Development of Thermotolerant Acetic Acid Bacteria Useful for Vinegar Fermentation at Higher Temperatures

Abstract

Thermotolerant acetic acid bacteria that can grow at 37 to 40°C were collected from places all over Thailand. They were divided into several groups according to their taxonomic and physiological properties, such as rapid ethanol oxidation, rapid acetate oxidation, cellulosic biopolymer formation, growth at 40°C, growth in 3% acetic acid, growth in 8% ethanol, formation of thermotolerant alcohol, and aldehyde dehydrogenases, etc. Though the complete taxonomic analysis has not been completed with all the strains, the majority of the acetic acid bacteria isolated have been confirmed to be classified as Acetobacter rancens subsp. pasteurianus, A. lovaniensis subsp. lovaniensis, A. aceti subsp. liquefaciens, and A. xylinum subsp. xylinum. They produced acetic acid at high temperatures such as 38 to 40°C. Even when acetic acid was initially added to 4%, they still oxidized ethanol to accumulate acetic acid, while 2% of the initial acetic acid was the upper limit for mesophilic strains*1 at higher temperatures. ...