Anabaena variabilis ATCC 29413 is a heterotrophic, nitrogen-fixing cyanobacterium containing both a Mo-dependent nitrogenase encoded by the nif genes and V-dependent nitrogenase encoded by the vnf genes. The nifB, nifS, and nifU genes of A. variabilis were cloned, mapped, and partially sequenced. The fdxN gene was between nifB and nifS. Growth and acetylene reduction assays using wild-type and ...

AIMS The objective of this study is to develop kinetic models based on batch experiments describing the growth, CO(2) consumption, and H(2) production of Anabaena variabilis ATCC 29413-U(TM) as functions of irradiance and CO(2) concentration. METHODS AND RESULTS A parametric experimental study is performed for irradiances from 1120 to 16100 lux and for initial CO(2) mole fractions from 0.03 t...

Physiological experiments indicate that Anabaena variabilis can express either a Vor a Fe-nitrogenase in addition to the conventional, Mo-containing enzyme complex. The occur­ rence o f the Fe-nitrogenase in A. variabilis can also be concluded from D N A -D N A hybridiza­ tion experiments using cloned anfW or nifW probes coding for the smaller subunit (= nitroge­ nase reductase) o f the Fe-nitr...

Light-induced proton efflux of Anabaena variabilis was found to be biphasic, the second phase being inhibited by the ATPase inhibitor nitrofen (2,4-dichloro-1-[4-nitrophenoxy]benzene). The first, fast phase was triggered by monochromatic light of 707 nanometers, whereas the second, slower phase was not. With 707 nanometers, light, respiratory O(2) uptake was inhibited. Using light composed of t...

Cyanobacteria are fascinating and versatile group of bacteria which are of immense biological importance. They are unique photosynthetic prokaryotes with an oxygenic photosynthesis process. They possess an array of protective mechanism comprising of antioxidants to eliminate the damages caused by the reactive oxygen species. Blooms caused by cyanobacteria are ubiquitous in temple ponds, lakes a...

Nitrogen-fixing cyanobacteria such as Anabaena variabilis ATCC 29413 use an uptake hydrogenase, encoded by hupSL, to recycle hydrogen gas that is produced as an obligate by-product of nitrogen fixation. The regulation of hupSL in A. variabilis is likely to differ from that of the closely related Anabaena sp. strain PCC 7120 because A. variabilis lacks the excision element-mediated regulation th...

High-affinity vanadate transport systems have not heretofore been identified in any organism. Anabaena variabilis, which can fix nitrogen by using an alternative V-dependent nitrogenase, transported vanadate well. The concentration of vanadate giving half-maximum V-nitrogenase activity when added to V-starved cells was about 3 x 10(-9) M. The genes for an ABC-type vanadate transport system, vup...

Filaments of the blue-green alga Anabaena variabilis permeabilized by dimethylsulfoxide (DMSO) produce increased amounts of 5-aminolevulinate in the presence of levulinic acid. The metabolic activity of the filaments remains unperturbed in the presence of up to 7.5% (v/v) DMSO. Studies utilizing DMSO-permeabilized filaments confirm that 5-aminolevulinate is synthesized preferably from glutamate...