Molds as Mefabolk Models 97 



Development of new and improvement of existing 

 methods will enhance chances of obtaining from nature 

 varieties of fungi that seldom, if ever, see the light of the 

 laboratory. For example, it is customary to facilitate isola- 

 tion of fungi by acidification of the medium in order to 

 suppress interfering bacteria and actinomycetes. This 

 method works, but it works to obtain only acid-tolerant 

 species. Actually, a considerable portion of the soil fungus 

 population is also suppressed by the elevated hydrogen-ion 

 concentration. A promising approach to this objective is 

 the use at neutral or slightly acid pH values of various 

 chemicals which selectively inhibit nonfungal organisms. 



The application of suitable and ingenious enrichment 

 and selective culture techniques with respect to utilization 

 of diverse individual chemical substrates will, I am sure, 

 reveal that, metabolically speaking, the fungi presently are 

 the most underrated of all the microorganisms. Products 

 of new catabolic pathways may have significance for the 

 applied microbiologist, as well as for his academic counter- 

 part. Metabolic properties hitherto unsuspected in fungi 

 are to be had simply by performing appropriate, skillful 

 experiments. Illustrative of the ranges unsuspected in these 

 organisms is the recent report (6) of the rather decided 

 formation of nitrate from reduced nitrogen compounds 

 by numerous soil isolates of A. fiavus, grown hetero- 

 trophically. I may mention also that M. Dworkin in my 

 laboratory has isolated a mold which makes rapid and 

 abundant growth with ethane gas (99 per cent purity) 

 as the sole source of carbon and energy, apparently the 

 first such fungus described as being capable of utilizing 

 a gaseous hydrocarbon. 



Synfhefic Acfivifles of Fungi 



My concentration up to this point on the catabolic as- 

 pects of fungi ought not to be interpreted as a purposeful 

 attempt to ignore the synthetic or anabolic activities of 



