Sixty-four accessions of Napier grass (Pennisetum purpureum Schum.), a forage crop of tropics and subtropics, were assessed for polymorphism in isozymes and total proteins (TP). The national germplasm collection exhibited polymorphism in all the three isozymes viz., malate dehydrogenase, glutamate oxaloacetate transaminase and peroxidase (POX) besides TP profile. Though POX and TP showed comparatively higher polymorphism, the study indicated the efficiency of three-enzyme system in identifying more than 90% of the accessions. The combination of TP and three-enzyme systems provided unique isozyme/TP banding patterns for all the 64 accessions leading to development of accession specific profile/fingerprints. In Napier, which is perennial with long vegetative phase, it is difficult to discriminate germplasm accessions based only on morphology. Thus biochemical markers could be efficiently utilized to complement morphological evaluations, in maintaining identity and purity of germplasm for proper conservation and management, for better use in breeding and for proprietary reasons.

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The present study investigated the antimicrobial and antibiofilm potential of biosurfactants derived from Lactobacillus fermentum Lf1, L. fermentum LbS4 and Lactobacillus plantarum A5 against clinical isolates of methicillin‐resistant Staphylococcus aureus (MRSA). The cell wall‐bound and intracellular biosurfactants were extracted by solvent extraction method. Fourier‐transform infrared spectroscopy‐based characterization of biosurfactants revealed the heterogeneous chemical composition involving proteins, fatty acids and carbohydrate moieties in LbS4 and A5, while only the sugar and lipid fractions in Lf1. Fatty acid profiling using Gas chromatography‐mass spectrometry indicated hexadecanoic acid and stearic acid as the predominant fatty acids in the biosurfactants of all these strains. Biosurfactants demonstrated dose‐dependent antibacterial action against MRSA isolates with the highest inhibition zone diameter (30·0 ± 0·0 to 35·0 ± 0·0 mm) recorded at 400 mg ml−1. Biosurfactants showed an excellent staphylococcal antibiofilm activity by preventing the biofilm formation and disrupting the preformed biofilms. Visual inspection through scanning electron microscopy witnessed the biosurfactants‐induced alteration in the cell membrane integrity and subsequent membrane pore formation on staphylococcal cells. Taken together, our findings emphasize the prospects of biomedical applications of biosurfactants as bactericidal and biofilm controlling agents to confront staphylococcal nosocomial infections.

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