Lactic acid (LA) fermentation by Lactobacillus salivarius ATCC 11741 immobilized on loofa sponge (LS) was evaluated. To increase the surface area of LS for cell immobilization, H 2 O 2 and chitosan were introduced as surface modifying reagents. Four chitosans of different molecular weights were separately coated on LS. All experiments were conducted in shaking flask mode at 100 rpm rotating speed and 37 o C with 5% CaCO 3 as a pH regulating agent. The effects of initial glucose concentration were investigated in the range of 20-100 g/l on LA fermentation by free cells. The results indicate that the maximum concentration of LA was produced with 50 g/l glucose concentration. The immobilized cell system produced 1.5 times higher concentration than free cells for 24 h of fermentation. Moreover, immobilized cells can shorten the fermentation time by 2-fold compared with free cells at the same level of LA concentration. At 1% (w/v) chitosan in 2% (v/v) acetic acid, the Yp/s and productivities of various molecular weights of chitosans were insignificantly different. Repeated batch fermentations showed 5 effective recycles with Yp/s and productivity in the range of 0.55-0.85 and 0.90-1.20 g/l.h, respectively. It is evident that immobilization of L. salivarius onto LS permits reuse of the system under these fermentation conditions. Scanning electron micrographs indicated that there were more intact cells on the chitosan-treated LS than on the untreated LS, thus confirming the effectiveness of the LS-chitosan combination when being utilized as a promising immobilization carrier for LA fermentation.

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The enzyme β-galactosidase (lactase; EC 3.2.1.23) is a commercially important enzyme due to its various applications in dairy and food industries, which are based on the β-galactosidase-catalysed hydrolysis of lactose into glucose and galactose. The objectives of this work were to identify novel and attractive sources of this industrially relevant enzyme, and to study the effect of selected growth parameters (carbon source, lactose concentration, nitrogen source, peptone concentration, initial pH and temperature) on the formation of β-galactosidase. Based on a screening of isolates from Tha Pai hot spring, Mae Hong Son Province, Thailand, strain B1.1 was selected for further studies. Strain B1.1 is a Gram-positive, rod-shaped, catalase-positive bacterium that forms endospores. Based on the sequence of the 16S rDNA determined, this isolate is most closely related to Anoxybacillus sp. and Bacillus sp., and hence the strain is designated as Bacillus sp. B1.1. β-Galactosidase was produced by this strain with lactose and peptone as carbon and nitrogen sources, respectively. Optimal enzyme production occurred at an initial culture pH of 8.5 and at 45 °C. Under these optimum culture conditions, maximal volumetric and specific β-galactosidase activity of 0.478 U mL -1 and 0.338 U mg -1 protein, respectively, were obtained after 13 h of cultivation in a medium contain 2.5% lactose, 2.0% peptone, 0.3% K 2 HPO 4 , 0.1% KH 2 PO 4 and 0.05% MgSO 4 ·7H 2 O.

Bacterial cellulose (BC), produced by some bacteria has received attention because its high purity and robust characteristics enable its use in medicine and industry. This study aimed to screen bacteria capable of producing BC from fruits, and to optimize the BC production in both traditional YE yeast fermentation and Schramm and Hestrin (SH) media. The rice washing drainage without any pretreatment as the sole carbon source in the yeast medium was also investigated for BC production in both static and agitated cultures. The bacterial strain Li1 isolated from apple (Malus pumila) was identified as Komagataeibacter (Gluconacetobacter) nataicola based on 16S rDNA sequence analysis. K. nataicola Li1 cultured in a YE medium produced significantly more BC than that in a SH medium in the static culture. Moreover, the weight yields of dry BC films obtained from rice washing drainage and YE media in the static cultures were not significantly different. However, in the agitated culture, the weight yields of dry BC films were more significant in the YE medium than in rice washing drainage medium. In addition, the structure and properties of BC were determined using SEM, FTIR, DSC and XRD. This study shows that rice washing drainage can be used as the carbon source for BC production by K. nataicola Li1.

Bacterial cellulose (BC) is a naturally produced as an exopolysaccharide from some bacteria. It has excellent properties over the plant cellulose and has numerous applications in many fields including food, pharmaceutical, textile, paper manufacturing and other industries. However, a major limitation of bacterial cellulose production is the high cost of carbon substrate. The study aims to reduce the cost of bacterial cellulose using a cheap carbon source. This study presents feasibility in the production of bacterial cellulose using the starchy effluent waste from the Thai fermented rice noodle manufacturing process as a low-cost substrate by Acetobacter xylinum TISTR 975. The optimizations of culture conditions for bacterial cellulose production were also investigated under static culture. The results indicated that starchy effluent waste from the Thai fermented rice noodle manufacturing process performs well for the production of bacterial cellulose by supplementing with 50 g/L sucrose and 2% olive oil under the static condition. The structure and physical properties of bacterial cellulose were characterized using SEM, FTIR and XRD. In summary, the starchy effluent waste from the Thai fermented rice noodle manufacturing process can be used to produce bacterial cellulose which is a high value-added, sustainable and green product.