Comparison of the efficiency of different cell lysis methods and different commercial methods for RNA extraction from Candida albicans stored in RNAlater.

backgroundObtaining sufficient RNA yield and quality for comprehensive transcriptomic studies is cumbersome for clinical samples in which RNA from the pathogen is present in low numbers relative to the nucleic acids from the host, especially for pathogens, such as yeasts, with a solid cell wall. Therefore, yeast cell lysis including cell wall disruption constitutes an essential first step to maximize RNA yield. Moreover, during the last years, different methods for RNA extraction from yeasts have been developed, ranging from classic hot phenol methods to commercially available specific kits. They offer different RNA yield and quality, also depending on the original storage medium, such as RNAlater.

resultsWe observed that, for C. albicans cells stored in Tryptic Soy Broth with 15% glycerol, 10 min of bead beating in a horizontal position in RiboPure Lysis Buffer provided complete cell lysis. Cell lysis efficiency was decreased to 73.5% when cells were stored in RNAlater. In addition, the RiboPure Yeast Kit (Ambion) offered the highest RNA yield in comparison with the automated platform NucliSENS easyMAG total nucleic extraction (bioMérieux) and the RNeasy Mini Kit (Qiagen) according to NanoDrop and Fragment Analyzer. Moreover, we showed that, in spite of the decrease of cell lysis efficiency after RNAlater storage, as compared to storage in TSB + 15% glycerol, RNAlater increased RNA yield during RNA extraction with both RiboPure Yeast Kit and easyMAG, as confirmed by Fragment Analyzer analysis and by RT-qPCR of the RNA from the Internal Transcribed Spacer 2.

conclusionsIn our hands, the most efficient cell lysis and highest RNA yield from C. albicans cells stored in RNAlater was obtained by horizontal bead beating in RiboPure Lysis Buffer followed by RNA extraction with the RiboPure Yeast Kit.