Involvement of the compatible solutes trehalose and sucrose in the response to salt stress of a cyanobacterial Scytonema species isolated from desertsoils

The response to moderate salt stress of a Scytonema species isolated from a soil crust in the arid region of central Australia was studied. An increas e in intracellular trehalose and sucrose concentrations was detected by NMR and HPLC analysis following salt stress, maximal amounts being produced by exposure to 150 mM NaCl after 48 h. When the organism was subsequently ret urned to normal growth conditions, the cellular concentrations of these sol utes decreased. The biosynthesis of trehalose and sucrose was studied and f ound, in both cases, to involve both sugar phosphate synthase and phosphata se enzymes. The combined synthase activities and the individual phosphatase activities in cell extracts were increased by salt stress. Trehalose phosp horylase was the only catabolic enzyme detected for trehalose; neither treh alase nor phosphotrehalase activities could be detected. This is the first report of trehalose phosphorylase activity in cyanobacteria. Both trehalose and sucrose phosphorylase activities increased in salt-stressed cells, whe reas the activity of invertase did not change. (C) 1999 Elsevier Science B. V. All rights reserved.