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Bioremediation has been widely used for clean-up of 1,2-dichloroethane (DCA) at contaminated sites. Only a small number of specific anaerobes, halorespiring bacteria (HRB), have been reported to degrade DCA. The goals of this research were the screening and isolation of HRB with capable dechlorination of DCA. HRB were screened and isolated from 7 enrichment cultures (ES1-ES7), from DCA-contaminated soils, on bicarbonate-buffered basal salts medium containing 10 mM acetate and 250 µM DCA under anaerobic conditions and analyzed by gas chromatography. The results showed that the mixed cultures of ES3 and ES5 could reductively dechlorinate DCA to ethylene via a direct reductive dihaloelimination pathway. In particular, ES5 showed rapid transformation of 250 µM DCA to ethylene within 6 days at 30 °C. Specific microbial populations of Vulcanibacillus spp., elucidated by polymerase chain reaction-denaturing gradient gel electrophoresis, were found only in ES3 and ES5, which was related to reductive dihaloelimination activities on DCA. A 16S rRNA gene analysis of isolate es5d8 from mixed culture ES5 revealed 2 strains of Vulcanibacillus spp. (KKU-DCA1 and KKU-DCA2) concerned with dechlorinating DCA. These findings suggested that Vulcanibacillus spp. were HRB that have the potential for detoxifying DCA.

Dextranase is commonly used for eliminating dextran contamination in sugar factory. This research, dextranase from Aspergillus allahabadii X26, was produced, purified and characterized including on dextran hydrolysis. A. allahabadii X26 was cultured in a medium containing 1% dextran T2000 as a carbon source in 5-l fermenter aerobically at 30 °C and obtain 110 U/ml crude extracellular dextranase activity within 9 days of incubation. Extracellular dextranase could be purified by the 2 steps of ammonium sulfate precipitation and affinity chromatography using Sephacryl S-300 HR. This resulted in 6.5-fold and a 39.1% recovery yield obtaining 3009 U/mg mg protein. The purified enzyme exhibited 66 kDa on SDS-PAGE and was specified as a glycoprotein. The optimum pH and temperature for enzyme activity were 5.8 and 55 °C, respectively. The enzyme exhibited thermostability in the range of 20–50 °C and pH 5–9 over the incubation period of 1.5 h. The dextranase activity was enhanced by Co2+, Mn2+ and Ca2+, whereas most ions and reagents did not inhibit its activity. The enzyme only had specificity to the α(1 → 6) glycosidic bond of dextran. Partial sequences of the enzyme determined by an ESI mass spectrometer showed similarity toward dextranase GH49. This purified dextranase (0.2 U/ml) from A. allahabadii X26 could degrade high molecular weight dextran into fragments of 5–10 kDa and oligodextrans within 5 min. These A. allahabadii X26 dextranase properties indicated high potential for dextran elimination in sugar production process.

Nitrogen (N) is an essential element for plant growth, widely applied as chemical N-fertilizer to improve yield of sugarcane. The elevated doses of fertilizers may have negative and unpredictable effects on the environment. Bio-fertilizers containing nitrogen fixing bacteria (NFB) are alternative and potential way to reduce application of chemical N-fertilizer. The NFB strain Enterobacter oryzae 3LSO1 isolated from rhizosphere soil of sugarcane can fix atmospheric dinitrogen (N2), produces indole-3-acetic acid as plant growth promoting substance. Therefore, this effective strain was developed as a vermiculite-based bio-product to enhance sugarcane growth. The bio-product was compared storing conditions at 10 and 30 °C for 30 or 60 days after formulation (DAF), and then its performance was evaluated. Result stated that the bio-product could be kept at 10 and 30 °C for up to 60 DAF without a decrease in the NFB population or a loss in its ability to fix N2. In a greenhouse experiment, commercial sugarcane variety Khon Kaen 3 applied with the E. oryzae 3LSO1 bio-product and planted with or without nitrogen fertilizer could increase the tiller number, plant height, fresh and dry weight, NFB population in soil and sugarcane, compared with the control. This E. oryzae 3LSO1 bio-product not only used as a bio-nitrogen fertilizer for sugarcane crops, but also reduced chemical N-fertilizer application for sustainable agriculture.

This experiment was conducted to investigate the utilisation of yeast waste as protein source to replace soybean meal in concentrate mixture on kinetic of gas, rumen ammonia-nitrogen and digestibility of nutrients by using in vitro gas production technique. The experimental design was a completely randomised design and the dietary treatments were replacing soybean meal with yeast wastein concentrate at the ratio of 100:0, 75:25, 50:50, 25:75 and 0:100, respectively. Yeast waste was obtained from KSL Green Innovation Public Co. Limited, Thailand. The gas production was recorded at 0, 0.5, 1, 2, 4, 6, 8, 12, 16, 24, 48, 72 and 96 h of incubation. The yeast waste contained 26.4% crude protein. Gas production from soluble fractions (a), gas production from the insoluble fraction (b), potential extent of gas production (a+b) and the gas production rate constants for the insoluble fraction (c) were not altered when increasing concentration of yeast waste replacing soybean meal (P > 0.05). Cumulative gas production (at 96 h of incubation) ranged from 69.3 to 72.8 mL and was similar among treatments. Ruminal NH3-N concentration was linearly increased (P < 0.05) whereas ruminal pH did not alter when inclusion various levels of yeast waste replacing soybean meal, which ranged from 15.2 to 19.1 mg/dL and 6.90 to 6.94, respectively. In vitro dry matter digestibility and in vitro organic matter digestibility did not changed by increasing levels of yeast waste in the diets (P > 0.05), except only in vitro dry matter digestibility at 12 h, which higher in soybean meal:yeast waste at 25:75 ratio (P < 0.05). Furthermore, propionate (C3) molar was linearly higher when compared between inclusion yeast waste and the control group whereas acetate was decreased quadratically (P < 0.05) and protozoal population tended to be decreased (P = 0.07) when increasing the level of replacing yeast waste. In conclusion, yeast waste could replace soybean meal in concentrate mixture with no negative effect on gas kinetics, rumen fermentation and in vitro digestibility, and therefore its use in animal feeding would contribute to a reduction in environmental pollution.

Dextran is a polysaccharide consisting of glucose monomers linked mainly by α(1–6) bonds, produced by numerous microorganisms. It is well known that dextran in cane detrimentally affects processing in the sugar industry. Many microorganisms have been isolated from sugarcane juice during the milling process at Mitr Phuveing Sugar Factory. These organisms were screened for their dextran producing property by selecting mucoid colonies on plate count agar (PCA), MRS agar and malt extract (ME) agar medium containing 10% sucrose. The secondary and tertiary screening was accomplished by growing them in sugarcane juice and complete liquid medium (CM) adding 10% sucrose, aerobically at the appropriate temperature for each isolate. The rapidly growing strains were selected. The bacterial strains were Klebsiella pneumoniae, Enterobacter cloacae, and Lactobacillus fermentum. Among these K. pneumoniae P100 produced the maximum concentration of dextran (6,800 ppm) at stationary phase within 12 h of incubation in CM. Biocide, Dimethyl Benzyl Ammonium Chloride (DBAC) (2 ppm) commonly used to inhibit some microorganisms in the modern cane milling process at Mitr Phuveing Sugar Factory, could not inhibit K. pneumoniae P100 within 30 minutes. From these experiments, the factory has changed the sanitization during the milling process, which has saved on biocide costs.

The modern milling process at Mitr Phuveing Sugar factory takes less than 10 min from cane stalk to mixed juice stage before the liming process. However, the microorganisms still affect sugar yield in the factory. The efficacy of dimethyl benzyl ammonium chloride (DBAC) and microbial contamination in the sugar cane juice from milling process were studied. The inhibitory effect of DBAC on the total microorganism, yeast and mold, and lactic acid bacteria in sugar cane juice was assessed aerobically by shaking at 45°C for 10 minutes. The concentration of sucrose and dextran were determined by High Performance Liquid Chromatography and Haze method of ICUMSA, respectively. The results showed that 2 and 6 ppm of DBAC cannot inhibit all kinds of microorganism within 10 minutes. The microbial population and dextran did not increase in sugar cane juice within 10 minutes. However, sucrose losses were noticed because of microbial utilization. Microbial population in the first, third and mixed juice in the milling process were monitored before and after sanitation by hot water and biocide application. The results showed that all kinds of microbial population varied with raw material. The microbial contaminations in some samples of sugar juice from the milling process were selected from plate count agar, malt extract agar and MRS agar medium containing 10% sucrose and identified by physiological and biochemical tests. The microbial contaminations found were mainly yeast: Saccharomyces cerevisiae, Candida guilliermondii and Candida tropicalis, and bacteria: Klebsiella pneumoniae, Lactobacillus fermentum, Enterobacter agglomerans and E. cloacae.