Effect of Gamma Irradiation on Microbial Load of Kalmegh

Whole plant powder of Kalmegh (Andrographis paniculata) was exposed to gamma irradiation at doses of 5 and 10 kGy in a Co 60 irradiator. Irradiated and unirradiated samples were stored at room temperature. Microbial load of whole plant powder were evaluated at 0, 6 and 12 months of storage. Results indicated that gamma irradiation reduced the total aerobic count and total fungal count in comparison to the non-irradiated sample. Further, the non-irradiated samples showed the presence of E.coli and Staphylococcus aureus. On irradiation there was a drastic reduction in E.coli and Staphylococcus aureus. Microbial load was found to be increased after 6 and 12 months of storage in the non-irradiated samples, where as there were no significant differences in the irradiated samples. A dose of 5 kGy could reduce the microbial load to acceptable levels, where as commercial sterility could be obtained at a dose of 10kGy. Thus, gamma irradiation can be used as a suitable technique for microbial decontamination of phytopreparations and products of Kalmegh and thus increase their shelf life and stability.