Endophytes and plant extracts of carica papaya linn. Exhibit promising antibacterial and in-vitro antitumor activity

Abstract

Microbes have always been the noteworthy source of antibiotics, enzymes and various other compounds. The emerging issue of multidrug resistance has increased the demand for mining out novel sources of antimicrobial agents. Thus, researchers are now trying to explore the underexplored microbial resources for getting new therapeutics. In this study, 42 endophytic bacteria were isolated, which includes 22 actinobacteria and 20 general bacterial strains from different parts (roots, shoots and leaves) of Carica papaya Linn. The crude extracts of endophytes and plant tissues showed remarkable antimicrobial activity against different pathogenic bacteria such as methicillin resistant Staphylococcus aureus (MRSA), E. coli and Pseudomonas aeruginosa. The extracts also exhibited notable in vitro cytotoxicity against colorectal carcinoma cell lines (HTC 116, ATTC CCL-247) by MTT assay, at the lowest concentration of 0.1mg/ml showing growth inhibition up to 80%. The plant extracts were more potent against MRSA and Bacillus, in comparison to the extracts of endophytic bacteria. Our findings suggested that endophytic bacteria and plant tissue extracts of medicinal plant Carica papaya are promising source of antimicrobial and antitumor compounds. The purification and identification of active compounds from these sources may yield some useful drug candidates.