No abstract

A number of expeditions to the area of Mar de Atacarna, Chile, 68" 15'W, 20" 30'S, have involved studies of the biological and chemical features of Lake Tebenquiche, situated in the interior of the salar. Chemically, Tebenquiche is hypersaline, with practically anoxic waters dominated by sodium and chloride ions but with high concentrations of sulphate also. The lake is surrounded and invaded by macrophytes, dominated by Scirpus olmeyi and Juncus, which provide organic material for the formation of bacterial mats. The fauna of limnetic crustaceans is almost exclusively ofArtemia salina. The most important genera of bacteria are: Marinomonas, Halobacterium, Acinetobacter and the sulphur reductors Vibrio and Bacillus. The Cyanobacteria are represented exclusively by Oscillatoria.

A large number of halophilic bacteria were isolated in 1984-1992 from the Atacama Saltern (North of Chile). For this study 82 strains of extreme halophilic archaea were selected. The characterization was performed by using the phenotypic characters including morphological, physiological, biochemical, nutritional and antimicrobial susceptibility test. The results, together with those from reference strains, were subjected to numerical analysis, using the Simple Matching (S(SM)) coefficient and clustered by the unweighted pair group method of association (UPGMA). Fifteen phena were obtained at an 70% similarity level. The results obtained reveal a high diversity among the halophilic archaea isolated. Representative strains from the phena were chosen to determine their DNA base composition and the percentage of DNA-DNA similarity compared to reference strains. The 16S rRNA studies showed that some of these strains constitutes a new taxa of extreme halophilic archaea.

A total of 174 moderately halophilic bacteria was isolated from an inland saltern with athalassohaline characteristics, located in La Mali, Granada, Spain. The results of 1 18 phenotypic tests were submitted to a numerical analysis with ten reference strains using simple matching (SsM) and Jaccard (S, ) coefficients. Clustering was done by the unweighted pairgroup method of association (UPGMA), single linkage and complete linkage analysis. Five phenons were found at the 67% similarity level (SsM). Phenon A included 74 strains assigned to Vibrio; 22 bacteria belonging to phenon B were assigned to the genus Alteromonas; strains of phenon C were assigned to Deleya (43 strains) and Acinetobacter (7 strains); phenon D resembled Pseudomonas (1 3 strains); phenon E could be related to Flavobacterium oceanosedimentum (9 strains).

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-4NT, grew optimally at 32 °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-4NT was 59·8 mol%. Analysis of 16S rRNA gene sequence similarity revealed that strain LTS-4NT was closely related to Chromohalobacter species; however, DNA–DNA hybridization of representative strain LTS-4NT 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-4NT (=CECT 5315T=DSM 14323T).