Cultures Of Cyanobacteria Research Articles

Comparative Composition of the Sheath of the Cyanobacterium Gloeothece ATCC 27152 Cultured with and without Combined Nitrogen

SUMMARY: The extracellular sheath was isolated from cultures of a unicellular diazotrophic cyanobacterium, Gloeothece ATCC 27152. Chemical analysis of lyophilized cell-free preparations indicated that the sheath was composed of an acidic heteropolysaccharide containing the neutral sugars rhamnose, 2-O-methylxylose, xylose, mannose, galactose and glucose, and the uronic acids mannuronic, glucuronic and galacturonic acid. Protein, pyruvic acid and O-acetyl and sulphate groups were also detected. Quantitative differences in the carbohydrate and protein content of the sheath were observed between material collected from cultures grown with and without a source of combined nitrogen. The extent to which the external layers bound cadmium ions was affected by these differences.

Control of pH and inorganic carbon in batch cultures of cyanobacteria

Synechococcus leopoliensis was grown in batch cultures gassed with air or CO2 in air to test for effects of gassing on pH drift and growth. A method is described whereby pH and inorganic carbon are held constant during rapid growth.

Control of matric water potential (ψm) in immobilised cultures of cyanobacteria

Three simple methods are described that permit cells of cyanobacteria, immobilised on filter supports, to be subjected to matric water stress that leads to a downshift in nitrogenase activity. In Nostoc commune, a desiccation-tolerant form, nitrogenase activity is more sensitive to water stress than the intracellular ATP pool. When it is dried rapidly to −99.5 MPa, nitrogenase activity ceases within 30 min while the ATP pool is maintained at 16.07 pmol ATP · μg protein−1. During short-term incubation, decreasing ψm from −0.10 to −23.1 MPa may result in an increased rate of CO2 uptake.

Control of matric water potential (ψm) in immobilised cultures of cyanobacteria

Control of matric water potential (ψm) in immobilised cultures of cyanobacteria

Two approaches to obtaining low, extracellular deoxyribonuclease activity in cultures of heterocyst-forming cyanobacteria

Six out of 158 axenic strains of heterocyst-forming cyanobacteria consistently failed to produce circles of clearing in agar medium containing DNA-methyl green. When tested with [3H]DNA and coliphage λDNA, supernatant fluids from cultures of two of these strains [University of Texas Culture Collection (UTEX) strain 2014 and 19-6C-C] showed no detectable deoxyribonuclease activity, and such fluids from another two of the six, and four others, showed low but detectable deoxyribonuclease activity. Covalently closed circular (plasmid) DNA was not detectably degraded by supernatant fluids from UTEX 2014 and 19-6C-C and from four of the other strains. When λ DNA was incubated with whole cells of certain strains, a sereis of fragments of discrete size was produced, perhaps by cell-bound, periplasmic, restriction endonucleases. Inclusion of one-tenth strength saline sodium citrate (SSC) in an eight-fold dilution of the medium of Allen and Arnon had little effect on growth of Anabaena variabilis American Type Culture Collection (ATCC) strain 29413 yet prevented all but slight degradation of plasmid pBR322 or of λ DNA.

Hydrogen Evolution Catalyzed by Hydrogenase in Cultures of Cyanobacteria

Abstract Cultures of Anabaena cylindrica, grown on media containing 5 mᴍ NH4Cl (which represses heterocyst formation), evolved hydrogen after a period of dark incubation under an argon atmosphere. This hydrogen production was not due to nitrogenase activity, which was nearly undetectable, but was due to a hydrogenase. Cultures grown on media with tungsten substituted for molybdenum had a high frequency of heterocysts (15%) and inactive nitrogenase after nitrogen starvation. The hydrogenase activity of these cultures was three-fold greater than the activity of non-heterocystous cultures. The effects of oxygen inhibition on hydrogen evolution by hetero-cystous cultures suggest that two pools of hydrogenase activity exist - an oxygen sensitive hydrogen evolution in vegetative cells and a relatively oxygen-resistent hydrogen evolution in heterocysts. In either case, inhibition by oxygen was reversible. Light had an inhibitory effect on net hydrogen evolution. Hydrogen production in vitro was much higher than in vivo, indicating that in vivo hydrogenase activity is limited by endogenous reductant supply.