Gold Magnetic Particles Purified Bacterial Genomic Dna

Recently, the magnetic composite particles based nucleic acid purifications are increasingly demonstrating its advantages. These nanoparticles possess a superparamagnetic property which allow for a quick and efficient purification after nucleic acid binding by using a permanent magnet. This centrifuge-free purification is suitable for automatic workstaition and meets the demand of the future needs. GoldMag(R) nanoparticles were synthesized by our research group and used for bacterial genomic DNA isolation in this study.First, we established a simple, rapid, nonhazardous and economical method for extraction of genomic DNA from Gram-negative bacteria. Data showed that the yield of DNA extracted by GoldMag(R) particles was about 20μg per 0.5 ml of E. coli culture (OD600=3.0), which was approximately three times as much as that of a commercial kit. The quality of DNA obtained was demonstrated by the absorbance ratio (OD260/OD280), which was between 1.7 and 1.9, and compatible with PCR amplification. In order to evaluate the stability of this method, E. coli and P. aeruginosa were used. The yeild of DNA extracted from E. col have an average intra-batch CV (coefficient of variance) of 3.98%(less than 4%), and an inter-batch CV of 8.41%. The yeild of DNA extracted from P. aeruginosa have an average intra-batch CV of 7.32%, and an inter-batch CV of 10.67%.This paper also conducted a preliminary study on the isolation of genomic DNA from Gram-positive bacteria. We determined the optimized concentrations of lysozyme and RNase that were used, and compared three sample pretreatment approaches. The yield of DNA extracted by this optimized method was 2-4μg per 0.5 ml Bacillus subtilis culture (OD600=3.0) with an OD260/OD280 ratio of 1.7-1.9. And the qualtity of DNA was quite suitable for PCR amplification.