US Researchers Call for Re-Evaluation of Microbial Testing of Cannabis Following New, Sequencing-Based Study
London, United Kingdom, June 16, 2016 --(PR.com)-- A new US study suggests that some of the medicinal benefits of dispensary grade Cannabis could be compromised because the flowers host potentially harmful yeasts and toxic molds, which cannot be detected by industry standard culturing techniques.
The report, ‘Cannabis microbiome sequencing reveals several mycotoxic fungi native to dispensary grade Cannabis flowers’, by Kevin McKernan and a team from Medicinal Genomics Corporation in Massachusetts, has passed peer review http://f1000research.com/articles/4-1422/v2
The authors say that with the availability of medical Cannabis in some US states and in other countries, there is an increasing regulatory requirement for the microbial testing of Cannabis samples for both medicinal and recreational applications.
However, scientists know relatively little about the nature of all the microbes that may commonly live on the Cannabis plant, and whether existing food industry-standard culture techniques can effectively identify potentially harmful organisms in dispensary-grade samples. Moreover, while regulations may require Cannabis growers to ‘heat kill’, or pasteurize Cannabis flowers to reduce their microbial content, pasteurization may not eliminate every pathogenic toxin or spore, McKernan’s team points out.
The researchers carried out what they claim is the first, next generation sequencing survey of microbes found in dispensary-derived Cannabis flowers, and compared their results with those cultured from the same samples using standard food-industry platforms.
Their results showed that the polymerase chain reaction (qPCR) and next generation sequencing approach identified a range of yeast and mold species in about a third of 17 Cannabis samples obtained from dispensaries in the US and the Netherlands. In contrast, three different standard culture platforms failed to detect all of the positive samples.
Kevin McKernan said: “Following the publication of the Cannabis genome and many other pathogenic microbial genomes, quantitative PCR tests have been developed that can accurately quantify fungal DNA present in Cannabis samples.
“We have detected the DNA of microbes and the genes that synthesize paxilline and citrinin. Further LC-MS/MS assay development is required to detect the presence of these synthesized toxins in the complex background of cannabinoids and terpenoids.”
Animal studies have previously shown that citrinin and paxilline can reduce or potentially interfere with the anti-seizure properties of the active Cannabis constituent, cannabidiol. Yet existing commercial antibody-based toxin assays are not designed to test for the citrinin and paxilline toxins in Cannabis.
The researchers conclude that culture-based techniques currently used for the microbial testing of Cannabis should be re-evaluated, and that additional sequencing-based studies need to be carried out to investigate qualitatively and quantitatively the extent of the Cannabis microbiome.
The team is particularly keen to examine whether the paxilline toxin is present in Cannabis samples, as even very tiny quantities could undermine the effects of the very low levels of cannabidiol that are commonly used to manage seizures.
Kevin McKernan said: “Based on the political and controversial nature of cannabis, this work would have been very difficult to publish in other journals. We believe the open peer review system at F1000Research is disruptive. It provides such higher quality review that it will be our default journal of choice going forward.”
Rebecca Lawrence, Managing Director of F1000, owner of F1000Research, said: “This is a fascinating study, and we are delighted to enable the researchers to quickly bring it into the public domain where its significance can be assessed by the wider scientific community.”
How to cite this article:
McKernan K, Spangler J, Zhang L et al. Cannabis microbiome sequencing reveals several mycotoxic fungi native to dispensary grade Cannabis flowers [version 2; referees: 2 approved]. F1000Research 2015, 4:1422
(doi: 10.12688/f1000research.7507.2)
For more information:
Andrew Baud, Tala (on behalf of F1000 Research), +44 (0) 20 3397 3383 or +44 (0) 7775 715775
About F1000Research
F1000Research is an open science publishing platform for life scientists that offers immediate publication and transparent peer review, avoiding editorial bias and ensuring the inclusion of all source data. This process helps scientists to avoid the traditional, anonymous, pre-publication peer-review process that can cause long delays before new results become visible.
All articles must pass an initial in-house quality check prior to publication on F1000Research. Following open, invited peer review where the referee’s name and affiliation and the referee reports are published alongside the article, authors can make revisions that are then published as new article versions.
Since its launch in January 2013, F1000Research has published more than 1000 articles across the life sciences, written by 4,000 authors. For more details on F1000Research go to www.f1000research.com
The report, ‘Cannabis microbiome sequencing reveals several mycotoxic fungi native to dispensary grade Cannabis flowers’, by Kevin McKernan and a team from Medicinal Genomics Corporation in Massachusetts, has passed peer review http://f1000research.com/articles/4-1422/v2
The authors say that with the availability of medical Cannabis in some US states and in other countries, there is an increasing regulatory requirement for the microbial testing of Cannabis samples for both medicinal and recreational applications.
However, scientists know relatively little about the nature of all the microbes that may commonly live on the Cannabis plant, and whether existing food industry-standard culture techniques can effectively identify potentially harmful organisms in dispensary-grade samples. Moreover, while regulations may require Cannabis growers to ‘heat kill’, or pasteurize Cannabis flowers to reduce their microbial content, pasteurization may not eliminate every pathogenic toxin or spore, McKernan’s team points out.
The researchers carried out what they claim is the first, next generation sequencing survey of microbes found in dispensary-derived Cannabis flowers, and compared their results with those cultured from the same samples using standard food-industry platforms.
Their results showed that the polymerase chain reaction (qPCR) and next generation sequencing approach identified a range of yeast and mold species in about a third of 17 Cannabis samples obtained from dispensaries in the US and the Netherlands. In contrast, three different standard culture platforms failed to detect all of the positive samples.
Kevin McKernan said: “Following the publication of the Cannabis genome and many other pathogenic microbial genomes, quantitative PCR tests have been developed that can accurately quantify fungal DNA present in Cannabis samples.
“We have detected the DNA of microbes and the genes that synthesize paxilline and citrinin. Further LC-MS/MS assay development is required to detect the presence of these synthesized toxins in the complex background of cannabinoids and terpenoids.”
Animal studies have previously shown that citrinin and paxilline can reduce or potentially interfere with the anti-seizure properties of the active Cannabis constituent, cannabidiol. Yet existing commercial antibody-based toxin assays are not designed to test for the citrinin and paxilline toxins in Cannabis.
The researchers conclude that culture-based techniques currently used for the microbial testing of Cannabis should be re-evaluated, and that additional sequencing-based studies need to be carried out to investigate qualitatively and quantitatively the extent of the Cannabis microbiome.
The team is particularly keen to examine whether the paxilline toxin is present in Cannabis samples, as even very tiny quantities could undermine the effects of the very low levels of cannabidiol that are commonly used to manage seizures.
Kevin McKernan said: “Based on the political and controversial nature of cannabis, this work would have been very difficult to publish in other journals. We believe the open peer review system at F1000Research is disruptive. It provides such higher quality review that it will be our default journal of choice going forward.”
Rebecca Lawrence, Managing Director of F1000, owner of F1000Research, said: “This is a fascinating study, and we are delighted to enable the researchers to quickly bring it into the public domain where its significance can be assessed by the wider scientific community.”
How to cite this article:
McKernan K, Spangler J, Zhang L et al. Cannabis microbiome sequencing reveals several mycotoxic fungi native to dispensary grade Cannabis flowers [version 2; referees: 2 approved]. F1000Research 2015, 4:1422
(doi: 10.12688/f1000research.7507.2)
For more information:
Andrew Baud, Tala (on behalf of F1000 Research), +44 (0) 20 3397 3383 or +44 (0) 7775 715775
About F1000Research
F1000Research is an open science publishing platform for life scientists that offers immediate publication and transparent peer review, avoiding editorial bias and ensuring the inclusion of all source data. This process helps scientists to avoid the traditional, anonymous, pre-publication peer-review process that can cause long delays before new results become visible.
All articles must pass an initial in-house quality check prior to publication on F1000Research. Following open, invited peer review where the referee’s name and affiliation and the referee reports are published alongside the article, authors can make revisions that are then published as new article versions.
Since its launch in January 2013, F1000Research has published more than 1000 articles across the life sciences, written by 4,000 authors. For more details on F1000Research go to www.f1000research.com
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