Evaluation of five DNA extraction methods for Probiotic yogurt and powder

Yogurt and Lactic acid bacteria( LAB) powder were chosen as samples.The sampling quantities,solvents of LAB powder and incubation time of lysozyme have been optimized to remove fats,proteins and polysaccharides.Then five commercialized DNA extraction kits were compared on their DNA extraction efficiency after sample pretreatment. The quality and quantity of the extracted DNA were evaluated by Nano Vue Plus and conventional PCR.It is showed that when the sampling quantity of yogurt was 100 mg,the DNA concentration was49.00 ng / μL,and A₂₆₀/A₂₈₀ ratio was 1.8. The milk was more suitable as the solvent for LAB powder compared to distilled water,and when the sampling quantity of LAB powder was 0.5 g / m L,the DNA concentration was 81.00 ng / μL.The best incubation time of lysozyme was 1 h,and the expanded incubation time had no significant improvement for cell lysis.The extracted DNA concentrations from five kits were all over 20 ng / μL,and the A₂₆₀/A₂₈₀ ratio was greater than or close to 1.8.Among the five kits,the one from Tiangen had the best DNA concentration and purity.It was proved that the established pretreatment method can effectively remove fats,proteins and polysaccharides.Each of the five kits can be used to extract DNA from yogurt and LAB powder,however,the choice should be made based on different experiment requests.