초록
<P><B>Abstract</B></P> <P>The formation of HoPS and oligosaccharides in sourdough fermentation improves bread quality but is dependent on the expression of glycansucrases by lactic acid bacteria. Data on the expression of dextransucrases by <I>Weissella</I> spp., however, are limited. This study therefore aimed to assess dextansucrase expression in <I>W</I>. <I>cibaria</I> 10 M, focusing on the effect of temperature. The effect of temperature on growth, oligosaccharide and dextran synthesis by <I>W</I>. <I>cibaria</I> 10 M was determined and the expression and activity of cell-associated dextransucrase from <I>W</I>. <I>cibaria</I> 10 M were investigated. The oligosaccharides profiles were measured by thin layer chromatography and high performance anion exchange chromatography coupled to pulsed amperometric detection. Dextran formation was quantified by size exclusion chromatography. <I>W</I>. <I>cibaria</I> grew fastest at 30 °C but oligosaccharide formation was highest at 20 °C or less. Dextransucrase expression as measured by reverse transcription quantitative PCR, SDS-PAGE, and activity of cell-associated dextransucrase were maximal at 15 °C. Cold shift incubation, characterized by incubation at 30 °C to obtain biomass, followed by shift to 6 °C to induce dextransucrase expression, supported high dextransucrase activity in laboratory media. Cold shift fermentation of wheat and sorghum sourdoughs supplemented with 15 or 30% sucrose increased the yields of oligosaccharides, and resulted in formation of 16 and 12 g/kg dextran in wheat and sorghum sourdoughs, respectively. Dextran formation was decreased in favour of oligosaccharide formation when doughs were supplemented with maltose. In conclusion, cold shift fermentation of sourdough with <I>W</I>. <I>cibaria</I> supports high dextran yields or formation of oligosaccharides without excess acidification.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>Weissella cibaria</I> produces a high molecular weight dextran. </LI> <LI> Dextransucrase DsrM is overexpressed at low temperature in sourdough. </LI> <LI> Cold shift sourdough fermentation increases dextran yields without excess acidification. </LI> </UL> </P>