Inoculation and colonization

InoculationInoculationIntroducing spores or living culture into a sterile jar, bag or plate. puts living genetics, either a spore syringe or liquid cultureLCLiquid culture: a sterilized sugar-water broth with living mycelium suspended in it, injected like a spore syringe but faster to take., into food that has been sterilized so nothing else is alive in it. ColonizationColonizationThe stretch where mycelium grows through grain or substrate until every part is white and knitted together. is everything that follows: the mycelium spreads through the grain or the brown rice cake until no bare food is left. Almost every contamination problem that shows up later started here, so this is the stage where care pays back the most.

There are two common starting points. PF Tek uses small half-pint jars of brown rice flour and vermiculite that are later fruited as cakes. Grain jars or bags (rye, millet, popcorn or birdseed) become grain spawnGrain spawnSterilized grain, such as rye or millet, fully colonized by mycelium and ready to inoculate bulk substrate. that is later mixed into bulk substrate. The steps below cover both.

PF Tek jar recipe

About 120 ml vermiculite, 60 ml brown rice flour and 55 g water per half-pint jar (Bible, p. 83)

Rye per quart jar

About 220 g dry rye, 200 ml water and a gram of gypsum, left to hydrate a day before cooking (Bible, p. 150–151)

Sterilizing PF jars

15 psi (250 °F / 121 °C) for 20 minutes once the weight starts rocking (Bible, p. 90–91)

Sterilizing grain

Longer, scaled to the load: under an hour for a small batch up to about 4 hours for 3 kg of rye at 15 psi (Bible, p. 152–153)

Spore syringe per PF jar

About 2 cc, split across four injection points (Bible, p. 95)

Colonizing temperature

Room temperature around 70–80 °F (21–27 °C); see the note on warmer advice below

First growth visible

A few days from spores; within about a day from liquid culture (Bible, p. 97)

Full colonization

About 3–4 weeks for PF jars from spores (Bible, p. 97–98); grain from liquid culture is often faster

1. 1.Let jars cool until they feel cold to the touch. Hot grain kills spores and invites bacteria.
2. 2.Work in a still air boxStill air boxA clear tub with arm holes that stops air currents while you open sterile jars, plates or bags. wiped down with a 1:9 bleach solution, and give the air five to ten minutes to settle before you open anything.
3. 3.Flame the needle until it glows, outside the box so the plastic does not melt, then let it cool for a moment. Shake the syringe to spread the spores.
4. 4.Inject at the edge of the jar, angled so the tip runs down the glass. That lets you watch growth start from the outside.
5. 5.Wipe the injection points again and label every jar with what went in and the date.

Somewhere dark, raised off the floor and steady in temperature. A closet shelf works. The book behind PF Tek calls about 70 °F (21 °C) fine and warns that cold rooms stall growth (Bible, p. 95). Its own general range for cubensis is 70–80 °F (21–27 °C) (Bible, p. 53). Forum growers often push 80–84 °F for speed, and a few go higher, but the warmer the jar, the better bacteria and green mould do too. Several sources put a contamination ceiling in the low 80s °F, so the safe middle is about 75–78 °F (24–26 °C).

Do not open jars to look. Condensation on the glass and mycelium pulling slightly away from the walls are both normal (Bible, p. 97). Grain jars can be shaken once, when growth covers about a third of the jar, to spread living grain through the rest. PF jars are never shaken.

• Healthy: bright white growth, either rope-like rhizomorphicRhizomorphicMycelium that grows in branching, rope-like strands, as opposed to even, cottony growth. strands or even, cottony tomentoseTomentoseEven, cottony mycelium without strands; normal for many cultures and not a sign of contamination. fuzz. Both are normal.
• Clear to amber droplets on white mycelium are metabolitesMetabolitesClear to amber droplets that bead on healthy mycelium under stress; harmless in small amounts.. Small amounts mean stress, not infection.
• Grain that looks wet, greasy or grey, a stall at a sharp line and a sour smell are wet spotWet spotA bacterial infection of grain that leaves kernels looking wet and slimy, stalls colonization and smells sour. bacteria. Throw the jar out.
• Any green, blue-green, pink, orange or black powder is mould. Do not open it indoors.
• Blue staining where a jar was knocked is bruising, not mould. It sits in the tissue and does not spread as dust.

A jar is ready when every surface, the bottom included, is white. Then wait. Mycelium keeps knitting the inside together for several more days after the outside looks finished. The Bible suggests about another week before birthing PF cakes (p. 97–98), and forum growers agree that a few days of consolidationConsolidationThe few days after a surface first looks white, when mycelium keeps thickening inside the substrate before fruiting conditions start. after the last bare spot disappears gives faster, more even pins. Grain spawn is best used soon after it is fully colonized; left for weeks it can start pinning inside the jar (Bible, p. 165–166).