Isolation of thermotolerant and high acetic acid-producing Acetobacter pasteurianus from Ivorian palm wine

The aim of this work was to identify acetic acid bacteria expressing technological characteristics for further use in vinegar production in tropical countries. It was focused on isolation and identification of thermotolerant acetic acid bacteria strains from Elaeis guineensis wine of Côte d’Ivoire (Ivorian palm wine). A screening was performed to find out strains with high vinegar production, tolerant against high ethanol, acid and sugar concentrations as well as tolerating high production temperatures. Among 104 isolated strains, 5 were selected for their growth ability, acetification capacity (acetic acid production higher than 30 g/l) and suroxydation at 37°C. Tolerance against 6% acetic acid and 9% ethanol was observed. Osmotolerance study showed tolerance against 5% and 10% glucose giving 100% and 50% relative growth, respectively. Resistance against desiccation showed survival rate of 50% at 37°C after 5 h treatment and 10% after 20 h treatment. The best aeration rate in flasks for acetification was 70%. Polyphasic identification study based on biochemical, physiological and molecular characterization showed that the 5 isolates were all Acetobacter pasteurianus. Owing to their potentialities, these strains may be used as starters in vinegar production after conducting preservation studies.