PROCESS FOR SELECTING POLYHYDROXYALKANOATE (PHA) PRODUCING MICRO-ORGANISMS

摘要

The invention relates to a process for selecting a polyhydroxyalkanoate (PHA) producing micro-organism from a natural source comprising a variety of micro-organisms, comprising steps of preparing a fermentation broth comprising the natural source and nutrients in water; creating and maintaining aerobic conditions in the fermentation broth; applying a feast- famine cycle comprising a feast phase and a famine phase, wherein the feast-famine cycle is started with feeding a carbon source to the fermentation broth, nutrients are fed in such amounts to the fermentation broth that the carbon source becomes limiting for the growth of the micro-organisms during the famine phase; the feast-famine cycle has a cycle time of at least 8 hours, and the feeding of the carbon source is performed during a small initial fraction of the feast famine cycle time; withdrawing a part of the micro-organisms during and/or at the end of the feast-famine cycle (referred to as solids withdrawal step); and repeating the feast-famine- cycle and the solids withdrawal step, such that an average solids retention time (SRT) of less than 4 days results. The invention also relates to a mixed culture or isolated microorganism which has an activity of producing PHA, obtainable by the said selection process, use thereof in a process for producing a PHA, and the resulting PHA containing microorganism.