RESUMO
Two extremely halophilic archaea, strains Al-5(T) and K-1, were isolated from Lake Tebenquiche (Atacama Saltern, Chile) and Ezzemoul sabkha (Algeria), respectively. Cells of the two strains were short-rod-shaped and Gram-negative; colonies were orange-pigmented. They grew optimally at 37-40 degrees C and pH 7.0-7.5 in the presence of 25 % (w/v) NaCl. Magnesium was not required. Polar lipid analysis revealed the presence of phosphatidylglycerol and phosphatidylglycerophosphate methyl ester, the absence of phosphatidylglycerosulfate, and the presence of sulfated diglycosyl diether and diether diglycosyl as the sole glycolipids. DNA G+C contents of strains Al-5(T) and K-1 were 52.4 and 52.9 mol% (T(m) method), respectively. 16S rRNA gene sequence comparison with database sequences showed that strains Al-5(T) and K-1 were most closely related to Halomicrobium mukohataei DSM 12286(T) (similarities of 97.5 and 96.9 %, respectively). DNA-DNA hybridization indicated that strains Al-5(T) and K-1 were members of a single species. However, DNA-DNA relatedness to Halomicrobium mukohataei was 55.7+/-2.5 %. A comparative analysis of phenotypic characteristics and DNA-DNA hybridization between the isolates and Halomicrobium mukohataei DSM 12286(T) supported the conclusion that Al-5(T) and K-1 represent a novel species within the genus Halomicrobium, for which the name Halomicrobium katesii sp. nov. is proposed. The type strain is Al-5(T) (=CECT 7257(T)=DSM 19301(T)).
Assuntos
Água Doce/microbiologia , Halobacteriaceae/classificação , Halobacteriaceae/genética , Argélia , Técnicas de Tipagem Bacteriana , Composição de Bases , Chile , DNA Arqueal/genética , Genes Arqueais , Genes de RNAr , Glicolipídeos/química , Halobacteriaceae/química , Halobacteriaceae/isolamento & purificação , Dados de Sequência Molecular , Fenótipo , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Cloreto de Sódio , Microbiologia da ÁguaRESUMO
A total of 52 strains of moderately halophilic bacteria isolated from hypersaline sediment of Lake Tebenquiche on the Atacama Saltern, Chile, were subjected to a taxonomic study. The morphological, physiological, biochemical and nutritional characteristics of the strains matched those described for the genus Chromohalobacter. Cells were Gram-negative, non-spore-forming, rod-shaped and motile. A black pigmentation was produced. One strain, designated LTS-4N(T), grew optimally at 32 degrees C. Growth occurred in media containing 0.5-25% (w/v) total salts; the optimum was 7.5% (w/v) total salts. The pH range for growth was 5-10. The G + C content of the DNA of strain LTS-4N(T) was 59.8 mol%. Analysis of 16S rRNA gene sequence similarity revealed that strain LTS-4N(T) was closely related to Chromohalobacter species; however, DNA-DNA hybridization of representative strain LTS-4N(T) failed to associate the strain with any species of the genus Chromohalobacter with validly published names. Therefore, the name Chromohalobacter nigrandesensis sp. nov. is proposed. The type strain is LTS-4N(T) (= CECT 5315T = DSM 14323T).
Assuntos
Água Doce/microbiologia , Halomonadaceae/classificação , Chile , DNA Ribossômico/química , Halomonadaceae/genética , Halomonadaceae/isolamento & purificação , Halomonadaceae/fisiologia , Fenótipo , Filogenia , RNA Ribossômico 16S/genéticaRESUMO
A novel extremely halophilic archaeon was isolated from Lake Tebenquiche, situated in the northern part of the Atacama Saltern, Chile. The cells of these micro-organisms were mostly irregularly disc-shaped. They grew in medium containing saturated concentrations of NaCl and did not require magnesium for optimal growth. The polar lipid composition revealed the presence of mannosyl-2-sulfate-(1-4)-glycosyl-archaeol, the main glycolipid of the genus Halorubrum, and two new glycolipids. The G+C content of the DNA was 63.2 mol%. Phylogenetic analysis of the 16S rRNA gene placed strain ALT6-92T within the Halorubrum cluster. The low DNA-DNA hybridization value justified classification in a new species for which the name Halorubrum tebenquichense sp. nov. is proposed. The type strain is ALT6-92T (= CECT 5317T = DSM 14210T).
Assuntos
Água Doce/microbiologia , Halobacteriaceae/classificação , Halobacteriaceae/crescimento & desenvolvimento , Cloreto de Sódio , Composição de Bases , Chile , DNA Ribossômico/análise , Halobacteriaceae/genética , Halobacteriaceae/isolamento & purificação , Lipídeos/análise , Dados de Sequência Molecular , Hibridização de Ácido Nucleico , Filogenia , RNA Ribossômico 16S/genética , Análise de Sequência de DNARESUMO
Las cianobacterias se encuentran en el medio natural tanto en aguas dulces como saladas. Ellas pueden desarrollarse en grandes masas formando "blooms" (florecimientos) en aguas dulces y saladas en diferentes partes del mundo, incluyendo América del Sur. Tales florecimientos, así como crecimientos axénicos de cianobacterias, pueden ser una rica fuente de péptidos lineales o cíclicos únicos, muchos de los cuales presentan actividad biológica. En el pasado la mayor atención ha sido puesta en las toxinas microcistina y nodulatoria. Estos péptidos ciclicos son hepatotoxinas que inhíben la proteína fosfatasa 1 y 2A, después de ingresar específicamente al hepatocito mediante la captación de las sales biliares. Sin embargo, en cianobacterias se están encontrando péptidos con otras actividades biológicas. No obstante, auque no se consideren tóxicos, estos péptidos tienen actividades biológicas tales como: una fuerte y específica inhibición de las proteasas (tripsina, quimo-tripsina, elastasa, trombina, plasmina y la enzima procesadora angiotensina), anticianobacterias, antialgas, antihongos, inmunosupresores y promotores de diferenciación celular. Ejemplos de péptidos cianobacteriales inhibidores de proteasas son las cianopeptolina. Las interacciones de microcistina/proteína fosfatasa y de cianopeptolina/proteasa, han sido bien estudiadas por difracción de rayos x en cocristales y la determinación de microcistina y de otros péptidos puede ser realizada por métodos químicos y biológicos. Ambas, microcistina y cianopeptolina han sido recientemente determinadas en blooms producidos en cuerpos de agua en Chile, utilizando cromatografía líquida de alta resolución (HPLC), espectrometría de masas (MALDI-TOF) (PSD), además de bioensayos de inhibición enzimática