Endophytes are microbes that colonize the internal tissue of the host plants. Endophytes from medicinal plants have become a hot topic for metabolite discovery. Bacterial endophytes were isolated from the leaf and stem samples of Withania somnifera (Ashwagandha), a medicinal plant known as Indian ginseng and screened for enzymes of biotechnological importance. All the isolates showed different enzymatic activities like amylase, protease and esterase, while no pectinase activity was detected. Isolate AS4, AS5 and BL3 were found to be amylase and esterase producers. Out of 10 endophytes, three isolates were identified by 16s rDNA amplification and sequencing. Two of them were Sarretia marcescence (AS5 and ASS2) and one Bacillus subtilis (BL3).

Endophytic bacteria are defined as those bacteria that colonize the internal tissue of the plant showing no external sign of infection or negative effect on their host (Holliday, 1989; and Schulz and Boyle, 2006). Bacterial endophytes colonize an ecological niche similar to that of phytopathogens, which makes them suitable as biocontrol agents (Berg et al., 2005). The endophytic niche offers protection from the environment for those bacteria that can colonize and establish in plant. These bacteria generally colonize the intercellular spaces, and they have been isolated from all plant compartments including seeds (Posada and Vega, 2005). Symptomless internal colonization of healthy plant tissues by microorganisms is a widespread and well-documented phenomenon. Endophyte is an allencompassing topographical term that includes all organisms which during a variable period of their life cycle colonize the living internal tissues of their hosts without producing symptoms of disease (Petrini, 1991). Common endophytes include a variety of bacteria, fungi and actinomycetes, and they can be isolated from wild (Brooks et al., 1994) or cultivated crops (Liu and Tang, 1996) of either the monocotyledonous (Fisher et al., 1992) or dicotyledonous plant groups (El-Shanshoury et al., 1996). Endophytic bacteria in a single plant host are not restricted to a single species but comprise several genera and species. No one knows if communities inside plants interact, and it has been speculated that beneficial effects are the combined effect of their activities. Endophytes from medicinal plants have become a hot topic for metabolite discovery because of their high biodiversity and predicted potential to produce novel compounds. Endophytic fungi produce bioactive metabolites which play an essential role in providing protection to their host against attack by other pathogen and environmental factors. Endophytes could lead to development of novel pharmaceutical agent against human disease. In the present investigation, endophytes were isolated from the medicinal plant, Withania somnifera (Ashwagandha). Withania somnifera (Ashwagandha) is a perennial shrub that belongs to the family Solanaceae. It is used for the preparation of health tonic that is used in general weakness and debility.

Biotechnology Journal, Stress Adaptation of Bacteria, Extremophiles, Bacterial Adaptation, Cytosolic Components, Denature Cellular Proteins, Reactive Oxygen Species, Monounsaturated Fatty Acids, Ultraviolet Radiation, Environmental Stress, Stress Management, Biological Systems, Cellular Economy.