Biosurfactant Production by Rhizospheric Bacteria Isolated from Biochar Amended Soil Using Different Extraction Solvents

Microbial-derived surface-active compounds (biosurfactants) have attracted attention due to their low toxicity, cost-effectiveness, biodegradable nature and environment compatibility. Due to paucity of knowledge in the production of biosurfactant by microorganisms from other sources such as biochar-amended soil, the present study investigates the potential of rhizospheric bacteria isolated from biochar amended soil of okra plant in the production of biosurfactants using different recovery techniques. Rhizospheric bacteria were screened for biosurfactant production using Haemolytic, Oil spreading, Drop collapse, Methylene blue method, Bacterial adhesion to hydrocarbon and Emulsification activity. The biosurfactant was extracted using different extraction solvents (acid precipitation, ethyl acetate, acetone, dichloromethane and chloroform/methanol). Degradation of hydrocarbon (diesel) was determined spectrophotometrically. A total of twenty-three rhizospheric bacteria were isolated from the soil of Abelmoschus esculentus (okra plant).  Nine isolates were positive for haemolysis with values between 1.1±0.2 mm by Enterobacter cloaca and 23.0±0.6 mm by Alcaligenes faecalis. Two isolates were positive for the drop collapse test. Only one isolate was positive for the methylene blue method. In the oil spreading test, ten isolates were positive and five isolates had the ability to adhere to hydrocarbons. Six isolates exhibited emulsification potential after 24 h, with the highest and lowest (65.9%) and (40.7%) recorded by Alcaligenes faecalis and Citrobacter sp, respectively. The biosurfactant produced by Alcaligenes faecalis using different recovery solvents showed that chloroform and methanol are the best extraction solvents and Alcaligenes faecalis was also able to degrade diesel oil over a period of 10 d. Conclusively, Alcaligenes faecalis recovered from soil amended sawdust biochar of okra plant is both a potent biosurfactant producer and an agent for remediating hydrocarbon-contaminated soil environments

Characterization of biosurfactant-producing bacterial strains isolated from agro-industrial wastes in southwestern, Nigeria

Introduction. The difficulty of managing trash and cleaning up the environment prompted interest in biosurfactants and surface-active proteins made by microbes. The study aims to augment bacterial isolates from agro-industrial wastes targeted for possible mass production of biosurfactants. Methods. Six agro-industrial wastes from Cassava, Palm kernel, and Sawdust from six agro-industrial sites within Ijebu area in Ogun State were collected for standard laboratory analyses in the Biotechnology Unit of the Federal Industrial Institute for Research, Oshodi (FIIRO). Five screening methods; blood hemolysis, lipase activity, blue agar hydrolysis, oil spreading, and emulsification index (EI24) were carried out to confirm biosurfactant production. Isolates with the highest hyper-production were subjected to 16rRNA molecular identification. Results. The study justified efficient biosurfactant production from 4 bacterial isolates out of 26 screened bacterial isolates from hydrocarbon degraders and 29 heterotrophic screened bacterial isolates, making a total of 55 screened bacterial isolates. Screening results reveal the emulsification capacities of identified Pseudomonas putida strain SG1, Acinetobacter baumanii strain MS14413, Bacillus zhangzhouensis strain cdsV18, and Burkholderia cepacia strain 717. Conclusion. Biosurfactant bacteria produced in all agricultural and industrial wastes considered in this study are capable of mass production.