Carbohydrate Enzyme Biotechnology Laboratory, Department of Bioscience and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, 781039, Assam, India.
Center for the Environment, Indian Institute of Technology Guwahati, Guwahati, Assam, 781039, India.
Appl Biochem Biotechnol. 2018 Jan;184(1):1-11. doi: 10.1007/s12010-017-2522-4. Epub 2017 Jun 1.
Weissella cibaria RBA12 produced a maximum of 9 mg/ml dextran (with 90% efficiency) using shake flask culture under the optimized concentration of medium components viz. 2% (w/v) of each sucrose, yeast extract, and KHPO after incubation at optimized conditions of 20 °C and 180 rpm for 24 h. The optimized medium and conditions were used for scale-up of dextran production from Weissella cibaria RBA12 in 2.5-l working volume under batch fermentation in a bioreactor that yielded a maximum of 9.3 mg/ml dextran (with 93% efficiency) at 14 h. After 14 h, dextran produced was utilized by the bacterium till 18 h in its stationary phase under sucrose depleted conditions. Dextran utilization was further studied by fed-batch fermentation using sucrose feed. Dextran on production under fed-batch fermentation in bioreactor gave 35.8 mg/ml after 32 h. In fed-batch mode, there was no decrease in dextran concentration as observed in the batch mode. This showed that the utilization of dextran by Weissella cibaria RBA12 is initiated when there is sucrose depletion and therefore the presence of sucrose can possibly overcome the dextran hydrolysis. This is the first report of utilization of dextran, post-sucrose depletion by Weissella sp. studied in bioreactor.
在 20°C 和 180rpm 的优化条件下培养 24 小时后，利用摇瓶培养，在优化的培养基成分浓度下，韦氏球菌 RBA12 最高可产生 9mg/ml 的葡聚糖（效率为 90%），其中每种蔗糖、酵母提取物和 KHPO 的浓度为 2%（w/v）。优化的培养基和条件用于在生物反应器中分批发酵中扩大韦氏球菌 RBA12 的葡聚糖生产规模，在 14 小时内最高可产生 9.3mg/ml 的葡聚糖（效率为 93%）。14 小时后，在蔗糖耗尽的条件下，细菌在静止期利用葡聚糖直到 18 小时。进一步通过补料分批发酵利用蔗糖进行了葡聚糖利用研究。在生物反应器中进行补料分批发酵生产葡聚糖 32 小时后可得到 35.8mg/ml。在补料分批模式下，与分批模式一样，葡聚糖浓度没有下降。这表明，当蔗糖耗尽时，韦氏球菌 RBA12 开始利用葡聚糖，因此蔗糖的存在可能会克服葡聚糖水解。这是首次在生物反应器中研究韦氏菌属在蔗糖耗尽后利用葡聚糖的报道。
