Endophytic fungi isolates recovered from Ocimum sanctum plant species and its In vitro Anti bacterial activity against Salmonella typhi and Salmonella typhimurium

Abstract

Food borne diseases are an important cause of morbidity and mortality worldwide. WHO identifies food borne disease outbreaks and incidents, including those arising from natural, accidental and deliberate contamination of food, as major global public health threats in the 21st century. Salmonella typhi and Salmonella typhimurium, which are rarely encountered outside endemic countries or in returned travelers and have a worldwide distribution. While the true incidence is unknown, there are an estimated 93.8 million episodes and 155,000 deaths each year. Various endophytes had been recovered from such medicinal herbs and produced secondary metabolites. However, the claims have least scientific justification as India has published limited literature on plants flora and its symbionts screened against S. typhi and S. typhimurium. In the present study biodiversity of endophytic fungi in seeds showed presence of 89 colonies which belonged to 9 genera with contribution of hyphomycetes (76.41%), ascomycetes (13.49%) coelomycetes (7.87%) and sterile mycelium (2.25%); Fusarium oxysporum (17.98%) and Alternaria alternata (16.85%) were dominant species and Chaetomium bostrycodes (5.62) was minimum. Alternaria alternata (Fr.) Keissler was selected for further investigation as potent bioactive metabolites producer. Optimization of semi-synthetic and synthetic media was carried out for large scale cultivation of Alternaria alternata for producing and purifying anti-salmonella metabolites from crude extract. Two out of 11 elutes exhibited activity percentage (18.18%) against S. typhi and S. typhimurium with mean values for concentration ranging at 300µg/ml, while other fractions were negative. The elute No. 4 (FRK1) and elute No. 9 (FRK 2) exhibited maximum activity against S. typhi and S. typhimurium (300µg/ml). The purified fractions FRK 1 and FRK 2 were further analyzed for Infra-Red spectroscopy Mass spectroscopy and Nuclear Magnetic Resonance. The purified compounds of Alternaria alternata (Fr.) Keissler were identified: FRK