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RESEARCH PRODUCT

Tropicibacter multivorans sp. nov., an aerobic alphaproteobacterium isolated from surface seawater.

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Strain MD5T, an aerobic marine alphaproteobacterium, was isolated from Mediterranean seawater at Malvarrosa beach, Valencia, Spain. The strain was characterized in a polyphasic study and was placed phylogenetically within the Roseobacter clade in the family Rhodobacteraceae . Phylogenetic analysis based on 16S rRNA gene sequences showed that strain MD5T is related to Tropicibacter naphthalenivorans C02T, Phaeobacter inhibens T5T, P. gallaeciensis BS107T and P. daeponensis TF-218T, with 96.9, 96.2, 96.1 and 96.1 % sequence similarity, respectively. Phylogenetic analyses also showed that strain MD5T forms a stable clade only with T. naphthalenivorans C02T. Strain MD5T requires Na+ plus a divalent cation (either Mg2+ or Ca2+) to grow, does not reduce nitrate to nitrite and uses a large number of carbohydrates as sole carbon sources. It is positive for β-galactosidase and urease activities and aesculin hydrolysis. Enzyme activities displayed in the API ZYM strip were alkaline phosphatase, leucine arylamidase, acid phosphatase and α-glucosidase. Major cellular fatty acids were summed feature 8 (C18 : 1ω7c and/or C18 : 1ω6c; 70.9 %) and C16 : 0 (8.2 %). The results of physiological and biochemical tests allowed clear phenotypic differentiation of this isolate from the only described species of the genus Tropicibacter . It is evident from the genotypic and phenotypic data obtained that the strain should be classified in a novel species in the genus Tropicibacter . The name Tropicibacter multivorans sp. nov. is proposed, with the type strain MD5T ( = CECT 7557T  = KCTC 23350T).