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A novel, non-motile coccoid, Gram-positive and non-endospore forming bacterium, designated Hv14b T , was isolated from the rhizosphere of the halophyte Arthrocnemum macrostachyum. It was observed to be catalase positive and oxidase negative and able to hydrolyse starch. MK-8(H2) was identified as the dominant menaquinone and the major cellular fatty acids were anteiso-C15 : 0 and iso-C15 : 0. The polar lipids comprised diphosphatidylglycerol, phosphatidylglycerol and an unidentified glycolipid. The 16S rRNA genes showed the highest 16S rRNA sequence identity with K. polaris DSM 14382 T , K. rosea DSM 20447 T and K. turfanensis DSM 22143 T . Based on the phenotypic and molecular features and DNA-DNA hybridization data, it is concluded that strain Hv14b T is proposed to represent a novel species in the genus Kocuria, Kocuria salina sp. nov., with the type strain Hv14b T =DSM 28714 T =CECT 9229 T .

Tetramethylbenzidine-H(2)O(2) staining of SDS-polyacrylamide gel is a widely used method for the specific detection of proteins with heme-dependent peroxidase activity. When this method was used with thylakoids from the halophytic plant Arthrocnemum macrostachyum, besides the cytochrome f and cytochrome b6 proteins usually found in higher plants and cyanobacteria, at least four additional bands were detected. One of them, a 46-kDa protein, was shown to be an extrinsic protein, and identified by mass spectrometry and immunoblotting as a 2-cys peroxiredoxin. Peroxidase activity was insensitive to oxidizing agents such as trans-4,4-diydroxy-1,2-dithiane or hydrogen peroxide, but was inhibited by treatment of thylakoids with reducing agents such as dithiothreitol or mercaptoethanol. By immunoblotting, it was shown that loss of peroxidase activity was paralleled by disappearance of the 46-kDa band, which was converted to a 23-kDa immunoreactive form. A dimer/monomer relationship between the two proteins is suggested, with the dimeric form likely being a heme-binding protein. This possibility was further supported by anionic exchange chromatography and de novo sequencing of tryptic fragments of the protein and sequence comparison, as most of the residues previously implicated in heme binding in 2-cys peroxiredoxin from Rattus norvegicus were conserved in A. macrostachyum. The amount of this protein was modulated by environmental conditions, and increased when salt concentration in the growth medium was higher or lower than the optimal one., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)