General review:
Fungi are: Eukaryotic, heterotrophic, absorptive organism that
develop rather diffuse, branched tubular body and reproducing by means of
spores.
Many fungi are pathogens of plants that are grown for food, shelter or
clothing. A smaller number are agents of diseases in animals, including man.
Many saprotrophic fungi attack and degrade raw or manufactured materials of
various kinds, such as foodstuffs, timber, textiles and leather. The economic
loss of such destruction, and the cost of prevention treatment, can be
enormous.
On the positive side, many saprotrophic fungi are useful to man. The use
of yeasts in baking and brewing is well known. Minor source of food include
edible mushrooms and truffles. Various fungi are used to give distinctive
flavors to ripening cheeses. Several extremely useful antibiotics are metabolic
products of fungi, e.g. penicillin.
Generalized sterile and safety
techniques:
1. Wear a clean lab coat to protect clothing and to
reduce possible contamination of cultures.
2. While in the laboratory avoid
any hand to mouth operations. such as eating, or licking adhesive labels.
3. Washhands thoroughly with soap and water, both before and after working with
cultures.
4. Keep work surface clear of any unnecessary objects (e.g., books,
purses, etc.)
5. Wash work surface with a capable disinfectant, such as 5% Lysol or
70% alcohol, both before and after working with cultures.
6. Culture transfers: The only articles of equipment needed to make a
transfer from the initial culture to a tube of sterile medium are a Bunsen gas
burner, and an inoculating loop or needle.
a. Hold both tubes in the left hand (fig. 1).
b. With the needle in the right hand. pass the entire length of the wire
through the flame until it has all been red
hot (fig. 2).
c. While still holding the needle, quickly remove the caps or plugs from
the tubes, holding them between the fingers of the right hand, (fig. 3). Flame
the mouths by passing them two or three times through the burner flames (fig.
4). Hold these tubes almost parallel to the table top if they contain a broth.
This will reduce the possibility of air-borne contaminants.
d. Touch the needle to the medium in the culture tube to be sure it is
cooled, and then to the culture mass. Apply the needle to the sterile medium in
the other tube (fig.5). This may be done either by streaking the surface of a
slant, making a stab into a semi-solid media, or swirling the needle in a
broth. It should be noted that it is not necessary to remove a large volume of
the culture mass with the needle. A slight touch will place more than enough on
the needle to make the inoculation.
e. Flame the mouths of the tubes and cap them.
f. Flame the inoculating needle until it is "red hot".
g. When Petri plates are used, place them on the table and lift the
cover only enough to maneuver the needle when inoculating.
7. If screw cap culture tubes are used, the cap should be kept loose to
allow the aerobic cultures to get oxygen. (Most common bacteria and molds fall
into this category).
8. It cultures are to be kept for an extended period, however, they
should be sealed tightly to prevent dehydration of the media, and then
refrigerated to
extend the shelf life.