Browsing by Author "Pramanik, Avijit"

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    Albomycin Uptake via a Ferric Hydroxamate Transport System of Streptococcus pneumoniae R6
    (JOURNAL OF BACTERIOLOGY, 2006-06) Pramanik, Avijit
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    Evaluation of bioactive secondary metabolites from endophytic fungus Pe stalotiopsis neglect a BAB-5510 isolated from leaves of Cupressus torulosa D.Don
    (3 Biotech, 2016) Pramanik, Avijit
    Six endophytic fungi were isolated from Cupressus torulosa D.Don and identified phenotypically and genotypically. The fungal cultures were further grown and the culture was extracted by two organic solvents methanol and ethyl acetate. The screening was carried out using the agar well diffusion method against human pathogen such as Escherichia coli, Salmonella typhimurium, Bacillus subtilis and Staphylococcus aureus. Isolated strain of Pestalotiopsis sp. was showing prominent antibacterial activity. The crude methanol and ethyl acetate extract of Pestalotiopsis sp. showed MIC of 6.25 mg/mL for S. typhimurium and S. aureus which showed its efficacy as a potent antimicrobial. The phytochemical screening revealed the existence of a diverse group of secondary metabolites in the crude extracts of the endophytic fungi that resembled those in the host plant extracts. On the basis of phenotypic characteristics and rDNA sequencing of the ITS region of the endophyte was identified as P. neglecta which turned out to be a promising source of bioactive compounds. There is little known about endophytes from C. torulosa D.Don. In this paper we studied in detail the identification of isolated endophytic fungi P. neglecta from C. torulosa D.Don and characterization of its active metabolite compounds. The partially purified second fraction (PPF) extracted from the fungal culture supernatant was subjected to gas chromatography followed by mass spectrometry which revealed the presence of many phytochemicals. These results indicate that endophytic fungi P. neglecta isolated from medicinal plants could be a potential source for bioactive compounds and may find potential use in pharmaceutical industry
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    Investigations of hemolytic activity and iron utilization sources of Vibrio alginolyticus ATCC 17749
    (2023) Vibhuti, R K; Pramanik, Avijit
    As iron plays an indispensable role in the various physiological process with the exception of Borrelia burgdorferi, it is a vital but constrained micronutrient. It is anticipated that the capability of this possible human pathogenic organism to use iron will be crucial for both the establishment of an infection in its hosts and for survival in the habitat. The current study aimed to determine the iron utilization spectrum and hemolytic activity of Vibrio alginolyticus ATCC 17749. The ability of V. alginolyticus ATCC 17749 to utilize iron-containing compounds was tested by agar plate growth promotion assay. It was also confirmed by liquid growth promotion assay where iron was restricted by 400 μM 2,2’-Bipyridyl. After that various iron sources of concentrations ranging from 0.1 μM to 10 μM were added for growth promotion of V. alginolyticus. Ferrous sulfate, ferrioxamine and hemin stimulated the growth of V. alginolyticus as a sole iron source while catechol and ferric dicitrate did not stimulate growth. Vibrio alginolyticus supernatant was found to be hemolytic and on the blood agar plate, V. alginolyticus ATCC 17749 showed a hemolytic zone. According to our research, hemolysin synthesis is strongly influenced by the iron concentration of the growth medium. Hemin is used as the only source of iron and hemolysis might represent virulence traits of Vibrio alginolyticus. Iron utilization systems might be a potential target for antibiotics or a controlling point for hemolysin expression.
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    Molecular Mechanism of Iron Transport Systems in Vibrio
    (2022) Pramanik, Avijit; Vibhuti R K
    The ability to acquire iron from the environment is often an important virulence factor for pathogenic bacteria and Vibrios are no exception to this. Vibrios are reported mainly from marine habitats and most of the species are pathogenic. Among those, the pathogenic vibrios eg. V cholerae, V. parahaemolyticus, V. vulnificus causes foodborne illnesses. Vibrios are capable of producing all different classes of siderophores like hydroxamate (aerobactin), catecholate (vibriobactin, fluvibactin), carboxylate (vibrioferrin), and amphiphilic (amphibactin). Every different species of vibrios are capable of utilizing some endogenous or xenosiderophores. Being Gram-negative bacteria, Vibrios import iron siderophore via TonB dependent transport system and unlike other Gamma proteobacteria these usually possess two or even three partially redundant TonB systems for iron siderophore transport. Other than selected few iron siderophores, most pathogenic Vibrios are known to be able to utilize heme as the sole iron source, while some species are capable of importing free iron from the environment. As per the present knowledge, the spectrum of iron compound transport and utilization in Vibrios is better understood than the siderophore biosynthetic capability of individual species.
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    Molecular mechanism of iron transport systems in vibrio
    (Journal of Pure and Applied Microbiology, 2022) Vibhuti, Raj Kamal; Pramanik, Avijit
    The ability to acquire iron from the environment is often an important virulence factor for pathogenic bacteria and Vibrios are no exception to this. Vibrios are reported mainly from marine habitats and most of the species are pathogenic. Among those, the pathogenic vibrios eg. V cholerae, V. parahaemolyticus, V. vulnificus causes foodborne illnesses. Vibrios are capable of producing all different classes of siderophores like hydroxamate (aerobactin), catecholate (vibriobactin, fluvibactin), carboxylate (vibrioferrin), and amphiphilic (amphibactin). Every different species of vibrios are capable of utilizing some endogenous or xenosiderophores. Being Gram-negative bacteria, Vibrios import iron siderophore via TonB dependent transport system and unlike other Gamma proteobacteria these usually possess two or even three partially redundant TonB systems for iron siderophore transport. Other than selected few iron siderophores, most pathogenic Vibrios are known to be able to utilize heme as the sole iron source, while some species are capable of importing free iron from the environment. As per the present knowledge, the spectrum of iron compound transport and utilization in Vibrios is better understood than the siderophore biosynthetic capability of individual species.