Bacillus Subtilis Strain Qst 713

Author : Raghavendra Joshi
Publisher :
ISBN 13 :
Total Pages : 178 pages
Book Rating : 4.:/5 (638 download)

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Download or read book Identification, Characterization of DNA Sequences Specific to Bacillus Subtilis with Biocontrol Potential and Development of PCR Assay Targeting Them in Multitemplate Environment written by Raghavendra Joshi and published by . This book was released on 2005 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Bacillus subtilis are free living, aerobic, endospore forming bacteria which are ubiquitous in agricultural systems. Some isolates produce antibiotic compounds that have been shown to suppress plant pathogens. This trait coupled with their ability to form spores make them attractive candidates as biocontrol agents. Several strains have been commercialized and sold as biopesticides and indicated for use against crop diseases. Others have been reported to induce systemic resistance in plants against different pathogens. Thus B.subtilis strains can act via different mechanisms to counter plant pathogens. In order to rapidly identify B. subtilis strains with biocontrol abilities in the soil or rhizosphere, it is important to develop a marker unique to the biocontrol strain. DNA markers can be useful for detection using PCR based techniques. Therefore a comparative genomics approach using the technique Suppressive Subtractive Hybridization(SSH) was undertaken to identify and characterize DNA markers unique to biocontrol strains of B. subtilis. Genomes of two commercialized biocontrol strains, QST713 and GB03, were subtracted from the genome of strain 168, which is a not a biocontrol strain. A total of 149 DNA fragments were obtained from this subtraction effort which were then cloned and sequenced. Eighty of those fragments matched Bacillus like sequences in GenBank. Several of these fragments were found to code for the biosynthesis of cyclic lipopeptides. Fragments from both GB03 and QST713 that had match to gene yndJ from the biocontrol strain B. amyloliquefaciens FZB42 were also obtained. Sixteen subtracted fragments shared a high degree of similarity to sequences found in multiple B.subtilis strains with proven biocontrol capacities. Oligonucleotide primers specific to nine of these genes were developed. The targeted genes included five genes involved in antibiotic synthesis (bmyB, fenD, ituC srfAA, and srfAB) and four additional genes (yndJ, yngG, bioA, and a hypothetical open-reading frame) not previously associated with biological control. All nine markers were amplified from three different commercialized biocontrol and four newly isolated B. subtilis strains with the exception of ituC, which was not detected in strain GB03. Sequencing of the amplified markers revealed that all of these seven isolates were genotypically distinct strains. Interestingly, all seven strains were significantly more effective at inhibiting the growth of Pythium ultimum and Rhizoctonia solani than 24 other B. subtilis isolates which lacked the amplifiable markers. Potential applications of these nine genetic markers include further delineations of the diversity, ecology, and biocontrol activities of B. subtilis.These markers were then utilized to develop a rapid PCR-based assay that would be able to characterize rhizosphere populations of B. subtilis. The primers were able to amplify fenD, bmyB and ituC without background from complex soil DNAspiked with only a few hundred cells.