The response of carbohydrate metabolism to the fluctuation of relative humidity (RH) in the desert soil cyanobacterium Phormidium tenue

• Published in: European journal of soil biology Vol. 48; no. 1; pp. 11 - 16
• Main Authors: Chen, Lanzhou, Yang, Yan, Deng, Songqiang, Xu, Yanhong, Wang, Gaohong, Liu, Yongding
• Format: Journal Article
• Language: English
• Published: Paris Elsevier Masson SAS 2012; Elsevier
• Subjects: Agronomy. Soil science and plant productions; arid zones; Biochemistry and biology; Biological and medical sciences; Biological soil crusts; Chemical, physicochemical, biochemical and biological properties; desert soils; Desiccation; DNA; Exoplysaccharides (EPS); Fundamental and applied biological sciences. Psychology; malondialdehyde; Oxidative damage; Phormidium tenue; photosynthesis; Physics, chemistry, biochemistry and biology of agricultural and forest soils; reactive oxygen species; relative humidity; soil crusts; Soil science; sucrose; sucrose-phosphate synthase; Exoplysaccharides (EPS); Oxidative damage; Desiccation; Biological soil crusts; Relative humidity; Oxidative stress; Fluctuations; Metabolism; Soil crusts; Phormidium; Desert soil; Cyanobacteria; Bacteria; Carbohydrate; Soil science
• ISSN: 1164-5563
• DOI: 10.1016/j.ejsobi.2011.10.002

The excreting of exopolysaccharides (EPS) is thought as one of the main protection ways for cyanobacteria in desert algal crusts to survive desiccation. But how cyanobacteria adjust their carbohydrate metabolism to survive this stress is not elucidated. In this study, we treated Phormidium tenue, a cyanobacterium isolated from biological soil crusts with the changes of relative humidity (RH) to simulate different levels of desiccation and investigated its carbohydrate metabolism. It was found that photosynthetic activity ( Fv/Fm) and cellular total carbohydrates production decreased significantly at low RH. But the production of EPS, reducing sugar, sucrose and the activity of sucrose phosphate synthase (SPS) increased significantly at low RH and reached maximum at 75% RH. Low RH could also cause the enhanced production of reactive oxygen species (ROS) generation, malondialdehyde (MDA) production and DNA strand breaks. However, when pretreated with exogenous 100 mg/L EPS, Fv/Fm and carbohydrate production were improved significantly, while ROS generation, MDA production and DNA strand breaks decreased significantly at various levels of RH in P. tenue. These results indicated that P. tenue in arid regions could enhance desiccation tolerance by adjusting the carbohydrate metabolism to eliminate ROS and decrease oxidative damage. ► Desiccation can induce oxidative damage. ► Desiccation can cause carbohydrate metabolism fluctuation. ► P. tenue depend on high relative humidity as water source to keep viability. ► The exogenous EPS could enhance tolerance to oxidative damage.