Screening of thermotolerant microorganisms and application for oil separation from palm oil mill wastewater

The characteristics of palm oil mill wastewater (POMW) were brown color, pH 3.8-4.3, temperature 48-55oC, total solids 68.2-82.1 g/l, suspended solids 26.2-65.6 g/l, oil and grease 19.1-25.1 g/l, COD 49.9-160.7g/l and BOD 32.5-75.3 g/l. After centrifugation (3,184 xg) of 50 ml POMW for 10 min, the POMW was separated into 3 layers: top (oil), middle (supernatant) and bottom layer (sediment). The sediment containeddry weight 1.19 g and oil and grease 1.07 g. In order to release oil and grease trapped in palm fiber debris in the POMW, cellulase- and/or xylanase-enzyme-producing and thermotolerant microorganisms wereisolated. The isolates SO1 and SO2 were isolated from soil near the first anaerobic pond of the palm oil mill. They were aerobic, Gram positive, rod shaped, thermotolerant microorganisms and produced cellulase 12.11 U/ml (3 days) and 7.2 U/ml (4 days), and xylanase 50.98 U/ml (4 days) and 20.42 U/ml (4 days), respectivelyin synthetic medium containing carboxymethycellulose as a carbon source. When these 2 isolates were added into the steriled POMW under shaking condition for 7 days, after centrifugation at 3,184 xg the isolate SO1gave the better % reduction of dry weight (64.66 %) and of oil and grease in the bottom layer (85.32 %) of the POMW

Combined effect of crude herbal extracts, pH and sucrose on the survival of Candida parapsilosis and Zygosaccharomyces fermentati in orange juice

The purpose of this study was to evaluate the antimicrobial activity of crude extracts of cinnamon and clove compared with potassium sorbate against food spoilage yeasts isolated from orange juice (Candidaparapsilosis and Zygosaccharomyces fermentati). The ethanolic extract of both cinnamon and clove showed activity against C. parapsilosis and Z. fermentati with minimum inhibitory concentrations (MIC) of 1.0 and0.5 mg/ml by agar dilution method, respectively. While potassium sorbate showed activity against both yeasts with MIC 0.4 mg/ml. The combined effect of pH, concentration of sucrose and cinnamon extract or cloveextract or potassium sorbate in orange juice on the survival of the isolated yeasts were studied using Response Surface Methodology. The pH of orange juice and the concentration of cinnamon or clove extracthad the most significant (P<0.05) effect on the survival of C. parapsilosis and Z. fermentati while concentration of sucrose had the least effect. Survival of C. parapsilosis and Z. fermentati was mostly affected by theconcentration of potassium sorbate but pH and the concentration of sucrose did not have significant effect on the survival of Z. fermentati

Optimization of exopolysaccharides production by Weissella confusa NH 02 isolated from Thai fermented sausages

Exoploysaccharides (EPSs) producing lactic acid bacteria (LAB) were isolated from Thai traditional fermented foods. Colonies exhibiting a clear zone and ropiness on modified MRS agar containing 2% (w/v) sucrose and 0.02% (w/v) bromocresol purple were selected for Gram staining and catalase test. From 140 isolates, 120 isolates were identified as LAB. However, only 14 strains were able to produce a large amount of EPSs (>5.9 g/l) when cultivated in modified MRS broth containing 2% (w/v) sucrose at 37ºC for 24 hrs. The highest viscosity and yield of EPSs were obtained from isolate NH 02. Based on 16S rDNA analysis, strain NH 02 was identified as Weissella confusa. Sucrose (40 g/l), an initial pH of modified MRS at 7.0, and a cultivation temperature of 37ºC were the optimum conditions, in which EPSs were produced at levels up to 18.08 g/l within 12 hrs. EPSs produced by W. confusa NH 02 contained only glucose and had a molecular mass of 1.13106Da. to 18.08 g/l within 12 hrs

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

Saccharification of cassava starch by Saccharomycopsis fibuligera YCY1 isolated from Loog-Pang (rice cake starter)

The main objectives of this study were to select amylolytic yeasts from Loog-Pang, a traditional starter culture for production of alcoholic foods and drinks in southern Thailand, and to optimize the saccharification of cassava starch to reducing sugar by the selected yeast isolate. Seventy-four yeast isolates were obtained from ten samples of Loog-Pang. The isolates were tested for amylolytic activity on Yeast-Peptone Cassava medium (YPC) contained 30 g/l of cassava starch.Only three isolates showed amylolytic activity which produced clear zone on the YPC agar. The best amylolytic strain with clear zone of 8 mm was identified by 26s rDNA as Saccharomycopsis fibuligera. The optimum medium for saccharification by Saccharomycopsis fibuligera. YCY1 was only 50 g/l of cassava starch in distilled water without nitrogen sources added and pH adjustment. The optimal saccharification conditions were 200 ml cassava starch (50 g/l) in 500 ml Erlenmeyer flask, shaking at 100 rpm and 37oC. Under these conditions, the highest reducing sugar was obtained 46±0.53 g/l after 120 h cultivation (84% of the theoretical yield)

Characteristics and oxidative stability of bread fortified with encapsulated shrimp oil

Characteristics and oxidative stability of bread fortified with micro-encapsulated shrimp oil (MSO) were determined. The addition of MSO could improve the loaf volume of bread. Chewiness,gumminess and resilience of resulting bread were decreased. Bread crust and crumb showed higher redness and yellowness when MSO was incorporated (P&lt;0.05). Microstructure study revealed that MSO remained intact with bread crumbs. The addition of MSO up to 3% had no adverse effect on bread quality and sensory acceptability. Oxidation took place in bread fortified with 5%MSO to a higher extent, compared with those with 1 or 3% MSO. Therefore, the bread could be fortified with MSO up to 3%