GRAIN CULTURE

Glass spawn jars broken Pressure cooker cooled too Allow cooker to descend to 

Crain spontaneously con- Introduction of alien spores Cool-down in sterile environ- 

Agar wedge sticks to glass Agar media too thin, either Use mycelium covered media 

Little or no growth after my- Grain too hot when inocu- Allow to cool to room tern- 

Poor strain. Contaminated strain. Discard strain. Obtain purer strain, make up more grain media and clean laboratory. 

---

With many species moderate crops can be produced on cased grain cultures. Or, the cultivator can go one step further and inoculate compost, straw or wood. In either case, the fruiting of mushrooms requires a high humidity environment that can be readily controlled. Without proper moisture, mushrooms don t grow. 

Figure 131 Cased grain culture of Agaricus brunnescens showing overlay and stroma.

Pseudomonas also contaminates agar and grain cultures, inhibiting mycelial growth. The use of antibiotics (gentamycin sulfate) or micron filters prevents outbreaks of this contaminant. A few species cause the mycelium to grow more rapidly and luxuriantly. Similarly, considerable attention has centered on the beneficial role of Pseudomonas putida and allies in the casing layer. This subject is discussed in detail in Appendix II. 

A saprophyte, occasionally to frequently seen on the straws of an inadequately pasteurized compost on wooden trays rarely spreading to the casing soil sometimes contaminating grain cultures and seldom seen on agar. In nature Dorafomyces is a major constituent of a soil s microflora. 

Suspended in the air is an invisible cloud of contaminants. These airborne spores are the primary source of contamination during agar and grain culture, and they are the major force defeating beginning cultivators. To control contamination, the cultivator must start with a sterile laboratory. Without pure culture spawn, the prospect for a good crop is slight, no matter how refined one s other techniques. 

---