Plant growth promoting pseudomonads play an important role in disease suppression and there is considerable interest in development of bio-marker genes that can be used to monitor these bacteria in agricultural soils....Plant growth promoting pseudomonads play an important role in disease suppression and there is considerable interest in development of bio-marker genes that can be used to monitor these bacteria in agricultural soils. Here, we report the application ofa PCR primer sets targeting genes encoding the main antibiotic groups. Distribution of the genes was variably distributed across type strains of 28 species with no phylogenetic groupingfor the detected antibioticsgenes, phlD for 2,4-diacetylphloroglucinol (2,4-DAPG) and phzCD for phenazine-1-carboxylic acid or hcnBC for hydrogen cyanide production. Analysis of field soils showed that primer sets for phlD and phzCD detected these genes in a fallowed neutral pH soil following wheat production, but that the copy numbers were below the detection limits in bulk soils having an acidic pH. In contrast, PCR products for the phzCD, pltc and hcnBc genes were detectable in mature root zones following plantingwith wheat. The ability to rapidly characterize populations of antibiotics producers using specific primer sets will improve our ability to assess the impacts of management practices on the functional traits of Pseudomonas spp. populations in agricultural soils.展开更多
The microbial community structure in various microaggregates in a loamy sand soil was investigated. The microaggregates were separated into outer and inner aggregates using a series of soil washes. Further physical fr...The microbial community structure in various microaggregates in a loamy sand soil was investigated. The microaggregates were separated into outer and inner aggregates using a series of soil washes. Further physical fractionation of inner aggregates was achieved by separation into coarse and fine sand as macroaggregate fractions, coarse and fine silt as microaggregate fractions, and clay. Research on microbial communities and soil microaggregates can aid in our understanding of soil microhabitats and microorganisms in soil structures, with applications that may contribute to increasing crop production and maintaining sustainable agriculture. In order to study the microbial community structure of aggregates, polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) was performed using 16S rRNA genes. The PCR-DGGE of the Bacteria Actinomycetes and Archaea showed divergent results between the different aggregate fractions. The results showed that the bacterial community structure was highly similar between bulk soil and clay;the inner aggregate community structure of Actinomycetes was closely related between coarse and fine sand and coarse silt, and the Archaea community structure of outer and inner aggregates was more similar than that of total bacteria or Actinomycetes.展开更多
文摘Plant growth promoting pseudomonads play an important role in disease suppression and there is considerable interest in development of bio-marker genes that can be used to monitor these bacteria in agricultural soils. Here, we report the application ofa PCR primer sets targeting genes encoding the main antibiotic groups. Distribution of the genes was variably distributed across type strains of 28 species with no phylogenetic groupingfor the detected antibioticsgenes, phlD for 2,4-diacetylphloroglucinol (2,4-DAPG) and phzCD for phenazine-1-carboxylic acid or hcnBC for hydrogen cyanide production. Analysis of field soils showed that primer sets for phlD and phzCD detected these genes in a fallowed neutral pH soil following wheat production, but that the copy numbers were below the detection limits in bulk soils having an acidic pH. In contrast, PCR products for the phzCD, pltc and hcnBc genes were detectable in mature root zones following plantingwith wheat. The ability to rapidly characterize populations of antibiotics producers using specific primer sets will improve our ability to assess the impacts of management practices on the functional traits of Pseudomonas spp. populations in agricultural soils.
文摘The microbial community structure in various microaggregates in a loamy sand soil was investigated. The microaggregates were separated into outer and inner aggregates using a series of soil washes. Further physical fractionation of inner aggregates was achieved by separation into coarse and fine sand as macroaggregate fractions, coarse and fine silt as microaggregate fractions, and clay. Research on microbial communities and soil microaggregates can aid in our understanding of soil microhabitats and microorganisms in soil structures, with applications that may contribute to increasing crop production and maintaining sustainable agriculture. In order to study the microbial community structure of aggregates, polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) was performed using 16S rRNA genes. The PCR-DGGE of the Bacteria Actinomycetes and Archaea showed divergent results between the different aggregate fractions. The results showed that the bacterial community structure was highly similar between bulk soil and clay;the inner aggregate community structure of Actinomycetes was closely related between coarse and fine sand and coarse silt, and the Archaea community structure of outer and inner aggregates was more similar than that of total bacteria or Actinomycetes.
