Can pesticides fail black mold and microbe PCR tests?

Laboratories and regulators want to test cannabis for more and more contaminants to ensure a high standard in the market. However, despite their critical importance, these tests are never perfect. There’s an uphill battle while preventing (trying) a wave of aspergillosis without killing quality products. Overcoming this problem with more detailed laboratory results means that certain pesticides may fail the black mold PCR tests due to hidden GMOs. But that depends on the particular formulation.

Some approved fungicides use a benign fungus as an active ingredient. These beneficial insects repel invasive types of mold and mildew, thus maintaining yield and quality. However, some ingredients may contain pollutants or recombinant genetics that would force a manufacturer to remediate according to strict guidelines; it is still a victim.

Given the transgenic IP, is the PCR better than the whole colony?

Total CFU (Colony Forming Unit) count is a test to measure the amount of microbial contamination. But not without restrictions, as we have to develop special tests to identify the few species that can colonize. The samples are grown on various growth media and either a human or a computer counts the total cell colony. However, different mold colonies can be better identified by a PCR test.

At the very least, one would think that a molecular test would be superior to a CFU count. PCR tests take a piece of genetic material and replicate that piece until enough samples can be collected and identified. And yet, molecular testing has its own limitations. For example, PCR cannot identify between live and dead cells without prior separation, so a benign fungus will still give a positive result.

PCR test (polymerase chain reaction). Photo by Analogicus courtesy of Pixabay.

Modified Black Mold Genetics, a Purpose and a Problem

Trichoderma is a naturally occurring mold that is vital to healthy agricultural soils. But the strain, KRL-AG2 from Bioworks, was once genetically engineered using DNA from a black mold, Aspergillus niger. A limitation is formed here; that is, a PCR test could detect the genetics of mold or bacteria that have been intentionally introduced into an approved ingredient. This particular gene can therefore lead to a false positive result. To avoid all of this, KRL-AG2 has a colony formation test based on specific growth media and morphology that are not affected by recombinant genetics.

And then the intellectual property for transgenic Trichoderma was abandoned by Bioworks in 2009. In 2002, however, they listed the harmful black mold strain as a possible contaminant. Since then, the pesticide maker has updated its formulation according to an email response from its Technical Services Manager.

Our current Trichoderma is non-transgenic and does not contain genes intentionally introduced from Flavalus or Aspergillus. Our formulation does not correspond to our knowledge [and should not] Contain F. flavalus or Aspergillus niger.

Erfan Vafaie, Ph.D. – Biowerk

Check each other’s work for cleaner pesticides and probiotics

Dr. Vafaie mentioned new quantifiable information that suggests it would be valuable to research. Additionally, PCR tests can still give a false positive or fail – if another company formulates its pesticides using a similar recombinant technology. But pesticides only seem to be part of the battle to ensure contaminated beneficial insects and their genetics don’t get into the farm.

Kyle Boyar, a research fellow at the University of California San Diego Skaggs School of Pharmacy with extensive experience in cannabis testing, recently published a chapter on the nuances of microbial testing in Recent Advances in the Science of Cannabis. Boyar’s concerns revolve around mold and mildew in the cannabis field and their surprising sources.

Anecdotal reports suggest that probiotic products used by certain growers may have contributed to some Aspergillus contamination. A lesson for breeders when you consider that the contamination was supposedly only discovered through third-party testing. Although approved pesticides are more stringent than probiotics and nutrients, mistakes are still possible. A peer-reviewed process where licensed manufacturers self-test third-party pesticides seems ideal for profitability of cultivation and consumer safety.

Let us know in the comments what you think of pesticide use in the cannabis industry. Have you ever grown grass and been plagued by a case of powdery mildew?

sources

1. US20090104165
2. Tut, G .; Magan, N .; Brain, P .; Xu, X. Critical evaluation of two commercial biocontrol agents for their effectiveness against B. cinerea under in vitro and in vivo conditions in relation to various abiotic factors. Agronomy 2021, 11, 1868.
3. Punja, ZK, Collyer, D., Scott, C., Lung, S., Holmes, J. & Sutton, D. (2019). Pathogens and Molds Affecting the Production and Quality of Cannabis sativa L. Frontiers in Plant Science, 10, 1120.
4. PMRA. RootShield Biological Fungicide, Trichoderma harzianum Rifai strain KRL-AG2. 2009. Government may.

Footnote (s)

https://doi.org/10.3390/agronomy11091868
https://doi.org/10.3389/fpls.2019.01120