ISPUB.COM The Internet Journal of Microbiology Volume 6 Number 1 1 of 8 Differential citral content of 15 lemongrass genotypes and their anti microbial property S Kumar, E Subudhi, S Nayak, S Sahoo Citation S Kumar, E Subudhi, S Nayak, S Sahoo. Differential citral content of 15 lemongrass genotypes and their anti microbial property. The Internet Journal of Microbiology. 2008 Volume 6 Number 1. Abstract In this present study antimicrobial activity of 15 promising cultivars of lemongrass were compared against 10 pathogenic microorganisms. Essential oil extracted from fresh leaves showed a distinctive variation in its oil percentage, citral content as well as antibacterial and antifungal potential against six bacterial and four fungal isolates. Direct correlation between citral content, a major constituent of the essential oil of lemongrass cultivars could not be established with their antimicrobial activity indices. MIC against Escherichia coli by plate dilution method was found to be very low (250μg/ml). Inhibition zone diameter study of essential oils showed higher range of inter-specific variation within the cultivars. The cultivar OD19 with highest antibacterial index (AbI) 27.2 has the best potential to prevent bacterial growth, followed by Pragati and SD68 with AbI 24.66 and 24.02. RRL (B) 27 has got the lowest AbI of 11.4, thus found to be highly susceptible to majority of test bacteria. Pseudomonas aeruginosa, the most sensitive bacteria to lemongrass oil having Inhibition zone diameter (IZD) ≥90mm irrespective of type of cultivar. Similarly all 4 fungal test strains used in this study were found to be highly sensitive to this essential oil showing no visual growth in the Petri dish. Under these experimental conditions, the inter-specific variations in anti bacterial potential of all fifteen distinct promising cultivars are more clearly evident but all genotypes possesses exceptionally good anti fungal property. ABBREVIATIONS AI- Antimicrobial Activity Index A b I -Antibacterial Activity Index A f I.- Antifungal Activity Index MIC-Minimum inhibitory concentration IZD-Inhibition zone diameter INTRODUCTION Lemongrass (Cymbopogon flexuosus Nees ex. Steud Wats) a perennial grass with lemony aura belongs to family Poaceae, though restricted in its distribution to selected patches of subtropical parts of Asia, Africa and America, has acclaimed significant global demand because of its varied range of applications in different industries viz; in perfumery and cosmetics for its lemon like scent, in food and beverage as flavoring and preservative agent, in agriculture as insect repellent, in soap, detergent and pharmaceuticals for its antimicrobial property, as well as in aroma therapy for its aromatic healing properties etc. 1 , 2 , 3 . Although all these rare qualities are bestowed with lemongrass essential oil alone, development and release of new improved variety by traditional breeding has been very infrequent. Chemical characterization and biological property study to understand the genotypic variation concerning above desirable properties, exists if any among cultivars released from different research stations of India, holds extremely significant. It is clear from the available literature that efforts are being taken by different groups of workers and of late some activity study has been reported on one/few released lemongrass varieties against one/few test organisms 4 , 5 , 6 , 7 , 8 as well as on genetic diversity amongst the cultivars 9 but neither concerted attempt has been taken to assay antimicrobial potential of many improved cultivars at large, screened against a group of microorganisms nor the effect of citral content on their antimicrobial activity has been reported. Keeping the above facts in view, one such attempt has been taken in the present work, to establish a correlation between citral content and the antimicrobial property of essential oil extracts from 15 rare, promising, genetically stable cultivars released from different research stations of India against a host of 10 microbial isolates, pathogenic either to animals or plants and food spoiling microorganisms so that role of genetic make up of different cultivars on variation of anti microbial property may be understood and future potential