| Hyperconcentrated sweet whey: a new culture medium that enhances Propionibacterium freudenreichii stress tolerance
Applied and Environmental Microbiology 2016， Propionibacterium freudenreichii is used as cheese ripening starter and as probiotic. Its reported physiological effects at the gut level, including modulation of bifidobacteria, of colon epithelial cells proliferation and apoptosis and of intestinal inflammation, rely on active metabolism in situ. Survival and activity are thus key factors determining its efficacy, making stress adaptation and tolerance bottlenecks for probiotic applications. Growth media and growth conditions determine tolerance acquisition. We have investigated the possibility to use sweet whey, a dairy byproduct, to sustain P. freudenreichii growth. It was used at different concentrations (dry matter) as a culture medium. Using hyperconcentrated sweet whey led to enhanced multistress tolerance acquisition, overexpression of key stress proteins, accumulation of intracellular storage molecules and compatible solutes, as well as enhanced survival upon spray-drying. A simplified process from growth to spray drying of propionibacteria was developed using sweet whey as a 2-in-1 medium to both culture and protect P. freudenreichii from heat and osmotic injury, without harvesting and washing step. Spray-drying being far cheaper and more energy-efficient than freeze-drying, this work opens new perspectives for the sustainable development of new starter and probiotic preparations with enhanced robustness.
链接:http://aem.asm.org/content/early/2016/05/16/AEM.00748-16.abstract |