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Table 2 Inability of RT-qPCR to detect invA mRNA in RNA extracts not treated with DNase I

From: Comparison of commercial RNA extraction kits for preparation of DNA-free total RNA from Salmonella cells

RNA extraction kit Manufacturer invA mRNA copies/rxn
RT-qPCR [Cq]a
invA DNA copies/rxn
qPCR [Cq]b
invA mRNA presence
(Cq qPCR - Cq RT-qPCR)c
RiboPure-Bacteria Ambion (1.9 ± 1.6) × 106 [25.5 ± 1.8] (1.8 ± 1.8) × 106 [24.8 ± 1.4] -0. 7 (Negative)
PureLink RNA Mini Invitrogen (1.2 ± 0.5) × 108 [18.8 ± 0.6] (1.5 ± 0.8) × 108 [18.5 ± 0.7] -0.3 (Negative)
RNeasy Mini QIAGEN (7.9 ± 2.2) × 107 [19.3 ± 0.4] (1.1 ± 0.3) × 108 [18.9 ± 0.4] -0.4 (Negative)
MasterPure RNA Purification EPICENTRE Biotechnologies (5.8 ± 0.8) × 108 [16.4 ± 0.2] (8.8 ± 0.9) × 108 [15.9 ± 0.2] -0.3 (Negative)
UltraClean Microbial RNA Isolation MoBio (2.2 ± 0.6) × 108 [17.8 ± 0.4] (3.4 ± 0.8) × 108 [17.3 ± 0.3] -0.5 (Negative)
  1. rxn, reaction.
  2. ainvA mRNA copies per reaction are mean values of 6 determinations ± standard deviations.
  3. binvA DNA copies per reaction are mean values of 6 determinations ± standard deviations.
  4. c- If <4 is negative or inconclusive for invA mRNA presence due to DNA contamination.
  5. Detection limit of the invA qRT-PCR and invA qPCR are 40 and 10 copies per reaction, respectively [7]