|446-2||Oceanicella actignis gen. nov., sp. nov., A HALOPHILIC SLIGHTLY THERMOPHILIC MEMBER OF THE ALPHAPROTEOBACTERIA|
|Autores:||Luciana Albuquerque (CNC - Center for Neuroscience and Cell Biology) ; Fred A. Rainey (DBS - Department of Biological Sciences, University of Alaska) ; Maria Fernanda Nobre (DCV - Department of Life Sciences, University of Coimbra) ; Milton S. da Costa (DCV - Department of Life Sciences, University of Coimbra / BIOCANT - Microbiology Unit, BIOCANT Biotechnological Park) |
The vast majority of the Alphaproteobacteria grow at temperatures which we generally designate as mesophilic, with maximum growth temperatures lower than about 45 ºC. However, a several organisms have been isolated from hot springs, namely Porphyrobacter tepidarius, P. cryptus, Rubritepida flocculans, Albidovulum inexpectatum, Elioraea tepidiphila and Tepidamorphus gemmatus with optimum growth temperatures in the neighbourhood of 50 ºC, but who do not grow at 60 ºC. We recently isolated four slightly thermophilic strains from a shallow marine hot spring on a beach, Praia do Fogo, at Ribeira Quente, on the Island of São Miguel in the Azores. Water samples were collected from small depressions dug in the sand during low tide at the sandy beach. Two isolates had sequence similarities identical with the type strain of A. inexpectatum. The other two isolates, designated PRQ-67T and PRQ-68, belonged to a previously unknown genus and species. Comparisons of 16S rRNA gene sequences show these strains to be most closely related (93.1-94.7% similarity) to species of the genus Amaricoccus, within the family Rhodobacteraceae. The strains PRQ-67T and PRQ-68 had an optimum growth temperature of about 50 ºC, growth range in medium containing between 1 and 9% NaCl and an optimum pH for growth between 7.5 and 8.0. Strains are non-pigmented and form non-motile pleomorphic cells that stain Gram-negative, are aerobic, oxidase and catalase positive. The major fatty acids are 18:1 ω7c and 18:1 ω7c 11-methyl. Ubiquinone 10 is the major respiratory quinone. Major polar lipids are phosphatidylcholine, phosphatidylglycerol and one aminolipid. Based on 16S rRNA gene sequence analysis, physiological and biochemical characteristics we describe a new species of a novel genus represented by strain PRQ-67T (=DSM 22673T =LMG 25334T) for which we propose the name Oceanicella actignis.
Palavras-chave: Oceanicella, Oceanicella actignis sp. nov., Alphaproteobacteria