Selection of a Bifidobacterium strain to complement resistant starch in a synbiotic yoghurt

Aims: To employ an in vitro screening regime to select a probiotic Bifidobacterium strain to complement resistant starch (Hi-maize(TM)) in a synbiotic yoghurt. Methods and Results: Of 40 Bifidobacterium isolates examined, only B. lactis Lafti(TM) B94 possessed all of the required characteristics. This isolate hydrolysed Hi-maize(TM), survived well in conditions simulating passage through the gastrointestinal tract and possessed technological properties suitable for yoghurt manufacture. It grew well at temperatures up to 45 degreesC, and grew to a high cell yield in an industrial growth medium. In addition to resistant starch, the organism nias able to utilize a range of prebiotics including inulin, and fructo-, galacto-, soybean- and xylo-oligosaccharides. Pulse field gel electrophoresis of restriction enzyme cut chromosomal DNA revealed that B. lactis Lafti(TM) B94 was very closely related to the B. lactis Type Strain (DSM 10140), and to the commercial strains B. lactis Bb-12 and B. lactis DS 920. However, B. lactis Lafti(TM) B94 was the only one of these isolates that could hydrolyse Hi-maize(TM). This phenotypic difference did not appear to be due to the presence of plasmid encoded amylase. Bifidobacterium lactis Lafti(TM) B94 survived without substantial loss of viability in synbiotic yoghurt containing Hi-maize(TM) during storage at 4 degreesC for six weeks. Conclusions: Bifidobacterium lactis Lafti(TM) B94 is a promising new yoghurt culture that warrants further investigation to assess its probiotic potential. Significance and Impact of the Study: In vitro screening procedures can be used to integrate complementary probiotic and prebiotic ingredients for new synbiotic functional food products.