Objective To compare four methods of bacterial genomic DNA extraction from Sprague-Dawley rat fecal samples.Methods Sixteen fecal samples with 106 cfu S.aureus and 4 fecal samples without S.aureus were equally divided into four groups.Bacterial genomic DNA were extracted by following methods:(1) Several wash by PBS plus phenol/chloroform purification;(2) Liquid nitrogen digestion plus column purification;(3) PBS wash plus column purification,and(4) Liquid nitrogen digestion followed by phenol/chloroform pur...