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On the trail of the Yak: Ancient Cordyceps in the Modern World

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#1 Severian



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Posted 17 October 2020 - 10:51 AM

Found a pdf book about cordyceps. Wanted to share







Reading through it now; published in 2004, it may be a bit out of date.




On the trail of the yak: pg43

Twenty-eight saturated and unsaturated fatty acids and their derivatives have been isolated from C. sinensis. Polar compounds of Cordyceps extracts include many compounds of hydrocarbons, alcohols, and aldehydes. (Zhou et al 1998) Particularly interesting are the range of polycyclic aromatic hydrocarbons (PAH) produced by Cordyceps sinensis as secondary metabolites. These PAH compounds react with the polypropylene used in common mushroom culture bags, resulting in the production of byproducts toxic to the Cordyceps that stunts the growth as the growing time progresses. Eventually, these polypropelene/PAH byproduct will kill the organism, making the cultivation of C. sinensis in this type of bag impractical. For extended periods of growth, C. sinensis must be grown in glass or metal containers. (Holliday et al 2004). These PAH compounds are present in the living culture, but are highly volatile compounds and are lost upon drying





Cultivation Details And Growth Parameters There are two methods used today in the cultivation of Cordyceps. The method primarily used in China is known as Liquid Culture or Fermentation, in which a small bit of Cordyceps tissue is inoculated into a sterilized liquid medium. It grows in this liquid environment very rapidly and is usually ready for harvest in about 5 days. The Cordyceps mycelium is harvested by filtering out from the liquid broth, after which it is dried and ground to a fine powder. After it is dried, it can be used as is, or further processed by extracting it with hot water or some other solvent, and the resulting extract either supplied as a liquid or again dried and powdered. The majority of Cordyceps available on the market is liquid cultured in this way. This results in a fairly good product, since this is a very economical method for large-scale production and the ease of controlling the growth parameters in large sealed tanks of liquid results in a very consistent product with very little variation in quality from batch to batch.


However there is a major drawback to the fermented Cordyceps; which is the loss of the extra-cellular compounds which Cordyceps produces. When the mycelium is filtered out of the culture broth and the residual liquid discarded, all of the bioactive extra-cellular compounds produced throughout the growth process are lost. These are many of the unique secondary metabolites produced by Cordyceps that have 44some of the most potent medicinal effects. Consider for a moment: In the fungal kingdom nearly everything of biological importance happens outside of the cell wall. This has to be so, since the fungi have no mouths. In order for it to feed, the mycelium grows up alongside a food source and exudes out through the cell - wall compounds to digest that food. Then it exudes other compounds that act as transport molecules, ones that bring the nutrients back across the cell wall and into the cell for use. And all the while it is exuding antimicrobial compounds to keep other organisms from competing with it for the food (these are the compounds we refer to as antibiotics). And other compounds which act in significant ways such as adjusting the pH of its surrounding environment.


Probably as much as 90% of the bioactive compounds of interest that are produced by the Cordyceps are in the liquid that is discarded after the mycelium is harvested. In the wild collected Cordyceps, the caterpillar body, which is harvested along with the fruitbody, is fully mummified with the Cordyceps mycelium. But more importantly, it acts as a natural reservoir for all of those exuded extra-cellular compound that were produced. The compounds, which were exuded outside of the mycelium, still remain in the caterpillar body. That is probably the main reason why wild collected Cordyceps is thought to be more potent than cultivated Cordyceps. It is the presence of these bioactive extra-cellular compounds, which were lost in the harvesting process of the liquid-cultivated type.


There is a second method of Cordyceps cultivation practiced, called the solid-substrate method or biomass method. In this type of cultivation, the Cordyceps is inoculated onto some type of sterilized solid nutrient source, usually a cereal grain or mixture of grains. It grows much more slowly on solid material than it does in liquid, but eventually the growth of the mycelium consumes most or all of the substrate and is ready for harvest. At this point, the entire contents of the growing container is harvested and dried; the mycelium, the residual substrate and the entire compliment of all the extra-cellular compounds which were produced throughout the entire growth process. In this way it is possible to capture these unique compounds, which are naturally lost when cultivated by fermentation technique. The quality potential would seem to be much greater when cultivated under solid substrate method verses liquid fermentation method.


However, it is not always that simple as to say Cordyceps produced by one 45method is better than the other. The final quality of the Cordyceps is determined by a number of factors, among which the most important are the particular strain chosen for cultivation, the substrate composition, the culture parameters (such as temperature and oxygen content) and the length of time that it is grown. When all the conditions are correct, there is less than 5% residual substrate in the solid substrate grown variety, and better than 95% Cordyceps material, including all of the extra-cellular compounds. When grown this way the quality is high indeed, often exceeding the potency of wild Cordyceps by a factor of five times! (Holliday 2004)


Due to the longer growing time required, it is much more costly to produce Cordyceps with the solid substrate method than by fermentation, and it is therefore generally more expensive in the marketplace. This creates a situation where many solid substrate cultivators are forced to harvest their Cordyceps crop earlier than is optimum, in order to keep their cost competitive with the fermented products on the market. This means that they are producing a less-than-ideal product, which may or may not be better than the fermented variety. In some cases the residual grain present in solid substrate Cordyceps is greater than 80%. This is one of the reasons it is so important that buyers demand a standardized analysis of theCordyceps they are contemplating purchasing. At present this standardized analysis is not commonplace, but it is becoming more so, as more people become educated in the uses and potential of this medicinal herb. As time progresses, we can expect to see the overall quality of cultivated Cordyceps to continue to increase.



Medium for maintaining stock cultures: The usual nutrient agar mixtures used in maintaining mycological cultures can almost all be used for maintaining Cordyceps cultures. It is worth noting that Cordyceps will usually adapt quickly to a new medium, which is both a blessing and a curse. A blessing in that almost any medium used to propagate the culture will support growth, but a curse in that the organism rapidly develops a preference to this new medium, probably through the generation of enzymes specific to the character of that particular medium. This will result in the culture loosing its growth vigor for a time when transferred to another medium. This also leads to early culture senescence when the culture is repeatedly grown generation after generation on the same medium.


The easy way around this issue is to constantly challenge the culture by transferring it onto a new medium with each successive generation. In this way, the culture is forced to maintain a broader spectrum of digestive enzymes to deal with the varying food sources, much as happens in nature. It also helps quite a bit to introduce some of the final substrate upon which the Cordyceps is to be grown into the maintenance medium. For example, if the Cordyceps is to be grown on a substrate of brown rice, it helps to add some finely ground brown rice to the agar upon which the culture is stored. That way, the Cordyceps has already been exposed to the end substrate and will have had time to develop the necessary enzymes to deal with this food source beforehand. When the organism is transferred from the agar onto the final substrate, a quicker growth is achieved, since the organism does not have to develop a new set of enzymes, as would be the case if it were seeing brown rice for the first time.


Some of the

nutrient agar mediums that have been found to support good mycelial growth are: Standard Malt Extract Agar

Standard Potato Dextrose Agar

Catfood Agar (10 grams dry catfood and 20 grams agar per L water)

Dogfood Agar (10 grams dry dogfood and 20 grams agar per L water)

Ovaltine Agar (10 grams Ovaltine drink mix, 20 grams agar per L water)


Mycelial Characteristics: Longitudinally radial, non-aerial, initially white, rapid growing, becoming densely matted. Some variations will turn yellowish to brown, and still some develop a translucent pink to orange tint, especially prominent upon exposure of the growing mycelium to sunlight but not to artificial light; and eventually, as the food source is completely consumed, the mycelium becomes increasingly dark and mud-like (30+ days). At approximately 14 days of growth or a bit later, the mycelium of some strains of Cordyceps sinensis begins to form small nodules (perhaps sclerotia?) on the surface of the substrate, appearing orange-brown to tan in color.


Most strains of Cordyceps sinensis tend to rapidly change growth characteristics in cultivation, sectoring readily and sometimes growing densely, while other times growing light. Changes in color occur in the mycelial growth, even when the tissue inoculums are taken from the same petri dish. These changes are not permanent, that is, they change from one 47growth form to another and back again with seemingly no reason. One possible explanation for this is the possibility that Cordyceps sinensis (and possibly other Cordyceps species as well) are not single organisms, but rather symbiotic colonies of two or more organisms, perhaps fungi and bacterial pairings. (Chen 2001) The changing growth characteristic can then perhaps be seen as different primacy growth stages, where one of the separate organisms out-grows the other(s), while later in time, or perhaps in a different container, the other organism(s) gain dominance in the culture. Further study is necessary to better understand the growth cycle of the Cordyceps sinensis mycelium in its varying forms.

Edited by Severian, 17 October 2020 - 11:10 AM.

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