Conversion of renewable substrates for biosurfactant production by Rhizopus arrhizus UCP 1607 and enhancing the removal of diesel oil from marine soil

Abstract Biosurfactants are surface active substances which reduce interfacial tension and are produced or excreted at the microbial cell surface. We evaluated the biosurfactant production by Aspergillus fumigatus and Phialemonium sp. in solid state processes using fixed-bed column reactors. We evaluated two media, rice husks alone (simple support) and rice husks plus defatted rice bran (complex support), both enriched with either soy oil or diesel oil. The highest water-in-oil emulsifying activity (EAw/o) obtained was 7.36 EU g-1 produced by A. fumigatus growing on complex support enriched with soy oil and supplied with air at a rate of 60 mL g-1 h-1, while Phialemonium sp. had a maximum production of 6.11 EU g-1 using the simple support with diesel oil and an aeration rate of 120 mL g-1 h-1. The highest oilin- water emulsifying activity (EAo/w) was 12.21 EU g-1 produced by Phialemonium sp. on the complex support enriched with diesel oil and at an aeration rate of 60 mL g-1 h-1, while A. fumigatus produced a maximum EAo/w of 10.98 EU g-1 when growing on the complex support with no additional carbon source and an aeration rate of 60 mL g-1 h-1.

Download Full-text

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

Applied Environmental Research ◽

10.35762/aer.2019.41.3.6 ◽

2019 ◽

pp. 71-81

Author(s):

Seun O. Adebajo ◽

Aderonke K. Akintokun ◽

Abidemi E. Ojo ◽

Dami M. Egbagbe ◽

Pius O. Akintokun ◽

...

Keyword(s):

Methylene Blue ◽

Diesel Oil ◽

Alcaligenes Faecalis ◽

Biosurfactant Production ◽

Rhizospheric Bacteria ◽

Recovery Techniques ◽

Low Toxicity ◽

Extraction Solvents ◽

Surface Active Compounds ◽

Amended Soil

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.

Download Full-text