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An organophosphate (OP) degrading chemotactic bacterial strain BUR11 isolated from an agricultural field was identified as a member of Pseudomonas genus on the basis of its 16S rRNA gene sequence. The strain could utilize parathion, chlorpyrifos and their major hydrolytic intermediates as sole source of carbon for its growth and exhibited positive chemotactic response towards most of them. Optimum concentration of parathion for its growth was recorded to be 200 ppm and 62% of which was degraded within 96 h at 37 °C. Growth studies indicated the strain to be moderately thermo-halo tolerant in nature. Investigation based on identification of intermediates of parathion degradation by thin layer chromatography (TLC), high performance liquid chromatography (HPLC), gas chromatography (GC) and liquid chromatography mass spectrometry (LC-MS/MS) provided evidence for possible existence of two pathways. The first pathway proceeds via 4-nitrophenol (4-NP) while the second proceeds through formation of 4-aminoparathion (4-APar), 4-aminophenol (4-AP) and parabenzoquinone (PBQ). This is the first report of chemotaxis towards organophosphate compound by a thermo-halo tolerant bacterium.

Tuberculosis, a life threatening disease caused by different strains of Mycobacterium tuberculosis is creating an alarming condition due to the emergence of increasing multi drug resistance (MDR) trait. In this study, in silico approach was used for the identification of a conserved novel virulent factor in Mycobacterium tuberculosis EAI5 (Accession no.CP006578) which can also act as potential therapeutic target. Systematic comparative search of genes that are common to strain EAI5 and other human pathogenic strains of M. tuberculosis enlisted 408 genes. These were absent in the non-pathogenic Mycobacterium smegmatis MC2155 and in the human genome. Among those genes, only the protein coding hypothetical genes (97 out of 408) and their corresponding products were selected for further exploration. Of these, 11 proteins were found to have notable conserved domains, of which one hypothetical protein (NCBI Acc No. AGQ35418.1) was selected for further in silico exploration which was found to have two functional domains, one having phosphatidylinositol specific phospholipase C (PI-PLC) activity while the other short domain with weak lectin binding activity. As PI-PLC contributes virulence property in some pathogenic bacteria with a broad range of activities, different bioinformatic tools were used to explore its physicochemical and other important properties which indicated its secretary nature. This PI-PLC was previously not reported as drug/vaccine target to the best of our knowledge. Its predicted 3D structure can be explored for development of inhibitor for novel therapeutic strategies against MDR-TB.

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The objective of this study was to understand the possible fate of 4-NP through the molecular mechanism and to identify potential enzymes involved in 4-NP biodegradation by Rhodococcus sp. strain BUPNP1. Biodegradation of 4-NP was detected spectrophotometrically at 400 nm and also confirmed by TLC and HPLC. Comparative study of proteomes was performed by 2-D gel electrophoresis followed by peptide mass fingerprinting and bioinformatic analysis to identify and/ or predict the possible functions of over-expressed proteins in 4-NP treated cells of BUNP1. Utilization of 4nitrophenol and its hydrolysis intermediate 4-nitrocatechol (4-NC) and 1,2,4-Benzenetriol as sole carbon source indicated the presence of genomic information encoding the enzyme necessary for the operation of 4-nitrophenol degradation pathway in the strain BUPNP1. It could transform 4-NP into 4-NC by monooxygenase whose major activity was detected during initial stage of degradation. The 4-NC further depleted in the medium to release nitrite ions. In order to investigate the molecular changes occurring d u r i n g d e g r a d a t i o n , a comparative study of proteome profiles was carried out where; 4nitrophenol treated cells were compared against cells grown on glucose as control. The comparative study indicated expression of several protein spots under 4-nitrophenol treated condition. This study showed the potential of BUPNP1 strain belonging to genus Rhodococcus towards induced expression of some unique proteins which might have possible role in 4-NP biodegradation process.

A bacterial strain, designated as MemCl4, capable of utilizing chlorpyrifos as sole source of carbon was isolated by enrichment culture from an agricultural soil sample of Burdwan District, West Bengal, India. It was identified as Acinetobacter sp. by using phenotypic and 16S rRNA gene-based molecular phylogenetic approach. The strain could degrade 98 % of chlorpyrifos within 144 h. Through thin layer chromatography, high-performance liquid chromatography and gas chromatographymass spectrometry analyses, 3,5,6 trichloro-2-pyridinol (TCP) was identified as the only major intermediate during such degradation. The strain could also utilize TCP as sole source of carbon for growth. Degradation studies indicated utilization of chlorpyrifos with formation TCP, followed by decrease in amount of TCP with gradual passage of time. This indicated evidence of mineralization of both chlorpyrifos and TCP by the strain. The Gram-negative and esterase-positive strain was capable of tolerating various heavy metal salts such as arsenite, arsenate, cadmium, chromium, copper, iron, lead, nickel and zinc on sucrose low-phosphate medium. The strain MemCl4 might be considered biotechnologically potential for bioremediation and or restoration of chlorpyrifos-contaminated agricultural fields. This is the first report of a chlorpyrifos-degrading, heavy metal-tolerant bacterium belonging to the genus Acinetobacter, to the best of our knowledge. The strain, however, could not degrade chlorpyrifos in the presence of two heavy metal salts tested (viz. arsenate and zinc sulfate).