Flask contaminants

Usually fungi, bacteria and algae are the organismas which contaminate the flasks . The mould appears in spots 4- 14 days after flasking . Risk of contamination decreases with time . These spots can be scooped away along with about one centimetre of the surrounding medium with a sterile plastic needle.

Baterial contamination appears as milky or pink spots . Once this has occurred the contents of the whole flask should be discarded . Bacterial spores are more difficult to kill than fungal spores , since they can withstand higher temperatures during sterilisation than fungal spores. Since prolonged autoclaving alters the chemical composition and pH of the medium , this method cannot be resorted to in order to kill the spores. The best preventive measure appears to be to stand the medium for three or four days in order to see whether any contamination has occurred . Inocculation of the seeds should bed done only after ensurinf that the medium is free of baterial or fungal spores.

But the best way to keep away contamination is to prevent the spores from coming in contact with the medium . Harvest pod before dehiscence and keep the seeds at 40 F over dessicating chemicals.