Comparative evaluation of antimicrobial properties of ruta graveolens and plumbago zeylanica against leuconostoc mesenteroides

The carbohydrate polymer dextran, majorly formed by Leuconostoc mesenteroides (gm + ve Lactic acid bacterium) is widely recognized as causing agent of large sucrose losses in sugar industry during different stages of processing. Recently the pathogenic potential of L mesenteroides has been established. Antibacterial activities of Ruta graveolens and Plumbago zeylanica extracts against several bacterial strains have been reported. The aim of this study was to evaluate the possible antimicrobial potential of Ruta graveolens stem and Plumbago zeylanica leaf extracts (chloroform, methanol, ethanol, aqueous) against major sugar loss causing Leuconostoc mesenteroides (MTCC *107). For this purpose, the bacterium L. mesenteroides was tested. Antimicrobial activity was done using agar well diffusion method. Tested extracts showed antibacterial activity against the selected bacterium L. mesenteroides. The test microorganism was more susceptible to methanolic extracts of both Ruta graveolens and Plumbago zeylanica with mean diameters of inhibition being 18.22mm, 22.35mm and MIC being 12.5mg/ml, 6.25mg/ml respectively, followed by ethanol, chloroform and aqueous extracts. Relatively less antimicrobial inhibitory activity was shown by aqueous extracts of both plants. The P. zeylanica leaves extracts shown comparatively better antimicrobial property than R. graveolens stem extracts as evidenced by mean zone of inhibition and MIC. These promising findings suggest the presence of antibacterial activity of the tested plants, exhibited by their bioactive compounds, and serving them as an alternative antimicrobial agents against sugar loss causing microorganism L. mesenteroides. Further, results are beneficial for sugar industry.