Osmotic adaptation of moderately halophilic methanogenic Archaeobacteria, and detection of cytosolic N,N-dimethylglycine

摘要: Methanohalophilus mahii SLP andMethanohalophilus halophilus Z-7982, two closely-related, moderately halophilic, methylotrophic methanogens, were tested for their adaptation to saline conditions. They grew in a wider range of salinities than previously reported, defined medium with as little 0.1 M NaCl, and high 4.0 NaCl forM. 4.5 mahii. Fastest growth occurred 1.5 1.0 halophilus. M. also media which was replaced by sucrose or KCl osmolytes up the osmolal equivalent 2 2.5 (these contained other sodium salts totaling about Na+). In either replacing NaCl,M. fastest at osmolalities approximately equiosmolal 1 NaCl.M. not only well wide osmosities, it tolerated rapid shifts osmolality. Cells subjected 10-fold hypertonic shift resumed without prolonged lag. When cells hypotonic shift, 90% lysed, but remaineder continued swell further lysis during next 45 min. Surviving growth.Methanohalophilus strains grown had low cytosolic Na+ concentrations; K+ concentrations 0.35 Organic osmotica cytosol include glycine betaine larger amounts N,N-dimethylglycine.