Ecology and genetic stability of Tn5 mutants of bean rhizobia in Sonoran desert soils.

Persistent Link:
http://hdl.handle.net/10150/184823
Title:
Ecology and genetic stability of Tn5 mutants of bean rhizobia in Sonoran desert soils.
Author:
Pillai, Suresh Divakaran.
Issue Date:
1989
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Five transposon Tn5 mutants of bean rhizobia (Rhizobium leguminosarum b.v. phaseoli) and the wild type strain were used in ecological studies to evaluate the efficacy of transposon Tn5 as a phenotypic marker in rhizobia for ecological studies in two Sonoran desert soils. All mutants possessed chromosomal insertions of the transposable element. Survival of each mutant strain was compared to that of the wild type strain under non stress, moisture stress and temperature stress conditions in Pima silty clay loam and Brazil to sandy loam. The genetic stability of Tn5 in terms of transposition of the element within the chromosome and the Tn5 coded antibiotic resistant phenotype was determined in cells recovered throughout the survival period. Under non stress conditions, the viable Tn5 mutant population decreased in size. Two mutants showed significantly (p < 0.01) lower populations than the wild type at the end of 30 days in the silty clay loam. In the sandy loam, four of the five mutant populations were significantly lower than the wild type. Tn5 was genetically stable in both soils. Under moisture stress conditions, the decline of the Tn5 mutant and wild type populations corresponded to a decline in soil moisture content. The finer textured soil afforded more protection to the cells than the coarse textured soil. There were no indications of Tn5 instability under moisture stress. In both soils under temperature stress, sizes of all populations declined rapidly and after 12 days, the mutant cells when screened using the Tn5 coded markers were significantly less in numbers than the wild type indicating a loss of Tn5 coded antibiotic resistance phenotype. There were no significant differences in numbers between wild type and mutant cells when screened using only the intrinsic markers. DNA:DNA hybridizations confirmed that the lack of Tn5 coded antibiotic resistance phenotype was probably not due to a deletion or transposition of the element. Under non stress conditions Tn5 is a useful ecological marker, but each Tn5 mutant has to be evaluated independently under specific environmental conditions to determine the efficacy of Tn5 as an ecological marker.
Type:
text; Dissertation-Reproduction (electronic)
Keywords:
Rhizobium.; Microbial genetic engineering.; Soil microbiology -- Arizona.; Plasmids.; Insertion elements, DNA.
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Microbiology and Immunology; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Pepper, Ian L.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleEcology and genetic stability of Tn5 mutants of bean rhizobia in Sonoran desert soils.en_US
dc.creatorPillai, Suresh Divakaran.en_US
dc.contributor.authorPillai, Suresh Divakaran.en_US
dc.date.issued1989en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractFive transposon Tn5 mutants of bean rhizobia (Rhizobium leguminosarum b.v. phaseoli) and the wild type strain were used in ecological studies to evaluate the efficacy of transposon Tn5 as a phenotypic marker in rhizobia for ecological studies in two Sonoran desert soils. All mutants possessed chromosomal insertions of the transposable element. Survival of each mutant strain was compared to that of the wild type strain under non stress, moisture stress and temperature stress conditions in Pima silty clay loam and Brazil to sandy loam. The genetic stability of Tn5 in terms of transposition of the element within the chromosome and the Tn5 coded antibiotic resistant phenotype was determined in cells recovered throughout the survival period. Under non stress conditions, the viable Tn5 mutant population decreased in size. Two mutants showed significantly (p < 0.01) lower populations than the wild type at the end of 30 days in the silty clay loam. In the sandy loam, four of the five mutant populations were significantly lower than the wild type. Tn5 was genetically stable in both soils. Under moisture stress conditions, the decline of the Tn5 mutant and wild type populations corresponded to a decline in soil moisture content. The finer textured soil afforded more protection to the cells than the coarse textured soil. There were no indications of Tn5 instability under moisture stress. In both soils under temperature stress, sizes of all populations declined rapidly and after 12 days, the mutant cells when screened using the Tn5 coded markers were significantly less in numbers than the wild type indicating a loss of Tn5 coded antibiotic resistance phenotype. There were no significant differences in numbers between wild type and mutant cells when screened using only the intrinsic markers. DNA:DNA hybridizations confirmed that the lack of Tn5 coded antibiotic resistance phenotype was probably not due to a deletion or transposition of the element. Under non stress conditions Tn5 is a useful ecological marker, but each Tn5 mutant has to be evaluated independently under specific environmental conditions to determine the efficacy of Tn5 as an ecological marker.en_US
dc.typetexten_US
dc.typeDissertation-Reproduction (electronic)en_US
dc.subjectRhizobium.en_US
dc.subjectMicrobial genetic engineering.en_US
dc.subjectSoil microbiology -- Arizona.en_US
dc.subjectPlasmids.en_US
dc.subjectInsertion elements, DNA.en_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineMicrobiology and Immunologyen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorPepper, Ian L.en_US
dc.contributor.committeememberSinclair, Norval A.en_US
dc.contributor.committeememberGerba, Charles P.en_US
dc.contributor.committeememberBourque, Don P.en_US
dc.contributor.committeememberMendelson, Neil H.en_US
dc.identifier.proquest9004974en_US
dc.identifier.oclc703274108en_US
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