Horticulture

Secrets in the Soil: Beneficial Microbes for Cannabis Cultivation

We live in an antimicrobial world where disease may lurk around any corner and hand sanitizer may seem like a godsend. There’s no doubt that there are microbes that infect our plants and food and can harm or kill us. The flip side is that there are also beneficial microbes like probiotics. Our attempts at ridding ourselves of bad microbes through antibiotics can take its toll on useful bacteria within our guts. In fact, the microbiota of our guts has been found to have massive implications on our well-being. [1]

Earth’s flora can benefit from good microorganisms, too, and a recent study considered beneficial microbes for Cannabis sativa. [2] When a cannabis plant gets biotically stressed, secondary metabolites like cannabinoids and terpenes can be affected. [3,4] Sometimes it’s the things that bug you that make you stronger.

For example, it’s been shown that things like poor soil [5], potassium deficiencies, and moisture increased delta-9-tetrahydrocannabinol (THC) in hemp [6]. Nitrogen-phosphorus-potassium (NPK) nutrients increased cannabigerol potency in flowers while decreasing cannabinol levels. [7]

The concentration and abundance of microbiota like bacteria and fungi can be modified by human mediation. The question is can they be modified to augment secondary metabolites in cannabis? The authors point to terpenoid indoles like serpentine in a type of periwinkle that increased when inoculated with strains of Staphylococcus and Micrococcus bacteria. [8]

Molecules like abscisic acid, gibberellins, and ethylene have been evaluated with cannabis [9], and it’s thought that these “exogenous inducers” could synergize with endophytic bacteria native to cannabis, thereby augmenting THC and CBD concentrations. Plant growth-promoting rhizobacteria like Pseudomonas and Bacillus have been considered for their ability to increase cannabinoid yield, but there’s a whole microbiome out there, and different organisms can do different tasks. The authors report “[d]ifferent microbes can colonize various areas of the root, increasing the total root biomass and nutrient acquisition capacity. Some microbial strains protect plants against pathogen attacks, while others improve the resilience and recovery of plants subjected to stress.”

A genetic analysis can seek out and identify microbial genes that might augment bioactive compounds in cannabis via their specific functionality. The authors elegantly report that “decoding the community profile of cannabis-associated microbes would produce a large list of microbes to choose from and its microbiota would unravel the complexity of stabilizing cannabinoid production.”

A study of five cultivars, including Bookoo Kush, Burmese, Maui Wowie, White Widow, and Sour Diesel identified a central cannabis bacterial population composed of Pseudomonas, Cellvibrio, Oxalobacteraceae, Xanthomonadaceae, Actinomycetales, and Sphingobacteriales. [10] Amazingly, the CBD potency linked with the structure of bacterial communities in the root system, and THC potency associated with soil properties that shape living soil diversity like temperature, pH, and salinity.

A microbial biostimulant called Mammoth P boosted aerial biomass by 16.5%, but no cannabinoid enhancement was detected. [11] Other studies have shown that microbial communities can evolve within cannabis with different cultivars revealing different microbial genera. [12] And as mentioned, microbes can stimulate secondary metabolite production. Trichoderma harzianum, for example, stimulated CBD and biomass yield in hemp. [13]

The point of all of this is to harness the power of the “core microbiota” in cannabis to boost secondary metabolites like cannabinoids and terpenes by “selecting microbes that enhance nutrient security, plant health, and chemical compound biosynthesis for a particular genotype…” [2] Given that this approach has worked for many other plants like corn, wheat, and soybeans, and the desire for more stabilized and sustainable cannabis cultivation is of interest, it’s worth diving in to the microbial pool to find natural ways to create symbiosis between your plants and their soil.

 

References

[1] Shreiner AB, Kao JY, Young VB. The gut microbiome in health and in disease. Curr Opin Gastroenterol. 2015;31(1):69-75. [journal impact factor = 3.287; times cited = 723]

 

[2] Ahmed B, Hijri M. Potential impacts of soil microbiota manipulation on secondary metabolites production in cannabis. J Cannabis Res. 2021;3(1):25. [journal impact factor = N/A; times cited = 1]

 

[3] Pate DW. Chemical ecology of Cannabis. J Int Hemp Assoc. 1994;2:32–7. [journal impact factor = N/A; times cited = 134]

 

[4] Gorelick J, Bernstein N. Elicitation: an underutilized tool in the development of medicinal plants as a source of therapeutic secondary metabolites. Adv Agron. 2014;124:201–30. [journal impact factor = 5.886; times cited = 91]

 

[5] Krejci Z. Changes with maturation in the amounts of biologically interesting substances of cannabis. In C. R. B. Joyce and S. H. Curry (Eds.). The botany and chemistry of Cannabis. London: Churchill; 1970. p. 49.

 

[6] Haney A, Kutscheid BB. Quantitative variation in the chemical constituents of marihuana from stands of naturalized Cannabis sativa L. in east central Illinois. Econ Bot. 1973;27:193–203. [journal impact factor = 1.731; times cited = 12]

 

[7] Bernstein N, Gorelick J, Zerahia R, Koch S. Impact of N, P, K, and humic acid supplementation on the chemical profile of medical Cannabis (Cannabis sativa L). Front Plant Sci. 2019;10:736. [journal impact factor = 4.298; times cited = 31]

 

[8] Etalo DW, Jeon JS, Raaijmakers JM. Modulation of plant chemistry by beneficial root microbiota. Nat Prod Rep. 2018;35:398–409. [journal impact factor = 13.423; times cited = 44]

 

[9] Taghinasab M, Jabaji S. Cannabis microbiome and the role of endophytes in modulating the production of secondary metabolites: an overview. Microorganisms. 2020;8. [journal impact factor = 4.128; times cited = 20]

 

[10] Winston ME, Hampton-Marcell J, Zarraonaindia I, et al. Understanding cultivar-specificity and soil determinants of the cannabis microbiome [published correction appears in PLoS One. 2014;9(9):e107415. Hartsel, Josh [corrected to Hartsel, Joshua A]]. PLoS One. 2014;9(6):e99641. Published 2014 Jun 16. doi:10.1371/journal.pone.0099641 [journal impact factor = 3.24; times cited = 50]

 

[11] Conant RT, Walsh RP, Walsh M, Bell CW, Wallenstein MD. Effects of a microbial biostimulant, Mammoth PTM, on Cannabis sativa bud yield. J Hortic. 2017;4:191. [journal impact factor = N/A; times cited = 17]

 

[12] Comeau D, Novinscak A, Joly DL, Filion M. Spatio-temporal and cultivar dependent variations in the cannabis microbiome. Front Microbiol. 2020;11:491. [journal impact factor = 5.640; times cited = 10]

 

[13] Kakabouki I, Tataridas A, Mavroeidis A, Kousta A, Karydogianni S, Zisi C, et al. Effect of colonization of Trichoderma harzianum on growth development and CBD content of hemp (Cannabis sativa L.). Microorganisms. 2021;9:518. [journal impact factor = 4.128; times cited = 4]

About the author

Jason S. Lupoi, Ph.D.

Jason S. Lupoi, Ph.D.

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