L-1, respectively. The bacterial strain was able to metabolize 25 mg L-1 fipronil with 86.14 % degradation in Dorn's broth medium under optimum conditions. Metabolites formed as a result of fipronil degradation were characterized with gas liquid chromatograph. A novel fipronil degradation pathway was proposed for S. acidaminiphila on the basis of metabolites formed. Non-sterilized soil inoculated with S. acidaminiphila was found to follow first order kinetics with a rate constant of 0.046 d-1. Fipronil sulfone, sulfide and amide were formed as the metabolites and were degraded below the quantifiable limit after 90 days of time period. Given the high fipronil degradation observed in the present study, S. acidaminiphila may have potential for use in bioremediation of fipronil contaminated soils.

Evaluating the potential of immobilized bacterial consortium for black liquor biodegradation.

Two indigenous bacterial strains, Bacillus megaterium ETLB-1 (accession no. KC767548) and Pseudomonas plecoglossicida ETLB-3 (accession no. KC767547), isolated from soil contaminated with paper mill effluent, were co-immobilized on corncob cubes to investigate their biodegradation potential against black liquor (BL). Results exhibit conspicuous reduction in color and lignin of BL upto 913.46 Co-Pt and 531.45 mg l(-1), respectively. Reduction in chlorophenols up to 12 mg l(-1) was recorded with highest release of chloride ions, i.e., 1290 mg l(-1). Maximum enzyme activity for lignin peroxidase (LiP), manganese peroxidase (MnP), and laccase (LAC) was recorded as 5.06, 8.13, and 8.23 U ml(-1), respectively, during the treatment. Scanning electron microscopy (SEM) revealed successful immobilization of bacterial strains in porous structures of biomaterial. Gas chromatography/mass spectroscopy (GC/MS) showed formation of certain low molecular weight metabolites such as 4-hydroxy-benzoic acid, 3-hydroxy-4-methoxybenzaldehyde, ferulic acid, and t-cinnamic acid and removal of majority of the compounds (such as teratogenic phthalate derivatives) during the period of treatment. Results demonstrated that the indigenous bacterial consortium possesses excellent decolorization and lignin degradation capability which enables its commercial utilization in effluents treatment system.