[en] Six strains of acetic acid bacteria were isolated from Moroccan local products and evaluated for their industrial vinegar production potential. Two of them, namely AF01 and CV01, isolated from apple (Malus domestica) and cactus (Opuntia ficus-indica) fruits, respectively, were selected and investigated for their thermoresistant and thermophilic properties. A biochemical and molecular study based on a 16SrDNA gene sequence analysis confirmed that the two isolated strains belong to Acetobacter pasteurianus with 99 % of homology. Their growth and acetic acid production capacity were compared with (1) the thermoresistant reference strain A. senegalensis isolated from mango (Senegal) and (2) other, wild acetic strains belonging to A. pasteurianus (LMG 1632, LMG 1607, LMG 1701, DSM 2324 and DSM 4491). The two strains showed very good growth and noticeable acetic acid production ability at high temperatures (38 to 41°C). A thermophilic character was noted for AF01 strain. Indeed, this bacterium grew better at 38 than at 30°C. Subsequently, a semi-continuous fermentation was performed in a 20L Bioreactor for both selected strains. A total amount of 7.64% and 10.08% acetic acid was achieved at the end of fermentation, respectively for AF01 and CV01 strains. Process fermentation of CV01 strain was marked by the ability to produce gluconic acid during acetic fermentation. Finally, an enzymatic study was carried out on the selected strains AF01 and CV01 to confirm the tolerance of their enzymes responsible for acetic fermentation process to high temperature. Results clearly showed that the two strains exhibited high ADH and ALDH enzyme activity at either 30 or 38 °C as compared to the mesophilic reference strain LMG 1632 which exhibited marked thermal inactivation rate. It is concluded that the two selected strains are well-suited to industrial use for vinegar production in Morocco.
