[Production of Kluyveromices fragilis biomass in deproteinized milk whey]

The milk whey from a mature cheese factory deproteinised by acid thermic coagulation (pH 4.5 and 90 degrees C), provides a good culture media for the production of Kluyveromices fragilis biomass. The optimal experimental conditions for the maximal production of biomass were established by using fermenters with different capacity and design. For lactose concentration of 15 g/l, pH 4.5, 30 degrees C and aireation between 0.25 and 1 VVM, the duplication time was below two hours and 98% of the lactose was consumed. The obtained yield in dried weight was between 36 and 49% (g biomass/g lactose). The biomass (without broken cell) contain 46% protein on dry base and showed an "in vitro" digestibility of 65%. The organic mass decreased 80% after 12 hour of fermentation. This process eliminates a polluting agent and simultaneously, produces a biomass that could have industrial use as a protein complement in feeds.