Taking the inhibitor tolerance to another level

  • Published: 10 February 2022
Have you heard about the inhibitor tolerance of SolisFAST® products? Throughout the years we have gotten feedback from our partners that the products in our SolisFAST® range have outperformed many competitors who advertise inhibitor tolerance as their main feature. Of course, as people of science, we needed to add another layer in it. So, we decided to put our SolisFAST® products to the test.

SolisFAST® DNA Polymerase is an in silico designed enzyme with fast extension rates and a programmed tolerance to inhibitory substances. While we were already aware that SolisFAST® products exhibited inhibitor tolerance, we never really considered it as a big thing. For us it was more about speed. So, to make things interesting we decided to push the limits even further and not just test how tolerant the products are, but also whether they can show good tolerance with really quick cycling protocols. To make it even more difficult, we picked 3 competitors who advertise inhibitor tolerance as their main feature. Here is what happened.

Products we tested:

Target: 72 bp albumin gene, 20 ng of human gDNA per reaction.
Tolerance criteria: delta Cq value ≤ 1 (compared to reaction without the inhibitor on the same qPCR plate).
Thermal protocols: Reactions were run on Bio-Rad CFX96 platform. A faster cycling protocol was used with SolisFAST® products (3 min 95°C, followed by 45 cycles of 3 sec 95 °C, 10 sec 60 °C), compared to competitor products (3 min 95 °C, followed by 45 cycles of 10 sec 95 °C, 30 sec 60 °C). Competitors’ programme was chosen according to their technical documentations.

To assess the inhibitor tolerance of our SolisFAST® probe-based qPCR mixes, a test system was created and the impact of individual inhibitors, mainly found in PCR reactions, to the products was evaluated. As previously mentioned, we used a really fast protocol for our products, which none of the competitors use. The estimated run time difference between the two mentioned protocols is approximately 20 minutes.

In total we tested 17 inhibitors from various different sources like soil, blood, urine, plants and sample preparation.

Representative inhibitors from different sources are seen in this table:

Why were these inhibitors chosen?

Tolerance to urea is beneficial for diagnostics of UTI-s (urinary tract infections), STD-s (sexually transmitted diseases) and also fecal samples. Pectin is a common inhibitor in plant samples. DMSO is often used in sample pre-treatment steps and also as a PCR enhancer. To get the most out of the positive effects of using DMSO, the PCR performance itself should not be inhibited by it. Therefore, tolerance to DMSO is an important feature. NaCl and PBS are also common inhibitors from sample preparation steps. Our performance is on par with ethanol, which can easily become a contaminating agent to a PCR reaction, as it is often used in sample preparation and DNA extraction processes. Humic acid is a challenge with soil samples, as well as environmental, sewage, water and sometimes plant samples. Last but not least, hematin may cause problems in analysis of blood samples.

There is a saying that slow and steady wins the race, but our SolisFAST® products performed way beyond expectations showing great inhibitor tolerance comparable to other top products on the market while being the fastest out of the bunch.

Right now it is also possible to order all the SolisFAST® products with a 20% discount from our E-shop, so there is no better time to test them out yourself and let us know how fast you got your results.

With this supporting information we encourage you to test our SolisFAST® products on your complex samples, where PCR inhibition is an issue and robust amplification is needed.

There will be more information coming soon, so stay tuned!