ABSTRACT. Twenty-one Rhizobium and Bradyrhizobium strains were tested in vitro against the mycelial growth of three
pathogenic fungi on solid and liquid media. All tested rhizobia and bradyrhizobia significantly suppressed the growth of the
three soil-borne root-infecting fungi (Fusarium solani, Macrophominia phasolina and Rhizoctonia solani) either in the absence
or presence of iron. This indicates that the siderophore played a minor role in the biocontrol potential of Rhizobium and
Bradyrhizobiura against pathogenic fungi. Pot experiments revealed that the numbers of propagules causing disease after
4 weeks of planting varied with species and host plant. The three most active Rhizobium and Bradyrhizobium strains (/L leguminosarum
bv.phaseoli TAL 182, B. japonicum TAL 377 and Bradyrhizobium sp. (lupin) WPBS 3211 D) tested under greenhouse
conditions for their ability to protect one leguminous (soybean) and two non-leguminous (sunflower and okra) seedlings from
root rot caused by Fusarium solani, Macrophominia phaseolina and Rlu'zoctonia solani provided significant suppression of
disease severity compared vath nonbacterized control in both leguminous and non-leguminous seedlings. Bradyrhizobium sp.
(iupin) WPBS 3211 D provided the lowest degree of resistance against all the tested pathogens with all host plants.

Pesticides (Brominal, Cuprosan and Fenvalerate) at 10 and 50 ppm suppressed growth, respiration and nitrogenase
activity of Azotobacter chroococcum, AzospiriIIum brasilense and Azospirillum ]ipos The inhibitory effect
on respiration of Asm. Iipoferum was most pronounced after 3 and 4 days.

ABSTRACr. In soil salinized with different concentrations of sodium chloride, the total counts of soil fungi were significantly
decreased during 11 weeks of incubation. Similarly, the total count of bacteria and actinomycetes were severely depressed by
increasing salinity level above 5 %. Invertase and urease activities were severely decreased as NaCi concentration increase
during the incubation. Also, the effect on nitrate reductase was inhibitory with most treatments.

ABSTRACT. The ability of Rhizobium and Bradyrhizobium strains to solubilize phosphate from hydroxyapatite was determined
in a medium containing NH4CI or KNO3. The presence of NH4 + in the medium resulted in higher solubilization of phosphate
as compared to the presence of KNO3, with the exception of R. leguminosarium by. viceae strain TAL 1236 and 1402 which
soluhilized comparable amounts of phosphate in a medium containing either KNO3 or NH4Ci. These results suggest that the
strains employ two different mechanisms for phosphate solubilization, one depending on the presence of NH4 +, the other not
requiring its presence. Temperature and aeration (02 demand) optima were 30 *C and 4.2 Hz (shaking frequency), respectively.
In nonsterile soil the tested strain (R. meliloti TAL 1236) was very effective in solubilizing rock phosphate.

Potential nitrogen-fixing freshwater photosynthetic bacteria of 32 isolates from the Aswan High Dam Lake were
investigated using the acetylene reduction technique to ascertain the magnitude of their contribution of fixed
nitrogen to the ecosystem. The superior nitrogen-fixing Rhodospirillaceae were Rhodocyclus gelatinosus and
Rhodomicrobium vannielii followed by Rhodobacter capsulatus, Rhodopseudomonas viridis and Rhodopseudomonas
palustris. High and moderate nitrogenase activities (534 to 1528 nmol ethylene produced/4 ml/h) were
found in 56% of the isolates, while the remainder showed low activities (76 to 477 nmol ethylene produced/4 ml/h).

Six strains and a commercial inoculant of Bradyrhizobium japonicum were evaluated in association with Glycine
max (L.) cultivar Clark. Inoculated and uninoculated plants were grown in pot and field experiments. Nodules were
counted and weighed and roots and shoots were separated and analysed for total nitrogen. In pot experiments,
two of six bacterial strains were superior to the other four, and to the commercial inoculant (Nitragin) in promoting
greater root and top growth and plant nitrogen accumulation. In the field experiment, there were indications that
environmental conditions may have affected nodulation by the bacteria. The strains could be divided into three
groups according to nodule efficiencies, accumulation of plant dry matter, and total nitrogen content. The greater
variations in nodule efficiencies of the tested strains could be attributed to the quantities of bacteroid, cytosol
protein and leghaemoglobin in the nodules.

ABSTRACT. Azotobacter chroococcum was isolated from straw-amended soil and found to utilize 4-hydroxybenzoic acid, resorcinol,
pyrocatechol and vanillic acid as sole carbon source. Growth and nitrogenase activity ofA. chroococcum were supported
by 8, 6 and 4 mmol/L of 4-hydroxybeazoie acid, rcsorcinoi and pyrocatechol, respectively, The generation time of 1.71 h in
4-hydroxybenzoie acid did not significantly differ from the generation time of 1.64 h, observed when grown in mannitol.
4-Hydroxybenzoic acid was utilized rapidly. However, the decomposition of other tested phenolic compounds set in only slowly.
It was concluded that this isolate has good potential to utilize some phenolic compounds released during biodegradation of
plant wastes

ABSTRACT. Seeds of three species of lupine (Lupinus tennis, L. triticale and L. albus) were tested to determine if the seed
contains diffusable substances toxic to bradyrhizobia. L. albus seeds were less toxic to bradyrhizobia, followed by L. triticale.
Six strains of Bradyrhizobium were evaluated for their resistance to the toxic substances in lupine seeds. Zones of growth inhibition
were determined on yeast-mannitol-agar medium surrounding surface-sterilized seed. The effect of surface sterilization
of seeds by different chemical treatments on seed toxicity was assessed. Seeds soaked in water for 1 h before placing on agar
surface significantly decreased the inhibition zone. Also, the effect of soaking seeds in water for 4 h before planting and inoculation
on nodulation, nitrogen fixation and plant growth were investigated. Addition of seed diffusate to soaked seeds significantly
decreased nodulation and plant growth. Autoclaving the seed diffusate had no effect on the toxicity of the seed diffusate.
Addition of the absorbent polyvinylpolypyrrolidone (PVPP) to seed diffusates significantly decreased the inhibitory effect of
seed diffusate on nodulation and plant growth. Seed diffusate substances were water-soluble, heat-stable and partially bound to
PVPP.

The effect of four bacterial and six fungal species on nodulation and growth of Vicia
faba cv. Giza 3 inoculated with Rhizobium leguminosarum biovar viceae strain RCR
1001 were assessed in a pot experiment. Bacillus cereus, Pseudomonasfluorescens,
Aspergillus niger and ,4. quadriliniatus either alive cells or sterile filtrate
significantly promoted nodulation, growth and nitrogen accumulation. Heat-killed
cells had no effect.

Pyrano[2,3-d]thiazoline-7-spiro-3
-(1
-substitutedindoline-2
-ones) 5a,b has been
synthesized and reacted with some nucleophile reagents to afford new
spirothiazolino[4,5:2
,3
]pyrano[6
,5
-d]pyrimidine derivatives 6a,b–13a,b, which
are analogues of some reported biologically active spiroheterocyclic compounds