Biofilms are a common problem in cannabis grow operations. These slimy layers of microbial colonies can clog the irrigation system, spread plant diseases and reduce oxygen levels in the nutrient solution.
One way to eliminate biofilms is with enzyme-based cleaners. Enzymes are biological catalysts, or biocatalysts, that trigger and accelerate chemical reactions in living things. They offer a practical, non-harmful approach to degrading and removing biofilm.
How enzymes degrade biofilms
Enzymes are proteins that catalyze specific chemical reactions. They are involved in all essential life processes; for instance, certain enzymes enable carbon dioxide to transfer from bodily tissue to the bloodstream—and thence to the lungs for exhalation. Every enzyme is designed to act on a particular substrate, also known as the targeted compound.
The enzymes used in biofilm cleaners target the biofilm’s extracellular polymeric substances (EPS), a complex matrix of macromolecules that acts as a protective barrier for microbes. When enzymes encounter the EPS, they degrade and tear the biofilm apart by continuously separating the EPS cells. This chemical reaction occurs at a blinding rate, resulting in new enzymatic compounds that separate off and catalyze new reactions.
Figure 1: Bacillus cereus biofilm on a stainless-steel surface after 48 hours of incubation: (A) Bacillus cereus biofilm with a visible EPS matrix. (B) A ring surface after a cleaning procedure with caustic soda (0.5%, 30 minutes at 45 °C). Some of the biofilm has been removed (5.2E+04 CFU). What remains on the surface is the entire biofilm structure. So, the EPS matrix is still protecting the microorganisms. (C) The ring surface after an enzyme-based cleaning procedure. The biofilm matrix has been removed and only bacterial cells are visible. Source: Boels, Gauthier. “Enzymatic Removal of Biofilms: A Report.” Virulence 2, no. 5 (2011): 490–489. doi:10.4161/viru.2.5.17317.
The efficacy of enzymes depends largely on the enzyme type and EPS composition. Ideally, if the correct enzyme or mixture of enzymes can be identified for the breakdown of specific substrates for a particular biofilm, biofilm removal is possible.
Once partly degraded, the biofilm matrix becomes more susceptible to removal through mechanical means such as flow, pressure or brushing.
Benefits of enzyme-based cleaners
Because enzymes are designed to interact with specific targeted compounds, they do not create byproducts or harmfully impact beneficial microorganisms in the grow operation.
This is a big advantage over disinfectants like chlorine-based products, which often have broad efficacy and leave behind residues that may harm crops or beneficial microorganisms, or erode equipment. Chemical agents can also be harmful to people, causing skin or respiratory irritation if not handled properly. Because disinfectants have been used for centuries, biofilm resistance to these products is also a concern; multiple applications of a chemical may be required to achieve complete removal. Figure 2 schematically illustrates the two approaches to removing biofilms.
Figure 2: Comparison of the effectiveness of traditional and enzyme-based cleaning techniques. Source: Liu, Xiaobo, Bo Tang, Qiuya Gu, and Xiaobin Yu. 2014. “Elimination of the formation of biofilm in industrial pipes using enzyme cleaning technique.” MethodsX 1: 130–136. https://doi.org/10.1016/j.mex.2014.08.008
Other traditional methods such as scrubbing remain effective, but they can be time and labor intensive. They may also cause surface damage to equipment in the grow operation.
Traditional biofilm removal methods also often result in the dispersion of biofilm microbes in a mobile, planktonic form,[1] allowing them to freely contaminate the grow operation.
An additional benefit of enzyme-based cleaners is that small amounts of enzymes can produce large reactions, so less product is required. They are also often commercially available in an immobilized form, providing continuous degradation of biofilm.
Need an enzyme-based cleaner? Emerald Harvest’s Hydra Clear is a safe and powerful multienzyme line cleaner with a 100-to-1 dilution ratio, so you can keep your cannabis grow operation clear of biofilm, consistently and easily.
[1] Bacteria either exist in a mobile, planktonic state where they freely disperse, or remain static as biofilms.
The Emerald Harvest Team
