• Sciences du Vivant/Ecologie, Environnement
  
• Sciences du Vivant/Microbiologie et Parasitologie/Bactériologie
  
• Sciences de l'environnement/Biodiversité et Ecologie
  
• Sciences de l'environnement/Environnement et Société
  
• Sciences de l'environnement/Milieux et Changements globaux
  
• Sciences de l'environnement/Ingénierie de l'environnement
  
• Planète et Univers/Océan, Atmosphère
  
• Sciences du Vivant/Ecologie, Environnement/Ecosystèmes
  
• Sciences du Vivant/Biodiversité/Systématique, phylogénie et taxonomie
  

Transfer of Pseudomonas pictorum Gray and Thornton 1928 to genus Stenotrophomonas as Stenotrophomonas pictorum comb. nov., and emended description of the genus Stenotrophomonas Abstract A polyphasic taxonomic approach including analysis of phenotypic, physiological and genotypic characteristics, 16S rRNA gene sequence and DNA–DNA hybridization analysis was used to determine the most consistent affiliation of Pseudomonas pictorum. Pseudomonas pictorum ATCC 23328 T exhibited phenotypic traits of members of the genus Stenotrophomonas including cellular fatty acid composition, quinone and limited range of substrates that could be used. Antibiotic susceptibility and physiological characteristics were determined. The DNA G+C content was 65.7 mol%. Phylogenetic analysis revealed that the type strains of Stenotrophomonas terrae, Stenotrophomonas humi, Stenotrophomonas nitritireducens and Stenotrophomonas acidaminiphila were the nearest relatives (16S rRNA gene sequence similarity of 98.0 to 98.8 %). All the other type strains of species of the genus Stenotrophomonas showed high 16S rRNA gene sequence similarities (96.8 to 97.2 %). DNA–DNA hybridizations revealed 31.0, 32.0, 43.3 and 43.6 % reassociation between Pseudomonas pictorum ATCC 23328 T and the type strains of S. terrae, S. humi, S. nitritireducens and S. acidaminiphila, respectively. Our overall results indicate that Pseudomonas pictorum should be transferred to the genus Stenotrophomonas as a novel species of this genus, Stenotrophomonas pictorum comb. nov. Since the original description of the genus Stenotrophomonas was made with only one species (Stenotrophomonas maltophilia), an emendation of the genus description is proposed in order to match better with the characteristics of the eleven novel species assigned to this genus since then. The first description of Pseudomonas pictorum proposed by Gray and Thornton [1] was a report of the phenotypic characteristics of cells and morphology of colonies. Over the years, phenotypic studies (cellular fatty acid composition, quinone type content of cells, polyamine pattern and ester-ase polymorphism) and phylogenetic analysis (16S rRNA gene sequences, gyrB sequence, full genome sequence) have clearly pointed out that Pseudomonas pictorum should rather be reclassified within the family Xanthomonadaceae lineage and that its closest relatives are species of the genus Stenotrophomonas [2–12]. As a consequence, the type strain of Pseudomonas pictorum has been included in several studies concerning the genomic and phenotypic diversity of the genus Stenotrophomonas in which this type strain was even sometimes presented as a member of Stenotrophomonas maltophilia, with which, however, it shows only 30 % DNA– DNA reassociation [4, 13, 14]. Despite this body of evidence and wide acceptance, Pseudomonas pictorum has still not been formerly assigned to the genus Stenotrophomonas. The aim of the present study was to determine the most consistent taxonomic position of Pseudomonas pictorum by a polyphasic taxonomic approach including analysis of phe-notypic, physiological and genotypic (16S rRNA gene sequence similarities and DNA–DNA hybridization) properties and characteristics of this species. Since no other Pseudomonas pictorum strain than the type strain is presently available in public culture collections and all the accessible cultures of the type strain are derived from the strain deposited in the Czech collection of microorganisms under the number CCM 284 T , our study was limited to the type strain. Cultures of all the type strains were prepared using nutrient broth media (3 g meat extract l À1 , 5 g peptone l À1 , 5 g yeast extract l À1). Unless otherwise indicated, cultures of microorganisms for performing phenotypic tests were prepared

Two novel strictly anaerobic bacteria, strains Bs105(T) and Bs107(T), were isolated from a deep aquifer-derived hydrocarbonoclastic community. The cells were rod-shaped, not motile and had terminal spores. Phylogenetic affiliation and physiological properties revealed that these isolates belong to two novel species of the genus Desulfotomaculum. Optimal growth temperatures for strains Bs105(T) and Bs107(T) were 42 and 45 degrees C, respectively. The estimated G+C content of the genomic DNA was 42.9 and 48.7 mol%. For both strains, the major cellular fatty acid was palmitate (C-16 : 0). Specific carbon fatty acid signatures of Gram-positive bacteria (iso-C-17 : 0) and sulfate-reducing bacteria (C(17 : 0)cyc) were also detected. An insertion was revealed in one of the two 16S rRNA gene copies harboured by strain Bs107(T). Similar insertions have previously been highlighted among moderately thermophilic species of the genus Desulfotomaculum. Both strains shared the ability to oxidize aromatic acids (Bs105(T) : hydroquinone, acetophenone, paratoluic acid, 2-phenylethanol, trans-cinnamic acid, 4-hydroxybenzaldehyde, benzyl alcohol, benzoic acid 4-hydroxybutyl ester; Bs107(T) : ortho-toluic acid, benzoic acid 4-hydroxybutyl ester). The names Desulfotomaculum aquiferis sp. nov. and Desulfotomaculum profundi sp. nov. are proposed for the type strains Bs105(T) (= DSM 24088(T) = JCM 31386(T)) and Bs107(T) (= DSM 24093(T) = JCM 31387(T)).

The current paper reports on the purification of an extracellular thermostable keratinase (KERCA) produced from Caldicoprobacter algeriensis strain TH7C1(T), a thermophilic, anaerobic bacterium isolated from a hydrothermal hot spring in Algeria. The maximum keratinase activity recorded after 24-h of incubation at 50 °C was 21000 U/ml. The enzyme was purified by ammonium sulfate precipitation-dialysis and heat treatment (2h at 50 °C) followed by UNO Q-6 FPLC anion exchange chromatography, and submitted to biochemical characterization assays. Matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF/MS) analysis revealed that the purified enzyme was a monomer with a molecular mass of 33246.10 Da. The sequence of the 23 N-terminal residues of KERCA showed high homology with those of bacterial keratinases. Optimal activity was achieved at pH 7 and 50 °C. The enzyme was completely inhibited by phenylmethanesulfonyl fluoride (PMSF) and diiodopropyl fluorophosphates (DFP), which suggests that it belongs to the serine keratinase family. KERCA displayed higher levels of hydrolysis and catalytic efficiency than keratinase KERQ7 from Bacillus tequilensis strain Q7. These properties make KERCA a potential promising and eco-friendly alternative to the conventional chemicals used for the dehairing of goat, sheep, and bovine hides in the leather processing industry.

A novel anaerobic, alkaliphilic, Gram-stain-positive, spore-forming bacterium was isolated from a carbonaceous hydrothermal chimney in Prony Bay, New Caledonia. This bacterium, designated strain 3bT, grew at temperatures from 30 to 43 °C (optimum 37 °C) and at pH between 7.8 and 10.1 (optimum 9.5). Added NaCl was not required for growth (optimum 0-0.2 %, w/v), but was tolerated at up to 4 %. Yeast extract was required for growth. Strain 3bT utilized crotonate, lactate and pyruvate, but not sugars. Crotonate was dismutated to acetate and butyrate. Lactate was disproportionated to acetate and propionate. Pyruvate was degraded to acetate plus trace amounts of hydrogen. Growth on lactate was improved by the addition of fumarate, which was used as an electron acceptor and converted to succinate. Sulfate, thiosulfate, elemental sulfur, sulfite, nitrate, nitrite, FeCl3, Fe(III)-citrate, Fe(III)-EDTA, chromate, arsenate, selenate and DMSO were not used as terminal electron acceptors. The G+C content of the genomic DNA was 33.2 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence indicated that the isolate is a member of the family Clostridiaceae, order Clostridiales within the phylum Firmicutes. Strain 3bT was most closely related to 'Alkaliphilus hydrothermalis' FatMR1T (92.2 % 16S rRNA gene sequence similarity), and was positioned approximately equidistantly between the genera Alkaliphilus, Anaerovirgula and Natronincola. On the basis of phylogenetic, genetic, chemotaxonomic and physiological properties, strain 3bT is proposed to represent a novel species of a new genus, for which the name Serpentinicella alkaliphila gen. nov., sp. nov. is proposed. The type strain of Serpentinicella alkaliphila is 3bT (=DSM 100013T=JCM 30645T).