Nonstarter lactic acid bacteria

During cheese production lactose is converted to lactic acid by starter lactic acid bacteria (LAB). Any unfermented lactose is converted to d- and L-lactate by nonstarter lactic acid bacteria (NSLAB) and racemization, respectively. Lactate can be oxidized by LAB in cheese to acetate, ethanol, formic acid, and carbon dioxide at a rate dependent on oxygen availability (McSweeney, 2004). Other pathways include conversion to propionate, acetate, water, and carbon dioxide by Propionibacterium spp. carbon dioxide and water by Penicillium spp. yeasts and butyric acid and hydrogen by Clostridium spp. The rate of lactose metabolism influences proteolysis and flavor formation (Creamer et al., 1985 Fox et al., 1990). 

Sgarbi, E., Bottari, B., Gatti, M., and Neviani, E. (2014) Investigation of the ability of dairy nonstarter lactic acid bacteria to grow using cell lysates of other lactic acid bacteria as the exclusive source of nutrients. Int J Dairy Technol http //dx.doi.orgl0.llll/1471-0307.12132. 

Sgarbi, E., Lazzi, C., Tabanelli, G., et al. (2013) Nonstarter lactic acid bacteria volatilomes produced using cheese components. J Dairy Sci 96, 4223-4234. 

Agarwal, S., Sharma, K., Swanson, B.G., et al. (2006) Nonstarter lactic acid bacteria biofilms and caldum lactate crystals in Cheddar cheese. J Dairy Sci 89,1452-1466. 

Somers, E.B., Johnson, M.E., and Wong, A.C. (2001) Biofilm formation and contamination of cheese by nonstarter lactic acid bacteria in the dairy environment. J Dairy Sci 84, 1926-1936. 

The lactic streptococci used in cheese manufacture produce only the l( + ) isomer of lactic acid (Lawrence et al. 1976). However, ripened cheeses contain both d(-) and l( + ) lactate isomers (T irner and Thomas 1980). Nonstarter bacteria (pediococci and lactobacilli) form d( —) lactate from residual lactose or by conversion of l( + ) lactate (Thomas and Crow 1983). 

---