Development of a SYBR safe™ technique for the sensitive detection of DNA in cesium chloride density gradients for stable isotope probing assays

SYBR safe™, a fluorescent nucleic acid stain, was evaluated as a replacement for ethidium bromide (EtBr) in cesium chloride (CsCl) density gradients for DNA stable isotope probing (DNA-SIP) assays. The separation of 12C- and 13C-labelled DNA using SYBR safe™ gave similar results to those obtained using EtBr with pure cultures and environmental samples exposed to a 13C-labelled substrate, while the detection limit of DNA was enhanced by the use of SYBR safe™ by at least 5 times. The results demonstrated that SYBR safe™ is a safe, sensitive and effective alternative to the use of ethidium bromide in CsCl density gradients for DNA-SIP assays.