Isolation of kefiran-producing lactic acid bacteria from kefir grain and improvement of kefiran productivity - Note

For the purpose of producing kefiran industrially, kefiran-producing lactic acid bacteria were isolated from kefir grain. In the first step, 38 strains were selected based on their stringiness. Among the 38 strains, one strain with 0.3 g-kefiran per liter-culture liquid was selected and identified as Lactobacillus kefiranofaciens. UV irradiation of the isolate resulted in 8 strains with stronger stringiness. By repeated UV irradiation of these 8 strains, 121 colonies were obtained, from which one strain, KF-75, with 0.9 g-kefiran per liter-culture liquid was finally obtained. By optimizing the medium and culture conditions in ajar fermenter, the kefiran productivity using strain KF-75 was enhanced to 2.5 g-kefiran per liter-culture liquid for 7 d.