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Acetic acid bacteria are gram-negative obligate aerobic bacteria assigned to the family Acetobacteraceae of Alphaproteobacteria . They are members of the genera Acetobacter , Gluconobacter , Gluconacetobacter , Acidomonas , Asaia , Kozakia , Swaminathania , Saccharibacter , Neoasaia , Granulibacter , Tanticharoenia , Ameyamaea , Neokomagataea , and Komagataeibacter . Many strains of Acetobacter and Komagataeibacter have been known to possess high acetic acid fermentation ability as well as the acetic acid and ethanol resistance, which are considered to be useful features for industrial production of acetic acid and vinegar, the commercial product. On the other hand, Gluconobacter strains have the ability to perform oxidative fermentation of various sugars, sugar alcohols, and sugar acids leading to the formation of several valuable products. Thermotolerant strains of acetic acid bacteria were isolated in order to serve as the new strains of choice for industrial fermentations, in which the cooling costs for maintaining optimum growth and production temperature in the fermentation vessels could be significantly reduced. Genetic modifications by adaptation and genetic engineering were also applied to improve their properties, such as productivity and heat resistance. [ABSTRACT FROM AUTHOR]

The article discusses the findings of a study which determined the role of genes in oxidative fermentation of D-sorbitol in Gluconobacter frateurii bacteria. The researchers described the oxidizing characteristic of the Gluconobacter in producing L-sorbose, 2- and 5-keto-D-gluconates, and the Miglitol drug. The experiment confirmed the identification and characterization of D-sorbitol dehydrogenase genes including sldR, xdhA, and perA.

We identified a novel flavoprotein-cytochrome c complex d-gluconate dehydrogenase (GADH) encoded by gndXYZ of Gluconobacter oxydans NBRC 3293, which is phylogenetically distinct from previously reported GADHs encoded by gndFGH and gndSLC of Gluconobacter spp. To analyze the biochemical properties of respective GADHs, Gluconobacter japonicus NBRC 3271 mutant strain lacking membranous d-gluconate dehydrogenase activity was constructed. All GADHs (GndFGH, GndSLC, and GndXYZ) were successfully overexpressed in the constructed strain. The optimal pH and KM value at that pH of GndFGH, GndSLC, and GndXYZ were 5, 6, and 4, and 8.82 ± 1.15, 22.9 ± 5.0, and 11.3 ± 1.5 m m, respectively. When the mutants overexpressing respective GADHs were cultured in d-glucose-containing medium, all of them produced 2-keto-d-gluconate, revealing that GndXYZ converts d-gluconate to 2-keto-d-gluconate as well as other GADHs. Among the recombinants, the gndXYZ-overexpressing strain accumulated the highest level of 2-keto-d-gluconate, suggesting its potential for 2-keto-d-gluconate production., (© The Author(s) 2022. Published by Oxford University Press on behalf of Japan Society for Bioscience, Biotechnology, and Agrochemistry.)

Acetobacter pasteurianus is a Gram-negative strictly aerobic bacterium that is widely used for the industrial production of vinegar. Three Acetobacter pasteurianus strains, SKU1108, NBRC 3283 and IFO 3191, have the same 16S rRNA sequence (100 % sequence identity) but show differences in thermotolerance. To clarify the relationships between phylogeny and thermotolerance of these strains, genome-wide analysis of these three strains was performed. Concatenated phylogenetic analysis of a dataset of 1864 orthologues has shown that the more thermotolerant strains, SKU1108 and NBRC 3283, are more closely related to each other than to the more thermosensitive strain, IFO 3191. In addition, we defined a dataset of 2010 unique orthologues among these three strains, and compared the frequency of amino acid mutations among them. Genes involved in translation, transcription and signal transduction are highly conserved among each unique orthologous dataset. The results also showed that there are several genes with increased mutation rates in IFO 3191 compared with the thermotolerant strains, SKU1108 and NBRC 3283. Analysis of the mutational directions of these genes suggested that some of them might be correlated with the thermosensitivity of IFO 3191. Concatenated phylogenetic analysis of these closely related strains revealed that there is a phylogenetic relationship associated with this phenotype among the thermotolerant and thermosensitive strains.