Abstract: The present disclosure generally relates to a method of manufacturing biological product using fermentation and subsequent purification of the biological product, such as an enzyme. By utilization of online biomass data for a feedback control in the fermenter, an efficient and stable cross-flow microfiltration operation can be performed with active cells.

Abstract: A method for producing a protein by culturing a cell capable of expressing the protein and which contains a methylotrophic yeast promoter for an enzyme of the methanol metabolic pathway controlling expression of the protein, in a fermentative batch process comprising a batch phase and a feeding phase, under conditions such that dissolved oxygen is continually present in the culture medium throughout the process, and about 1% to about 100% of the carbon source during the feeding phase is a sugar or sugar polymer, which sugar or sugar polymer is provided in such an amount that the sugar or sugar polymer is continually depleted by the cell and therefore is substantially undetectable in the culture medium; and isolating the protein on completion of the feeding phase.