Evaluating antibacterial and anticancer activity of crude extracts of bacterial endophytes from Crinum macowanii Baker bulbs.

ABSTRACT

The results from this study revealed that crude extracts isolated from bacterial endophytes obtained from Crinum macowanii bulbs showed activity against both Gram-positive and Gram-negative pathogenic bacteria, while Acinetobacter guillouiae crude extracts displayed anticancer activity. This study aimed to isolate and characterize bacterial endophytes and their crude extracts from C. macowanii bulbs. Endophytes were isolated using validated surface sterilization techniques, followed by phenotypic and genotypic profiles of the isolates. Crude extracts were extracted from the endophytes using ethyl acetate, while methanoldichloromethane (11) was used to obtain crude extracts from the bulbs. Antibacterial activity of crude extract from each endophyte was investigated against selected pathogenic strains using the broth microdilution method, and anticancer activity against U87MG glioblastoma and A549 lung carcinoma cells was determined by the MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxy-phenyl)-2-(4-sulfophenyl)-2H-tetrazolium) assay. Acinetobacter guillouiae, Pseudomonas moraviensis, Pseudomonas sp., Rahnella aquatilis, Bacillus cereus, Novosphingobium sp., Raoultella ornithinolytica, and Burkholderia tropica were successfully isolated. The crude extracts from the majority of endophytes showed antibacterial activity, ranging from 0.125 to >16.00 mg/ml against Gram-negative and Gram-positive pathogenic bacteria. Acinetobacter guillouiae extracts showed a high bioactive potential against U87MG glioblastoma cell lines by reducing their growth by 50% at concentrations of 12.5, 6.25, and 3.13 µg/ml. Crude extracts isolated from C. macowanii bulbs showed potential for possible drug lead against common pathogenic bacteria.