Article Subject:Microbial Biotechnology 10.30699/ijmm.13.4.251Background and Aims: The use of ethanol-temperature-resistant Acetobacter strains to produce vinegar on an industrial scale is important due to their sensitivity to high ethanol concentration as substrate and high energy consumption for acetator cooling. The aims of this study were to isolate and identify high temperature and ethanol resistant Acetobacter strains as starter for production of vinegar. Materials and Methods:The banana alcoholic extract was transferred to the fermenter medium and after 24 h incubation at 30°C, colonies with transparent zone were purified as acetic acid bacteria and examined macroscopically and microscopically. The resistance to high temperature in constant ethanol and time as well as resistance to high ethanol in constant temperature and time were investigated. Results:The studies of AAB isolate grown in the Carr medium showed that it was a Acetobacter strain. According to the single-factor optimization, this species was able to grow in a Carr medium containing 9% ethanol at 40°C after 72 h. Conclusion:This is the first report of an AAB isolation from banana in Iran. This bacterium, as a new resistant strain to high levels of ethanol and temperature, was identified as Acetobacter ghanensis KBMNS-IAUF-6 and its 16S-rDNA sequence was deposited in GenBank, NCBI, under the accession number of MK968570. This new strain can be suggested as a high temperature and ethanol resistant strain for producing banana vinegar on a semi-industrial and industrial scale.

Background Recently production of several types of vinegar using new strains of acetic acid bacteria is challenging. Results In this research we isolated a new strain of A. okinawensis from Iranian nectarine we obtained from nectarine garden at Isfahan, Iran. According to 16s-rDNA molecular analysis we named that Acetobacter okinawensis strain KBMNS-IAUF-1 and its partial 16s-rDNA sequence was deposited in GenBank, NCBI under the accession number of MG544095.1. The tolerance of A. okinawensis KBMNS-IAUF-1 against ethanol concentrations of 2%-10% and high temperatures of 34-38°C was investigated. This strain had good growth and acid production in 2%-5% ethanol at high temperature of 38°C and as a thermo-tolerant AAB had good growth in 5% ethanol at 38°C. Also produced 6% acetic acid in an economical industrial culture medium at high temperature of 38°C using a fermentor apparatus we designed for vinegar production. Conclusions This is the first report of isolation and identification of Acetobacter okinawensis KBMNS-IAUF-1 from Iranian nectarine as a high thermo- ethanol- tolerant AAB capable of high acetic acid production in a short period of time and is a very good candidate for production of a new type of vinegar, nectarine vinegar, in high temperatures and ethanol concentrations. The thermo- ethanol-tolerant AAB as potential for production of new types of vinegar with suitable flavor could be an asset in food microbiology as well as industrial biotechnology.