Production, characterization and antibacterial activity of prodigiosin pigment produced by Pseudoalteromonas rubra BF1A IBRL associated with a marine macroalgae Enteromorpha sp.

Abstract

Aims: Marine bacteria are a great source of natural pigments, which can be used as colouring agent in food, textile, cosmetics and aquaculture industry to overcome the drawbacks poses by the synthetic pigments. The aim of the study is to identify the potential bio pigment producer, determine the antimicrobial susceptibilities, and characterize the pigment produced. Methodology and results: In this study, the surface attached marine bacteria isolated from the surface of seaweed, Enteromorpha sp. has been identified as Pseudoalteromonas rubra BF1A IBRL through the molecular identification step. This species produced intracellular and extracellular red pigment with antibacterial activity. The susceptible bacteria include Bacillus subtilis, Bacillus cereus, Methicillin Resistant Staphylococcus aureus, Staphylococcus aureus and also Acinetobacter anitratus with inhibition zone ranges from 7.33 to 10.33 mm, whereas Minimum inhibitory concentration (MIC) values ranges from 0.055 to 8.88 mg/mL. The UV/vis analysis indicated that the maximal absorbance of ISO and DE pigment extract were at 531 and 534 nm, respectively. Based on the antimicrobial activity, the extracellular extract poses greater antibacterial activity, thus was selected as the potential pigment extract and were further evaluated. The Thin Layer Chromatography (TLC) profile of the DE extract showed one major band under visible light ((Rf = 0.87) and the bioautography analysis of the pigmented band showed positive activity against both Gram-positive and Gramnegative bacteria. The pigment in DE extract was identified as prodigiosin based on the spectroscopic properties, presumptive test and HPLC analysis. Conclusion, significance and impact of study: This study highlights the dual benefits of the P. rubra BF1A IBRL pigment extract, which exhibited both tinctorial and pharmacology benefits, thus it can be act as colouring agent with own preservative value in food, textile, or cosmetics industries.