Sasithorn Kongruang

pH Stability of Ultrasonic Thai Isolated Monascus Purpureus Pigments

mutation s were carried out for 4 generations in order to develop efficient food colorants and to study the enhancement of secondary metabolites. The results showed that monacolin K could not be detected in fermented broths from any of the 4 generations. Mutant generations from TISTR3002, contained citrinin at concentrations in G0 (wild type), G1, G2, G3 and G4 of 18.48, 0.01, 64.98, 2.34 and 110.96 µg/ml, respectively. A quantitative analy sis of pigments was performed on all generations and results indicated that the stability of derivatives of yellow, orange and red pigments was greatest at pH 8. A significant increase in pigment stability was gained when TISTR 3002 was ultrasonically induced up to G4. Pigment derivatives of all generations of TISTR 3002 exhibited a greater stability in the basic pH range when compared with an acidic pH range.

Ultrasonic pretreatment enhanced the enzymatic hydrolysis of rice straw

Rice straw can be utilized to use as a raw material for production of biofuel due to its content with a high amount of sugar in a form of 35–40% w/w cellulose and 25–30% w/w hemicelluloses. The effect of ultrasonic treatment to enhance the saccharification process of the enzymatic hydrolysis from rice straw was investigated. Two frequencies at 20 and 24 kHz of ultrasonic treatment were used for 80 min on rice straw before the enzymatic hydrolysis was applied by using commercially available enzyme cocktails: Accellerase™ 1000, Cellic CTec and NS 50013 at 50°C for 48 h. The result was found that the glucose concentration of pretreated rice straw was significantly higher than that of untreated rice straw (p < 0.0001). At frequency of 24 kHz, the glucose concentration of all enzymes was significantly greater than that of enzymes at frequency of 20 kHz (p<0.0001). When treating the rice straw with the Accellerase™ 1000 was yield significantly the highest glucose concentration among the other enzymes (p<0.0001). These results reviewed that the ultrasonic pretreatment could enhance the saccharification process resulting in the acceleration of enzymatic hydrolysis.

Red bacterial cellulose production by fermentation of Monascus purpureus

Red and yellow pigments are secondary metabolic products secreted by Monascus purpureus strains on bacterial cellulose Acetobacter xylinum TISTR 975. In this paper, we study pigments secreted by the strains M. purpureus TISTR 3002, M. purpureus TISTR 3180 and M. purpureus TISTR 3385 grown in Modified Yeast Malt Extract. The experiment was carried out on a rotating shaker at 250 rpm under 30°C for 14 days. The results showed that the rate of red pigment production by 3385, 3002 and 3180 are 0.093, 0.036 and 0.029 UA, respectively. TISTR 3385 revealed the highest pigment production with a ratio of 1.18 times 3002 and 1.68 times 3180. The substrate consumption decreased with increasing fermentation time. The results also showed that 3385 substrate consumption of 0.168 g/L/day was 1.22 times higher than that of 3180 (0.138 g/L/day) and 1.85 times higher than 3002 (0.091 g/L/day). Total color differences were also evaluated and showed that 3002 exhibited a 2.25 times higher color yield (1.51 unit/day) than 3385 (0.67 unit/day) and 3.78 times higher than 3180 (0.40 unit/day). Results revealed that this red bacterial cellulose contained 3.41 g/L carbohydrate, 0.054 g/L protein, 20% (w/v) lipid, 95% (w/w) moisture content with mineral values of calcium, iron and phosphorous of 10, 4 and 1 mg/100g, respectively. Monacolin K and citrinin were not found in fermented bacterial celluloses. The pigmented color derived from Monascus bacterial cellulose can therefore be used as a safe food source that is not contaminated by citrinin.

Ethanol production from rice straw using ultrasonic pretreatment

Pretreatment is one of the approaches to yield the higher saccharification process leading to optimization of ethanol yield. The effect of ultrasonic pretreatment on ethanol production from rice straw was studied. A 0.16 kW/L ultrasonic treatment was applied to treat rice straw during enzymatic hydrolysis and fermentation process. The enzymatic hydrolysis process was carried out at 50°C and pH 4.8 by using a commercial enzyme and followed by fermentation with S.cereviceae. Morphological structure of rice straw was analyzed by a scanning electron microscopy (SEM) and the glucose concentration was detected by biochemistry analyzer. The result showed that the structure of rice straw after ultrasonic treatment showed a breaking of lignin and exposition of cellulose surface. The glucose concentration of the pretreated rice straw increased significantly by 57.65% (p = 0.003) when compared to the untreated rice straw. The total ethanol concentration of the untreated was not obviously different from the pretreated rice straw. Results revealed that ultrasonic treatment could enhance the ethanol production from rice straw.

Identification of citrinin biosynthesis gene under the ultrasonic induction of Monascus purpureus

Polyketide synthases are multifunctional enzymes that involve the synthesis of pigments and mycotoxin which is normally known as citrinin. The gene involving citrinin biosynthesis especially, acyltransferase in polyketide synthase gene of M. purpureus TISTR 3541 isolated in Thailand as the wild type and the ultrasonic induced mutation of this wild type as the mutants (generations 1–4, G1–G4) was investigated. The transcription level of the acyltransferase in M. purpureus TISTR 3541 wild type (G0) and of mutants (G1 to G4) was studied by using RT-PCR with the actin gene as a positive control. The nucleotide sequences were analyzed by using Automated DNA Sequencing. Results showed that the nucleotide sequences of acyltransferase in polyketide synthase gene of M. purpureus mutants and wild type were absolutely similar. When the sequence comparison was aligned, the obtained nucleotide sequence showed 100% sequence similarity with pksCT gene that involving in citrinin biosynthesis in M. purpureus. The RT – PCR results were in agreement with real – time PCR analysis which was showed that shape intact DNA band of M. purpureus TISTR 3541 G2 more than other generations resulting in the better acyltransferase expression than others.

Solvent Stability of Ultrasonic Mutants of Monascus purpureus Pigments

The stability to solvent is one of crucial parameters to apply Monascus pigment in food and textile industries. Ultrasonic induced mutants from Monascus purpureus TISTR 3002 were tested for the solvent stability in order to select the best pigment producer with the wide range of solvents. Reports of pigment stability percentages of all generations were shown. Estimation of Monascus pigments can be expressed as the total pigment yield (y) from the results of the significant parameters (solvents, yellow, orange and red pigments) on multiple linear regression. The color yield value equations can be represented as y = 0.132 (+0.35) + 1.278 (+0.35) *(yellow) + 1.235(+0.35)*(red). The maximum total pigment yield gained from these strains was the results of the contribution of yellow and red pigments. Optimization analysis indicated that G4 was the best pigment producer that could sustained the wide range of solvents with the highest residual solvent stability. application. We have previously shown that the stabilities of color derivatives of Monascus pigments under various pH are greatly enhanced once the ultrasonic induced up to G4, compared to an original red pigment, and various pH affecting the stability of pigments were kinetically analyzed as the first-order rates of decay (14). In this study, the extracellular pigments from ultrasonic mutants were used as model compounds for testing for the solvent stability, the Gibbs energy and first order rates of degradation were evaluated. The possible models for total pigment yield under accounting for generations, yellow, orange and red pigments were reported.

Gelatin-Bacterial Cellulose Composite Sponges Thermally Cross-Linked with Glucose for Tissue Engineering Applications

Freeze-drying and thermal cross-linking techniques were used to prepare gelatin-bacterial cellulose (GB) composite sponges for potential application as scaffolds in tissue engineering. To avoid the use of toxic and costly cross-linking agents, glucose was used to cross-link the gelatin via the Maillard reaction. The effects of the weight ratio of gelatin to bacterial cellulose (BC) and the cross-linking conditions (temperature and duration) on the GB sponges were examined. An open and highly interconnected porous structure was attained for the GB sponge with a gelatin:BC weight ratio of 25:75 that was cross-linked at 140°C for 3h. Its high porosity, good swelling properties, good structural stability in water, non-toxicity and good biocompatibility against Vero cell are promising for its application as a scaffold for tissue engineering.