TEMPERATURE TOLERANCE OF THREE SAND-CONSOLIDATING CYANOBACTERIAL STRAINS

Cyanobacterial crusts occur in semiarid and arid regions throughout the world. They play an important role in maintaining and improving the state of the environment. To speed up their recovery in degraded ecosystems, inoculation of soils with mass – cultured cyanobacterial strains has been recommended in recent years. Temperature is one of the most important environmental factors, which affect mass culture and field inoculation of the sand-consolidating cyanobacterial strains. Studying the temperature tolerance of these cyanobacterial strains is helpful for application of cyanobacterial inoculation techniques, and then reestablishment of cyanobacterial crusts. Three experiments were conducted to measuring temperature tolerance of three cyanobacterial strains: The growth curves of Microcoleus vaginatus, Scytonema javanicum and Phormidium tenue were examined under room temperature; three strains were cultured in open conditions using carrier cluture method under 2, 5, 10, 15, 25 and 35℃ respectively, and their growth and morphological observation were studied; S. javanicum was cultured under 10, 15, 20, 25 and 30℃ respectively and its biomass, phycobiliprotein content, photosynthetic activity, carotenoids content and scytonemin content were investigated. The results were as follow: (1) P. tenue grew faster than M. vaginatus and S. javanicum in the liquid medium; (2) Liquid medium should be preferred for mass culture of these cyanobaterial strains, because growth rate of these strains in liquid medium was faster than in carrier; P. tenue growing in carriers was easily contaminated with some bacteria and these bacteria should be inhibited by antibiotics; (3) Optimal cultivation temperature for S. javanicum was about 25-30℃ for short-term (18d) culture and about 15-20℃ for long-term (30d) culture.