Potential Biosurfactant-producing Bacteria from Pharmaceutical Wastewater using Simple Screening Methods in South-West, Nigeria

Emerging multiple opportunities for industrial production and environmental applications have focused increasing research attention on biosurfactants in recent years. Hydrocarbon-polluted soils have proved a major source of biosurfactant-producing bacteria. In this study an alternative method of producing biosurfactants was established, based on pharmaceutical effluents. Pharmaceutical effluents are a rich source of complex organic compounds with potential as a substrate for microbial biosurfactant production. A successful biosurfactant screening assay is achieved when a combination of different methods are employed. Biosurfactant producing bacteria were isolated from pharmaceutical effluent and identified by biochemical methods. The best biosurfactant producer was identified by a molecular method. The biosurfactant screening techniques employed were drop collapse assay, haemolytic assay, oil spreading assay, bacteria adhesion to hydrocarbon assay and emulsification assay. Analysis of haemolytic activity indicated that 35 isolates (44.30 %) produced beta-haemolysis, 12 isolates (15.19 %) produced gamma-haemolysis, while 32 isolates (40.51 %) produced alpha-haemolysis. The highest zone of clearance was 42.0±1.73 by isolate DF7 and lowest zone of clearance was obtained from isolate GC5 of 12.0±0.73. Screening of the 35 isolates using the oil spreading test showed that 28 isolates (80.0 %) were positive, while 7 isolates (20.0 %) were negative. The highest zone of clearance for the oil in water was 19.0±0.1 by DF1 while the lowest zone was 4.3±0.33 by MB3. The drop collapse test revealed that 22 isolates (78.57 %) were positive and 6 isolates (21.43 %) were negative. At 0 h, the highest emulsification percentage was 74.4 % by Bacillus licheniformis and the lowest was 42.5 % by Arthrobacter globiformis. After 24h, the highest emulsification value (69.23 %) was obtained for Bacillus clausis, while the lowest value (30.84 %) was obtained for Arthrobacter globiformis. The findings demonstrated the ability of the isolates to produce biosurfactant, and confirmed the capacity of Bacillus clausis isolated from pharmaceutical effluents as a potential bacteria for biosurfactant production

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