Professional Marijuana Grower


Yeast, Regulations and Its Indirect Role in Photosynthesis

Posted January 2nd, 2019 by Eric Lancaster in ,

You never know where your day is going to take you. I received an email from a customer who had run a sample of one of our products through a cannabis testing lab. The customer was concerned because the product tested positive for lots of ‘yeast and mold’. Their concern was two-fold: 1) Some states are requiring anything used in a grow to be free of yeast and mold for fear of contaminating the plants and getting people sick; 2) They were concerned the yeast and molds could harm the plants.

My initial reply was, “Of course it tested positive, our product contains yeast.” Yeast will cause a yeast and mold test to produce a positive result. However, the tests are not testing only for pathogens vs beneficials.  This means the tests will pick up everything including beneficial microbes. Yeast and fungi will show up and cause a grower to fail. This is part of the reason why people using compost teas or other probiotic farming methods in their grow are failing state lab tests. It is not they necessarily have a “dirty” grow, have used pesticides, or have toxic mold on their plants. In some cases, they used some type of probiotic culture to spray their plants during

the flowering stage, most likely in a mixed tea like compost tea. (To avoid testing positive for yeast and mold on a plant, do not spray any microbial products on the upper parts of the plants once they go into flower.) Some states are now making restrictions on anything that goes into the grow area to be free of any microbes (yeast, mold, fungus, etc.) and for it to be registered with the State Department of Agriculture. This could possibly lead to being unable to use beneficial fungi such as VAM inside a cannabis grow at any stage of growth and, since yeast and mold are everywhere, quite possibly the end of legal outdoor grows for commercial sale.

The ignorance is astounding and it is what happens when people who do not grow cannabis plants write the regulations. They are ignoring decades old research proving how essential microorganisms are to growing plants. Needless to say, this is frustrating for a company that sells beneficial microbial products.

I still needed to answer the second concern about yeasts being good or bad for plants. My response, “the yeast produce various substances that are good for plants” needed some more reasons why. I started to dig around on the internet first by finding some common enzymes produced by Saccharomyces cerevisea, the yeast in our main product, EM•1® Microbial Inoculant.  I found the following 7 enzymes studied in a paper by Christoph Beck and H. Kaspar Von Meyenburg published all the way back in 1968!(1) These enzymes were  succinate-cytochrome c oxidoreductase, malate dehydrogenase, nicotinamide adenine dinucleotide-linked glutamate dehydrogenase, malate synthase, isocitrate lyase, aldolase, and nicotinamide adenine dinucleotide phosphate (NADP+)-linked glutamate dehydrogenase. (Imagine that this type of information has been around for 50 years and people are still ignorant as to how important microbes are to plant and human health!).

I am no expert about enzymes, but I do know they are specialized proteins that speed up specific reactions…and, they are all produced by microbes. So, I needed to find out what each of these do and started looking a couple of these up. The first was aldolase. It has a critical role in breaking down carbon bonds in glycolysis (the breakdown of sugars). Succinate-cytochrome c oxidoreductase plays a critical role in biochemical generation of ATP (energy).  Isocitrate lyase has been found to have anti-fungal properties, metabolizes acetate and fatty acids, and fights mycobacterium tuberculosis, Candida albicans, L maculans, Rhodococcus fascians (a few human and plant pathogens here).

Lastly, I took a look at nicotinamide adenine dinucleotide phosphate (NADP+)-linked glutamate dehydrogenase and I noticed the common factors with just these 3 enzymes…they are all involved in photosynthesis. So, I started watching presentations on YouTube on photosynthesis and noticed none of the presentations would say where NADP+ came from or where ADP came from. The answer is that they come from an interaction of microbes with sugars and are metabolites produced by yeast. Both are crucial to energy conversion (both in light (daytime) and without light events (night time) on the cellular level in the Calvin Cycle where G3P or glyceraldehyde-3-phosphate (a carbohydrate which can be used to build glucose, starch, cellulose or other molecules that the plants need).

The role yeast has to play in breaking down sugars into small enough particles that the ADP and NaDP+ are to fuel photosynthesis seems to never be addressed. Yet, this all occurs in the chloroplasts and will end up having a huge impact on how well a cannabis plant will grow and the production of oxygen so we can breathe. Pretty wild! I’ll have to keep reading on enzymes effects on plant hormones and share what I learn in another article.

Eric Lancaster is Executive Vice President of TeraGanix, Inc., the exclusive North America distributor of Effective Microorganisms® and EM® Bokashi products. He is the technical expert on Effective Microorganisms® for the US market. For more information, visit

  1. Christoph Beck, H. Kaspar Von Meyenburg. Enzyme Pattern and Aerobic Growth of Saccharomyces cerevisiae Under Various Degrees of Glucose Limitation. Journal of Bacteriology Aug 1968, 96 (2) 479-486; DOI:

Calvin Cycle Image courtesy of Khan Academy.

Saccharomyces cerevisea image courtesy of

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