Aims: To compare the physiological behaviour of Bi®dobacterium infantis ATCC 15697 growing on synthetic oligofructose or its components. Methods and Results: The studies were carried out in regulated or non-regulated batch cultures on semi-synthetic media. Differences between the carbohydrate utilization patterns with glucose, fructose, sucrose and fructo-oligosaccharides (FOS) were determined. Glucose was the preferred substrate for growth and biomass production, whereas fructose was the best for lactate and acetate production. With sucrose, biomass production reached the level obtained with glucose, whereas with FOS, more metabolites were produced, as with fructose. In a mixture of FOS, the shorter saccharides were used ®rst and fructose was released in the medium. Fructofuranosidase, an enzyme necessary to hydrolyse FOS, was inducible by fructose. Conclusions: Glucose contained in FOS and sucrose might sustain growth and cell production, while fructose might enable the production of major metabolites. Signi®cance and Impact of the Study: A better understanding of the bi®dogenic nature of oligofructose has been gained.

Aims: To characterize the b-fructofuranosidase of Bifidobacterium infantis ATCC 15697 and to compare it with other bacterial b-fructofuranosidases. Methods and Results: The b-fructofuranosidase of B. infantis ATCC 15697 was purified 46AE8 times over the crude extract by anion exchange chromatography, ultrafiltration and gel filtration. The sequence of 15 amino acid residues of the NH 2 terminal was determined. This enzyme was a monomeric protein (M r 70 kDa) with b-fructofuranosidase and invertase activities. The isoelectric point was pH 4AE3, the optimum pH 6AE0 and pKas (4AE5 and 7AE2) of two active groups were obtained. The activities were inhibited by Hg 2+ and p-chloromercuribenzoic acid (pCMB). The optimal temperature was 37°C and activities were unstable at 55°C. b-fructofuranosidase activity was more efficient than that of invertase with V m ⁄ K m ratios of 0AE65 and 0AE025 · 10 )3 l min )1 mg )1 , respectively. The enzyme catalyses the hydrolysis of fructooligosaccharides, sucrose and inulin at relative velocities of 100, 10 and 6, respectively. Conclusions: The enzyme of B. infantis ATCC 15697 is an exo-inulinase which has b-fructofuranosidase and invertase activities. This protein was different from the b-fructofuranosidase of another strain of B. infantis (B. infantis JCM no. 7007). Significance and Impact of the Study: A better knowledge of bacterial b-fructofuranosidases, especially from bifidobacteria, has been gained.

Botrytis cinerea is an important fungal pathogen particularly dreaded in the cool climate vineyard. It is responsible for important damage, especially the decrease in foamability of sparkling wines, such as Champagne. Different studies have shown that proteins are largely involved in the stabilization of Champagne foam despite their low concentration. Other works demonstrated changes in the electrophoretic characteristics of must proteins originating from botrytized grapes, although the cause of such alterations was never explained. In the first part of this study, results showed the release by B. cinerea of 3.5 mg/L total proteins in a synthetic liquid medium. Among these proteins, the presence of a protease activity on bovine serum albumin (BSA) and must proteins was demonstrated by using a colorimetric method and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. In the model wine, the Bradford method showed a BSA loss of 66% after 24 h and a loss of 96% after 120 h. In the same model wine, the soluble must protein concentration decreased by 35% after 1 week and by 53% after 2 weeks while the control showed no protein loss. B. cinerea proteases were then able to degrade BSA and must proteins and were above all active at must and wine pH and in the presence of ethanol and SO(2). The second part of this work was dedicated to the relationship between the presence of B. cinerea proteases and its effects on the synthetic wine foaming properties. The addition of a B. cinerea culture medium (1/33 v/v) to the synthetic wine containing 21 mg/L soluble grape proteins induced a decrease in foamability by 60% after 1 week. For BSA in the model wine, the foamability decreased by 32% after 24 h and by 95% after 120 h, as shown by the colorimetric method. These experiments demonstrate for the first time the relationship between B. cinerea protease activity and the decrease in wine foaming properties.

Some parameters of fermentation have been determined for Clostridium absonum in a chemostat by using a chemically defined medium with glucose as the sole source of carbon and energy. Steady-state continuous cultures were achieved at two dilution rates (D). Trends of the carbon flow were determined by comparison of ratios between the specific rates of formation of the three products of metabolism (lactate, acetate, butyrate). Chenodeoxycholate induced the 7alpha- and 7beta-hydroxysteroid dehydrogenases of C. absonum. In the presence of this inducer, the growth yield and the carbon recovery decreased, the carbon flow distribution was altered favoring acetate production, and a deficit in the reoxydation of nucleotidic cofactors was observed. In the presence of chenodeoxycholate, C. absonum would favor the production of energy at the expense of the reoxidation of nucleotidic cofactors so as to ensure its growth, and the epimerization of chenodeoxycholate to ursodeoxycholate.