Thermoresistant properties of acetic acids bacteria isolated from tropical products of Sub-Saharan Africa and destined to industrial vinegar

Among 17 strains isolated from over-producing fruits, such as mangos, and cereals, two specific acetic acids bacteria, CWBI-B418 and CWBI-B419, were selected for their ability of growth and acetate production at higher temperatures. They have confirmed as Acetobacter tropicalis and A. pasteurianus, respectively, through phylogenetic study based on the 16S rDNA gene sequence analysis. The nucleotide sequence data of CWBI-B418 and CWBI-B419 strains had been deposited in the GenBank database under the respective accession nos. AY883036 and AY883035.In an other hand, their ability of growth and acetification with those of the wild-type strain A. pasteurianus LMG 1625T showed that CWBI-B418 and CWBI-B419 strains developed an optimum of growth without any appreciable lag phase and a high level of acetic acid production at 35 and 38 °C, respectively. The ability of growth and acetification of the wild strain was impossible under such conditions. The CWBI-B418 and CWBI-B419 strains exhibited then thermoresistance and acidoresistance property. The measure of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) activity (two enzymes membrane-bound involved in acetic fermentation), realized on a range of temperatures from 25 to 40 °C, showed an increasing denaturation more marked in the wild type strain. The inactivation constant of the enzymes ADH and ALDH of these strains was indeed much lower than that of the wild strain. By taking into account of all these physiological potentialities, the use of the CWBI-B418 and CWBI-B419 strains in industrial vinegar production in Sub-Saharan Africa would make it possible to reduce in a considerable way the cooling water expenses.