Phisit Seesuriyachan

Exopolysaccharides from lactic acid bacteria: structural analysis, molecular weight effect on immunomodulation.

Exopolysaccharides (EPS) obtained from the culture medium of Lactobacillus confusus TISTR 1498 were investigated to determine their molecular characteristics and the effect of molecular weight (Mw) on immunomodulatory activity. The EPS mainly consisted of carbohydrates (81.9±2.4%) with only one type of monosaccharide, D-glucose, which was mostly connected by α-(1→6) glycosidic linkages. The EPS itself was unable to stimulate RAW264.7 cells to produce pro-inflammatory mediator nitric oxide (NO) and cytokines. However, considerable stimulation of RAW264.7 cells was observed by the low Mw of EPSs having Mw values≤70×10(3)g/mol. The partially hydrolyzed EPS stimulated RAW264.7 cells to induce considerable NO and various cytokine production such as TNF-α, IL-1β, IL-6 and IL-10 via up-regulation of their mRNA expression. In addition, the degradation Iκ-B and the phosphorylation of c-Jun NH2-terminal kinase (JNK) were facilitated by BW-30 and MW-40, suggesting that the partially hydrolyzed EPS stimulated RAW264.7 cells through the activation of NF-κB and JNK pathways.

Optimization of cellulase-free xylanase production by thermophilic streptomyces thermovulgaris TISTR1948 through Plackett-Burman and response surface methodological approaches

Cellulase-free xylanase production by thermophilic Streptomyces thermovulgaris TISTR1948 was cultivated in a basal medium with rice straw as sole source of carbon and as an inducible substrate. Variable medium components were selected in accordance with the Plackett-Burman experimental design. The optimization conditions of physical factors (pH and temperature levels) were then combined in further studies through the response surface methodology approach. Only two significant components, rice straw and yeast extract, were chosen for the optimization studies. A second-order quadratic model was constructed by central composite design (CCD). The model revealed that both pH and temperature levels were significant, and were dependent on xylanase production. Under these experimental designs, the xylanase yield increased from 51.11 to 274.49 U/mL (3,400 to 10,000 U/g of rice straw) or about 537% higher than an unoptimized basal medium. The optimum conditions to achieve maximum yield of xylanase were 27.45 g/L of rice straw and 5.42 g/L of yeast extract under relatively neutral conditions of pH 7.11, 50.03 °C, and a incubation period.

Eco-friendly processing in enzymatic xylooligosaccharides production from corncob: Influence of pretreatment with sonocatalytic–synergistic Fenton reaction and its antioxidant potentials

Delignification can be considered as a feasible process to pretreat lignocellulosic biomass in xylooligosaccharides production after the performance and efficiency has been improved through a few modifications. This study compared various pretreatment strategies such as Fenton, sonocatalytic, and sonocatalytic-synergistic Fenton employed on corncob in order to expose lignin content and saccharides to enhance the xylooligosaccharides yield by enzymatic hydrolysis. The dissolution of lignin and xylooligosaccharides production of corncob was enhanced by ultrasound assisted TiO2 and Fenton reaction. The corncob pretreated with a sonocatalytic-synergistic Fenton reaction gave the highest release of the lignin concentration level (1.03 g/L), dissolution level (80.25%), and xylooligosaccharides content (46.45 mg/g substrate). A two-step pretreatment processes consisting of the alkali treatment (pretreatment) and sonocatalytic-synergistic Fenton process (posttreatment) illustrated that subsequent enzymatic hydrolysis could be enhanced considerably. The release of the lignin concentration and xylooligosaccharides content were 33.20 g/L and 174.81 mg/g substrate, respectively. The antioxidant potential of xylooligosaccharides showed significant differences regarding the amount of xylooligosaccharides and the phenolic compounds produced.

Production of xylooligosaccharides from corncob using a crude thermostable endo-xylanase from Streptomyces thermovulgaris TISTR1948 and prebiotic properties

Production of xylooligosaccharides (XOs) from corncob using the thermostable endo-xylanase from Streptomyces thermovulgaris TISTR1948 was investigated using KOH pretreatment, followed by enzymatic hydrolysis. The optimal reaction time for production of XOs was 12 h, after which xylobiose comprised a majority of products, and a low xylose content was observed. The optimal conditions for production of XOs were studied using a central composite design. At an enzyme concentration of 129.43 U/g of substrate, 53.80°C, and pH 6.17, the yield of XOs reached 162.97 mg/g of substrate or 752.15 mg/g of hemicellulose in KOH-pretreated corncob. The prebiotic properties of XOs derived from corncob were also investigated using in vitro fermentation of those XOs with the known probiotic strains Lactobacillus casei TISTR1463, L. lactis TISTR1464, and L. plantarum TISTR1465. XOs derived from corncob were comparable to commercial XOs for an ability to enhance the growth of the specified probiotic lactobacilli.

Optimization of Exopolysaccharide Overproduction by Lactobacillus confusus in Solid State Fermentation under High Salinity Stress

It is believed that high concentrations of sodium chloride (NaCl) suppress the biosynthesis of exopolysaccharide (EPS) in lactic acid bacteria (LAB). Nevertheless, overproduction of EPSs due to high salinity stress in solid state fermentation performed on an agar surface was demonstrated in this study using a response surface methodology via a central composite design (CCD). Under optimized conditions with NaCl 4.97% and sucrose 136.5 g/L at 40.79 h of incubation, the EPS yield was 259% (86.36 g/L of EPS), higher than the maximum yield produced with the modified MRS medium containing only 120 g/L of sucrose without NaCl (33.4 g/L of EPS). Biosynthesis of EPS by Lactobacillus confusus TISTR 1498 was independent of biomass production. Our results indicated that high salinity stress can enhance EPS production in solid state fermentation.

Reactive blending of thermoplastic starch and polyethylene-graft-maleic anhydride with chitosan as compatibilizer.

Cassava starch was melt-blended with glycerol (70/30wt%/wt%) at 140°C to prepare thermoplastic starch (TPS). Chitosan (CTS) was premixed with starch and glycerol, in acidified water (lactic acid 2wt%), at 1, 5 and 10wt%/wt%. TPS/CTS was then melt-blended (160°C) with polyethylene-graft-maleic anhydride (PE-MAH). Phase determination and scanning electron microscopy indicated TPS/PE-MAH/CTS had a co-continuous morphology and CTS-induced phase inversion to give dispersed PE-MAH particles in a TPS matrix. Tensile strength at break and elongation, melt viscosity, fracture toughness and water contact angle of TPS/PE-MAH were improved by CTS incorporation. TPS/PE-MAH/CTS blends decreased the melting temperature of TPS and PE-MAH compared to the neat polymers. FTIR confirmed a reaction had occurred between amino groups (NH2) of CTS and the MAH groups of PE-MAH. This reaction and the enhanced miscibility between TPS and CTS improved the mechanical properties of the TPS/PE-MAH/CTS blend, particularly at 5wt%/wt% CTS.

Characterization of the native form and the carboxy‐terminally truncated halotolerant form of α‐amylases from Bacillus subtilis strain FP‐133

Two amylases, amylase I and amylase II from Bacillus subtilis strain FP‐133, were purified to homogeneity and characterized. Their stabilities toward temperature, pH, and organic solvents, and their substrate specificities toward polysaccharides and oligosaccharides were similar. Under moderately high salt conditions, both amylases were more stable than commercial B. licheniformis amylase, and amylase I retained higher amylase activity than amylase II. The N‐terminal amino acid sequence, genomic southern blot analysis, and MALDI‐TOFF‐MS analysis indicated that the halotolerant amylase I was produced by limited carboxy‐terminal truncation of the amylase II peptide. The deduced amino acid sequence of amylase II was >95% identical to that of previously reported B. subtilis α‐amylases, but their carboxy‐terminal truncation points differed. Three recombinant amylases — full‐length amylase corresponding to amylase II, an artificially truncated amylase corresponding to amylase I, and an amylase with a larger artificial C‐terminal truncation — were expressed in B. subtilis. The artificially truncated recombinant amylases had the same high amylase activity as amylase I under moderately high salt conditions. Sequence comparisons indicated that an increased ratio of Asp/Glu residues in the enzyme may be one factor responsible for increasing halotolerance.

Solid State Fermentation for Extracellular Polysaccharide Production by Lactobacillus confusus with Coconut Water and Sugar Cane Juice as Renewable Wastes

Extracellular polysaccharide (EPS) production by Lactobacillus confusus in liquid and solid state fermentation was carried out using coconut water and sugarcane juice as renewable wastes. High concentrations of EPS of 62 (sugarcane juice) and 18 g/l of coconut water were produced in solid state fermentation when nitrogen sources were reduced 5-fold from the original medium.

Green and chemical-free process of enzymatic xylooligosaccharide production from corncob: Enhancement of the yields using a strategy of lignocellulosic destructuration by ultra-high pressure pretreatment

In this study, the pressures at 50-500MPa were evaluated at different time to pretreat and further enzyme hydrolysis. The ultra-high pressure (UHP) pretreatment at 100MPa for 10min led to improved accessibility of enzyme for conversion of xylan to xylooligosaccharide (XOS). The maximum XOS yield of 35.6mg/g substrate was achieved and firstly reported at 10% (w/v) of substrate, 100U of endo-xylanase/g corncobs and incubation time of 18h. The enzymatic hydrolysis efficiency was increased by 180.3% and released a high amount of xylobiose. The UHP pretreatment relatively did not affect to the composition of corncob, but decreased 34.3% of lignin. Interestingly, antioxidant activities of XOS using UHP pretreatment were higher than untreated corncob. The UHP pretreatment improved lignocellulosic destructuration and XOS yields in a shorter time without the need of chemicals, implying that UHP could be an effective pretreatment of biomass with a chemical-free process.

Statistical modeling and optimization for exopolysaccharide production by Lactobacillus confusus in submerged fermentation under high salinity stress

In the last two decades, many studies have been reported that a high concentration of NaCl suppresses exopolysaccharide (EPS) production in lactic acid bacteria. In the present study, however, the enhancement of EPS production by Lactobacillus confusus under high salinity stress in submerged fermentation was demonstrated using response surface methodology via a full factorial design. Under the optimized conditions of 3.33% NaCl, 20 g/L sucrose, and 35 h of incubation, the EPS yield was 10.87 g/ L with 178% higher than the maximum yield (6.12 g/L of EPS) produced from the modified MRS medium without NaCl. Biomass production was independent of EPS production. A high yield of biomass was obtained in the culture with 0.23% NaCl. This results indicate that high salinity stress by NaCl can enhance EPS production in submerged fermentation in uncontrolled pH cultivations by inducing the production of cell-associated dextransucrase.