The present study aimed to isolate, characterize, and evaluate beneficial bacterial isolates from medicinal plant rhizosphere soils and fermented dairy products for their potential applications in antibiotic discovery, enzyme production, and gut health improvement. Soil isolates designated as S4, S5, and S6 and a probiotic isolate (D1) from curd were obtained using conventional microbiological techniques and characterized based on their morphological and biochemical properties. The soil isolates were presumptively identified as Bacillus spp., while the probiotic isolate was identified as Lactobacillus spp.
The antimicrobial activity of the isolated microorganisms was assessed against selected bacterial pathogens. Among the soil-derived isolates, S6 displayed the highest antibacterial potential. In general, crude culture extracts produced stronger inhibitory effects than the corresponding ethyl acetate extracts, suggesting that the active antimicrobial compounds were more effective in their crude form. In addition to their antibacterial properties, the selected soil isolates were capable of producing the commercially important enzymes L-asparaginase and streptokinase, as demonstrated through qualitative screening and enzyme activity assays. These observations indicate that these isolates possess considerable potential for applications in the pharmaceutical and biotechnology sectors.
The probiotic isolate D1 exhibited several desirable probiotic characteristics. It showed antagonistic activity against Staphylococcus aureus, tolerated acidic conditions and bile salts, and remained viable under simulated gastrointestinal conditions, indicating its potential to survive passage through the human digestive tract. However, under the conditions used in this study, D1 did not exhibit detectable production of either L-asparaginase or streptokinase.
The results suggest that medicinal plant rhizosphere soils and fermented dairy products serve as valuable reservoirs of beneficial microorganisms with antimicrobial, enzymatic, and probiotic capabilities. To fully explore their practical potential, future investigations should focus on molecular identification, detailed characterization of bioactive metabolites, and large-scale validation studies. Such research would provide a stronger foundation for the development of these microorganisms for applications in healthcare, food biotechnology, pharmaceutical manufacturing, and other industrial biotechnological processes.
