Effects of drought and salt stresses on man-made cyanobacterial crusts

As a primary successional stage of biological soil crusts (BSCs) cyanobacterial crusts form firstly in the arid and semiarid areas At the same time they suffer many stress conditions such as drought salt etc In this study we constructed man-made cyanobacterial crusts with Microcoleus vaginatus Gom and comparatively studied the effects of drought and salt stresses on the crusts The results showed that crust growth and photosynthetic activity was significantly inhibited by the stress conditions (P < 0 05) and inhibitory effect Increased with the increasing stress intensity and treated time Compared with salt stress drought completely stopped crust metabolic activity so the crust biomass was conserved at a higher level which meant that drought itself might provide the crusts some protection especially when the crusts simultaneously suffered drought and salt stresses That is very important for the survival of crusts in the high-salt areas In addition to some extent the crusts could adapt to the stress conditions through metabolic adjustment In our experiment we found the accumulation of exopolysaccharides (EPS) increased under stress conditions within a certain threshold (C) 2010 Elsevier Masson SAS All rights reserved