Isolation and identification of thermo- ethanol-tolerant Acetobacter pasteurianus KBMNS-IAUF-3 and Acetobacter senegalensis KBMNSIAUF-5 strains from fig-peach and nut-grape fruits and investigation of their potential for vinegar production

Due to the high energy consumption for cooling of fermentors, isolation of thermo-tolerant Acetobacter strains to produce vinegar is necessary. On the other hand, these thermo-tolerant strains should tolerate against high percentage of ethanol, which can be used as a source of carbon. The purposes of this study were to isolate and identify thermo-resistant AAB strains from different fruits and investigation of their resistance to the high ethanol concentrations. In order to isolate the AAB strains, the extracts dilutions of fig-peach and nut-grape fruits were prepared, cultivated in Frateur culture media and incubated at 30°C for 24 hours. The individual colonies with round transparent zone were isolated and purified using same condition. The isolates for macroscopic, microscopic and biochemical evaluations were transferred to the Carr culture media. Then the resistance of the isolates against different high temperature and ethanol concentrations were measured. Finally, the molecular identification of isolates was carried out. One strain was isolated from each fruit sample. The overoxidation property in Carr medium as well as macroscopic, microscopic, biochemical and molecular characterizations showed that the isolates were related to Acetobacter spp. The isolated Acetobacter spp. were able to grow in Carr culture media with 7 percent ethanol and 38°C after 24 hours-incubation so they were considered as thermo- ethatol-resistant AAB spp. The isolated AAB from fig-peach and nut-grape were named Acetobacter pasteurianus KBMNS-IAUF-3 and Acetobacter senegalensis KBMNS-IAUF-5 and their 16s ribosomal sequences were deposited in GenBank, NCBI under the accession numbers of MG547345.1 and MG547383.1 respectively.