AUTHOR=Song Wenjuan , Zhao Chenxi , Zhang Daoyong , Mu Shuyong , Pan Xiangliang 

TITLE=Different Resistance to UV-B Radiation of Extracellular Polymeric Substances of Two Cyanobacteria from Contrasting Habitats

JOURNAL=Frontiers in Microbiology

VOLUME=7

YEAR=2016

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2016.01208

DOI=10.3389/fmicb.2016.01208

ISSN=1664-302X

ABSTRACT=<p>The effects of UV-B radiation (UVBR) on photosynthetic activity (Fv/Fm) of aquatic <italic>Synechocystis</italic> sp. and desert <italic>Chroococcus minutus</italic> and effects on composition and fluorescence property of extracellular polymeric substances (EPSs) from <italic>Synechocystis</italic> sp. and <italic>C. minutus</italic> were comparatively investigated. The desert cyanobacterium species <italic>C. minutus</italic> showed higher tolerance of PSII activity (Fv/Fm) to UVBR than the aquatic <italic>Synechocystis</italic> sp., and the inhibited PSII activity of <italic>C. minutus</italic> could be fully recovered while that of <italic>Synechocystis</italic> sp. could be partly recovered. UVBR had significant effect on the yield and biochemical composition of EPS of both species. Protein-like and humic acid-like substances were detected in EPS from <italic>Synechocystis</italic> sp., and protein-like and phenol-like fluorescent compounds were detected in EPS from <italic>C. minutus.</italic> Proteins in EPS of desert and aquatic species were significantly decomposed under UVBR, and the latter was more easily decomposed. The polysaccharides were much more resistant to UVBR than the proteins for both species. Polysaccharides of <italic>Synechocystis</italic> sp. was degraded slightly but those of <italic>C. minutus</italic> was little decomposed. The higher tolerance to UVBR of the desert cyanobacterium can be attributed to the higher resistance of its EPS to photodegradation induced by UVBR in comparison with the aquatic species.</p>