Mesophilic lactobacilli

Properly made cheese is quite a hostile environment for bacteria due to a low pH, moderate-to-high salt in the moisture phase, anaerobic conditions (except at the surface), lack of a fermentable carbohydrate and the production of bacteriocins by the starter. Consequently, cheese is a very selective environment and its internal non-starter microflora is dominated by lactic acid bacteria, especially mesophilic lactobacilli, and perhaps some Micrococcus and Pediococcus. 

Many bacteria have the ability to produce ethanol, but relatively few taxa contain bacteria that produce ethanol as a major end product. Ethanol-producing species can be found among aerobic, anaerobic, and facultative anaerobic bacteria within the family Enterobacteriaceae and the genera Bacillus, Bacteroides, Bifidobacterium, Clostridium, Euhacterium, Lactobacillus, and many others (Wiegel 1980). Examples of mesophilic (O Table 3.4) and thermophilic (O Table 3.5) bacteria that can produce one or more moles of ethanol per mole of glucose metabolized have been compiled by Wiegel (Wiegel 1980,1992). 

Cultured butter is made from milk fat to which a mesophilic starter culture has been added to enhance its flavor, principally that of diacetyl. Diacetyl, made from citrate by LAB, enhances buttermilk s storage properties. Lactobacillus lactis or mixed cultures that contain Lb. lactis, Leuconostoc citrovorum, and Leu. dextranicum are used (Early 1998). Fat (cream) is separated from skim milk by centrifugation of milL The cream is pasteurized and inoculated with selected starter cultures. The ripened cream is then churned. The cream separates again into cream butter and its byproduct sour buttermilk, which has limited use because of its high acidity. 

Jensen, M.P, Ardo, Y., and Vogensen, F.K. (2009) Isolation of cultivable thermophilic lactic add baderia from cheeses made with mesophilic starter and molecular comparison with dairy-related Lactobacillus helveticus strams. Lett Appl Microbiol 49, 396-402. 

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