abstract osmoreguolation is a physiological processes that plant cell uses to maintain water balance and it is generally caused by metabolite accumulation inside the cell. inoculated legumes by some drought tolerant sinorhizobium isolates helps osmoreguolation by increasing biological nitrogen fixation. in order to find some drought tolerant sinorhizobium isolates, 80 isolates were isolated and...

Nitrogen-starved Plectonema boryanum 594 cultures flushed with N(2)/CO(2) or A/CO(2) (99.7%/0.3%, vol/vol) exhibited nitrogenase activity when assayed either by acetylene reduction or hydrogen evolution. Oxygen evolution activities and phycocyanin pigments decreased sharply before and during the development of nitrogenase activity, but recovered in the N(2)/CO(2) cultures after a period of acti...

A second nitrogenase activity has been demonstrated in Rhodospirillum rubrum. This nitrogenase is expressed whenever a strain lacks an active Mo nitrogenase because of physiological or genetic inactivation. The alternative nitrogenase is able to support growth on N2 in the absence of fixed N. V does not stimulate, nor does Mo or W inhibit, growth or activity under the conditions tested. The pro...

In Azotobacter vinelandii cells, the short-term inhibition of nitrogenase activity by NH4Cl was found to depend on several factors. The first factor is the dissolved oxygen concentration during the assay of nitrogenase. When cells are incubated with low concentrations of oxygen, nitrogenase activity is low and ammonia inhibits strongly. With more oxygen, nitrogenase activity increases. Cells in...

azotobacter vinelandii, a gamma-proteobacterium, is an obligate aerobic free-living gram-negative soil bacterium capable of fixing nitrogen. oxygen transfer rate into the cell is reduced by the increase of alginate concentrations during the course of a. vinelandii cultivation. this phenomenon provides a low intracellular oxygen concentration needed for nitrogenase activity. the aim of this stud...

Effects of prolonged darkness on nitrogenase activity in vivo, nitrogenase activity in vitro, and the amounts of nitrogenase proteins were studied in symbiotic Frankia. Plants of Alnus incana (L.) Moench in symbiosis with a local source of Frankia were grown for 9 to 10 weeks in an 18/6 hour light/darkness cycle. After 12 hours of a light period, the plants were exposed to darkness for up to 40...

BACKGROUND AND AIMS Tuberculate ectomycorrhizae are a unique form of ectomycorrhiza where densely packed clusters of mycorrhizal root tips are enveloped by a thick hyphal sheath to form a tubercle. The functional significance of such a unique structure has not previously been established. The purpose of the present study was to investigate and measure the potential nitrogenase activity associat...

Nitrogenase activity estimated in the rhizospheres of rice, maize and different tropical grasses grown under controlled laboratory conditions was shown to depend upon plant species. High nitrogenase activity (2000-6000 nmoles CzH4 h-' g-' dry root) occurred in rice rhizosphere, this activity being only 10 times lower than that of symbi0ticsystems;inthe rhizosphere of many other grasses grown in...

The production of nitrogenase enzyme and auxins by free living diazotrophs has the potential to influence the growth of host plants. In this study, diazotrophs were grown in the presence of various concentrations of nitogen (N) to determine the optimal concentration of N for microbial growth stimulation, promotion of gaseous N (N2) fixation, and phytohormone production. Therefore, we investigat...

The objectives of this study were to determine whether attached nodules of soybean (Glycine max L. Merr.) could adjust to gradual increases in rhizosphere pO(2) without nitrogenase inhibition and to determine whether the nitrogenase activity of the nodules is limited by pO(2) under ambient conditions. A computer-controlled gas blending apparatus was used to produce linear increases (ramps) in p...