Viable, but not culturable, state

A general adaptation to the beer environment by BSR LAB is the modification of both cell size and morphology. Diminished cell size and a notable rounding or shrinking of bacilli or rod-shaped cells (i.e. taking on a coccoid appearance) have been noted for several BSR LAB isolates following beer- adaptation (Asano et al., 2007). This phenomenon has been proposed to be an attempt by the cell to reduce surface area in contact with beer and to help membrane-associated tolerance genes (e.g. hop tolerance) deploy more efficiently (Suzuki et al., 2006; Suzuki, 2011). Furthermore, increased time in beer results in induction of a viable, but not culturable (VNBC) state in LAB cells. Such cells are not detectable by routine non-beer culture media on which they would normally grow colonies, but are alive and capable of renewed metabolic activity through continued exposure to routine media (Deng et al., 2014; Oliver, 2005). Understanding both the conditions inducing the VBNC state in a variety of different BSR LAB and how to retrieve the culturable phenotype more efficiently is of extreme utility to brewers in accurately detecting where BSR LAB exist in their brewery. Investigation into the genetics and transcriptional activity of BSR LAB throughout their VNBC cycle would also increase the understanding and be of upmost importance for a wide range of industries dependent on LAB.

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