Isolation, Screening and Characterization of Biosurfactant-Producing Bacteria from Household Wastewater and Their Potential in Plant Growth Promotion

Amphiphilic secondary metabolites of microbial origin, biosurfactants can lower interfacial and surface tension and create stable emulsions. Biosurfactants have become viable substitutes for synthetic surfactants in industrial formulations, agriculture, and environmental remediation due to their biodegradability, low toxicity, and functional stability in harsh environmental conditions. The current study's objectives were to separate and screen bacteria that produce biosurfactants from home wastewater, characterise biosurfactant production using quick qualitative assays, and assess their possible applicability for applications that promote plant development. Two wastewater sources—boiled corn water and rice washing water—were selectively cultivated after being supplemented with hydrocarbon substrates. Oil spreading, the emulsification index (E24), and modified drop-collapse assays were used to assess the synthesis of biosurfactants. Using cultural, microscopic, and biochemical traits, two bacterial isolates with different morphologies were isolated and identified. The isolates were identified as an Actinomycetes-like bacteria and Pseudomonas aeruginosa. Compared to the cooked corn water isolate, the rice-water isolate showed a bigger drop-collapse diameter and a relatively higher emulsification activity (48%). The work supports their potential use in environmentally friendly and plant growth-promoting agricultural operations and shows that it is feasible to isolate effective biosurfactant-producing bacteria from inexpensive household wastewater.