Finding the right culture media

Before we as mushroom farmers can grow mushrooms, we have to cultivate our mushroom strains first. This could be done by a company from which we buy our spawn or culture media, or we prepare the culture media ourselves.

The type of culture media you or the company chooses determines the quality of the strain or to be more precise the mycelium growth rate, the density, and the purity of the strain.

In today’s article, I want, therefore, to address certain aspects that help you find the right culture media for your mushroom strain.

Types of culture media[1]

When talking about culture media, we have to first talk about the different types of culture media that have various kinds of purposes. Culture media can be divided by their composition (basal or enriched), their function (selective or storage), and by their source (natural or synthetic).

As a culture media can be put in several of these categories, the distinction can be a little bit tricky. For example, media could be enriched by using synthetic components to work as a selective media. You, therefore, could place it in all three categories.

It sounds complicated, but it isn’t. Everything you have to remember is that each media has a purpose. That’s it.

Basal media

Basal media are those that may be used for growth (culture) of fungi that do not need enrichment of the media.

Enriched media

The media are enriched usually by adding nutrients, such as sugars, metal compounds, amino acids, and vitamins[2].

Selective media

These media favor the growth of a particular fungus by inhibiting the growth of undesired fungi and bacteria. Antibiotics may be added to a medium for inhibition.

Storage media

Media used for storing the fungi for an extended period.

Natural media[3]

Natural media are composed of natural substrates, such as herbaceous or woody stems, seeds, leaves, cornmeal, wheat germ, and oatmeal, etc. Natural media are usually easy to prepare, but they have the disadvantage of their unknown composition. Some examples include corn meal agar, potato dextrose agar, V-8 juice agar, and dung agar.

Synthetic media[4]

Synthetic media, on the other hand, contain ingredients of known composition. These types of media can be duplicated with precision each time they are made and contain defined amounts of carbohydrates, nitrogen, and vitamin sources.

To give you an idea about the plethora of culture media, here is a list I put together during my research.

List of culture media

YMA – Yeast Malt Agar
SDA – Saboraud’s Dextrose Agar
GPA – Glucose Peptone Agar
GTA – Glucose Tryptone Agar
MEA – Malt Extract Agar
PDA – Potato Dextrose Agar
MS – Murashige & Skoog’s
ISA – Iron sulfite Agar
YGA – Yeast Glucose Agar
PEA – Pea Extract Agar
MEA – Maize Extract Agar
PCA – Potato Carrot Agar
YPDA – Yeast Potato Dextrose Agar
WGA – Wheat Grain Agar
WPA – Wheat Peptone Agar
CDA – Czapek Dox Agar
CA – Carrot Agar
HAM – Hamada
HEN – Hennerberg
HOP – Hoppkins
LIL – Lilly & Barnet Medium
MC – Mushroom complete
HWK – Hawkers
RIC – Richards
MPA – Milk Powder Agar
KCM – Koser Citrate Medium
OA – Oatmeal Agar
TM – Trebouxia Medium
MRB – Martin’s rose bengal
DGA – Dichloran Glycerol Agar
DM – Dimmick Medium
BM – Bilai Medium
Harrold Medium
EEA – Elm Extract Agar
SMA – Saboraud’s Maltose Agar
GAA – Glucose Alanine Agar
WA – Water Agar
V8 – V8 Juice Agar
CMA – Cornmeal Agar
YpSs – Emerson YpSs Agar
MPDA – Martin’s Peptone Dextrose Agar
ESA – Ebiose Sucrose Agar
SMAY – Saboraud’s Maltose Agar + Yeast
SDAY – Saboraud’s Dextrose Agar + Yeast
CZYA – Czapek Yeast Extract Agar
EA – Elliott’s Agar
BM – Burkholder Medium
HM – Houston’s media
JA – Jensen Agar
KA – Krainsky Agar
…

The impact of these different culture media can be seen in the following video. In it I talk about 12 different once and their influence on the mycelium growth rate.

Each of these culture media can be placed in the mentioned category based on their composition. To do so, we have to dissect them and take a look at their formulas.

70+ Formulas of culture media

The following table 1 contains 9 out of 70+ formulas I collected throughout my research. If you are interested in the list, I put all the formulas together into an eBook.

As you can see, the list (Tab. 1) contains many different ingredients, of which only 50% are mentioned in this list.

Ingredient (g/l)	YMA	SDA	GPA	MEA	PDA	MS	ISA	YGA	PEA
Agar	20/15	15	20	15	20		15	15	20
Aspargine
Dextrose	10/0	40			20			10
Glucose			10
Malt extract	3/20		0/15	30
Peptone	5/0	10	0/10
Potatoes					200
Pea									40
Sucrose						30
Yeast extract	3/2		0/10					10
K2HPO4						0.17
MgSO4						0.37
CaCl2						0.44
KNO3						1.9
NaCl			5/0
KI						0.83mg
H3BO3						0.62mg
MnSO4						0.0223
ZnSO4						0.86mg
Na2MoO4						0.25mg
CuSO4						0.02mg
CoCl2						0.025mg
Fe(III)citrate							0.5
Na2SO3							0.5
Casein enzymic hydrolysate							10

Table 1: Media and their compositions (Abbreviation see list of culture media)[5]

But how about the difference between these various cultural media?

Let us take a look at the following figure 1. In this graph, the effect of different culture media on the mycelial growth of Agrocybe aegerita was tested.

The highest growth rate was achieved with MEA (Malt Extract Agar). While PDA and YMA are relatively close to each other.

Figure 1: Effect of different culture media on the growth rate of Agrocybe Aegerita[6]

If we take a look at the cultivation of Pleurotus sapidus grown on various culture media, we get a similar result. MEA, PDA, and YMA lead to the highest growth rates, while GPA, SDA, and CDA had the lowest growth rates.

To understand this pattern, we have to go even deeper and take a look at each component of the formulas. This means we have to understand which carbon source and which nitrogen source works the best.

Figure 2: Effect of different culture media on the growth rate of Pleurotus sapidus[7]

Influence of carbon sources

Below I listed some common carbon sources. Their impact on the mycelial growth rate can be seen in figure 3 and figure 4.

Sucrose
Sorbital
Lactose
Xylose
Fructose
Glucose
Galactose
Dextrose
Maltose
Manitol
Starch

In figure 3, the mycelial growth of Ganoderma lucidum was investigated. It was found in this study, that Dextrose followed by Galactose and Fructose are resulting in the highest growth rate.

While, for example, Sorbitol, Lactose, or Glucose lead to the lowest growth rate.

Figure 3: Effect of different carbon sources on the growth rate of Ganoderma lucidum[8]

Let’s take a look at two more mushroom strains. In figure 4, the influence of different carbon sources on the mycelial growth rate of Pleurotus sajor-caju (actually Lentinula sajor-caju) and Pleurotus florida was analyzed.

While both strains behave very similarly, we can see a difference between the two strains and Ganoderma lucidum. While Ganoderma lucidum prefers, for example, Dextrose, the Pleurotus sajor-caju, and Pleurotus florida don’t. Their growth rate for Dextrose is roughly 50 % lower than if they would be growing on, for example, starch or Fructose.

Figure 4: Effect of different carbon sources on the growth rate of Pleurotus sajor-caju and Pleurotus florida[9]

Influence of nitrogen sources

Besides the carbon source, the nitrogen source plays a similarly important role when it comes to the mycelial growth rate. I found the following nitrogen sources while searching for this article.

Methionine
Potassium nitrate
Alanine
Arganine
Histidine
Urea
Glycine
Ammonium phosphate
Calcium nitrate
Ammonium acetate
Sodium nitrate
Ammonium chloride
Proline
Ammonium ferrous sulphate

Let’s take again a look at the effect these nitrogen sources have on the mycelial growth rate. First, we take a look at Ganoderma lucidum (Fig. 5) and then at Pleurotus sajor-caju and Pleurotus florida (Fig. 6).

As figure 5 indicates, Ganoderma lucidum grows the fastest on Arginine, Glycine, and Ammonium acetate.

Figure 5: Effect of different nitrogen sources on the growth rate of Ganoderma lucidum[10]

The two strains Pleurotus sajor-caju and Pleurotus florida prefer Ammonium nitrate (II) and Ammonium chloride (I) instead.

Figure 6: Effect of different nitrogen sources on the growth rate of Pleurotus sajor-caju and Pleurotus florida[11]

For all three strains, we can conclude that the best nitrogen source would be Ammonium.

Influence of the pH Level

After taking a look at the carbon sources and nitrogen sources (let’s call them internal factors), we will now go over the next factor, which is an external one.

The next figure 7 shows the impact of the pH on the mycelial growth rate of Ganoderma lucidum. While we see almost no difference between pH 5 to 8, at a pH 9, the growth rate starts to drop.

As we know that particular contaminations like, for example, Trichoderma prefers a more acidic environment, we can use this knowledge to our advantage.

We can make the culture media more alkaline and therefore suppressing the growth of Trichoderma without hurting the growth rate of Ganoderma lucidum.

Figure 7: Effect different pH level on the growth rate of Ganoderma lucidum[12]

Influence of the temperature

Besides the pH level as an external factor, the temperature at which we cultivate our culture media is playing a significant role in the mycelial growth rate, too.

Let’s take a look at our three mushroom strains again. The first figure (Fig. 8) shows the effect of different temperatures on the mycelial growth rate of Ganoderma lucidum.

As the graph indicates, the highest mycelial growth rate can be achieved between 25 °C and 30 °C (77°F and 86°F)

Figure 8: Effect of temperature on the growth rate of Ganoderma lucidum[13]

We see similar results when looking at figure 9. Here the two strain Pleurotus sajor-caju and Pleurotus florida were cultivated at different temperature levels.

For Pleurotus florida, the best performance was achieved at 22.5 °C (72.5°F). At the same time, Pleurotus sajor-caju prefers a little higher temperature (here 27.5 °C or 81.5°F).

Figure 9: Effect of temperature on the growth rate of Pleurotus sajor-caju and Pleurotus florida[14]

Influence of the lighting

The last external factor is light. As I wrote in my articles, “Do mushrooms need light” and “How light will impact your mushroom yield” lighting plays for certain mushrooms a vital role.

To see the interplay between culture media and lighting/darkness, we take a look at figure 10. Here the mycelial growth rate of Cordyceps militaris is tested on several different cultural media, which are placed in light or in darkness.

The mean mycelial growth rate for the cultivation both in light and in darkness was found to be 66 mm.

If we take a closer look, the cultivation in darkness achieved a higher mycelial growth rate by roughly 13 % with a range of -12 % to +57 % depending on the culture media.

The most significant difference was found in WA, CMA, and V8.

Figure 10: Influence of different culture media on the mycelial growth rate of Cordyceps militaris under light and dark conditions[15]

Final Thoughts

Finding the right culture media for their own mushroom strain can be a challenge. But doing it is worthwhile. It not only increases productivity but the quality of the strain as well.

To find the best culture media, you have to know what your mushroom prefers as carbon sources as well as a nitrogen source. If you figured that out, mixing the ingredients together is easy.

To give you a jump start, I put all the 70+ formulas together in an eBook which you can find here.

Now I want to hear from you:

Which culture media are you using today?
Which culture media are you going to try after reading my article?

Let me know by leaving a quick comment.