[Hydroxyectoine synthesis and release under osmotic shock in Cobetia marina CICC10367]

To obtain hydroxyectoine-producing strain with tolerance to osmotic shock and improve hydroxyectoine productivity by adopting "bacteria milking" process.

We isolated a strain from salt lake, and then carried out the identifications of morphology, physiological and biochemical characteristics of the strain. We also investigated the effects of the medium and its NaCl concentration on the hydroxyectoine synthesis of this strain. Under optimal condition, hydroxyectoine was produced by adopting "bacteria milking" process.

A hydroxyectoine-producing strain was obtained and identified as Cobetia marina CICC10367 (C. marina CICC10367). It could enhance hydroxyeceoine synthesis when the medium adopting monosodium glutamate as the sole source of carbon and nitrogen at 90 g/L NaCl. The highest synthesized hydroxyectoine concentration was 694.5 mg/L in the above described medium. After the "bacteria milking" process of six osmotic shock, the total concentration of hydroxyectoine was 4179.0 mg/L, the productivity was 597.0 mg/L/d, and the conversion rate of hydroxyectoine on substrate was 80.2 mg/g.

C. marina CICC10367 was able to synthesize hydroxyectoine under NaCl induction and tolerant to osmotic stress. The hydroxyectoine productivity and conversion rate of hydroxyectoine on substrate were both significantly improved by adopting "bacteria milking" process.