Cyclic growth of lactobacilli in beer

J.L. FERNANDEZ AND W.J. SIMPSON 1994. Beer-spoilage lactic acid bacteria displayed unusual growth characteristics in beer. Cycles of growth and death occurred, as assessed by the ability of the organisms to form colonies on a range of solid growth media, or grow in liquid media, including beer and modified de Man, Rogosa and Sharpe medium. During the death phase, the viable cell count fell by more than 99.9%. The cells were dead rather than nonculturable. Staining with acridine orange showed that they remained physically intact during the death phase. It seems that cycles of 'cryptic growth' occur in beer. Cells isolated from different stages of the growth cycle produced similar growth curves when re-inoculated into beer, showing that selection of adapted cells does not occur.