Department of Chemical Engineering, Indian Institute of Technology Guwahati, Guwahati 781 039, Assam, India.
Department of Chemical Engineering, National Institute of Technology (NIT), Tiruchirapalli 620 015, Tamil Nadu, India.
Bioresour Technol. 2018 May;256:302-311. doi: 10.1016/j.biortech.2018.02.024. Epub 2018 Feb 7.
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 α-helix and β-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.
本研究报告了氧化葡萄糖酸杆菌利用粗甘油发酵生产 1,3-二羟基丙酮（DHA），并通过超声处理进行了发酵强化。发酵使用游离细胞和固定化细胞（在聚氨酯泡沫载体上）进行，初始甘油浓度分别为 20、30 和 50g/L。在 20%占空比下进行超声处理，可使甘油消耗提高 60-84%，而细胞形态无明显变化。粗甘油发酵中 DHA 产率较低归因于可能形成了抑制性产物。初始甘油浓度为 50g/L 时 DHA 产率略有降低，归因于底物抑制。固定化细胞可获得更高的 DHA 生产力。从经超声处理的氧化葡萄糖酸杆菌中提取的细胞内蛋白质的圆二色性分析表明，α-螺旋和β-折叠含量显著降低。这种蛋白质结构的构象变化可能会增强细胞内甘油脱氢酶的活性，这表现在氧化葡萄糖酸杆菌对甘油的代谢增强方面。
