干旱区生态环境知识资源中心

The phosphomonoesterase activity of a microbial community dominated by Chroococcidiopsis in a rock sample from the Antarctic dry desert was compared with that of a non-axenic culture of the cyanobacterium isolated from the same rock in order to establish whether the organism differed in its properties when immobilized in the rock. The pH optimum (9.5) was the same, but the response to temperature and light both differed. In the case of temperature, the optimum was much higher in culture. Light flux at the low value of 8 mu mol photon m(-2) s(-1) was slightly inhibitory for a crushed rock sample, but enhanced activity of the cultured material. Although materials both showed a typical (apparent) Michaelis-Menten relationship, the values for K-m and V-max differed. It is suggested that study of natural immobilized systems is important for the development of procedures to use immobilized phototrophs for practical purposes.