A novel alternative prospect to prevent bacterial infections without inhibiting the growth is to apply chemicals that inhibit quorum sensing mechanism of the pathogens. Antiquorum property of 61 medicinal plants was evaluated by the ability of their leaf extract(s) to inhibit production of pigment (violacein in Chromobacterium violaceum MTCC 2656, pyocyanin in Pseudomonas aeruginosa MTCC 2297) or swarming in P. aeruginosa MTCC 2297. The most prospective plants (for the development of quorum sensing inhibitor), showing inhibition of violacein production without affecting bacterial growth, were Astilbe rivularis, Fragaria nubicola and Osbeckia nepalensis.
The draft genome sequence of a novel strain, Pseudomonas sp. MR 02, a pyomelanin-producing bacterium isolated from the Mahananda River at Siliguri, West Bengal, India, is reported here. This strain has a genome size of 5.94 Mb, with an overall G+C content of 62.6%. The draft genome reports 5,799 genes (mean gene length, 923 bp), among which 5,503 are protein-coding genes, including the genes required for the catabolism of tyrosine or phenylalanine for the characteristic production of homogentisic acid (HGA). Excess HGA, on excretion, auto-oxidizes and polymerizes to form pyomelanin.
Objectives: This study aims to investigate ampicillin catabolism in a pandrug-resistant strain, Pseudomonas sp. MR 02 of P. putida lineage. Methods: The characterization of carbapenem resistance was done following the standard protocol. The broth macrodilution method was used to determine the MIC values of antimicrobial agents both in the presence and in the absence of phenylalanine-b-naphthylamide. High MIC values (>10 000 mg/L) of ampicillin led to speculation that it may serve as a growth substrate, and thus minimal medium was used to evaluate ampicillin as a nutrient. The growth of MR 02 was measured in minimal medium in the presence or absence of 0.4 mM EDTA, supplemented with ampicillin as sole carbon, nitrogen and energy source. RNA-seq was used to generate expression profiles of genes in ampicillin or glucose-grown cells. The bla NDM-1 gene of MR 02 was cloned in the pHSG398 vector and expressed in Escherichia coli DH5a. Results: Phenotypic analysis along with genome sequence data identifies Pseudomonas sp. MR 02 as a pandrug-resistant strain. Transcriptome data has revealed that bla NDM-1 was among the top 50 differentially expressed genes in ampicillin grown cells compared to the glucose grown cells in the minimal medium. Heterologous expression of bla NDM-1 gene in E. coli DH5a enabled its growth and subsistence on ampicillin as the sole source of carbon and energy. Discussion: The ability of a pandrug-resistant Pseudomonas sp. MR 02 to consume ampicillin for growth has a huge implication in the bioremediation of b-lactam residues in the environment. Vivek
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