Dileep N. Deobagkar

Structural chemistry and In vitro antitubercular activity of acetylpyridine benzoyl hydrazone and its copper complex against Mycobacterium smegmatis.

Acetylpyridine benzoyl hydrazone (APBH) 1 and its copper complex [[(APBH)CuCl](2)].(EtOH) 2 were structurally characterized by elemental analysis, magnetic measurements, spectroscopy, electrochemistry and single crystal X-ray diffraction studies. The ligand assumes Z-isomeric form and planar geometry in solid state, coordinating through pyridyl nitrogen, azomethine nitrogen and the carbonyl oxygen of the benzoyl group. The copper complex is dimeric and has a distorted octahedral geometry in which the two copper atoms are bridged by two chloride atoms. Antimycobacterial screening of ligand and its copper compound against Mycobacterium smegmatis shows clear enhancement in the antitubercular activity upon copper complexation.

Potential application of protease isolated from Pseudomonas aeruginosa PD100

A protease isolated from Pseudomonas aeruginosa PD100 could act in the presence of SDS and Tween 80. This protease could be useful for degradation of protein in the presence of solvent, dehairing of cow skin and degradation of natural proteins. The immobilized protease showed 15-20% increases in temperature stability and the entrapped enzyme retained 83% of its initial activity after six cycles. With respect to properties of the enzyme and its capability for degradation of different protein sources, this protease finds potential application for waste treatment, used in detergents and leather industry. Proteases execute a large variety of functions and have important biotechnological applications. Proteases represent one of the three largest groups of industrial enzymes and find application in detergents, leather industry, food industry, pharmaceutical industry and bioremediation processes (Anwar and Saleemuddin, 1998; Gupta et al. 2002). Probably the largest application of proteases is in laundry detergents, where they help removing protein based stains from clothing (Banerjee et al. 1999). For an enzyme to be used as an detergent additive it should be stable and active in the presence of typical

Serratia odorifera a Midgut inhabitant of Aedes aegypti mosquito enhances its susceptibility to dengue-2 virus

Mosquito midgut plays a crucial role in its vector susceptibility and pathogen interaction. Identification of the sustainable microflora of the midgut environment can therefore help in evaluating its contribution in mosquito-pathogen interaction and in turn vector competence. To understand the bacterial diversity in the midgut of Aedes aegypti mosquitoes, we conducted a screening study of the gut microbes of these mosquitoes which were either collected from fields or reared in the laboratory “culture-dependent” approach. This work demonstrated that the microbial flora of larvae and adult Ae. aegypti midgut is complex and is dominated by Gram negative proteobacteria. Serratia odorifera was found to be stably associated in the midguts of field collected and laboratory reared larvae and adult females. The potential influence of this sustainable gut microbe on DENV-2 susceptibility of this vector was evaluated by co-feeding S. odorifera with DENV-2 to adult Ae. aegypti females (free of gut flora). The observations revealed that the viral susceptibility of these Aedes females enhanced significantly as compared to solely dengue-2 fed and another gut inhabitant, Microbacterium oxydans co-fed females. Based on the results of this study we proposed that the enhancement in the DENV-2 susceptibility of Ae. aegypti females was due to blocking of prohibitin molecule present on the midgut surface of these females by the polypeptide of gut inhabitant S. odorifera.

Adaptive larval thermotolerance and induced cross‐tolerance to propoxur insecticide in mosquitoes Anopheles stephensi and Aedes aegypti

Abstract. Fourth‐instar larvae of mosquitoes Anopheles stephensi and Aedes aegypti normally died within 90 min at 43d̀C. Pre‐exposure to high but sublethal temperatures conferred adaptive thermotolerance, dependent on the temperature and the duration of pre‐exposure. Adaptive cross‐tolerance to propoxur (a carbamate insecticide) was also induced in larvae by pre‐exposing them to sublethal temperatures. Pre‐exposure to sublethal concentrations of propoxur was found to confer cross‐thermotolerance to a lower extent. These results suggest that the shock proteins (e.g. heat shock proteins) induced by unrelated stress factors play an important role in the development of adaptive cross‐protection (stress response) to other stress conditions.

Dengue-2-virus-interacting polypeptides involved in mosquito cell infection.

For the design of effective antiviral strategies, understanding the fundamental steps of the virus life cycle, including virus–host interactions, is essential. We performed a virus overlay protein binding assay followed by proteomics for identification of proteins from membrane fractions of A7 (Aedes aegypti) cells, C6/36 (Aedes albopictus) cells and the midgut brush border membrane fraction of Ae. aegypti mosquito that bind to dengue-2 virus. Actin, ATP synthase β subunit, HSc 70, orisis, prohibitin, tubulin β chain, and vav-1 were identified as dengue-2-virus-binding proteins. Our results suggest that dengue-2 virus exploits an array of housekeeping proteins for its entry in mosquito cells.

Synthesis and extracellular accumulation of silver nanoparticles by employing radiation-resistant Deinococcus radiodurans , their characterization, and determination of bioactivity

There has been rapid progress in exploring microorganisms for green synthesis of nanoparticles since microbes show extraordinary diversity in terms of species richness and niche localization. Microorganisms are easy to culture using relatively inexpensive and simple nutrients under varied conditions of temperature, pressure, pH, etc. In this work, Deinococcus radiodurans that possesses the ability to withstand extremely high radiation and desiccation stress has been employed for the synthesis of silver nanoparticles (AgNPs). D. radiodurans was able to accumulate AgNPs in medium under various conditions, and process optimization was carried out with respect to time, temperature, pH, and concentration of silver salt. AgNPs were characterized using UV/vis spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, and Fourier transform infrared spectroscopy. The microbially synthesized AgNPs exhibited good antimicrobial activity against both Gram-negative and Gram-positive organisms and anti-biofouling activity. Their ability to inhibit growth and proliferation of cancer cell line was also examined, and it could be seen that AgNPs synthesized using D. radiodurans exhibited excellent anticancer activity.

THE GLUCANASES OF CELLULOMONAS

Cellulomonas is a unique bacterium possessing not only the capacity to degrade various carbohydrates, such as starch, xylan and cellulose, but crystalline cellulose as well. It has developed a complex battery of glucanases to deal with substrates possessing such extensive microheterogeneities. Some of these enzymes are multifunctional, as well as cross inducible, possessing a multi-domain structure; these enzymes are thought to have arisen by the shuffling of these domains. Intergeneric hybrids have been constructed between Cellulomonas and Zymomonas so as to enhance the industrial potential of this organism. This review examines the unique features of this microorganism and evaluates its key role in the conversion of complex wastes to useful products, by virtue of its unusual attributes.

Transfer of DNA coding for cellulases from Cellulomonas species to Bacillus subtilis by protoplast fusion

SummaryCellulose utilising hybrids between Cellulomonas spp. and Bacillus subtilis were isolated after PEG mediated protoplast fusion. These stable hybrids selected using genomic markers harboured DNA from both the parents. Higher CMCase and β-glucosidase activities were detected extracellularly in case of one of the hybrids unlike only CMCase in case of Cellulomonas.

Hyper production of β-glucosidase by an Aspergillus sp.

SummaryAn Aspergillus sp. was isolated which secreted high levels of β-glucosidase in growth medium. The maximum activity(10 IU/ml of β-glucosidase and 22.6 IU/ml of cellobiase) was obtained in cellulose medium supplemented with wheat bran. The pH and temperature optima for this enzyme were 4.5 and 65°C respectively.

Characterization of the role of the RadS/RadR two-component system in the radiation resistance of Deinococcus radiodurans

Deinococcus radiodurans shows extraordinary tolerance to DNA damage, and exhibits differential gene expression and protein recycling. A putative response regulator, the DRB0091 (RadR) ORF, was identified from a pool of DNA-binding proteins induced in response to gamma radiation in this bacterium. radR is located upstream of drB0090, which encodes a putative sensor histidine kinase (RadS) on the megaplasmid. Deletion of these genes both individually and together resulted in hypersensitivity to DNA-damaging agents and a delayed or altered double-strand break repair. A ΔradRradS double mutant and a ΔradR single mutant showed nearly identical responses to gamma radiation and UVC. Wild-type RadR and RadS complemented the corresponding mutant strains, but also exhibited significant cross-complementation, albeit at lower doses of gamma radiation. The radS transcript was not detected in the ΔradR mutant, suggesting the existence of a radRS operon. Recombinant RadS was autophosphorylated and could catalyse the transfer of γ phosphate from ATP to RadR in vitro. These results indicated the functional interaction of RadS and RadR, and suggested a role for the RadS/RadR two-component system in the radiation resistance of this bacterium.