Bacterial populations display high heterogeneity in viability and physiological activity at the single-cell level, especially under stressful conditions. We demonstrate a novel staining protocol for multiparameter assessment of individual cells in physiologically heterogeneous populations of cyanobacteria. The protocol employs fluorescent probes, i.e., redox dye 5-cyano-2,3-ditolyl tetrazolium chloride, 'dead cell' nucleic acid stain SYTOX Green, and DNA-specific fluorochrome 4',6-diamidino-2-phenylindole, combined with microscopy image analysis. Our method allows simultaneous estimates of cellular respiration activity, membrane and nucleoid integrity, and allows the detection of photosynthetic pigments fluorescence along with morphological observations. The staining protocol has been adjusted for, both, laboratory and natural populations of the genus Phormidium (Oscillatoriales), and tested on 4 field-collected samples and 12 laboratory strains of cyanobacteria. Based on the mentioned cellular functions we suggest classification of cells in cyanobacterial populations into four categories: (i) active and intact; (ii) injured but active; (iii) metabolically inactive but intact; (iv) inactive and injured, or dead.

• MeSH
• barvení a značení metody   MeSH
• časové faktory MeSH
• fluorescenční barviva metabolismus   MeSH
• fluorescenční spektrometrie MeSH
• indoly metabolismus   MeSH
• organické látky metabolismus   MeSH
• sinice cytologie   metabolismus   MeSH
• tetrazoliové soli metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• 5-cyano-2,3-ditolyltetrazolium MeSH Prohlížeč
• DAPI MeSH Prohlížeč
• fluorescenční barviva MeSH
• indoly MeSH
• organické látky MeSH
• SYTOX Green MeSH Prohlížeč
• tetrazoliové soli MeSH

Although desiccation tolerance of Microcoleus species is a well-known phenomenon, there is very little information about their limits of desiccation tolerance in terms of cellular water content, the survival rate of their cells, and the environmental factors inducing their resistance to drying. We have discovered that three Microcoleus strains, isolated from terrestrial habitats of the High Arctic, survived extensive dehydration (to 0.23 g water g(-1) dry mass), but did not tolerate complete desiccation (to 0.03 g water g(-1) dry mass) regardless of pre-desiccation treatments. However, these treatments were critical for the survival of incomplete desiccation: cultures grown under optimal conditions failed to survive even incomplete desiccation; a low temperature enabled only 0-15% of cells to survive, while 39.8-65.9% of cells remained alive and intact after nitrogen starvation. Unlike Nostoc, which co-exists with Microcoleus in Arctic terrestrial habitats, Microcoleus strains are not truly anhydrobiotic and do not possess constitutive desiccation tolerance. Instead, it seems that the survival strategy of Microcoleus in periodically dry habitats involves avoidance of complete desiccation, but tolerance to milder desiccation stress, which is induced by suboptimal conditions (e.g., nitrogen starvation).

• Klíčová slova
• CTC dye, SYTOX Green, cyanobacteria, desiccation tolerance, fluorescence staining, nitrogen starvation, viability,
• Publikační typ
• časopisecké články MeSH