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

Bacterial population diversity in Sataw-Dong, a traditional fermented stink bean, during fermentation using the combination of culturedependent and culture independent methods through DGGE technique

Sataw-Dong is a pickled plant-based food in which stink beans (Parkia speciose) undergo spontaneous fermentation in brine and has its characteristic flavors and tastes. The changes in bacterial flora during Sataw-Dong fermentation was investigated using culture-dependent and culture-independent methods. Molecular approaches applying PCR-denaturant gel gradient electrophoresis (PCR-DGGE) was used as culture-independent. The bacterial profile targeting the V3 region of the 16S rRNA gene indicated lactic acid bacteria (LAB) belonged to Lactobacillus plantarum, Lactobacillus fermentum, Lactobacillus pentosus and Enterococcus feacium. Results showed L. plantarum was the predominant species among LAB. Species of plant and environmental flora, such as Cohnella collisoli, Erwinia billingiae, Enterobacter cloacae, Klebsiella pneumoniae and Staphylococcus cohnii, were detected at the early period of fermentation and thereafter disappeared due to the presence of dominant LAB. The combination of molecular techniques was greatly effective in accessing and profiling bacterial community for a successful application in selection of potential starter cultures

Biosurfactants from marine microorganisms

Biosurfactants are the surface-active molecules synthesized by microorganisms. With the advantage of environmental compatibility, the demand for biosurfactants has been steadily increasing and may eventually replace their chemically synthesized counterparts. Marine biosurfactants produced by some marine microorganisms have been paid more attention, particularly for the bioremediation of the sea polluted by crude oil. This review describes screening of biosurfactant-producing microorganisms, the determination of biosurfactant activity as well as the recovery of marine surfactant. The uses of marine biosurfactants for bioremediation are also discussed

Production of biosurfactants using substrates from renewable-resources

Surface-active compounds commonly used in industries are chemically synthesized. However, biosurfactants have been paid increasing attention to replace the synthetic surfactants owing to their advantages such as biodegradability and low toxicity. Nowadays, the use of biosurfactant has been limited due to the high production cost. Nevertheless, biosurfactants can be produced with high yield by some microorganisms, especially Pseudomonas sp. These microorganisms can use the various renewal resources, especially agroindustrial wastes, as the potential carbon sources. This leads to the greater possibility for economical biosurfactant production and reduced pollution caused by those wastes

Physical, biochemical and genetic characterization of enterocin CE5-1 produced by Enterococcus faecium CE5-1 isolated from Thai indigenous chicken intestinal tract

Enterocin CE5-1 produced by Enterococcus faecium CE5-1 isolated from the chicken gastrointestinal tract was active in the wide range of pH 2-10 and temperature 30-100°C and sensitive to proteolytic enzymes and -amylase. It remained active after storage at -20°C for 2 months. Moreover, enterocin CE5-1 showed antibacterial activity against lactobacilli, bacilli, listeria, staphylococci and enterococci, especially antibiotic-resistant enterococci. In vitro study of enterocin CE5-1 decreased the population of Ent. faecalis VanB from 6.03 to 4.03 log CFU/ml. The lethal mode of action of enterocin CE5-1 appeared to be pore and filament formation in the cell wall. PCR sequencing analysis revealed the presence of two open reading frames (ORFs), containing enterocin CE5-1 (entCE5-1) and enterocin immunity (entI) gene. Therefore, enterocin CE5-1 from Ent. faecium CE5-1 could possibly be used as an antimicrobial agent to control foodborne pathogen, spoilage bacteria and antibiotic-resistant enterococci in foods, feeds and the environments

Production and characterization of bioemulsifier from a marine bacterium, Acinetobacter calcoaceticus subsp. anitratus SM7

Marine bacterium strain SM7 was isolated as a bioemulsifier-producing bacterium from oil-spilled seawater in Songkhla lagoon, Thailand. It was identified as Acinetobacter calcoaceticus subsp. anitratus based on morphology, biochemicalcharacteristics and 16S rRNA sequence. A. calcoaceticus subsp. anitratus SM7 produced an extracellular emulsifying agent when grown in a minimal salt medium (pH 7.0) containing 0.3% (v/v) n-heptadecane and 0.1% (w/v) ammoniumhydrogen carbonate as carbon source and nitrogen source, respectively, at 30oC with agitation rate of 200 rpm. Crude bioemulsifier was recovered from the culture supernatant by ethanol precipitation with a yield of 2.94 g/l and had a criticalemulsifier concentration of 0.04 g/ml. The crude bioemulsifier was capable of emulsifying n-hexadecane in a broad pH range (6-12), temperatures (30-121oC) and in the presence of NaCl up to 12% (w/v). The bioemulsifier was stable in saltsolution ranging from 0 to 0.1% (w/v) of MgCl2 and CaCl2. The broad range of pH stability, thermostability and salt tolerance suggested that the bioemulsifier from A. calcoaceticus subsp. anitratus SM7 could be useful in environmentalapplication, especially bioremediation of oil-polluted seawater

Survival of encapsulated potentially probiotic Lactobacillus plantarum D6SM3 with bioemulsifier derived from spent yeast in simulated gastrointestinal conditions

The effect of encapsulation with three kinds of emulsifier (Tween 80, gum arabic and bioemulsifier extracted from spent yeast) on the survival of Lactobacillus plantarum D6SM3 in simulated gastrointestinal tract during storage at 4°C and room temperature was investigated. The survival of all encapsulated cells treated in simulated gastric juice was higher than free cells at both pH 2.5 and 3.0. The viability of the free and encapsulated cells showed a gradual decline throughout the storage period at 4°C. However, the viability rapidly declined at room temperature. In addition, the droplet size distribution of encapsulated cells was compared between those with and without an emulsifier by using the laser diffraction method. The particle size and polydispersity value of encapsulated cells were controlled better in emulsion with emulsifier added. The surface of encapsulated cells with emulsifier exhibited smoother characteristics than those without emulsifier