The occurrence of antibiotics in surface waters has been reported worldwide with concentrations ranging from ng L-1 to low µg L-1 levels. During environmental risk assessments, effects of antibiotics on algal species are assessed using standard test protocols (e.g., the OECD 201 guideline), where the cell number endpoint is used as a surrogate for growth. However, the use of photosynthetic rela...

Nitrogen-fixers can contribute significant amounts of nitrogen (N) and impact ecosystem functioning in diverse aquatic and terrestrial ecosystems. What determines N-fixer abundance still remains poorly understood. Here we experimentally investigate major environmental controls on the abundance of N-fixers: nitrogen to phosphorus (N:P) ratio and light. We grew a N-fixer, cyanobacterium Anabaena ...

The toxicity of 7 herbicides to the three cyanobacteria was tested in this work. The results indicated that: (1) There was a highly significant relationship between dried weight or chlorophyll-a and OD680nm for tested cyanobacteria; (2) the toxicity of the tested herbicides with the order from high to low was: photosynthesis-inhibiting > ACCase inhibitor > protox inhibiting herbicides; (3) the ...

The seasonal dynamics of cyanobacterial and diatom assemblages in 11 water bodies along a mesoto hypertrophic gradient were compared. The cyanobacterial and diatom communities are characterised according to representative species of each algal class, selected by data reduction following principal component analyses and discriminant analysis. The cyanobacterial and diatom assemblages of the four...

Phosphorus-starved cells of Anabaena flos-aquae rapidly increase their capacity to reduce acetylene to ethylene when they receive phosphorus. This response may be used as a bioassay for detecting available phosphorus in aquatic ecosystems. The sensitivity of the method compares favorably with conventional methods for measuring dissolved orthophosphate, and has the additional advantage that it m...

Glucose 6-phosphate dehydrogenase (EC 1.1.1.49) has been partially purified from Anacystis nidulans and Anabaena flos-aquae by means of ammonium sulfate fractionation and exclusion gel chromatography and the kinetic properties determined.Glucose 6-phosphate dehydrogenase from these blue-green algae exhibits Michaelis-Menten kinetics at pH 6.7. At this pH, Km values of 0.37 mm for glucose 6-phos...

A wide range of microorganisms was tested to determine their sensitivity to low concentrations of bisulfite-sulfite and nitrite, solubility products of SO2 and NO2, respectively. Photosynthesis by blue-green algae (cyanobacteria) was more strongly inhibited by 0.1 mM bisulfite-sulfite and 1 mM nitrite at pH 6.0 than photosynthesis by eucaryotic algae and respiration of bacteria, fungi, and prot...

Gas vesicles are organelles that provide buoyancy to the aquatic microorganisms that harbor them. The gas vesicle shell consists almost exclusively of the hydrophobic 70-residue gas vesicle protein A, arranged in an ordered array. Solid-state NMR spectra of intact collapsed gas vesicles from the cyanobacterium Anabaena flos-aquae show duplication of certain gas vesicle protein A resonances, ind...

From our experimental evidence that iron lirnitation greatly increases the extracellular concentration of strong copper-complexing agents in cultures of Anabaena flos-aquae and Anabaena cyhdrica, and that the iron-algal exudate complex is much more stable than the copper complex, we conclude that strong copper-complexing agents released by filamentous blue-green algae are siderophores. Further ...