Productivity improvement in L-sorbose biosynthesis by fedbatch cultivation of Gluconobacter oxydans
2002
Giridhar, R.V.N. (Indian Inst. of Technology, New Delhi (India)) | Srivastava, A.K.
The effect of increased (100, 200 and 300gl sup(-1) ) initial sorbitol concentrations (S sub0 ) was investigated in the sorbitol to sorbose bioconversion process. Batch cultivations with a S sub0 of 100, 200 and 300gl sup(-1) were completed at 10, 14 and 24 h with a corresponding overall sorbose productivity of 10.1,14.3 and 12.4gl sup(-1) h sup(-1) respectively. The decrease in sorbose productivity at S sub0 =300gl sup(-1) was attributed to the inhibition by sorbitol of culture growth and product formation. In order to eliminate substrate inhibition, two identical fed-batch cultivations were performed in which a highly concentrated (500gl sup(-1) ) sorbitol solution was added at a constant feed rate (0.2lh sup(-1) ) in the exponential phase of growth. The Fed-batch culture initiated with S sub0 =225gl sup(-1) exhibited an enhanced accumulation of sorbose (336.2gl sup(-1) ) but with a processing time of 24 h, and a productivity of 14.0 gl sup(-1) h sup(-1) . While, the fed-batch culture initiated with S sub 0 =100gl sup(-1) accumulated 279.7gl sup(-1) of sorbose with an increase in productivity of 17.6gl sup(-1) h sup(-1) in 16 h.
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