Swaminathania salitolerans gen. nov., sp. nov., a salt-tolerant, nitrogen-fixing and phosphate-solubilizing bacterium from wild rice (Porteresia coarctata Tateoka)

Abstract

A novel species, Swaminathania salitolerans gen. nov., sp. nov., was isolated from the rhizosphere, roots and stems of salt-tolerant, mangrove-associated wild rice (Porteresia coarctata Tateoka) using nitrogen-free, semi-solid LGI medium at pH 5·5. Strains were Gram-negative, rod-shaped and motile with peritrichous flagella. The strains grew well in the presence of 0·35 % acetic acid, 3 % NaCl and 1 % KNO3, and produced acid from l-arabinose, d-glucose, glycerol, ethanol, d-mannose, d-galactose and sorbitol. They oxidized ethanol and grew well on mannitol and glutamate agar. The fatty acids 18 : 1ω7c/ω9t/ω12t and 19 : 0cyclo ω8c constituted 30·41 and 11·80 % total fatty acids, respectively, whereas 13 : 1 AT 12–13 was found at 0·53 %. DNA G+C content was 57·6–59·9 mol% and the major quinone was Q-10. Phylogenetic analysis based on 16S rRNA gene sequences showed that these strains were related to the genera Acidomonas, Asaia, Acetobacter, Gluconacetobacter, Gluconobacter and Kozakia in the Acetobacteraceae. Isolates were able to fix nitrogen and solubilized phosphate in the presence of NaCl. Based on overall analysis of the tests and comparison with the characteristics of members of the Acetobacteraceae, a novel genus and species is proposed for these isolates, Swaminathania salitolerans gen. nov., sp. nov. The type strain is PA51T (=LMG 21291T=MTCC 3852T).