Agar as a Carbon Source and its Effect on the Utilization of Other Carbon Sources by Acetate Non-utilizing (acu) Mutants of Aspergillus nidulans

Abstract

When conidia of A. nidulans were incubated in a defined liquid medium lacking a C source, there was essentially no growth but when dilute suspensions of conidia were placed on the same medium solidified with agar a large proportion of the conidia formed isolated colonies which grew at rates similar to those on glucose plates. Agar acted as a significant C source. It appears that A. nidulans utilizes agar by degradation of the polymers. Ways in which agar can obscure growth tests for the utilization of potential C sources are illustrated. In addition to serving as a C source for some strains, agar can inhibit growth of others, such as acu mutants.