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Haloactinospora alba gen. nov., sp. nov., a halophilic filamentous actinomycete of the family Nocardiopsaceae Shu-Kun Tang, 1 3 Xin-Peng Tian, 1,2 3 Xiao-Yang Zhi, 1 A novel halophilic, filamentous, actinomycete strain, designated YIM 90648 T , was isolated from a salt lake in Xinjiang Province, north-west China, and subjected to a polyphasic taxonomic study. Optimal growth occurred at 37 6C, pH 7.0-8.0 and 15 % (w/v) NaCl. The aerial mycelium of strain YIM 90648 T formed long chains of spores at maturity and the spores were cylindrical with smooth surfaces. Spore chains with pseudosporangia at the end were borne on the substrate mycelium and most spores had wrinkled surfaces. Strain YIM 90648 T contained mesodiaminopimelic acid as the diagnostic diamino acid and galactose and ribose as the major wholecell components. The phospholipids were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylcholine and phosphatidylinositol mannoside. MK-10(H 8 ), MK-11(H 4 ), MK-11(H 6 ) and MK-11(H 8 ) were the predominant menaquinones. The major fatty acids were i-C 16 : 0 and ai-C 17 : 0 . The DNA G+C content was 68 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain YIM 90648 T formed a distinct lineage within the family Nocardiopsaceae and showed 16S rRNA gene sequence similarity of 93.3-95.0 % with members of the family Nocardiopsaceae. On the basis of the polyphasic evidence, a novel genus and species, Haloactinospora alba gen. nov., sp. nov., is proposed to accommodate this isolate. The type strain of Haloactinospora alba is YIM 90648 T (5DSM 45015 T 5CCTCC AA 206008 T ).

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A novel actinomycete strain, GW25-5(T), was isolated from a soil sample collected from the Fildes Peninsula, King George Island, West Antarctica. The strain was characterized by white to grey aerial mycelia, which were differentiated to straight to flexuous spore chains, with rod-shaped smooth spores. The cell wall of strain GW25-5(T) contained LL-diaminopimelic acid (A(2)pm) and traces of meso-A(2)pm. Whole-cell sugars were galactose and minor amounts of mannose and glucose. The predominant menaquinones were MK-9(H(6)) (49%), MK-9(H(8)) (24%) and MK-9(H(4)) (12%). The phospholipids contained DPG, PE, PI, PIM and PL(s). The major cellular fatty acids were iso-C(16:0) and anteiso-C(15:0). Genomic DNA G+C content of strain GW25-5(T) was 70.0 mol%. BLAST result showed that strain GW25-5 has the 16S rRNA gene sequence highest similarity of 97.5% with members of genus Streptomyces and phylogenetic analysis indicated that this strain belongs to the genus Streptomyces. DNA-DNA relatedness values of strain GW25-5(T) with the closest species of Streptomyces purpureus LMG 19368(T) and Streptomyces beijiangensis YIM 6(T) were significantly lower than 70% of the threshold value for the delineation of genomic species. A polyphasic taxonomic investigation based on a judicious combination of genotypic and phenotypic characteristics revealed that the organism represents a novel species of the genus Streptomyces. Thus, we propose strain GW25-5(T) as the type strain of this novel species, Streptomyces fildesensis (=CGMCC 4.5735(T) = YIM 93602(T) = DSM 41987(T) = NRRL B 24828(T)).

Previous studies focused on psychrophilic adaptation generally have demonstrated that multiple mechanisms work together to increase protein flexibility and activity, as well as to decrease the thermostability of proteins. However, the relationship between high and low temperature adaptations remains unclear. To investigate this issue, we collected the available predicted whole proteome sequences of species with different optimal growth temperatures, and analyzed amino acid variations and substitutional asymmetry in pairs of homologous proteins from related species. We found that changes in amino acid composition associated with low temperature adaptation did not exhibit a coherent opposite trend when compared with changes in amino acid composition associated with high temperature adaptation. This result indicates that during their evolutionary histories the proteome-scale evolutionary patterns associated with prokaryotes exposed to low temperature environments were distinct from the proteome-scale evolutionary patterns associated with prokaryotes exposed to high temperature environments in terms of changes in amino acid composition of the proteins.