Correlation between rifampicin-resistance of slow-growing Rhizobium strains and their ability to express nitrogenase activity in culture

Pankhurst, C

doi:10.1016/0378-1097(82)90096-9

Cited by 4 publications

(6 citation statements)

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“…As the mutants obtained previously were not characterized in great biochemical detail, the interpretation of a selective involvement of RNA polymerase in nif derepression [2] may have been premature. It cannot be ruled out completely, however, that the mutants obtained by others were indeed genetically and phenotypically different from the ones described here, and that the physiological effects observed [3][4][5] were species-or strain-specific.…”

Section: Nitrogen Fixation Activity In Rifampicin-resistant Mutantscontrasting

confidence: 57%

“…(3) It is known that only a limited number of slow-growing Rhizobium strains are able to derepress nitrogenase activity in free-living culture. When grown aerobically, such strains were found to be significantly more resistant to rifampicin than strains unable to express nitrogenase activity [5]. The molecular basis for this correlation remains obscure.…”

Section: Introductionmentioning

confidence: 99%

“…Although a careful biochemical analysis was not done, Pain [2] has argued that a mutationally altered RNA polymerase might have caused the ineffective phenotype.(2) In free-living nitrogen-fixing cultures of slow-growing rhizobia rifampicin was found to inhibit the expression of nitrogen fixation much more selectively than cellular growth [3,4].(3) It is known that only a limited number of slow-growing Rhizobium strains are able to derepress nitrogenase activity in free-living culture. When grown aerobically, such strains were found to be significantly more resistant to rifampicin than strains unable to express nitrogenase activity [5]. The molecular basis for this correlation remains obscure.In contrast to these reports is our recent finding that the RNA polymerase subunits from aerobically grown Rhizobium japonicum ceils and from nitrogen-fixing cells have the same electrophoretic properties [6].…”

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confidence: 99%

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Free-living and symbiotic nitrogen fixing ability of Rhizobium japonicum is unaffected by rifampicin resistance mutations

Regensburger

1984

FEMS Microbiology Letters

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The hypothesis that rifampicin resistance mutations (possibly leading to altered RNA polymerases) have a pleiotropic effect on symbiotic nitrogen fixation was tested using the Rhizobium japonicum-soybean symbiosis. A total of 20 spontaneous rifampicin-resistant mutants of R. japonicum strain 110 were analyzed biochemically. RNA polymerase assays revealed that the enzyme from 15 mutants was indeed rifampicin-insensitive. Two of these mutants were found to possess an enzyme with an electrophoretically altered B subunit. All rifampicin-resistant mutants were able to form nodules on soybeans and fix nitrogen symbiotically; free-living nitrogen fixation under microaerophilic culture conditions was also unaffected. INTRODUCTIONSeveral previous reports have indicated that perhaps a structurally distinctive or modified RNA polymerase may have a selective influence on the ability of certain Rhizobium strains to express nitrogenase activity in free-living culture or in symbiosis.(1) Pankhurst [1] and Pain [2] have isolated rifampicin-resistant mutants of both fast-and slow-growing strains of Rhizobium. These mutants were able to nodulate their respective host plants, but some of them were found to have greatly reduced symbiotic effectiveness. Although a careful biochemical analysis was not done, Pain [2] has argued that a mutationally altered RNA polymerase might have caused the ineffective phenotype.(2) In free-living nitrogen-fixing cultures of slow-growing rhizobia rifampicin was found to inhibit the expression of nitrogen fixation much more selectively than cellular growth [3,4].(3) It is known that only a limited number of slow-growing Rhizobium strains are able to derepress nitrogenase activity in free-living culture. When grown aerobically, such strains were found to be significantly more resistant to rifampicin than strains unable to express nitrogenase activity [5]. The molecular basis for this correlation remains obscure.In contrast to these reports is our recent finding that the RNA polymerase subunits from aerobically grown Rhizobium japonicum ceils and from nitrogen-fixing cells have the same electrophoretic properties [6]. This suggest that no chemical modification of the enzyme occurs when cells undergo this metabolic differentiation.In the present report we have isolated rifampicin-resistant mutants of R. japonicum, and were 0378-1097/84/$03.00

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Section: Nitrogen Fixation Activity In Rifampicin-resistant Mutantscontrasting

confidence: 57%

Section: Introductionmentioning

confidence: 99%

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confidence: 99%

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Free-living and symbiotic nitrogen fixing ability of Rhizobium japonicum is unaffected by rifampicin resistance mutations

Regensburger

1984

FEMS Microbiology Letters

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“…Previous reports have shown that antibiotic resistance in root nodule bacteria is common (2,12,20) although there is a considerable amount of variation within and between species. Cole and Elkan (3) suggested that multiple antibiotic resistance is characteristic of B. japonicum.…”

Section: Discussionmentioning

confidence: 99%

Fatty Acids, Antibiotic Resistance, and Deoxyribonucleic Acid Homology Groups of Bradyrhizobium japonicum

Kuykendall

Roy

O'Neill

et al. 1988

International Journal of Systematic Bacteriology

929

621

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The fatty acid compositions and multiple antibiotic resistance patterns of 32 strains of Bradyrhizobium japonicum correlated with two major deoxyribonucleic acid homology groups. In group I, the fatty acid composition was 1.3% 16:l cis9 acid, 3.6% 16:lC acid, 8.8% 16:O acid, 1.2% 19:0 cyclopropane acid, and 81.2% 18:l acid. Group I1 contained 0.5% 16:lC acid, 11.1% 16:O acid, 0.8% 17:O cyclopropane acid, 24.7% 19:O cyclopropane acid, and 62.3% 18:l acid. Group I strains were susceptible to rifampin (500 pglml), tetracycline (100 pglml), streptomycin (100 pg/ml), chloramphenicol (500 pg/ml), erythromycin (250 pglml), carbenicillin (500 pg/ml), and nalidixic acid (50 pg/ml), whereas group I1 strains were resistant to these antibiotics. Both groups were resistant to trimethoprim (50 pg/ml) and vancomycin (100 pglml).Bradyrhizobium japonicum (Jordan 1982) (formerly Rhizobium japonicum) is the slow-growing symbiont of soybeans. This species is comprised of two highly divergent taxonomic groups which should be phenotypically distinguishable. The deoxyribonucleic acid (DNA)-DNA hybridization studies of Hollis et al. (8) established DNA homology groups I, Ia, and 11. These groups were characterized with respect to acidic extracellular polysaccharide composition and phenotypic ex planta nitrogenase expression. Groups I and Ia were reported to be quite distinct from DNA homology group I1 according to both of these criteria (9). Using some of the same strains, Stanley et al. (21) characterized the DNA nucleotide sequence divergences in and proximal to known symbiotic genes and concluded that strains of B . japonicum comprise two symbiotic genotypes (sTI and sTII) consistent with separate species designations.Whole-cell fatty acid profiles of strains grown under standardized conditions have been used for identification (1, 4,18) and classification of many bacteria (10, 17), but not in the genus Bradyrhizobium. Pankhurst et al. (20) correlated rifampin resistance in some slow-growing rhizobial strains with in vitro nitrogenase activity. This observation, together with that of Huber et al. (9) that only DNA homology group I1 strains express nitrogenase in vitro, suggested to us that patterns of antibiotic resistance might also distinguish the groups. In this paper we report that whole-cell fatty acid profiles correlate with DNA homology groups I and I1 of Hollis et al. (8) and that patterns of high-level resistance to antibiotics distinguish the two DNA homology groups. MATERIALS AND METHODSBacterial strains. All USDA strains were obtained from H. H. Keyser and D.Weber, U. S. Department of Agriculture (USDA), Beltsville, Md.; strain ATCC 10324 was obtained from the American Type Culture Collection, Rockville, Md.; strains 5631, 5633, D193, D209, THA6, and 8' were obtained from G. H. Elkan, North Carolina State University, Raleigh; and strains 61A.50 and 61A76 were obtained from S. Smith, Nitragin Co., Milwaukee, Wis. Strains that exhibit rifampin resistance and tetracycline resistance were purified by streaking onto a mediu...

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“…On the other hand, the extremely low dose of carbaryl and 2,4-D showed stimulation in (10-20%) nitrogenase activity, and a similar trend was observed in the case of uptake hydrogenase activity. A positive correlation between rifampicin resistance and nitrogenase activity was demostrated in Rhizobium species (12). Rhizobium mutants resistant to antibiotics interfere with or inhibit cell wall/membrane synthesis (1) often accompanied by the loss of symbiotic effectiveness (7).…”

mentioning

confidence: 99%

Effect of carbaryl and 2,4-D to nitrogenase and uptake hydrogenase in agar cultures and root nodules formed by Rhizobium leguminosarum.

Maheshwari

Saraf

1994

J. Gen. Appl. Microbiol.

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Pesticides have been found to affect microorganisms both individually (5) as well as at the ecosystem level (17). Antibiotic-resistant mutants of Rhizobium inhibit cell wall synthesis and decrease effectiveness under symbiotic conditions (11). It is considered that the physiological integrity of the rhizobial cell wall is important for its symbiotic effectiveness (11). In our earlier studies with Rhizobium japonicum treated with pesticides under explanta conditions, we have suggested the involvement of the cell membrane and the respiratory pathway (8). However, our present knowledge at the cellular and biochemical level of pesticide effects is fragmentary. The present study deals with action of carbaryl-and 2,4-D-treated isolates at the symbiotic level. In addition, investigations were carried out to assess nitrogenase and uptake hydrogenase activities in asymbiosis and symbiosis.Growth of Rhizobium on medium containing carbaryl and 2,4-D. Pure cultures of R.leguminosarum PR-2005 were obtained from National Chemical Laboratory, Pune, India. R. leguminosarum (PR-PSR-1) was isolated from root nodules of Pisum sativum cultivated in agriculture fields and authenticated by various biochemical tests as mentioned in Bergey's Manual of Systematic Bacteriology (4). The pure cultures were maintained on Yeast Extract Mannitol (YEM) agar slants (18). Stock solutions of carbaryl (L-naphthyl methyl carbamate) and 2,4-D (2,4-dichlorophenoxyacetic acid) were prepared in ethanol (0.1%) and the appropriate quantity was added to the presterilized medium. The organisms were allowed to grow to their exponential phase of growth (48 h) at 28±1°C and their specific growth rate was calculated. Vo/V of 2 (inserted Figure) was calculated and plotted

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Correlation between rifampicin-resistance of slow-growing Rhizobium strains and their ability to express nitrogenase activity in culture

Cited by 4 publications

References 6 publications

Free-living and symbiotic nitrogen fixing ability of Rhizobium japonicum is unaffected by rifampicin resistance mutations

Free-living and symbiotic nitrogen fixing ability of Rhizobium japonicum is unaffected by rifampicin resistance mutations

Fatty Acids, Antibiotic Resistance, and Deoxyribonucleic Acid Homology Groups of Bradyrhizobium japonicum

Effect of carbaryl and 2,4-D to nitrogenase and uptake hydrogenase in agar cultures and root nodules formed by Rhizobium leguminosarum.

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