Citrate production from hydrocarbons by use of a nonsterile,semicontinuous cell recycle system

In order to minimize product toxicity, decrease fermentation cost, prolong the effective production phase, and shorten the lag phase before production in the citrate-hydrocarbon fermentation by Candida lipolytica ATCC 8661, the use of a nonsterile semicontinuous cell recycle system was investigated. Model experiments demonstrated that portions of the fermentor broth could periodically be removed and centrifuged under nonaseptic conditions with the cells being added to fresh medium and returned to the fermentor. Citrate production continued, however with repeated semicontinuous cell recycle, acid production gradually decreased. It was postulated that this decrease could be attributed largely to physiological trauma and that a truly continuous cell recycle system would minimize these effects and permit maintenance of higher citrate production rates.