Abstract

Bhoj Raj Singh *, Vidya Singh , Raj Karan Singh and N. Ebibeni

Out of the 1114 strains belonging to 29 genera and 105 species of microbes (molds, yeasts and bacteria) isolated from different sources [clinical cases, environment (water, air, soil, droppings of lizards and birds), food and healthy animals], 38.2% were sensitive to lemongrass oil discs containing 50 µg oil/disc. All molds, yeasts, Lactobacillus acidophilus, Morganella morganii, most of the Bacillus spp. strains (84.3%), aeromonads (78%), Edwardsiella spp. (73.9%), 53.6% pseudomonads, 53.1% streptococci and 50% of Budvicia aquatica and Leminorella ghirmontii strains were sensitive to lemongrass oil (LGO). On the other hand, all Hafnea alvei, Laclercia adecarboxylata, Xenorhabdus luminescens and majority of Salmonella enterica (98.3%), Citrobacter spp. (93.7%), Providencia spp. and Kluyvera cryocrescens (83.3%), Enterobacter spp. (78.2%), Proteus spp. (78%), Escherichia spp. (77.7%), enterococci (73.7%), Serratia spp. (75%) and Erwinia ananas (75%), Pragia fontium (70.6%), staphylococci (69.8%) and Klebsiella spp. (62.7%) strains were resistant to LGO. MIC of LGO for sensitive strains (tested against discs containing 50 µg LGO) varied from 1 µg to 32 µg /ml while none of the resistant strains had MIC <64 µg LGO/ ml. MIC for yeast strains was the least i.e., 1 µg LGO/ ml. LGO had microbicidal activity on E. coli, S. aureus and Candida albicans. LGO instantly killed C. albicans and E. coli, and S. aureus in 10 min at 1 mg/ ml concentration, indicating of its wide spectrum antimicrobial activity at easily achievable concentrations. Study also indicated that LGO is more effective on enterococci in aerobic instead of microaerophilic growth conditions, it is indicative that in-vivo sensitivity results may differ from in-vitro tests.