Selected recovery of proteins from fermentation broths

Claim 1

A process for separating and recovering a selected protein or selected group of proteins from a fermentation broth containing a mixture of selected and non-selected proteins comprising the steps of: (a) removing when present substantially all initial turbidity from said broth; (b) subsequently passing said broth into and out of a membrane desalting apparatus in contact with one surface of one or more semi-permeable membranes, said membrane separating said broth stream from an adjacent salt receiving stream thereby causing a decrease in the salt concentration of said broth; (c) said broth being adjusted in pH to within substantially the collective isoelectric point range of the non-selected protein sufficient to cause the formation of a first turbid phase containing essentially the said non-selected proteins and a first liquid phase enriched in the said selected protein; (d) subsequently removing substantially all of said first formed turbid phase; (e) passing the remaining first liquid phase into and out of said desalting apparatus to further decrease the salt concentration; (f) adjusting the pH to within the isoelectric point of the selected protein of interest thereby forming a second turbid phase enriched in the said selected protein of interest; (g) and separating the said second turbid phase for subsequent resuspension or purification.