Abstract

Hazelnut husk is one of the most abundant agricultural residue in Turkey. Valorization of this lignocellulosic biomass would provide a promoting alternative for economical production of pullulan. In this study, dried hazelnut husk hydrolysate was used directly as fermentation medium for pullulan production by a domestic strain of Aureobasidium pullulans. The aim of this work was the optimization of some fermentation medium parameters by central composite design using response surface methodology (RSM). The effects of (NH₄)₂SO₄ concentration, the volume of concentrated H₂SO₄ and the amount of ground hazelnut husk on pullulan production were optimized by RSM. The optimum levels of the fermentation parameters defined as 7.2 gL⁻¹, 2.5 mL and 20 g, respectively. The maximum pullulan and exopolysaccharide concentrations were determined as 74.39 and 75.95 gL⁻¹_, respectively in the optimum conditions. Specific growth rate of the strain was found as 0.097 h⁻¹. FTIR spectral attributes confirmed the structure of pullulan. Thermal decomposition temperature of synthesized pullulan was found as 247.15 °C. This study showed that hazelnut husk was one of the novel substrate for production of the pullulan by A. pullulans AZ-6. No previous work was found to utilize dried hazelnut husk as fermentation medium for pullulan production by A. pullulans.

摘要

榛子壳是土耳其最丰富的农业残留物之一。这种木质纤维素生物质的价值化将为普鲁兰多糖的经济生产提供一种促进性的替代方案。在这项研究中，将干燥的榛子壳水解产物直接用作发酵培养基，用于通过出芽短梗霉的国产菌株生产普鲁兰多糖。这项工作的目的是使用响应面方法 (RSM) 通过中心组合设计优化一些发酵培养基参数。_{(NH 4} ) ₂ SO _{4浓度、浓H 2} SO ₄体积的影响RSM 优化了磨碎的榛子壳对普鲁兰多糖生产的用量。发酵参数的最佳水平分别定义为7.2 gL ^-1、2.5 mL和20 g。在最佳条件下，_普鲁兰多糖和胞外多糖的最大浓度分别确定为 74.39 和 75.95 gL ^{-1 。}菌株的特定生长速率被发现为0.097 h ^-1。FTIR 光谱属性证实了支链淀粉的结构。合成支链淀粉的热分解温度为 247.15 °C。该研究表明，榛子壳是A. pullulans生产普鲁兰多糖的新型底物之一AZ-6。以前没有发现利用干燥的榛子壳作为发酵培养基用于A. pullulans生产普鲁兰多糖的工作。