Identification and Oxidation Products of Gluconobacter Strains Isolated from Fruits and Flowers in Thailand

The intent of the study is to identify and screen the oxidative products of acetic acid bacteria (AAB) from fruits and flowers in Thailand. Twenty-four isolates of AAB isolated from 22 fruit samples and two flower samples were grouped and identified at the species level in the genus Gluconobacter on the basis of their phenotypic and chemotaxonomic characteristics including molecular techniques. They were divided into four groups and identified as G. frateurii (Group 1, four isolates), G. japonicus (Group 2, two isolates), G. thailandicus (Group 3, 6 isolates), and G. oxydans (Group 4, 12 isolates) using 16S-23S rRNA gene internal transcribed spacer regions (ITS) restriction analysis and 16S-23S rRNA gene ITS phylogenetic analysis. All isolates were screened for dihydroxyacetone (DHA) and L-sorbose production. The test isolates produced DHA ranged from 25.24 to 42.52 g/l at 30°C. G. oxydans isolate PHD-27 produced a large amount of DHA. The test isolates produced L-sorbose ranged from 15.77 to 39.68 g/l at 30°C. G. frateurii isolate PHD-30 produced a largest amount of L-sorbose.