Glucose fermentation by Propionibacterium microaerophilum: effect of pH on metabolism and bioenergetic.
pH affected significantly the growth and the glucose fermentation pattern of Propionibacterium microaerophilum. In neutral conditions (pH 6.5-7.5), growth and glucose fermentation rate (qs) were optimum producing propionate, acetate, CO(2), and formate [which together represented 90% (wt/wt) of the end products], and lactate representing only 10% (wt/wt) of the end products. In acidic conditions, propionate, acetate, and CO(2) represented nearly 100% (wt/wt) of the fermentation end products, whereas in alkaline conditions, a shift of glucose catabolism toward formate and lactate was observed, lactate representing 50% (wt/wt) of the fermentation end products. The energy cellular yields ( Y(X/ATP)), calculated (i) by taking into account extra ATP synthesized through the reduction of fumarate into succinate, was 6.1-7.2 g mol(-1). When this extra ATP was omitted, it was 11.9-13.1 g mol(-1). The comparison of these values with those of Y(X/ATP) in P. acidipropionici and other anaerobic bacteria suggested that P. microaerophilum could not synthesize ATP through the reduction of fumarate into succinate and therefore differed metabolically from P. acidipropionici.
Koussémon
Marina
M
Laboratoire de Microbiologie IRD, IFR-BAIM, Université de Provence et de la Méditerranée, ESIL case 925, 13288 Marseille Cedex 9, France.
Combet-Blanc
Yannick
Y
Ollivier
Bernard
B
D002245:Carbon Dioxide; D003470:Culture Media; D004734:Energy Metabolism; D005285:Fermentation; D005947:Glucose / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D011424:Propionibacterium / Q000254:growth & development* / Q000378:metabolism*
D003470:Culture Media; D002245:Carbon Dioxide; D005947:Glucose