Phenolic Contents, Antioxidant Capacity and Antibacterial Activity of Extracts from Bacillus spp. Associated with The Leaves of Some Medicinal Plants

Bacteria living inside the plant tissues produce an array of bioactive phenolic compounds similar to their host plants with a broad spectrum uses in medicinal and pharmacological industries. In this study, five species related to genus Bacillus i.e., Bacillus cereus Mp1, Bacillus zhangzhouensis Mp2, Bacillus drentensis Mp3, Bacillus vallismortis Mp4, and Bacillus velezensis CLT81 were isolated from the leaf tissue of Solenostema argel, Calotropis procera, and Hibiscus sabdariffa. The ethyl acetate extracts of these species were subjected to the evaluation of phenolic contents, antioxidant capacity and antibacterial activity. Results revealed that Mp1, Mp2, Mp3, Mp4, and CLT81 are potent source of natural bioactive phenolic compounds i.e., phenolic acids, flavonoids and tannins with considerable antioxidant capacity, and antibacterial activity against common pathogenic bacteria i.e., Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumonia, Salmonella typhi, and Streptococcus agalactiae. Therefore, these Bacillus species may gain great benefit in the pharmaceutical industry as potential candidates for the development of new drugs.