Auxanographic Techniques in Biochemical Genetics

SUMMARY: Details are given of the ‘auxanographic𠀙 method for identifying growthfactor requirements of micro-organisms, and particularly of mutant strains differing from a parent strain in having additional growth-factor requirements. Cells are distributed in a nutritionally deficient agar medium which is allowed to set in a Petri dish. Possible required nutrients are then spotted on the agar surface, thus enabling the corresponding exacting mutants to grow at those localities. The technique is only a labour-saving device which can be extremely efficient in shortening the preliminary steps in the work. It can also be applied to other uses, such as the identification of competitive interactions between nutrilites.