Lactobacilli are the most common beer-spoilage bacteria,regardless of beer type.The aim of this study was to investigate the viable but nonculturable (VBNC) state of a hard-to-detect beer-spoilage lactobacilli,Lactobacillus acetotolerans.With the prolonged contact with beer,L.acetotolerans strain in culturable state was found to show decreased culturability.Total cell counts remained constant throughout the induction process as determined by acridine orange direct counting.After 17 subcultures in degassed beer,1-mL aliquots of the strain culture were no longer detectable on MRS agar despite the presence of about 105 viable cells,indicating that a large population of cells entered into VBNC state.Furthermore,L.acetotolerans could be also induced loss of culturability but maintenance of viability by stimulating at 0℃ within 90 days.Adding the catalase in appropriate concentration enabled the VBNC cells induced by beer adaptation and low-temperature storage to become culturable again with resuscitation time of 4 days and 3 days,respectively.The scanning electron microscopy results showed that cells gradually changed in shape from short rods to coccoids,and decreased in size when they entered the VBNC state.Further studies suggested that both the VBNC and resuscitated cells might still exhibit beer-spoilage ability.