Milind Mohan Naik
Goa University
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Featured researches published by Milind Mohan Naik.
Ecotoxicology and Environmental Safety | 2013
Milind Mohan Naik; Santosh Kumar Dubey
Lead (Pb) is non-bioessential, persistent and hazardous heavy metal pollutant of environmental concern. Bioremediation has become a potential alternative to the existing technologies for the removal and/or recovery of toxic lead from waste waters before releasing it into natural water bodies for environmental safety. To our best knowledge, this is a first review presenting different mechanisms employed by lead resistant bacteria to resist high levels of lead and their applications in cost effective and eco-friendly ways of lead bioremediation and biomonitoring. Various lead resistant mechanisms employed by lead resistant bacteria includes efflux mechanism, extracellular sequestration, biosorption, precipitation, alteration in cell morphology, enhanced siderophore production and intracellular lead bioaccumulation.
Ecotoxicology and Environmental Safety | 2012
Milind Mohan Naik; Anju Pandey; Santosh Kumar Dubey
A bacterial isolate from Mandovi estuary Goa, India, which can resist 0.6mM lead nitrate in Tris-buffered minimal medium was identified as Pseudomonas aeruginosa and designated as strain WI-1. PCR amplification clearly revealed presence of bmtA gene encoding bacterial metallothionein responsible for metal sequestration and AAS analysis proved intracellular bioaccumulation of 26.5mg lead/gram dry weight of cells. SDS-PAGE analysis confirmed lead induced bacterial metallothionein with molecular weight 11 kDa, which corresponds to the predicted bmtA gene. Significant growth inhibition of phytopathogenic fungi Fusarium oxysporum NCIM 1008 by siderophore-rich culture supernatant was also observed. Pot experiment with Pisum sativum L inoculated with this strain revealed higher seed germination percentage and significant growth promotion than uninoculated seeds in a soil amended with 7.704 g/kg lead, which indicates amelioration of lead toxicity. This lead resistant strain showed cross tolerance to cadmium, mercury and Tributyltin chloride (TBTC) along with resistance to multiple antibiotics.
African Journal of Biotechnology | 2010
Anju Pandey; Milind Mohan Naik; Santosh Kumar Dubey
Identification and action of several antibacterial metabolites produced by a fish pathogen Vibrio parahaemolyticus strain An3 from marine ecosystem of Goa has been demonstrated. Antibacterial activity of the crude cell extract of the test bacterium has been evaluated against indicator pathogenic bacterial strains such as Acinetobacter sp. An2, Aeromonas hydrophila strain An4, Staphylococcus arlettae strain An1 and Alteromonas aurentia strain SE3 by agar well diffusion method which clearly demonstrated comparatively more significant inhibitory effect on indicator bacteria as compared to several commonly used antibiotics. Gas chromatography mass spectrometry (GC-MS) analysis of crude cell extract of the test organism interestingly revealed presence of indole, phenyl acetic acid, n-(3methyl-1, 2, 4-oxadiazol-5-yl) - 1- pyrrolidine carboximidamide, pyrrolopyrazines, tetramethyl pyrazine and other important phenolic compounds which may be responsible for antibacterial activity against indicator microorganisms tested. It has been clearly demonstrated that V. parahaemolyticus strain An3 produced several medically important organic metabolites during cultivation suggesting it as a potential candidate for production of several antibacterial metabolites to control pathogenic bacterial strains causing serious fish and human diseases.
Letters in Applied Microbiology | 2013
Milind Mohan Naik; Dnyanada S. Khanolkar; Santosh Kumar Dubey
A lead‐resistant bacteria isolated from soil contaminated with car battery waste were identified as Providencia alcalifaciens based on biochemical characteristics, FAME profile and 16S rRNA sequencing and designated as strain 2EA. It resists lead nitrate up to 0·0014 mol l−1 by precipitating soluble lead as insoluble light brown solid. Scanning electron microscopy coupled with energy‐dispersive X‐ray spectrometric analysis (SEM‐EDX) and X‐ray diffraction spectroscopy (XRD) revealed extracellular light brown precipitate as lead orthophosphate mineral, that is, Pb9 (PO4)6 catalysed by phosphatase enzyme. This lead‐resistant bacterial strain also demonstrated tolerance to high levels of cadmium and mercury along with multiple antibiotic resistance. Providencia alcalifaciens strain 2EA could be used for bioremediation of lead‐contaminated environmental sites, as it can efficiently precipitate lead as lead phosphate.
Journal of Marine Biology | 2010
Anju Pandey; Milind Mohan Naik; Santosh Kumar; Dubey
A pathogenic Aeromonas hydrophila strain An4 was isolated from marine catfish and characterized with reference to its proteolytic and hemolytic activity along with SDS-PAGE profile (sodium dodecyl sulphate-Polyacrylamide gel electrophoresis) of ECPs (extracellular proteins) showing hemolysin (approximately 50 kDa). Agar well diffusion assay using crude cell extract of the bacterial isolate clearly demonstrated antibacterial activity against indicator pathogenic bacteria, Staphylococcus arlettae strain An1, Acinetobacter sp. strain An2, Vibrio parahaemolyticus strain An3, and Alteromonas aurentia SE3 showing inhibitory zone >10 mm well comparable to common antibiotics. Further GC-MS analysis of crude cell extract revealed several metabolites, namely, phenolics, pyrrolo-pyrazines, pyrrolo-pyridine, and butylated hydroxytoluene (well-known antimicrobials). Characterization of EPS using FTIR indicated presence of several protein-related amine and amide groups along with peaks corresponding to carboxylic and phenyl rings which may be attributed to its virulent and antibacterial properties, respectively. Besides hemolysin, EPS, and protease, Aeromonas hydrophila strain An4 also produced several antibacterial metabolites.
Archive | 2012
Milind Mohan Naik; Anju Pandey; Santosh Kumar Dubey
Metals are an intrinsic part of the earth’s crust. With rapid industrialization and urbanization, enormous amounts of industrial wastes including metal wastes are accumulating, which require special treatment. Wastes from mining and metal refining industries, sewage sludge, power plant wastes and waste incineration plants often contain substantial amounts of toxic heavy metals viz. Hg, Cd, Pb, As, Sb, Zn, Cu which pose serious treat to the environment and need to be removed from the source of pollution. Microorganisms from metal polluted habitats possess a variety of inherent mechanisms to tolerate high levels of toxic metals which include precipitation of metals as phosphate, sulphide, carbonate; volatilization via methylation/ethylation; physical exclusion in membranes and extracellular polymeric substances (EPS); energy driven metal efflux system and intracellular sequestration mediated by metallothionein like proteins. For the last several decades, metal resistant microorganisms including marine bacteria have been considered a potential alternative for heavy metal recovery and bioremediation resulting in the development and refinement of many bioremediation technologies for removal of toxic metals form contaminated soils and aqueous mining and industrial wastes/effluents. Interestingly, these bioremediation technologies are economically viable, environmental friendly and value added processes.
Archive | 2017
Milind Mohan Naik; Santosh Kumar Dubey
With rapid industrialisation, enormous amounts of industrial waste including heavy metals have accumulated in marine environments over several decades and require special attention. Untreated wastes from mining, metal refining industries, battery manufacturing industries, sewage sludge, power plants and waste incineration plants often contain substantially high levels of lead (Pb) and mercury (Hg); when dumped into marine and estuarine waters, these pose serious threat to environmental biota and urgently need to be removed from polluted marine/estuarine sites. Lead and mercury are non-bioessential, persistent and hazardous heavy metal pollutants of environmental concern. Bioremediation of heavy metals using Pb- and Hg-resistant bacteria has become a potential alternative to the existing technologies for the removal and/or recovery of toxic Pb and Hg from waste waters before releasing it into marine/estuarine water bodies for environmental safety. Various strategies through which marine/estuarine bacteria resist high concentrations of lead/mercury include efflux mechanisms, extracellular sequestration, biosorption, precipitation, reduction, volatilisation, alteration in cell morphology, enhanced siderophore production, altered permeability, demethylation and intracellular bioaccumulation. These unique characteristics of marine/estuarine bacteria proved to be an ideal tool in bioremediation of lead and mercury from contaminated marine and estuarine environmental sites.
Thalassas: an International Journal of Marine Sciences | 2017
Milind Mohan Naik; Meghanath Shambhu Prabhu; Sanika Samant; Pranaya Milind Naik; Shilpa Shirodkar
This study focuses on the extracellular synthesis of silver nanoparticles (AgNPs), carried out using the culture supernatant of silver resistant Pseudomonas aeruginosa strain SN5 isolated from Mandovi estuarine mangrove water sample. AgNPs were characterized using X-Ray diffraction (XRD) analysis which showed high intensity peaks at 28° and 32.5°, characteristic of silver oxide (Ag2O) and confirmed its crystalline nature by referring Joint Committee on Powder Diffraction Standards (JCPDS), File No. 00–076-1393. Transmission electron microscopy (TEM) analysis revealed the nano sized AgNPS particles in the range of 35 nm – 60 nm. AgNPs showed antibacterial activity against both standard cultures of Gram positive and Gram negative bacterial human pathogens. Moreover, the AgNPs also showed antibacterial activity against ampicillin resistant Staphylococccus aureus strain VN3 and ciprofloxacin resistant Vibrio cholera strain VN1 isolated from Mandovi estuary, Goa India, polluted with human feces, domestic and hotel waste. These AgNPs exhibited better antibacterial activity as compared to AgNPs synthesized from plant extract of Honey suckle mistletoe and star anise. Interestringly, synergistic activity was observed when synthesized AgNPs were used in combination with antibiotics ampicillin and ciprofloxacin against ampicillin resistant Staphylococccus aureus strain VN3 and ciprofloxacin resistant Vibrio cholera strain VN1. Thus these AgNPs can be employed in cosmetics and wound dressings as a nanoweapon to control human bacterial pathogens.
Brazilian Journal of Microbiology | 2014
Dnyanada S. Khanolkar; Milind Mohan Naik; Santosh Kumar Dubey
A bacterial isolate capable of utilizing tributyltin chloride (TBTCl) as sole carbon source was isolated from estuarine sediments of west coast of India and identified as Pseudomonas stutzeri based on biochemical tests and Fatty acid methyl ester (FAME) analysis. This isolate was designated as strain DN2. Although this bacterial isolate could resist up to 3 mM TBTCl level, it showed maximum growth at 2 mM TBTCl in mineral salt medium (MSM). Pseudomonas stutzeri DN2 exposed to 2 mM TBTCl revealed significant alteration in cell morphology as elongation and shrinkage in cell size along with roughness of cell surface. FTIR and NMR analysis of TBTCl degradation product extracted using chloroform and purified using column chromatography clearly revealed biotransformation of TBTCl into Dibutyltin dichloride (DBTCl2) through debutylation process. Therefore, Pseudomonas stutzeri strain DN2 may be used as a potential bacterial strain for bioremediation of TBTCl contaminated aquatic environmental sites.
Biodegradation | 2012
Milind Mohan Naik; Anju Pandey; Santosh Kumar Dubey