Presentation Title

Analysis of exopolysaccharide production and nodulation phenotypes of non-mucoid Burkholderia tuberum transposon insertion mutants

Start Date

November 2016

End Date

November 2016

Location

HUB 302-#105

Type of Presentation

Poster

Abstract

Beta-rhizobia, Burkholderia tuberum STM678, was originally isolated from nodules of the tropical South African plant Aspalathus carnosa. B. tuberum’s ability to engage in a nitrogen fixing symbiosis and nodulate a variety of legumes makes it of interest for agricultural and ecological purposes. A study was conducted to further identify genes that contribute to the production of exopolysaccharide (EPS), which is known to play a role in attachment and infection in many microbial-host interactions. Transposon mutagenesis was used to obtain B. tuberum mutants, which were screened for a non-mucoid phenotype, indicative of decreased EPS production. An EPS assay conducted on YMA with brilliant blue and congo red dyes showed alteration in the ability of some mutants to also uptake the dyes. Molecular methods were used to identify the location of the mutations, which were found in genes coding for a tyrosine-protein kinase Etk/Wzc, a glycosyl-transferase involved in cell wall bisynthesis, and His Kinase A (phospo-acceptor) domain-containing proteins. Further tests are being conducted to determine the mutants’ nodulation phenotypes using a bean host, Phaeseolus vulgaris. Results of the nodulation assay will be compared to EPS alterations to determine the effect of the gene mutation on plant-microbe interaction. Strains expressing delayed nodulation, nod-, or nif- will undergo reinsertion of their wild type genes to confirm the requirement of the gene for nodulation.

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Analysis of exopolysaccharide production and nodulation phenotypes of non-mucoid Burkholderia tuberum transposon insertion mutants

HUB 302-#105

Beta-rhizobia, Burkholderia tuberum STM678, was originally isolated from nodules of the tropical South African plant Aspalathus carnosa. B. tuberum’s ability to engage in a nitrogen fixing symbiosis and nodulate a variety of legumes makes it of interest for agricultural and ecological purposes. A study was conducted to further identify genes that contribute to the production of exopolysaccharide (EPS), which is known to play a role in attachment and infection in many microbial-host interactions. Transposon mutagenesis was used to obtain B. tuberum mutants, which were screened for a non-mucoid phenotype, indicative of decreased EPS production. An EPS assay conducted on YMA with brilliant blue and congo red dyes showed alteration in the ability of some mutants to also uptake the dyes. Molecular methods were used to identify the location of the mutations, which were found in genes coding for a tyrosine-protein kinase Etk/Wzc, a glycosyl-transferase involved in cell wall bisynthesis, and His Kinase A (phospo-acceptor) domain-containing proteins. Further tests are being conducted to determine the mutants’ nodulation phenotypes using a bean host, Phaeseolus vulgaris. Results of the nodulation assay will be compared to EPS alterations to determine the effect of the gene mutation on plant-microbe interaction. Strains expressing delayed nodulation, nod-, or nif- will undergo reinsertion of their wild type genes to confirm the requirement of the gene for nodulation.