Antibacterial assay guided isolation of a novel hydroxy-substituted pentacyclo ketonic compound from Pseudomonas aeruginosa MBTDCMFRI Ps04

Abstract

Antimicrobial compounds from the natural source have gained greater relevance because of their wide spectrum of possible applications, especially in the aquaculture industry where pathogenic threat and antibacterial resistance are serious concerns. In this regard, Pseudomonas aeruginosa MBTDCMFRI Ps04 (P. aeruginosa Ps04) strain isolated from the tropical estuarine habitats of Cochin was evaluated for its antibacterial potential against major aquaculture pathogens. The physiological conditions for the maximum production of the active metabolite were also optimized. An activity-guided approach was employed further to isolate and characterize the secondary metabolite responsible for the inhibitory potential. It was found that the cell free supernatant (CFS) of P. aeruginosa Ps04 exhibited strong antibacterial activity against major aquaculture pathogens belonging to the genus Vibrio and Aeromonas and retained its potential even at 30% (v/v) dilution. The highest antibacterial activity was detected from 3rd day culture, grown in glycerol alanine media (1% each) as carbon and nitrogen source, respectively, at 30°C, pH 7.0 and at a salinity of 20 parts per thousand (ppt). The activity of the antagonistic principle was found to be stable against variations in pH (pH 2-pH 12), temperature (up to 120°C) and enzymatic treatments. Bioassay-guided purification followed by spectroscopic characterization of active fractions of P. aeruginosa Ps04 revealed that the compound 4-Hydroxy-11-methylpentacyclo [11.8.0.0 2,3 .0 11, 12 .0 16,17 ]henicosa-1,3,5,8(9),17-penten-14-one is responsible for its major antibacterial activity. The results of this study indicated that P. aeruginosa Ps04 has beneficial antibacterial properties which could be used in developing novel antimicrobial therapeutics against a variety of aquaculture pathogens.

Evaluation of Bioactive Secondary Metabolites from Ponyfish Associated Bacteria (<i>Photobacterium leiognathi</i>)

“…A collection of bands in the region of 1408.04 are due to the S=O sulfate group, while the absorption band in the region 1093.64 cm -1 are C-F structuring functional group of Ether and alkyl halides functional group present wavelength of 557.43 cm -1 structure of C-Br-group. FTIR spectra of the crude extract of the marine bacterium Pseudomonas aeruginosa revealed major bands at 3396.01 cm -1 , 2928.88 cm -1 , 1726.24 cm -1 , 1510.88 cm -1 , 1726 cm -1 , and 1046.43 cm -1 (Nair et al 2021).…”