Extraction of high quality DNA from polysaccharides-secreting xanthomonads

Abstract

A DNA extraction method using CTAB was used for the isolation of genomic DNA from ten Xanthomonas  campestris pathovars, ten isolates of Xanthomonas albilineans and one isolate of Pseudomonas  rubrisubalbicans. High quality DNA was obtained that was ideal for molecular analyses. Extracellular polysaccharides were effectively removed thus resulting in DNA that dissolved easily and was well digested by restriction enzymes. All of the other methods tested resulted in the coprecipitation of the polysaccharides together with the nucleic acids upon addition of alcohol so that even high yields could not compensate for this contamination. DNA obtained by the CTAB method was used for cloning, Southern hybridizations and PCR for up to three years after the extraction.

Keywords: Polysaccharides, CTAB, polymerase chain reaction, DNA.