A stirred ceramic membrane reactor (SCMR) incorporating asymmetric porous ceramic tubes was found to be effective for maintaining high filtrate flux over a long period of filtering culture. Alumina ceramic fillers with mean pore diameters of 0.5 mu m at the surface and 25 mu m in the inner rough phase were fitted inside a jar-fermentor, Filtering performance was enhanced by stirring the culture broth at a higher rate, Membrane fouling was also prevented by stirring, Using this bioreactor system, a dense cell culture of Lactococcus lactis, which is damaged by metabolites produced in the culture supernatant, was attempted by the filtering culture method with the aid of an automatic feeding and altering system. Preliminary tests on the medium composition in batch cultures showed that the cell growth was severely impaired by excessive consumption of substrates such as glucose, Polypepton, and yeast extract, Even in a fed-filtering culture, the cell concentration was as low as 38 g/l with 56% viability after a 220-h cultivation period with the feeding of a substrate solution containing 12 g/l glucose and 4 g/l yeast extract powder. A high cell concentration of 141 g/l with 94% viability after 238-h cultivation was achieved by fed-filtering massive amounts of a diluted substrate solution containing 6 g/l glucose and 2 g/l yeast extract. Both the yield and productivity of cells were also increased by controlling the feeding of the diluted fresh medium and filtering the supernatant of the dense cell culture. The filtrate volume reached sixty-four times that of the original working volume in the fermentor. The average dilution rate was 0.3 h(-1) through the filtering culture, These results showed that the long-lasting and high permeability capacity of the SCMR system fitted with an asymmetric membrane enabled facilitated increases in the concentration and productivity of the cells by continuously removing inhibitory by-products at a high dilution rate.