Maejo University -- Mushroom Cultivation Training + Sustainability Program

Maejo University is an agricultural university on the outskirts of Chiang Mai. The campus is large and contains many rather scenic agricultural installations but few people. 

We walk through one large building that seems completely empty except for cases of enormous insects mounted with pins. After hearing voices down a hallway, we knock on an office door and discover we are in the wrong building.

A man in the office redirects us to another nearby large white building, where a similar process repeats. I lose the specifics here, as all conversations have been in Thai.

Eventually we find a young man who is knowledgeable about the mushroom cultivation/education program, though I didn’t catch his actual position. At this point, all program specifics and questions are being translated and this kind of mediated conversation invites imprecise language and some inaccuracy, so some details may reflect that.

The mushroom cultivation area consists of a large covered platform with a pile of substrate, wood or coal-fired steam sterilization stations, and a series of concrete huts. The substrate in this case is rubber tree sawdust, lime to lower the pH, and likely some other nitrogen source. The University experimented with a few different types of substrate ranging from other types of sawdust, rice hulls, sugar cane bagasse, and straw, but settled on rubber tree sawdust because the mushrooms seemed to grow the best on it. All substrates are sourced from local agricultural waste— when a professor at Maejo later describes the program, he emphasizes the focus on sustainability and rural poverty reduction.

The program is rather clever, with a three-fold impact.  The first impact is the reuse of agricultural waste products, the second is the production of a nutritious and popular food resource, and the third is the creation of an accessible education resource so farmers can fully apply mushroom cultivation practices on their own. The University produces mushrooms and refines the process based on available materials, holds workshops that allow local rural farmers to grow their own mushrooms and purchase pure cultures from the University lab, and sells pre-made inoculated bags to local villagers who don't have the resources to have a full growing operation. These bags sell for 7 baht each, and can produce (in best conditions) 5 flushes of mushrooms, each worth 12 baht, giving the producer ~50 baht of profit ($1.60) per bag.

The young man leads us through their cultivation system, naturally starting with substrate and ending with growing sheds. Notably, this operation is geared towards primary decomposers and doesn't require the substrate composting like farms growing Agaricus species. This makes for a simpler process. 

Substrate and steam pasteurizing equipment. Substrate was mainly rubber tree sawdust.

Ash chute in the sterilizer -- a wood/coal fire heats water into steam which is funneled into industrial drums containing bags of substrate

Bags of sterilized substrate, ready to be inoculated

Pure culture of various strains. Pieces of the "parent" bottle are used to inoculate other bottles (containing agar or potato dextrose substrate) to maintain the same genetic strain. Pieces of the "parent" bottles are also used to inoculate bottles of millet seed which is then used to inoculate larger bags of growing substrate.

This strain exudes a dark liquid. Each strain/species' colony looks a bit different. I'm not sure which species this is, as bottles were grouped and labelled in Thai.

Millet seeds are inoculated by pure culture. The fully colonized seeds are then used to inoculate the bags of substrate. Colonized millet is also sold to farmers who make their own substrate bags. The quality and purity of a strain is a critical part of mushroom farming.

Closeup of myceliated millet.

Inoculated millet seeds visible at the top of a recently sterilized bag of substrate.

"Front" of mycelium as it grows throughout the substrate, top to bottom. It may take a week or more to get to this point. Probably a Pleurotus species.

A particularly beautiful growth pattern. Species uncertain.

Fully colonized bags, ready to be placed in a temp/humidity (semi)controlled room for fruiting.

A stack of bags in the fruiting room.

Fruiting. Because of inconsistencies between common names, scientific names, labeling, and translation, I'm refraining from naming most of the specimens pictured in this post. For example, these were labelled as "Grey oyster mushrooms, Pleurotus sajor-caju (Fr.)Singers", but according to the Wikipedia article referencing a Stamets book, cultivators commonly call warm-weather varieties of Pleurotus pulmonarius this name even though this species doesn't realllly exist as a separate entity and the actual P. sajor-caju was moved to the Lentinus genus... but there was also a Lentinus species in the same room though I don't think it was L. sajor-caju. Again, I'm going to refrain from labeling so I don't perpetuate any incorrect information.

Underside detail

The product.

Consequences of some form of bacterial contamination.

Another product.

Product in situ.

Ganoderma spp. (lingzhi) growing in a dark shed. The spores are used in cosmetics and the fruiting body is made into a tea popular in Asian traditional medicine. 

They take a long time to grow, but produce an abundance of spores. Spores and fruiting body command a relatively high price.

 While this operation seems successful in terms of producing mushrooms and providing accessible education and resources, there are some hurdles to the implementation of low-tech agricultural waste to mushroom programs. First, the strains themselves have to be sourced and maintained. In large-scale production operations like Phillips in PA (see earlier post), the pure culture strain is carefully selected for efficiency and quality, and the initial plates of culture are frozen in liquid nitrogen to maintain the earliest culture and avoid strain degradation. While a huge amount of mushroom culture can be made from a tiny amount of mycelium, this mycelium is not immortal, and if you culture the culture of a culture (etc.) the strain can start to deteriorate over time. Liquid nitrogen storage is simply not available in low-tech or small scale operations. While at this scale strain degradation can be less of a problem simply because less mycelium is produced, "parent" cultures are maintained and bags are inoculated vertically from the "parent" cultures rather than horizontally. This reduces the opportunity for contamination as well.

Another major concern with the reuse of agricultural wastes is substrate contamination. While fungi can often break down carbon-based contaminants, they are also capable of accumulating metals. If a metal-containing pesticide is applied to a crop, and the crop is then used for mushroom production, it is possible that the mushroom will be contaminated as well. It is notable that rubber trees are sometimes treated with arsenic trioxide (pesticide).



Thank you achaan Morakot for your kindness and generosity during my time in Chiang Mai.