A Gram-stain-negative, strictly aerobic, rod-shaped, non-flagellated, non-spore-forming and gliding marine bacterium, designated strain CC-AMZ-304^T, was isolated from coastal surface seawater near Taichung harbour, Taiwan. Strain CC-AMZ-304^T predominantly synthesized zeaxanthin and thus formed yellow colonies on marine agar. The novel strain showed an unstable phylogenetic position, although sharing high pairwise 16S rRNA gene sequence similarities of 95.9–94.9, 95.7 and 95.1–93.9 % with Gaetbulibacter species (n = 4), Aestuariibaculum suncheonense SC17^T and Bizionia species (n = 7), respectively. The polar lipid profile of strain CC-AMZ-304^T consisted of phosphatidylethanolamine, five unidentified lipids, one unidentified phospholipid, two unidentified aminolipids and one unidentified glycolipid. The major (>5 % of the total) fatty acids were iso-C_15 : 0, iso-C_15 : 1 G, iso-C_17 : 0 3-OH, iso-C_15 : 0 3-OH and C_15 : 1ω5c. The DNA G+C content was 36.0 mol%. Menaquinone-6 (MK-6) was the sole respiratory quinone and the major polyamine was triamine sym-homospermidine. Phylogenetic distinctiveness, unique polar lipid composition, presence of significant amounts of branched hydroxyl fatty acids (iso-C_17 : 0 3-OH and iso-C_15 : 0 3-OH) and a low amount of anteiso-C_15 : 0, and several additional distinguishing biochemical features clearly discriminated strain CC-AMZ-304^T from the type species of the genera Aestuariibaculum and Gaetbulibacter . Thus, based on data from the present polyphasic study, strain CC-AMZ-304^T is considered to represent a novel species of a new genus within the family Flavobacteriaceae , for which the name Aquibacter zeaxanthinifaciens gen. nov., sp. nov. is proposed; the type strain of Aquibacter zeaxanthinifaciens is CC-AMZ-304^T ( = JCM 18557^T = BCRC 80463^T). Emended descriptions of the genera Aestuariibaculum and Gaetbulibacter are also proposed.

An aerobic, Gram-stain-negative, spiral or rod-shaped, non-spore-forming, diazotrophic bacterium (strain CC-LY743^T) was isolated from a fermentative tank in Taiwan. Strain CC-LY743^T was able to grow at 20–37 °C and pH 6.0–8.0 and tolerated up to 3.0 % (w/v) NaCl. It was positive for nitrogen fixation, with activity of 10.6 nmol ethylene h⁻¹. 16S rRNA gene sequence analysis of strain CC-LY743^T showed highest similarity to Azospirillum picis DSM 19922^T (96.1 %), Azospirillum oryzae JCM 21588^T (96.0 %) and Azospirillum rugosum DSM 19657^T (96.0 %) and lower similarity (<96.0 %) to all other Azospirillum species. Highest nifH gene sequence similarities were obtained with Azospirillum brasilense BCRC 12270^T (92.0 %), Azospirillum formosense BCRC 80273^T (92.3 %) and A. rugosum DSM 19657^T (91.8 %). It was positive in the rapid identification by a genus-specific primer set. The predominant quinone system was ubiquinone 10 (Q-10) and the DNA G+C content was 69.6±0.1 mol%. The major fatty acids found in strain CC-LY743^T were n-C_16 : 0, C_19 : 0 cyclo ω8c, C_14 : 0 3-OH/C_16 : 1 iso I, C_16 : 1ω7c/C_16 : 1ω6c and C_18 : 1ω7c/C_18 : 1ω6c. Based on its phylogenetic, phenotypic and chemotaxonomic features, strain CC-LY743^T is considered to represent a novel species within the genus Azospirillum for which the name Azospirillum fermentarium sp. nov. is proposed. The type strain is CC-LY743^T ( = BCRC 80505^T = JCM 18688^T = LMG 27264^T).

An aerobic, Gram-stain-negative, rod-shaped, DDT-resistant bacterium, designated strain CC-ALB-2^T, was isolated from the Arabidopsis thaliana rhizosphere. Strain CC-ALB-2^T was able to grow at 25–37 °C, at pH 5.0–8.0, with 1.0 % (w/v) NaCl and tolerate up to 200 mg l⁻¹ DDT. 16S rRNA gene sequence analysis of strain CC-ALB-2^T showed highest sequence similarity to Novosphingobium stygium KCTC 2891^T (97.1 %) and Novosphingobium soli DSM 22821^T (96.8 %), and lower levels of similarity (<97.0 %) to other species of the genus Novosphingobium . The major fatty acid profile consisted of C_14 : 0 2-OH (13.1 %), C_16 : 0 (10.0 %), C_15 : 0 iso 3-OH (5.8 %), C_16 : 1ω7c/C_16 : 1ω6c (summed feature 3, 24.7 %) and C_18 : 1ω7c/C_18 : 1ω6c (summed feature 8, 42.4 %). The polar lipid profile constitutes sphingoglycolipid, glycolipid, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidyldimethylethanolamine, phosphatidylglycerol and phosphatidylcholine. The polyamine pattern showed a predominance of spermidine as the major polyamine. The predominant quinone system was ubiquinone (Q-10). The DNA G+C content was 68.9±0.1 mol%. Based on the phylogenetic, phenotypic and chemotaxonomic features, strain CC-ALB-2^T is proposed to represent a novel species of the genus Novosphingobium for which the name Novosphingobium arabidopsis sp. nov. is proposed. The type strain is CC-ALB-2^T ( = BCRC 80571^T = JCM 18896^T).

A Gram-negative, spiral or rod-shaped, non-spore-forming diazotrophic bacterium, designated CC-Nfb-7^T, was isolated from agricultural soil in Yunlin County, Taiwan. 16S rRNA gene sequence analysis showed that strain CC-Nfb-7^T was most closely related to Azospirillum brasilense DSM 1690^T (97.4 % 16S rRNA gene sequence similarity), Azospirillum rugosum IMMIB AFH-6^T (96.8 %) and Azospirillum oryzae JCM 21588^T (96.6 %); <96.5 % 16S rRNA gene sequence similarity was found with all other members of the genus Azospirillum . DNA–DNA relatedness between strain CC-Nfb-7^T and A. brasilense DSM 1690^T, A. rugosum DSM 19657^T and A. oryzae JCM 21588^T was 38.9, 30.1 and 31.8 %, respectively. The respiratory quinone was ubiquinone Q-10. The major fatty acids were summed feature 8 (consisting of C_18 : 1ω7c and/or C_18 : 1ω6c), summed feature 3 (consisting of C_16 : 1ω7c and/or C_16 : 1ω6c), summed feature 2 (consisting of C_14 : 0 3-OH and/or iso-C_16 : 1 I), C_16 : 0, C_18 : 0 2-OH and C_16 : 0 3-OH. The polar lipids consisted mainly of phosphatidylglycerol, phosphatidylcholine and one unidentified phospholipid. Furthermore, moderate amounts of phosphatidylethanolamine, phosphatidyldimethylethanolamine and one unidentified aminophospholipid were also detected. Strain CC-Nfb-7^T could be distinguished from members of phylogenetically related species by differences in phenotypic properties. On the basis of morphological, chemotaxonomic and phylogenetic data, strain CC-Nfb-7^T represents a novel species within the genus Azospirillum , for which we propose the name Azospirillum formosense sp. nov. The type strain is CC-Nfb-7^T ( = BCRC 80273^T = JCM 17639^T = DSM 24137^T).