I doubt that Fleming could have obtained a grant for the discovery of penicillin on that basis [a requirement for highly detailed research plans] because he could not have said, 'I propose to have an accident in a culture so that it will be spoiled by a mould falling on it, and I propose to recognize the possibility of extracting an antibiotic from this mould.
It has been demonstrated that a species of penicillium produces in culture a very powerful antibacterial substance which affects different bacteria in different degrees. Generally speaking it may be said that the least sensitive bacteria are the Gram-negative bacilli, and the most susceptible are the pyogenic cocci ... In addition to its possible use in the treatment of bacterial infections penicillin is certainly useful... for its power of inhibiting unwanted microbes in bacterial cultures so that penicillin insensitive bacteria can readily be isolated.