Microbes such as yeast or bacteria are difficult to lyse due to their thick cell wall, which makes nucleic acid extraction difficult. Gram positive bacteria for example, have a cell envelope comprised of the plasma membrane and a thick cell wall containing peptidoglycans. The most common technique for microbial extraction is the use of chemical lysis reagents such as ionic detergent followed by physical grinding with mortar and pestle in liquid nitrogen. The Precellys® homogenizers offer an alternative and more effective lysing solution for DNA and RNA extraction to be used for molecular biology research, such as sequencing, PCR or cloning.
With the new 15 ml tube designed for micro-organisms lysing, you can reach a higher volume (up to 9 ml) of lysed suspension at once.
After 24h of incubation at 37°C, results were observed. The plate count is linear for E. coli over the range of 30 – 300 CFU on a standard sized Petri dish. We kept the two dilutions in this range to calculate the lysing efficiency.
Table1: results of the lysing step with 9 ml of bacterial suspension, in duplicate. Each lysing suspension was spread on an agar plate in duplicate (100 μl).
Concentration of the starting solution was validated by spreading 100 μl on agar plate of corresponding dilution.
Figure1: E-coli culture
The VK05 15ml kit is very efficient as we observed percentage of mortality > 95% after lysing in comparison with the initial suspension of bacteria.