Rhizobium Lupini Research Articles

THE EFFECT OF WATER-SOLUBLE POLYMERS ON THE SURVIVAL OF NODULE LUPINE BACTERIA (RHIZOBIUM LUPINI)

The work is devoted to the assessment of survival of nodule lupine bacteria ( Rhizobium lupini ) on seeds and to the study of the opportunities to increase the terms between seed inoculation and their sowing. It has been evaluated the effect of such water-soluble polymers as sodium alginate, carboxymethyl cellulose, polyvinyl alcohol (4-88, 4-98) and polyvinylpyrrolidone on survival of nodule lupine bacteria. The number of surviving nodule bacteria of lupine R. lupini (str. 363a and 367a) was determined on inoculated lupine seeds of the variety ‘Oligarkh’ after 24 hours after inoculation with a control working solution (20% bacterial suspension in water), as well as with the solutions modified with five percent of such water-soluble polymers as sodium alginate, carboxymethylcellulose (CMC), polyvinyl alcohol of 2 grades (PVA 4-88 and PVA 4-98) and polyvinylpyrrolidone (PVP). The experiment has identified PVP as the most effective polymeric rhizobium protector among all above-mentioned ones because the number of surviving bacteria in the PVP variant was significantly larger than the control variant and in 2–3 times larger than in the variants with other polymers. There has been studied dynamics of bacteria death from the moment of inoculation and after 2, 4, 8, 24, 48 and 168 hours in various variants of the experiment. The effectiveness of PVP as a rhizobium protector on inoculated seeds was determined, its optimum concentration was identified.

ИЗУЧЕНИЕ ВЛИЯНИЯ БИОПРЕПАРАТА НА ОСНОВЕ КЛУБЕНЬКОВЫХ БАКТЕРИЙ RHIZOBIUM LUPINI НА БОБОВЫЕ И ЗЛАКОВЫЕ КУЛЬТУРЫ

More and more scientific research has been aimed at studying the fixation of “biological nitrogen”, namely microorganisms-symbionts and biological preparations based on them recently. Many years of experiments and production practice clearly show that the microorganisms that fix nitrogen are of greater importance to enrich the soil with nitrogen and increase yields. Rhizobium nodule bacteria, being in symbiosis with bean plants, are absorbed from the atmosphere and supply the plant with the necessary amount of biologically bound nitrogen. Based on these data, the aim of our study is to study the effect of the biological product on the germination, growth and weight of the vegetative mass of legumes and cereals. A comparative analysis of the biological product based on Rhizobium lupini bacteria RL-1 strain with commercial preparations has been carried out. In the experiment the following agricultural crops have been used: peas, wheat, rapeseed, beans. As a result it has been found that RL-1 has a positive effect on the germination, length and mass of vegetative mass of plants. Thus, the length of pea’s offshoots is more by 73 %, rapeseed – by 44 %, wheat –by 60 %, beans – by 12 %. The preparation has also shown a positive effect to the weight of green mass, for example, the weight of peas plants is 50% higher than the controlled ones, rapeseed – by 12 %, wheat-by 90 %, beans – by 14 %. The study relates to the development of microbiological fertilizer plants. As a result of the analysis it was found that the investigated biopreparation based on nodule bacteria R. lupini promotes growth, better germination, increase the green mass of crops.

The morphogenesis of lupine root nodules during infection by Rhizobium lupini

The development of root nodules in <em>Lupinus luteus</em> infected by <em>Rhizobium lupini</em> was studied using cytological methods. The results obtained from examination of material sampled 6, 9, 13, 15, 20, 29 and 60 days after infection are given. The successive stages of development are described and the cytological characteristics of the tissue are presented. The mitotic divisions of the root cortex parenchyma cells, which initiated the formation of the nodule primordium, were accompanied by structural changes in the root hairs and divisions in the root pericycle. The development of the nodule was associated with the activity of the lateral meristems, which encompass both the infected cells and cells not containing bacteroids Characteristics of bacteria found in the symplast and apoplast of the bacteroid tissue are given.

Yeşil gübrelemede kullanılan bakla (Vicia faba L.) bitkisinin brokoli verimi üzerine etkilerinin belirlenmesi

The aim of this study was to determine the effects of using faba bean plant as green manure upon the subsequently grown plant. First in the experimentation, Rhizobium lupini bacterium was inoculated to faba bean plant in order to see the effect of inoculation. In the second stage of the experiment, bean plant was buried in the soil as green manure after its development and planting of Marathon F1 hybrid broccoli cultivar was performed after incubation. The experiment was planned with four replications according to the randomized block experimental design. Optimal fertilizers were administered with fertigation technique considering the soil characteristics. A statistical increase at 1% significant level was obtained at plant weight, plant length and number of nodules which were the analyzed characteristics of faba bean plant with bacterium inoculation. In the study, green manure application caused significant increases at curd weight, total yield, curd diameter, plant length and number of main leaves of the broccoli plant according to the green manure administration control conditions. Moreover, whereas the nitrogen and organic matter content levels of the soils taken after green manure administration increased, a decrease at pH levels of the soils was experienced. The research results showed that applications bacterium into the faba bean caused a positive effect upon the general characteristics of the faba bean and it also increased yield and other characteristics of the subsequent plant when it was used as green manure.

Aldonic Acids: A Novel Family of nod Gene Inducers of Mesorhizobium loti, Rhizobium lupini, and Sinorhizobium meliloti

Molecular signals, such as flavonoids (or nonflavonoid type), nod gene-inducers, and bacterial lipochitin oligosac-charides (LCOs) act as modulators of species specificity during early stages of infection in Rhizobium spp.-legume interactions. The fact that signaling in Lupinus albus remains to be determined prompted us to investigate the flavonoid signal responsible for nod gene induction in Rhizobium lupini. A screening method was used based on the measurement of β-galactosidase activity of R. lupini strains harboring nodC::lacZ fusions in the presence of (i) authentic lupin isoflavones, (ii) carbohydrate-like inducers, and (iii) high-pressure liquid chromatography (HPLC)-fractionated lupin seed effusates and root exudates, as putative nod gene inducers. The results indicate that both erythronic and tetronic acids (4-C sugar acids) led to low but significant increases in β-galactosidase activities, compared with the controls. In addition, lupi-wighteone, a monoprenylated isoflavone, exerts a synergistic effect with the carbohydrate-like inducers, compared with other isoflavone treatments. The natural occurrence of aldonic acids in L. albus root exudates and seed effusates has been demonstrated by HPLC analysis. When tested with nodC::lacZ fusions, tetronic acid resulted in nod gene induction in Sinorhizobium meliloti. In addition, a combination of luteolin and tetronic acid promotes further increases in S. meliloti nod gene expression, as shown by β-galactosidase assays. Incorporation studies with [14C]LCO precursors confirmed the inductive role of both erythronic and tetronic acids in promoting LCO biosynthesis in R. lupini cultures, and of tetronic acid in Mesorhizobium loti and S. meliloti. Hydrolysis of the LCOs with various enzymes substantiated their putative identities. These results are discussed in relation to the impact of these unusual signal molecules on our knowledge of flavonoid signaling in Rhizobium-legume symbiosis.

Identification and nucleotide sequence of Rhizobium meliloti insertion sequence IS Rm6, a small transposable element that belongs to the IS3 family

The insertion sequence IS Rm6 is a small transposable element identified in Rhizobium meliloti strain GR4 by sequence analysis. Two copies of this IS element were found in strain GR4, one of them is linked to the nfe genes located on plasmid pRmeGR4b. IS Rm6 seems to be widespread in R. meliloti. Data suggest that IS Rm6 is active in transposition at an estimated frequency of 2 × 10 −5 per generation per cell in strain GR4. This 1269-bp element carries 27 26 - bp terminal imperfect inverted repeats with six mismatches and a direct target site duplication of 4 bp. The IR terminate with the dinucleotide 5′-TG as all the members of the IS3 family. In addition, as other IS belonging to the IS3 family, IS Rm6 carries two open reading frames (ORFA and ORFB) with a characteristic translational frame-shifting window in the overlapping region. Furthermore, IS Rm6 putative transposase contains the triad of amino acids called DDE motif. Comparison of the IS Rm6 DNA sequence and the putative proteins encoded with sequences derived from the EMBL, GenBank, PIR and Swissprot databases showed significant similarity to IS that belongs to the IS3 family with a highest homology to a subclass containing IS476 from Xanthomonas campestris, IS407 from Burkholderia cepacia, and ISR1 from Rhizobium lupini.

Purification of an α- l-fucoside-binding protein from Rhizobium lupini

Lectins associated with the bacterial cell surface of Rhizobium lupini strain LL13 were evidenced by erythrocyte agglutination, by aggregation of neoglycoprotein coated beads and by spectrofluorimetry using fluoresceinylated neoglycoproteins. At pH 5.0, a specific binding of the fluorescein-labelled neoglycoprotein bearing α- l-fucose was observed. The binding of this labelled neoglycoprotein is a saturable phenomenon and is inhibited by the same unlabelled neoglycoprotein. Extracts of R lupini obtained by disrupting a bacterial pellet through a French press were stabilized at pH 5.6 by gel filtration and purified to homogeneity by affinity chromatography on Agarose A4 substituted with α- l-fucose. A protein with a M r κ 19 000 was specifically eluted from this affinity column with l-fucose. Isoelectric focusing of this sample yielded a single band with p l near 6.7. This protein specifically aggregated l-Fuc-BSA-coated microspheres. The results obtained in the present study indicate that we have purified from Rhizobium lupini strain LL13, a l-fucose binding protein as a lectin.

Stability of the Nitrogen Concentration of Inoculated White Lupins during Pod Development

The general pattern of decrease of the 'critical' plant N concentration (i.e. minimum concentration required for maximum growth rate) during growth has been described for several C3 non grain-legume species, and this can be used as a reference curve for diagnosis of N nutrition in these species. The present study was undertaken to investigate changes of N concentration during growth of a grain legume, in different conditions of N nutrition. White lupin (Lupinus albus L.) was grown for six crop seasons in field trials in which inoculation with Rhizobium lupini, nitrogen fertilizer rate, cultivar and plant density were density were manipulated. The yield and dry matter production of noninoculated plants were lower than, or at the best similar to, those of inoculated plants, whatever the level of N supply. From anthesis to the beginning of seed filling, the N concentration of shoots of inoculated plants was found to be remarkably stable between years, N fertilization regimes, cultivars, and for individual plants within a plot. Nitrogen concentration only varied with plant density. By contrast, the N concentration of noninoculated plants was highly variable and generally lower than that of inoculated plants, whatever the level of N supply. The high and stable N concentration of inoculated plants did not appear to be necessary for maximum growth rate but seemed to be required for maximum production of seed dry matter and N. The potential use of these results to diagnose, in any white lupin crop, an inefficiency of the lupin-R. lupini interaction is evaluated.

The rigidity of bacterial flagellar filaments and its relation to filament polymorphism

We determined and correlated the rigidity of Salmonella typhimurium, Escherichia coli, and Rhizobium lupini flagellar filaments representing various structural and polymorphic states (plain, complex, straight, superhelical, and right- and left-handed). Persistence length, from which the filament's rigidity and other parameters (Young's modulus, bending force constant, buckling persistence length, flexural deformation, and flexural time) were derived, was determined from electron micrographs of isolated, negatively stained filaments. Outer diameters and radii of strong intersubunit connectivity were determined from three-dimensional image reconstructions and radial mass density profiles from scanning transmission electron microscopy. All filaments appear to be highly rigid with no evident correlation with their helical sense or superhelicity. The complex filament of R. lupini is rigid to the extent that it becomes brittle. The overall flexibility of the flagellum seems to stem mainly from the hook and not from the filament. Polymorphism is probably related to the propelling properties and hydrodynamic shape of the filament rather than to its rigidity.

Measurement of Aspartate Aminotransferase-P2 in Developing Lupin Nodules Using a Two Site ELISA Employing Monoclonal Antibodies

Leguminous root nodules contain two forms of aspartate aminotransferase (AAT). AAT-P1 is con- stitutively expressed in roots and nodules, whereas the second isoenzyme, AAT-P2, is induced in developing nodules. A two site ELISA system was developed to quantify AAT-P2 in nodule extracts. The assay comprised two affinity-purified monoclonal antibodies directed against different epitopes on the AAT-P2 molecule. The sensitivity was less than 200 pg mL-1, and AAT-P2 could be quantified in the range 1 to 15 ng mL-1. The assay was specific for AAT-P2, and did not measure AAT-P1. The assay was used to specifically measure AAT-P2 in the developing legume root nodule formed by the symbiotic liaison between Rhizobium lupini NZP2257 and the roots of Lupinus angustifolius L. The ELISA method, which measures AAT-P2 protein, was contrasted with an approach which relied on the heat lability of AAT-P2 at 60°C to measure individual isoenzyme catalytic activity.

Natural 15N enrichment of amide‐exporting legume nodules

The natural 15N abundance of amide‐exporting nodules was compared to that of shoots in 12 plant species. Nodules were statistically less abundant in 15N than shoots in one of three cultivars of Pisum sativum L., in Vicia faba L. and in Medicago sativa L., but the 15N depletion of nodules was very samall. Nodules were statistically more abundant in 15N than shoots in Trifolium pratense L., depending on time during the growing season, Cyamopsis tetragonaloba L. Taub. and 7 Lupinus species, but the enrichment was small except for C. tetragonalova and 6 Lupinus species. Nodules of 3 Lupinus species infected with Rhizobium lupini isolated from Lupinus subcarnosa Hook, were only slightly enriched in 15N, but nodules of two of these species were substantially enriched in 15N when infected with a mix of other Rhizobium lupini strains. The third species, L. texensis Hook., was not infected by this mix of strains. Differences in 15N abundance between nodules and other tissues of amide‐exporting and ureide‐exporting nodules from several studies are tabulated. All ureide‐exporting nodules in this tabulation are enriched in 15N. Amide‐exporting nodules are considerably more variable in this regard. These results confirm that events associated with ureide synthesis or transport cannot be the sole cause of the substantial 15N enrichment seen in nodules.

Rhizobial inoculant for iprodione-treated lupin seed: evaluation of an iprodine-resistant Rhizobium lupini

Lupin nodulation is reduced when seed of this legume is treated with commercial inoculant (Rhizobium lupini WU425) and the fungicide Rovral (a.i. iprodione). The number of WU425 colonising soil beneath lupin seedlings established without iprodione was greater than where iprodione was used. R. lupini CC606B has greater tolerance of iprodione than WU425; 85% of CC606B survived 15 min in iprodione (Rovral 16 g/L), compared with <1% survival of WU425. CC606B fixed as much nitrogen as WU425 on serradella grown in sand culture, but it nodulated lupin poorly in the field. It was shown that CC606B comprised bacteria that were either positive or negative for nodulation of serradella and lupin. Thus, an isolate of CC606B (CC606B/1), able to form nodules on lupin and serradella and also tolerant of iprodione (Rovral 16 g/L), was selected and compared with WU425 as inoculants of lupin, in field trials with and without iprodione seed treatment. In the treatments without the fungicide, CC606B/1, like its parent, failed to nodulate lupin as extensively as WU425. CC606B/1 was unable to colonise soil beneath lupin crops as well as WU425. With iprodione, nodulation by CC606B/1 was significantly worse than without the fungicide; so the tolerance level of CC606B/1 to iprodione was insufficient. With these treatments it was shown that nodule abundance in late winter was related to the abundance of rhizobia in the soil beneath lupin seedlings in early winter. When there were fewer nodules, less dry matter was produced; but grain yield was not affected by the reductions in nodulation and dry matter. The implications of these changes on N2 fixation and lupin effects on soil N are discussed. Other species and strains of Rhizobium varied in their ability to survive iprodione.

The narrow-leafed lupin (Lupinus angustifolius L.) as a nitrogen-fixing rotation crop for cereal production. I. Indices of nitrogen fixation

Experiments to develop indices of N2 fixation activity for the narrow-leafed lupin (Lupinus angustifolius L.) are reported. In Experiment 1 Unicrop narrow-leafed lupins were inoculated at sowing with effective Rhizobium lupini WU425. The conversion factor relating C2H2 reduction to N2 fixation was not constant throughout growth but increased from 0.9 (50-60 day period) to 6.6 (110-120 days). A nodulation index [(nodule wt/shoot wt) x 100], developed to account for plant size, declined with increasing nitrate supply and with increasing plant age. However, minor shifts in the nodulation index represented large shifts in plant dependence on N2 fixation (p), when plants were 60-100% dependent on N2 fixation. Concentrations of nitrate in extracts of the shoot axes and nodulated roots increased with increasing nitrate supply. Although the presence of nitrate in the rooting medium was evidenced by its presence in xylem exudate, the relationship between nitrate supply and the nitrate contents of xylem exudate was generally poor. Functions were developed to describe the relationships between the nodulation index and p, and between both shoot and root nitrate and p. Other experiments highlighted the synchrony of nitrate supply and its appearance in root tissues and the lack of diurnal fluctuations in nitrate concentrations of plant parts.

Nodulation studies on legumes exotic to Australia: Lupinus and Ornithopus spp

In a series of glasshouse and field experiments, the symbiotic characteristics of 24 lines of Lupinus and Ornithopus species and 20 strains of Rhizobium lupini were defined. Rhizobium lupini inoculant established readily in several soils and lupins grown in the field responded to inoculation by improved nodulation, growth and yield. It is concluded that lupin crops sown on new land need to be inoculated to achieve optimum yield. At three sites, field-grown lupins responded to increasing rates of inoculation up to the rate recommended by the inoculant manufacturer. At two of the sites there was no further response to higher rates, but at the third there was a continuing response up to 125x (inoculation rate). Lupin seed was preinoculated, using gum arabic adhesive, up to 33 days before sowing without significant loss of viability or nodulating capacity of the inoculant. Seed coating with several materials did not improve inoculant viability on preinoculated seed. In glasshouse experiments, hostxstrain interactions in nitrogen fixation were frequent and substantial. They occurred at three levels of taxonomic relationship, viz, between the genera Lupinus and Ornithopus, between different species within the same genus, and between different lines of the same lupin species. Hostx strain interactions were also observed in field experiments but were less frequent and smaller than in the glasshouse. These observations have implications for the 'single-strain inoculant policy that applies to the manufacture of commercial lupin and serradella inoculant in Australia.

Sensitivity of Lupin (Lupinus angustifolius L.) Root Nodulation to Iprodione (Rovral) Fungicide.

Pteiooneete serosa (Kirchn.) Hughes, which causes brown leaf spot and Pleiochaeta root rot of narrow-leaf lupin (Lupinus angustifolius L.) (4,6), is a problem in southern Australia (7), particularly in wetter winters at sites where lupin crops have been grown previously. The foliar disease is controlled with seed and foliar applications of iprodione (Rovral<!» (1,7): the seed dressing at the rate of 2.5 g/kg seed is preferred for economic reasons, as well as providing seedling protection against root diseases caused by P. satosa and Rhizoctonia spp. The bacterium Rhizobium lupini is also applied to lupin seed to obtain benefits of nitrogen fixation (3). The inoculant Is a mixture of R. tuplni strain WU425 and ground peat applied with adhesive at 2.5 g/kg seed. Some fungicides are toxic to particular Rhizobium strains (5) and thus jeopardise this inoculation. Although we have measured the survival of R. luplni WU425 to be 1.6% after 15 min in a solution of 16 g iprodlone/I, the recommended method for luplns Is to apply inoculant first and then a coating of iprodlone (Registrar of Pesticides, Dept. Agriculture, N.S.w.). This paper reports the reduction of root nodulation when inoculated seed was treated with iprodione. The lupin cultivar, Illyarrie, was treated with iprodione and legume inoculant at the recommended rates. At site 1, sown on 2 May 1985,20 km west of Wagga Wagga, fungicide and Inoculant were applied In various combinations (Table 1), including a spray of inoculant Into the sowing furrow (2). In some treatments, sowing was delayed up to 48 h after fungicide/inoculant

SENSITIVITY AND ADAPTATION OF SELECTED RHIZOBIA AND AGROBACTERIA TO PARAQUAT

Sensitivity to paraquat as function of growth varied considerably among 15 rhizobia from seven cross-inoculation groups and 13 agrobacteria from five different species. No relationship was evident between the sensitivity and the "fast-growing" or the "slow-growing" characteristics among the rhizobia. The agrobacteria were uniformly less sensitive. Maximum stabilized paraquat resistance induced by the adptations ranged from 200 μg paraquat∙mL−1 in Rhizobium lupini 112, to 20 000 μg paraquat∙mL−1 in Agrobacterium radiobacter R-590 and A. tumefaciens A6-K1. No relationship was found between the sensitivity and the adaptability. Identical lytic patterns with six bacteriophages confirmed the relationship between the adapted and parent cultures suggesting no genetic effect of paraquat on susceptibility to lysis. The bacteria-plant symbiont interaction, including nodulation, plant weight, vigor and color, was unaffected by the adaptations to paraquat resistance. Similarly, the adaptations exerted no effect on tumorigenicity of A. tumefaciens A6-K1. Key words: Rhizobia, agrobacteria, adaptation, herbicides, paraquat, N2-fixation

Structure of complex flagellar filaments in Rhizobium meliloti

The complex flagella of Rhizobium meliloti 2011 and MVII-1 were analyzed with regard to serology, fine structure, subunits, and amino acid composition. The serological identities of flagellar filaments of the two strains were demonstrated by double immunodiffusion with antiflagellin antiserum. The filaments had a diameter of 16 nm. Their morphology was dominated by the prominent undulations of an external three-start helix running at a 10-nm axial distance and at an angle of 32 degrees. Faint nearly axial striations indicated the presence of a tubular core of a different helical order. The complex filaments consisted of 40,000-dalton flagellin monomers. Typically, the amino acid composition was 3 to 4% higher in nonpolar residues and 5 to 7% lower in aspartic and glutamic acids (and their amides) than that of plain flagellar proteins. There were no immunochemical relationships among Pseudomonas rhodos, Rhizobium lupini, and R. meliloti complex flagella, suggesting that the latter represent a new class.

A three-dimensional reconstruction of the complex flagellar filament of Rhizobiwn lupini

The bacterial flagellum is composed of a basal body (the putative motor), a hook (the putative universal coupling), and a helical filament (the propellor). Based on their distinctive morphologies in the electron microscope, there are two different types of flagella: the plain flagellum and the complex flagellum. Most bacteria have plain flagella. Complex flagella are found in only a few species of bacteria: Rhizobium lupini, Rhizobium meliloti and Pseudomonas rhodos, and are associated with motility in a viscous medium.The most prominent feature of the complex flagellum is what seems to be an outer sheath consisting of a three-stranded helical winding (Fig. 1), which is absent from plain filaments (Fig. 2, Salmonella typhimurium). The sheath, however, does not arise from the presence of an additional subunit since the complex filament (like the plain flagellum) is made from a single species of protein, flagellin.

Greenhouse evaluation of growth parameters related to birdsfoot trefoil and red and white clover production on an and IC mission silt loam

Abstract Birdsfoot trefoil (Lotus tenius), red clover (Trifolium pratense) and white clover (Trifolium repens) were evaluated as potential forage legumes on andic soils. A greenhouse study was used to evaluate the influence of soil pH on: (1) the establishment and growth of these forage legumes, (2) N and P quantity and concentration, and (3) Rhizobium lupini and Rhizobium trifolii survival. Aluminum sulfate and finely‐ground calcium carbonate were used to adjust soil pH. Soil pH's were 4.8, 5.1, 5.6, 6.2, 6.4, 6.9, 7.0 and 7.4. Birdsfoot trefoil, red clover and white clover were grown in 15 cm pots in the greenhouse and harvested five times at approximately 20‐day intervals. Yield was measured and plant material was analyzed for total N and P. Populations of R. lupini and R. trifolii were monitored using the MPN technique. Manipulation of pH in the Mission soil was found to have a significant effect on the growth of the three forage legumes, tissue N and P concentration and uptake, and on the survival of...

Mg 2+ adenosine triphosphatase from cell envelopes of free-living and bacteroid forms of Rhizobium lupini strain NZP2257

A procedure for the purification of Mg 2+ adenosine triphosphatase (EC 3.6.1.3) from free-living and bacteroid forms of Rhizobium lupini NZP2257 is described. The enzyme was released from cell envelopes using Triton X-100 and purified by gel filtration on Ultrogel AcA 22, followed by preparative gel electrophoresis on agarose. The purified ATPase had a molecular weight of about 355,000, as determined from sedimentation coefficients on sucrose gradients. Kinetic analysis of activity of the enzyme from free-living R. lupini showed it to be typical of F 1-type Mg 2+ ATPases from bacteria. Mg stimulated activity at pH 7.0, although, when present as the free ion, Mg caused non-competitive inhibition ( K I = 1.5 mM). Maximum activity with ATP occurred over a broad pH range from 6.0 to 10.5. ATP, GTP, and UTP, and, to a much lesser degree, CTP and ADP, were hydrolyzed by the enzyme. Hydrolysis of glucose 6-phosphate was not observed. The K m for ATP at pH 7.0 was 0.67 and for GTP 1.4 m m. ATPase activity was inhibited by ADP, and competitive with ATP ( K I = 0.18 mM ). Azide also caused inhibition but fluoride and DCCD had no effect. Native and sodium dodecyl sulfate-gel electrophoretic analysis revealed no obvious differences between ATPases from free-living and bacteroid forms of R. lupini.