Isolation and characterisation of moderately halophilic bacteriumHalomonas ventosae DL7 synthesizing ectoine as compatible solute
ABSTRACT A moderately halophilic Gram-negative bacterium, strain DL7, was isolated from saltern sediment of Dalian, China. Phylogenetic
analysis based on 16S rRNA gene sequences indicated that this isolate belongs to the genusHalomonas. Based on the taxonomic and DNA sequence in addition to high DNA-DNA homologies, we concluded that this strain was similar
with the type strain ofHalomonas ventosae. Ectoine, one of the representative compatible solutes, was mainly detected in the cells as a result of1H- and13C-NMR measurements when grown in the presence of wide concentration ranges of NaCl. The results showed that higher amount
of ectoine was synthesized in a shorter incubation time compared with those of other strains reported earlier.
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ABSTRACT: Salinivibrio costicola subsp. yaniae is a moderately halophilic bacterium which can grow over a wide range of salinity. In response to external osmotic stress (1-3 M NaCl), S. costicola subsp. yaniae can accumulate ectoine, glycine betaine, and glutamate as compatible solutes. We used suicide plasmids pSUP101 to introduce transposon Tn1732 into S. costicola subsp. yaniae via Escherichia coli SM10 mediated by conjugation. One Tn1732-induced mutant, MU1, which was very sensitive to the external salt concentration, was isolated. Mutant MU1 did not grow above 1.5 M NaCl and did not synthesize ectoine, but accumulated Ngamma-acetyldiaminobutyrate, an ectoine precursor, as confirmed by (1)H-NMR analysis. From these data, we concluded that ectoine performs a key role in osmotic adaptation towards high salinity environments in strain S. costicola subsp. yaniae.Bioscience Biotechnology and Biochemistry 09/2008; 72(8):1977-82. · 1.27 Impact Factor