Rufibacter sediminis H-1产胞外多糖发酵条件优化及多糖保湿和乳化性能研究

Fermentation condition optimization,moisturing and emulsifying properties of exopolysaccharides produced by Rufibacter sediminis H-1

微生物胞外多糖产量的提高和功能的探索,是当前天然多糖研究的热点。基于实验室自主分离和鉴定的细菌新种Rufibacter sediminis H-1,使用硫酸-苯酚法测定胞外多糖产量,利用单因素和响应面试验优化发酵条件,在干燥环境中定时称量多糖质量并计算保湿率,将多糖溶液与不同疏水性底物按照一定体积混合计算乳化率。结果表明:菌株R.sediminis H-1最佳产糖条件为温度27.5℃、接种量8.5%、海藻糖质量浓度2.6 g/L、酵母浸粉质量浓度1.50 g/L、pH 7.0,该条件下多糖产量为140.49 mg/L;48 h多糖保湿率仍为82%,接近甘油和透明质酸;多糖对橄榄油、汽油、大豆油、二甲苯和菜籽油的乳化率分别为92.85%、97.43%、98.57%、50.28%和34.28%。对R.sediminis H-1发酵的工艺优化进一步提高了多糖产量,多糖具有良好的保湿作用且对部分油类和烃类具有较好的乳化效果和乳化稳定性。

Production improvement and function exploration of microbial extracellular polysaccharides are very important for the current study on natural polysaccharides. In this paper, based on a novel bacterial species type strain Rufibacter sediminis H-1 isolated and identified in our laboratory, the yield of exopolysaccharide was determined by sulfuric acid and phenol method. The fermentation conditions were optimized by single factor and response surface methodology experiments, and its emulsification and moisturizing properties were studied. According to the results of the single factor test, the factors that had a significant effect on the production of extracellular polysaccharide by strain H-1 were screened out as independent variables, and the response surface test was carried out through the Box-Behnken central combination design. Exopolysaccharide was dissolved in glycerol, hyaluronic acid, and distilled water to the concentration of 5 g/L solution, Tween 80 was used as a positive control, and an equal amount of hydrophobic substrate(olive oil, gasoline, soybean oil, rapeseed oil or xylene) was mixed with exopolysaccharides at 3∶ 2(V/V) with a high-speed homogenizer. Then, the mixture was left standing at room temperature for 12, 24, 36 and 48 h, and the emulsification rate was the ratio of the volume of the emulsified layer to the total volume. The results indicated that the best sugar production conditions of strain R. sediminis H-1 were temperature 27.5 ℃, inoculation amount 8.5%, trehalose 2.6 g/L, yeast extract powder 1.50 g/L, pH value 7.0, its yield of exopolysaccharide was 140.49 mg/L. The moisturizing rate of the polysaccharide was still 82% at 48 h, which was close to those of glycerol and hyaluronic acid;the emulsification rates of the polysaccharides for olive oil, gasoline, soybean oil, xylene and rapeseed oil were 92.85%, 97.43%, 98.57%, 50.28%, and 34.28%, respectively. The yield of polysaccharides from R. sediminis H-1 was obviously increased after the optimization of fermentation condition. The polysaccharide product showed a good moisturizing and emulsification effect and emulsion stability for some oils and hydrocarbons.