Open AccessHomoduplex and Heteroduplex Polymorphisms of the Amplified Ribosomal 16S-23S Internal Transcribed Spacers Describe Genetic Relationships in the “ Bacillus cereus Group”
Author(s) -
Daniele Daffonchio,
Ameur Chérif,
Sara Borin
Publication year - 2000
Publication title -
applied and environmental microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.552
H-Index - 324
eISSN - 1070-6291
pISSN - 0099-2240
DOI - 10.1128/aem.66.12.5460-5468.2000
Subject(s) - heteroduplex , bacillus cereus , bacillus thuringiensis , biology , bacillus anthracis , cereus , spacer dna , genetics , internal transcribed spacer , microbiology and biotechnology , ribosomal rna , dna , bacteria , gene
Bacillus anthracis ,Bacillus cereus ,Bacillus mycoides ,Bacillus pseudomycoides ,Bacillus thuringiensis , andBacillus weihenstephanensis are closely related in phenotype and genotype, and their genetic relationship is still open to debate. The present work uses amplified 16S-23S internal transcribed spacers (ITS) to discriminate between the strains and species and to describe the genetic relationships within the “B. cereus group,” advantage being taken of homoduplex-heteroduplex polymorphisms (HHP) resolved by polyacrylamide gel electrophoresis and silver staining. One hundred forty-one strains belonging to the six species were investigated, and 73 ITS-HHP pattern types were distinguished by MDE, a polyacrylamide matrix specifically designed to resolve heteroduplex and single-strand conformation polymorphisms. The discriminating bands were confirmed as ITS by Southern hybridization, and the homoduplex or heteroduplex nature was identified by single-stranded DNA mung bean nuclease digestion. Several of the ITS-HHP types corresponded to specific phenotypes such asB. anthracis or serotypes ofB. thuringiensis . Unweighted pair group method arithmetic average cluster analysis revealed two main groups. One includedB. mycoides ,B. weihenstephanensis , andB. pseudomycoides . The second includedB. cereus andB. thuringiensis ,B. anthracis appeared as a lineage ofB. cereus .