Melanin production by Rhizobium meliloti GR4 is linked to nonsymbiotic plasmid pRmeGR4b (140 MDa). Transfer of this plasmid to GR4-cured derivatives or to Agrobacterium tumefaciens enables these bacteria to produce melanin. Sequence analysis of a 3.5-kb PstI fragment of plasmid pRmeGR4b has revealed the presence of a open reading frame 1,481-bp that codes for a protein whose sequence shows stro...

A study was conducted to determine the significance of starvation resistance to the ability of a species to survive in sewage and lake water. Tests were conducted for periods of up to 14 days. Rhizobium meliloti and one fluorescent and one nonfluorescent strain of Pseudomonas were resistant to starvation because their population sizes did not fall appreciably in buffer and sterile lake water, a...

We developed a rapid, inexpensive method for isolating and identifying Rhizobium leguminosarum by. phaseoli strains from bean root nodules. The method can be used for other small or medium-sized nodules such as those of clover, alfalfa and peas. With this method, one person can process 115 nodules/h. Using a simple apparatus made of plexiglass and machine bolts, we simultaneously crushed 24 sur...

The effect of host plant cultivar on H(2) evolution by root nodules was examined in symbioses between Pisum sativum L. and selected strains of Rhizobium leguminosarum. Hydrogen evolution from root nodules containing Rhizobium represents the sum of H(2) produced by the nitrogenase enzyme complex and H(2) oxidized by any uptake hydrogenase present in those bacterial cells. Relative efficiency (RE...

Rhizobium leguminosarum bv trifolii is the effective nitrogen fixing microsymbiont of a diverse range of annual and perennial Trifolium (clover) species. Strain WSM2304 is an aerobic, motile, non-spore forming, Gram-negative rod, isolated from Trifolium polymorphum in Uruguay in 1998. This microsymbiont predominated in the perennial grasslands of Glencoe Research Station, in Uruguay, to competi...

The symbiotic characteristics of Rhizobium trifolii strains 1-01 and 2-01 were evaluated both individually and in various combinations on two cultivars (Mt. Barker and Woogenellup) of subterranean clover (Trifolium subterraneum L.). Nodules were observed on day 8 independent of cultivar or strain. Cultivar differences were measured in nodulating efficiency by 1-01 since 54% of the primary nodul...

A rearrangement between the symbiotic plasmid (pRleVF39d) and a nonsymbiotic plasmid (pRleVF39b) in Rhizobium leguminosarum bv. viciae VF39 was observed. The rearranged derivative showed the same plasmid profile as its parent strain, but hybridization to nod, fix, and nif genes indicated that most of the symbiotic genes were now present on a plasmid corresponding in size to pRleVF39b instead of...

Pyruvic acid and O-acetyl groups are the major noncarbohydrate substituents in exopolysaccharides (EPS) produced by fast-growing species of Rhizobium. EPS substituent variations were observed among strains of the same species. The amounts of these substituents also varied with culture age; pyruvic acid increased in the EPS of all four species, whereas O-acetyl increased in Rhizobium trifolii an...

Nitrogenase (EC 1.7.99.2) activity in pea (Pisum savitum) nodules formed after infection with Rhizobium leguminosarum (lacking uptake hydrogenase) was measured as acetylene reduction, H(2) evolution in air and H(2) evolution in Ar:O(2). With detached roots the relative efficiency, calculated from acetylene reduction, showed a decrease (from 55 to below 0%) with increasing temperature. With exci...

abstract arsenic (as) contamination of soils is a global problem. legumes are often used in remediation of contaminated sites because of their capacity to fix nitrogen. in the present study, the effects of inoculation of bean (by rhizobium leguminosarum bv. phaseoli) on plant uptake and tolerance to arsenic were investigated. an experiment with a factorial arrangement, two levels of inoculation...