Abstract:Pediococcus damnosus(P. damnosus) is one of the most commonly-found beer-spoilage bacteria in breweries. This study compared the ability of biofilm and planktonic cells of beer-spoilage P. damnosus to enter a viable but putatively non-culturable (VBNC) state. Planktonic and biofilm cells of five beer-spoilage P. damnosus were cultured at 26 ℃ in the lager beer. The results showed that both biofilm and planktonic cells could be induced to enter the VBNC state, however, the state-transition time was variable. It took a minimum of 70 days for the biofilm cells to enter the VBNC state, while 126~189 days for the planktonic cells. The presence of VBNC cells in biofilms was further confirmed by PCR coupled with propidium monoazide pretreatment that amplified genes 16S rDNA and horA. In addition, the biofilm cells were more resistant to 0.025 mol/L NaOH comparing to the planktonic cells, while the biofilm cells in the VBNC state showed more endurance comparing to the planktonic cells under the same state. In conclusion, this study confirmed that in the brewing process, compared to the planktonic cells, the biofilm of P. damnosus could be more easily induced into VBNC state and had stronger tolerance to alkali under low pH, high concentration of bitter hops, ethanol and other pressure conditions.
