以糖蜜酸水解液为原料制备PHB的工艺优化

以制糖工业的副产品糖蜜为原料，通过酸水解法制备乙酰丙酸（LA），再用富含LA的糖蜜水解液发酵生产生物可降解塑料聚羟基丁酸酯（PHB）。本文采用单因素和响应面方法对糖蜜酸水解条件进行优化，得到最优反应条件为液固比1.24 mL/g、反应温度146 ℃、反应时间1 h。该反应条件下LA的最高产率达到44.09%，大大优于未优化时LA的产率（17.39%），也优于已报道的响应面法优化硫酸催化甘蔗糖蜜制备LA的产率（30.11%）。随后利用该水解液培养杀虫贪铜菌（Cupriavidus necator），48 h后生物量达到2.99 g/L，菌体中PHB含量达到细胞干重的14.85%。结果表明:通过优化水解反应条件能够明显提高糖蜜酸水解制备LA的产率；富含LA的糖蜜酸水解液直接用于PHB的生产具备可行性。

Optimization of Molasses Acid Hydrolysis Process as Feedstock for PHB Preparation

In this study, a by-product of sugar industry was used as raw material, and levulinic acid (LA) was prepared by acid hydrolysis from molasses, and hydrolyysate fermentation with LA-rich produce biodegradable plastic polyhydroxybutyrate (PHB). In this paper, single factor and response surface method were used to optimize the hydrolysis conditions of molassic acid. The optimal reaction conditions were worked out and were as follows: liquid-solid ratio 1.24 mL/g, reaction temperature 146 ℃, reaction time 1 h. Under this condition, the highest yield of LA reached 44.09%, significantly better than LA yield without optimization (17.39%), which was better than the yield of LA optimized by response surface method for the preparation of SUGARcane molasses catalyzed by sulfuric acid (30.11%). The biomass of Cupriavidus necator was 2.99 g/L after 48 h, and the PHB content of Cupriavidus necator reached 14.85% of cell dry weight. The results show that the optimized conditions of acid hydrolysis process could significantly improve the yield of LA from molasses. It is feasible to use the molasses hydrolysate rich in LA as a feedstock for PHB production.