Effects of culture conditions on Pectinatus cerevisiiphilus and Pectinatus frisingensis metabolism: a physiological and statistical approach

Abstract

The genus Pectinatus has been often reported in beer spoilage with off-flavours. The bacteria are strictly anaerobic, Gram-negative rods. Propionate and acetate are the main fermentation products from glucose in the two species belonging to the genus, P. cerevisiiphilus and P. frisingensis. Amino acids routinely present at a high level in beer were not growth substrates for both species, and a significant accumulation of succinate was observed with lactate as growth substrate. Both Pectinatus ssp. showed almost identical fermentation balances on glucose. Growth kinetics of both glucose-grown species were unchanged under a N2, H2 or 20% CO2-containing atmosphere. Combinations of culture medium pH values from pH 3 x 9 to pH 7 x 2, of glucose levels between 5 and 55 mmol l-1, and of lactate concentrations varied from 4 to 40 mmol l-1 demonstrated that biomass and volatile fatty acids production were proportional to glucose concentration for both Pectinatus species. A significant increase of volatile fatty acid production was measured for both species at the lowest pH values with a lactate or a glucose concentration increase. The maximum biomass production was observed at pH 6 x 2 for P. cerevisiiphilus, and between pH 4 x 5 and pH 4 x 9 for P. frisingensis. Glucose and lactate or pH value were dependent with regard to propionate and acetate production in P. frisingensis. On the other hand, the variations of these three parameters were independent with regard to biomass production for both strains, and to volatile fatty acids production for P. cerevisiiphilus. Addition of ethanol to glucose-grown cultures completely inhibited growth at 1 x 3 mol l-1 ethanol for P. cerevisiiphilus, and at 1 x 8 mol l-1 for P. frisingensis.

125th Anniversary Review: Microbiological Instability of Beer Caused by Spoilage Bacteria

“…Of the two genera, Pectinatus is more tolerant to a low pH environment and a pH value of 4.1 is required for retardation of growth 57 , although the presence of ethanol reduces the resistance of Pectinatus to low pH in a dose-dependent manner. The maximum biomass production was observed at pH 6.2 for P. cerevisiiphilus and between pH 4.5 and 4.9 for P. frisingensis 155,156 , indicating that P. frisingensis is more acidophilic. On the other hand, the retardation in the growth of Megasphaera was observed in beer with pH value of 4.5 62 , but the growth was reported to still occur in beer with the pH value of 4.38 but not pH 4.0 59 .…”

“…For example, this species is able to maintain a higher intracellular pH than the external pH even at pH 4.5 28 . In fact, P. frisingensis was found to grow optimally at pH values in the range of 4.1 and 5.1 and was shown to grow, although poorly, at an ethanol content up to 1.2 mol/L (7.2% (w/v)) 156 . In comparison with P. frisingensis, P. cerevisiiphilus and M. cerevisiae exhibited somewhat lower levels of ethanol tolerance and grew less well in a low pH environment 61,156 .…”

“…In fact, P. frisingensis was found to grow optimally at pH values in the range of 4.1 and 5.1 and was shown to grow, although poorly, at an ethanol content up to 1.2 mol/L (7.2% (w/v)) 156 . In comparison with P. frisingensis, P. cerevisiiphilus and M. cerevisiae exhibited somewhat lower levels of ethanol tolerance and grew less well in a low pH environment 61,156 . These observations indicate that P. frisingensis is potentially the most frequent species associated with beer spoilage incidents among these species.…”

Pectinatus, Megasphaera and Zymophilus

“…A number of studies on Pectinatus growth in the culture medium as a function of temperature, pH and ethanol concentration have been performed (Tholozan et al, 1996;Tholozan et al, 1997;Chihib and Tholozan, 1999a;Chihib et al, 1999b) including modeling of growth and metabolite production (Membré and Tholozan, 1994;Watier et al, 1996b). In general, the parameters derive from those encountered in beer production, including rapid temperature changes in pasteurization and cooling before bottling.…”

Review: Gram Negative Bacteria in Brewing

“…P frisingensis is better adapted to acidic and thermal environments compared to other Pectinatus species [88]. P. frisingensis can metabolise a wider range of fermentable sugars but it cannot utilise ethanol, maltose and essential amino acids [76] [97]. P. cerevisiiphilus, P. frisingensis and P. haikarae are reported to have strong beer spoilage ability mainly in unpasteurised and low alcohol content beer [91].…”