Characterization and phylogenetic analysis of biosurfactant-producing bacteria isolated from palm oil contaminated soils

Biosurfactant-producing bacteria were isolated from 89 different soil samples contaminated with palm oil in 35 palm oil industry sites in the south of Thailand. The phylogenetic diversity of the isolates was evaluated by 16S rRNA gene analysis. Among 1,324 colonies obtained, 134 isolates released extracellular biosurfactant when grown on low-cost substrates by a drop collapsing test. Among these, the 53 isolates that showed the highest biosurfactant production on different substrates were found to belong to 42 different bacterial genera. Among these sixteen (Caryophanon; Castellaniella; Filibacter; Geminicoccus; Georgenia; Luteimonas; Mesorhizobium; Mucilaginibacter; Nubsella; Paracoccus; Pedobacter; Psychrobacter; Rahnella; Sphingobium; Sphingopyxis and Sporosarcina) were first reported as biosurfactant-producing strains. By using low-cost, agro-industrial by-products or wastes, Azorhizobium doebereinerae AS54 and Geminicoccus roseus AS73 produced extracellular biosurfactant, which exhibited the lowest surface tension reduction (25.5 mN/m) and highest emulsification activity (69.0%) when palm oil decanter cake and used palm oil was used as a carbon sources, respectively. Overall, this is the first study of a phylogenetic analysis of biosurfactant-producing bacteria from palm oil refinery industry site and their ability to produce biosurfactant on renewable substrates

Biosurfactant production by <i>Bacillus subtilis </i>TD4 and <i>Pseudomonas aeruginosa </i>SU7 grown on crude glycerol obtained from biodiesel production plant as sole carbon source

396-406This study presents isolation of biosurfactant (BS)-producing bacteria, Bacillus subtilis TD4 (BsTD4) and Pseudomonas aeruginosa SU7 (PaSU7), from palm oil contaminated soil. BS production was done by using a minimal salt medium with used crude glycerol as carbon and commercial monosodium glutamate as nitrogen source. After microbial cultivations at 30°C under optimum conditions, BSs produced by BsTD4 and PaSU7 reduced surface tension of culture supernatant to 30 mN/m with BS yield of 2.65 and 2.25 g/l, respectively. BSs could reduce surface tension of pure water to 26.0 and 28.0 mN/m with critical micelle concentration (CMC) of 12 mg/l (BsTD4) and 20 mg/l (PaSU7). BS produced by BsTD4 exhibited higher oil recovery efficiency than that produced by PaSU7. Both BSs could recover oil more effectively than synthetic surfactants, could enhance solubility of PAHs, and can emulsify various oil and hydrophobic compounds

Microbial diversity analysis of thermophilic hydrogen-producing consortia from hot spring in the south of Thailand and evaluate cashew apple juice as a substrate

This study aims to develop thermophilic hydrogen-producing consortia from ten sediment samples of hot springs in southern Thailand by repeated batch cultivation at 60°C with fructose, glucose and combination of fructose and glucose. The promising hydrogen production potentials consortia were obtained from thermophilic enriched cultures and encoded as NST1 consortia. NST1 consortia exhibited the maximum hydrogen yields of 259 ml/g sugar consumed when fructose-glucose mixed was used as a substrate. PCR amplified 16S rDNA product was separated by using denaturing gradient gel electrophoresis (DGGE) to identify the diversity of bacteria in NST1 consortia. The phyologenetic profile of the NST1 consortia showed a significant diversity in the microbial community, where major nucleotide sequences were affiliated to class Clostridia, followed by Bacteroidetes, Deltaproteobacteria, and Flavobacteria. Time course of hydrogen production revealed that NST1 consortia gave the maximum hydrogen yield of 540 ml H2 /g sugar consumed after 96 hrs of cultivation when 60% of cashew apple juice was used as a substrate

Utilization of palm oil mill effluent as a novel and promising substrate for biosurfactant production by Nevskia ramosa NA3

This paper introduces palm oil mill effluent as a promising substrate for biosurfactant production. Potential strains ofbacteria were isolated from various hydrocarbon-contaminated soils and screened for biosurfactant production with the helpof the drop collapse method and surface tension measurements. Out of 26 isolates of bacteria, the strain NA3 showed thehighest bacterial growth with the highest surface tension reduction of 27.2 mN/m. It was then identified as Nevskia ramosaNA3 by biochemical and 16S rRNA sequence analysis. The Plackett-Burman experimental design was employed to determinethe important nutritional requirements for biosurfactant production by N. ramosa NA3 under controlled conditions. Six outof 11 factors of the production medium were found to significantly affect the production of biosurfactant. FeCl2 and NaNO3had a direct proportional correlation with the biosurfactant production. Commercial sugar, glucose, K2HPO4 and MgCl2showed inversely proportional relationship with biosurfactant production in the selected experimental range