The purpose of this study was to achieve the high cell density cultivation of Escherichia coli and improve the efficiency of L-tryptophan production. E. coli TRTH was used as the L-tryptophan producer. The fermentation experiments were carried out with 4 different amounts of seed culture inoculum and KH2PO4. The effect of KH2PO4 addition on cell growth, acid production, phosphate consumption, sugar and acid conversion, and by-product accumulation were analyzed. The results showed that with 20% (V/V) inoculum and 10 g/L of KH2PO4 , the cell density reached the highest (65.39 g/L), with the final L-tryptophan yield being 59.55 g/L. Comparing with the results before optimization, the lag phase of the fermentation was significantly shorter, which means cell growth was quicker. The utilization rate of raw materials was greatly increased, and the accumulation of the by-products was lowered, thus, the overall level of fermentation was improved. This finding provides a highly feasible new strategy for lowering cost for the high cell density cultivation of E. coli in L-tryptophan fermentation application. At the same time, it provides a reference for the developing regulations for phosphate in L-tryptophan fermentation.
ZHANG Zhen
,
XIONG Haibo
,
XU Qingyang
. L-tryptophan fermentation by high cell density culture of Escherichia coli[J]. Food and Fermentation Industries, 2019
, 45(23)
: 15
-20
.
DOI: 10.13995/j.cnki.11-1802/ts.022033
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