MUCOR AND RHIZOPUS 



89 



the mycelium. It may be identified by the peculiar spiny columella 

 and the prickles on the spores. 



Although the preceding species form but small amounts of alcohol, 

 another Mucor belonging to the Cymomucor group, M. Rouxii (some- 

 times called M. Rouxianus) has been used industrially for the pro- 

 duction of alcohol. It secretes both diastase and zymase and can 

 therefore produce alcohol directly without any malting process. It 

 is used in the Orient for preparing 

 alcoholic beverages from rice, which 

 are often called wines. The fungus 

 is sometimes marketed under the 

 name Chinese yeast in little balls of 

 rice meal, much as yeast cakes are 

 marketed in the Occident. It has 

 been used commercially for alcoholic 

 production in Europe. More than 5 

 per cent of alcohol is produced in 

 the fermentation. This species may 

 be recognized by the characteristic 

 Cymomucor branching of the sporan- 

 giophores, the spherical columellae, 

 and large oval spores. In the sub- 

 merged mycelium, large irregular, 

 thick-walled cells may be formed. 

 Like the Racemomucors mentioned 

 above, black chlamydospores appear 

 in the aerial mycelium and budding 

 yeast-like cells in submerged portions. Abundant fat globules may 

 develop in the mycelium, especially on starchy substrates; these 

 take on a deep yellow color. 



There are several other species related to M. Rouxii which have 

 been isolated from other oriental yeasts, as M, Prainii from India 

 and M. javanicus from Java. 



Some authors have grouped together those Mucors whiish tend to 

 break up into round oidia, or to produce numerous chlamydospores, 

 in a separate genus, Chlamydomucor, but these structures are found 

 in so many different kinds of molds that they should not be given 

 much weight in classification. 



Rhizopus nigricans is by far the most common of all the molds be- 

 longing to the Phycomycetes. It is continually encountered in all 

 kinds of bacteriological work as an air contamination, and is par- 

 ticularly annoying because of its ability, by means of its stolons, 



Fig. 39. Rhizopus nigricans: a, 

 mature sporangium; b, ruptured 

 sporangia, showing the flattened 

 columellae (note the funnel- 

 shaped expansion, apophysis, of 

 the sporangiophore beneath the 

 columella) ; c, spores ; d, a rhi- 

 zoid or holdfast; e, zygospore; 

 /, diagram showing mode of 

 growth by runners. 



