Dextran Utilization During Its Synthesis by Weissella cibaria RBA12 Can Be Overcome by Fed-Batch Fermentation in a Bioreactor
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 K2HPO4 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.
KeywordsWeissella cibaria Dextran Sucrose Bioreactor
The authors would like to thank Mr. Katla Srikanth and Dr. Senthilkumar Sivaprakasam of Department of Biosciences and Bioengineering, IIT Guwahati for suggestions and discussion regarding batch and fed-batch processes using bioreactor. The research work was supported by a project grant (BT/PR1518/PID/6/613/2011) from Department of Biotechnology (DBT), New Delhi, India to Dr. A. Goyal. The bioreactor procured through grant was received from Indo-Finland joint project (BT/IN/Finland/08/AG/2011) from Department of Biotechnology, Ministry of Science and Technology, New Delhi, India to Dr. A. Goyal.
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Conflict of Interest
The authors declare that they have no conflict of interest.
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