Screening of blastocladialean fungi for antibiotic production by a modified "cross-streak" test

In this study, fungi of the order Blastocladiales were screened for the production of antibiotics, by a procedure based on the "cross-streak" test. In this test, the investigated organism or potential "antagonist" is inoculated so as to grow along the diameter line of the agar medium in a Petri dish. Subsequently, potentially susceptible microbes (usually bacteria) are streaked perpendicularly to the growth line. Inhibition of growth of a test microbe in the vicinity of that line suggest that the antagonist secretes one or more diffusible antibiotics. The blastocladialean fungi screened numerous isolates of several species of Allomyces : A. arbuscula , A. macrogynus , A. anomalus , A. neo-moniliformis , A. reticulatus , A. catenoides and A. moniliformis . Also screened were one isolate each of Blastocladiella emersonii , Blastocladiopsis elegans , Blastocladiopsis parva , and Catenaria anguillulae .