It’s well known that plants express Terpenes as a response to their environment and as a communication language with microbes and insects. What is less well known is that bacteria are quite effective at synthesizing terpenes and are also involved in modification of plant terpenes.

Yamada et al

Yamada et al


Terpene synthesis seems quite common in bacteria although the terpenes do not seem to be the terpenes most commonly seen in Cannabis.


screen-shot-2016-11-29-at-3-24-03-pmDespite this, fumigation of plants with antibiotics changes the terpene profile of the plants suggesting the bacteria are involved in terpene modification or metabolism of precursors.



What is the impact of the microbial load of Cannabis flowers on terpene production? Lets pull two samples from a local dispensary and have a look. Harijuana is an ocimene dominant strain sold in Massachusetts dispensaries. Ocimene is a known anti-fungal compound. White Fire is a Limonene and Linalool dominant strain. Limonene is used as a food preservative to prevent spoilage. Linalool has strong anti-microbial properties.


16S bacterial profiles of different strains from the same producer

  • Harijuana is Ocimene dominant. Click on links to see Krona chart.
  • White Fire is Limonene and Linalool dominant.

Here is another example of these 16S reports on a Hydro’s root bacteria compared to its Flower bacteria. Can you tell which one is Root and which is soil?


One hint can be found in the Ralstonia picketti gene known as  “Terpene utilization protein AtuA”.

A second hint can be found in Azospirillum lipofecums genome with this entire terpenoid synthesis pathway. Notice parts of this pathway utilize IPP and Mevalonate. These are precursors to cannabinoids and terpenes. One can see these pathways lead to sesquiterpenes and triterpenoid biosynthesis. This bacteria is found in both samples but is more prevalent in one versus the other. There are also “acne” bacteria associated with human contact in one sample while we see soil bacteria in the other. Acidovorax sp. Strain KKS102 is found in soils and known for its degradation of PCBs.



It is important to reflect on the fact that we have CFU/g as a microbial threshold in safety testing?  It would appear knowing the precise microbial make up is more relevant to safety than just anything that can form a colony. Without getting more specific, we will continually fail products for beneficial microbes and likely limit the diversity of terpenes we can see in cannabis. These false positive microbial fails will induce more unwarranted fungicide use (Eagle-20).