ISOLATION AND IDENTIFICATION OF AN ACETOBACTER ISOLATE FROM CASHEW APPLE AS A POTENTIAL STRAIN FOR VINEGAR PRODUCTION

ABSTRACT Vinegar is defined as a sour liquid containing 4% solution of acetic acid is produced from sugary materials by alcoholic fermentation. In the base of microbial starters, vinegars could be contained of more than 50 types of volatile and aromatic substances that responsible for their sweet taste and smelling. Recently the vinegar industry has a great proportion in agriculture, food and microbial biotechnology. The acetic acid bacteria are from the family Acetobacteraceae. The genus Acetobacter that is primarily used in vinegar manufacturing plants is a gram negative, obligate aerobe coccus or rod shaped bacterium with the size 0.6 -0.8 X 1.0 -4.0 µm, nonmotile or motile with peritrichous flagella and catalase positive -oxidase negative biochemically. Some strains are over oxidizer that could convert acetic acid to carbon dioxide and water. In this research one Acetobacter native strain with high acetic acid productivity was isolated from cashew apple .We used two specific culture media include Carr medium and Frateur medium. In addition to high acetic acid production and high growth rate, this strain had a good tolerance against ethanol concentration that was examined using modified Carr media with 5%, 7% and 9% ethanol concentrations. While the industrial strains of acetic acid bacteria grow in the thermal range of 28 -30 °C, this strain was adapted for growth in 34 -36°C after 96 hours incubation period. These dramatic characteristics suggest a potential strain in production of cashew vinegar with a sweet smell and different nutritional properties in comparison to other vinegar types. The lack of growth after 24, 48 and 72 hours incubation at 34 -36 °C and the growth after 96 hours indicates a good and fast thermal flexibility of this strain as a significant characteristic of biotechnological and industrial strains