Comparison of Artemia–bacteria associations in brines, laboratory cultures and the gut environment: a study based on Chilean hypersaline environments

13 páginas, 6 figuras, 2 tablas
The brine shrimp Artemia (Crustacea) and a diversity of halophilic microorganisms coexist in natural brines, salterns and laboratory cultures; part of such environmental microbial diversity is represented in the gut of Artemia individuals. Bacterial diversity in these environments was assessed by 16S rRNA gene denaturing gradient gel electrophoresis (DGGE) fingerprinting. Eight natural locations in Chile, where A. franciscana or A. persimilis occur, were sampled for analysis of free-living and gutassociated bacteria in water from nature and laboratory cultures. The highest ecological diversity (Shannon’s index, H’) was found in brines, it decreased in the gut of wild and laboratory animals, and in laboratory water. Significant differences in H’ existed between brines and laboratory water, and between brines and gut of wild animals. The greatest similarity of bacterial community composition was between brines and the gut of field animals, suggesting a transient state of the gut microbiota. Sequences retrieved from DGGE patterns (n = 83) exhibited an average of 97.8 % identity with 41 bacterial genera from the phyla Proteobacteria (55.4 % of sequences match), Bacteroidetes (22.9 %), Actinobacteria (16.9 %) and Firmicutes (4.8 %). Environment-exclusive genera distribution was seen in Sphingomonas and Paenibacillus (gut of field animals), Amaricoccus and Ornithinimicrobium (gut of laboratory animals), and Hydrogenophaga (water of laboratory cultures). The reported ecological and physiological capabilities of such bacteria can help to understand Artemia adaptation to natural and laboratory conditions.
Mauricio Quiroz acknowledges project FONDEF D09I1256 (Artemia), National Commission for Scientific and Technological Research (CONICYT), Chile, for support to carry out this work at the Centre for Advanced Studies of Blanes (CEAB), Girona, Spain, which is part of his Master thesis in Natural Resources at Universidad de los Lagos, Osorno. Work in Spain was supported by project DARKNESS (CGL2012-32747) from the Spanish Office of Science (MINECO) to EOC.