| Summary: | Two novel strains AV382 and AV436 were isolated from a submerged industrial bioreactor for production of apple cider vinegar in Kopivnik (Slovenia). Both strains showed very high (≥98.2%) 16S rRNA gene sequence similarities with <i>Komagataeibacter</i> species, but lower 16S–23S rRNA gene internal transcribed spacer (ITS). The highest similarity of the 16S–23S rRNA gene ITS of AV382 was to <i>Komagataeibacter kakiaceti</i> LMG 26206<sup>T</sup> (91.6%), of AV436 to <i>Komagataeibacter xylinus</i> LMG 1515<sup>T</sup> (93.9%). The analysis of genome sequences confirmed that AV382 is the most closely related to <i>K. kakiaceti</i> (ANIb 88.2%) and AV436 to <i>K. xylinus</i> (ANIb 91.6%). Genome to genome distance calculations exhibit for both strains ≤47.3% similarity to all type strains of the genus <i>Komagataeibacter</i>. The strain AV382 can be differentiated from its closest relatives <i>K. kakiaceti</i> and <i>Komagataeibacter saccharivorans</i> by its ability to form 2-keto and 5-keto-D-gluconic acids from glucose, incapability to grow in the presence of 30% glucose, formation of C<sub>19:0</sub> cyclo <i>ω</i>8c fatty acid and tolerance of up to 5% acetic acid in the presence of ethanol. The strain AV436 can be differentiated from its closest relatives <i>K. xylinus</i>, <i>Komagataeibacter sucrofermentans,</i> and <i>Komagataeibacter nataicola</i> by its ability to form 5-keto-D-gluconic acid, growth on 1-propanol, efficient synthesis of cellulose, and tolerance to up to 5% acetic acid in the presence ethanol. The major fatty acid of both strains is C<sub>18:1</sub><i>ω</i>7c. Based on a combination of phenotypic, chemotaxonomic and phylogenetic features, the strains AV382<sup>T</sup> and AV436<sup>T</sup> represent novel species of the genus <i>Komagataeibacter</i>, for which the names <i>Komagataeibacter</i><i>melaceti</i> sp. nov. and <i>Komagataeibacter melomenusus</i> are proposed, respectively. The type strain of <i>Komagataeibacter melaceti</i> is AV382<sup>T</sup> (= ZIM B1054<sup>T</sup> = LMG 31303<sup>T</sup> = CCM 8958<sup>T</sup>) and of <i>Komagataeibacter melomenusus</i> AV436<sup>T</sup> (= ZIM B1056<sup>T</sup> = LMG 31304<sup>T</sup> = CCM 8959<sup>T</sup>).
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