Jl. Tholozan et al., EFFECTS OF CULTURE CONDITIONS ON PECTINATUS-CEREVISIIPHILUS AND PECTINATUS-FRISINGENSIS METABOLISM - A PHYSIOLOGICAL AND STATISTICAL APPROACH, Journal of Applied Bacteriology, 80(4), 1996, pp. 418-424
The genus Pectinatus has been often reported in beer spoilage with off
-flavours. The bacteria are strictly anaerobic, Gram-negative rods. Pr
opionate and acetate are the main fermentation products from glucose i
n the two species belonging to the genus, P. cerevisiiphilus and P. fr
isingensis. Amino acids routinely present at a high level in beer were
not growth substrates for both species, and a significant accumulatio
n of succinate was observed with lactate as growth substrate. Both Pec
tinatus ssp. showed almost identical fermentation balances on glucose.
Growth kinetics of both glucose-grown species were unchanged under a
N-2, H-2 or 20% CO2-containing atmosphere. Combinations of culture med
ium pH values from pH 3 . 9 to pH 7 . 2, of glucose levels between 5 a
nd 55 mmol l(-1), and of lactate concentrations varied from 4 to 40 mm
ol l(-1) demonstrated that biomass and volatile fatty acids production
were proportional to glucose concentration for both Pectinatus specie
s. A significant increase of volatile fatty acid production was measur
ed for both species at the lowest pH values with a lactate or a glucos
e concentration increase. The maximum biomass production was observed
at pH 6 . 2 for P. cerevisiiphilus, and between pH 4 5 and pH 4 . 9 fo
r P. frisingensis. Glucose and lactate or pH value were dependent with
regard to propionate and acetate production in P. frisingensis. On th
e other hand, the variations of these three parameters were independen
t 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 . 3 mol l(-1)
ethanol for P. cerevisiiphilus, and at 1 . 8 mol l(-1) for P. frisinge
nsis.