Investigations in sonication-induced intensification of crude glycerol fermentation to dihydroxyacetone by free and immobilized Gluconobacter oxydans
Investigations in sonication-induced intensification of crude glycerol fermentation to dihydroxyacetone by free and immobilized Gluconobacter oxydans
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DOI：
10.1016/j.biortech.2018.02.024
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发表时间：
2018-05-01
影响因子：
11.4
通讯作者：
Moholkar, Vijayanand S.
中科院分区：
文献类型：
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作者：
Dikshit, Pritam Kumar;Kharmawlong, Gracel Joe;Moholkar, Vijayanand S.
本研究报道了氧化葡萄糖产二羟基丙酮(DHA)的粗甘油发酵，并用超声波强化发酵。利用游离细胞和固定化细胞(在聚氨酯泡沫载体上)对甘油的初始浓度分别为20、30和50g/L进行发酵，在20%占空比的条件下超声处理可使甘油消耗量增加60%-84%，而细胞形态没有明显变化。粗甘油发酵中DHA产量较低是由于可能形成抑制产物所致。当甘油初始浓度为50g/L时，DHA产量略有下降，这归因于底物抑制。固定化细胞获得了较高的DHA产率。对经超声波处理的氧化革兰氏杆菌细胞内蛋白质进行圆二色谱分析，发现α-螺旋和β-折叠的含量显著减少。这些蛋白质结构的构象变化可以增强细胞内甘油脱氢酶的活性，这表现为氧化葡萄糖促进了甘油的代谢。
This study reports crude glycerol fermentation by G. oxydans for dihydroxyacetone (DHA) production, and intensification of fermentation with sonication. Fermentation was carried out using both free and immobilized cells (on polyurethane foam support) for initial glycerol concentrations of 20, 30 and 50 g/L. Sonication at 20% duty cycle enhanced glycerol consumption by 60-84% with no significant change in cell morphology. Lesser DHA yield in crude glycerol fermentation was attributed to possible formation of inhibitory products. Slight reduction in DHA yield for initial glycerol concentration of 50 g/L was attributed to substrate inhibition. Higher DHA productivity was obtained for immobilized cells. Circular dichroism analysis of intracellular proteins obtained from ultrasound-treated G. oxydans revealed significant reduction in alpha-helix and beta-sheet content. These conformational changes in protein structure could augment activity of intracellular glycerol dehydrogenase, which is manifested in terms of enhanced metabolism of glycerol by G. oxydans.