Anaerobic Growth of Molds Isolated from Fermentation Starters Used for Foods in Asian Countries

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Abstract
Ragi, murcha, look pang, bubod, chiu-chu and Chinese yeast are used as starters for a number of fermentations based on rice and cassava in the Orient. The starter consists regularly of certain species of Mucor, Rhizopus and Amylomyces, and not of other molds, even though the production of starters is often made under unsanitary conditions. All 60 isolates from these starters from Indonesia, Philippines, Nepal, China, Taiwan and Thailand grew under anaerobic conditions. The Mucor isolates belong in the section Racemosus and possess numerous chlamydospores. A survey of strains representative of 12 families of the Zygomycetes indicates that species of most genera will not grow under anaerobic conditions. The 3 genera in which some species grow under anaerobic conditions are Mucor, Rhizopus and Amylomyces (Mucorales: Mucoraceae). Amylomyces is like Rhizopus in that growth is strictly filamentous under anaerobic conditions, further providing their close relationship. Heterothallic Mucor mating types of the species that grew under anaerobic conditions failed to produce zygospores when tested under anaerobic conditions. One homothallic species likewise failed to produce zygospores. In Amylomyces, chlamydospore production was almost completely suppresed under anaerobic conditions. None of the species tested formed sporangia in the absence of O2. When the starter cultures of Mucor were tested with 5% CO2, 10% H2, and 85% N2 in an anaerobic system, growth was similar to that of cultures in an aerobic environment; however, the growth was greatly reduced when CO2 was omitted from the anaerobic mixture (10% H2, 90% N2).