Influence of hydrogen-consuming bacteria on cellulose degradation by anaerobic fungi

• Published in: Applied and Environmental Microbiology Vol. 56; no. 12; pp. 3793 - 3797
• Main Authors: MARVIN-SIKKEMA, F. D, RICHARDSON, A. J, STEWART, C. S, GOTTSCHAL, J. C, PRINS, R. A
• Format: Journal Article
• Language: English
• Published: Washington, DC American Society for Microbiology 01.12.1990
• Subjects: Anaerobiosis; Animals; bacteria; Biological and medical sciences; Biology of microorganisms of confirmed or potential industrial interest; Biotechnology; cellulose; Cellulose - metabolism; celluloses; celulosa; champignon; Euryarchaeota - physiology; fermentacion; Fermentation; Fundamental and applied biological sciences. Psychology; fungi; Fungi - metabolism; hongos; Hydrogen - metabolism; methanobacterium; Mission oriented research; Neocallimastix; Physiology and metabolism; protozoa; rumen; Rumen - microbiology; selenomonas; Selenomonas ruminantium; Anaerobiosis; Biodegradation; Fungi; Hydrogen transfer; Enzyme; Cellulase; Microorganism culture; Fermentation; Thallophyta
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/aem.56.12.3793-3797.1990

The presence of methanogens Methanobacterium arboriphilus, Methanobacterium bryantii, or Methanobrevibacter smithii increased the level of cellulose fermentation by 5 to 10% in cultures of several genera of anaerobic fungi. When Neocallimastix sp. strain L2 was grown in coculture with methanogens the rate of cellulose fermentation also increased relative to that for pure cultures of the fungus. Methanogens caused a shift in the fermentation products to more acetate and less lactate, succinate, and ethanol. Formate transfer in cocultures of anaerobic fungi and M. smithii did not result in further stimulation of cellulolysis above the level caused by H2 transfer. When Selenomonas ruminantium was used as a H2-consuming organism in coculture with Neocallimastix sp. strain L2, both the rate and level of cellulolysis increased. The observed influence of the presence of methanogens is interpreted to indicate a shift of electrons from the formation of electron sink carbon products to H2 via reduced pyridine nucleotides, favoring the production of additional acetate and probably ATP. It is not known how S. ruminantium exerts its influence. It might result from a lowered production of electron sink products by the fungus, from consumption of electron sink products or H2 by S. ruminantium, or from competition for free sugars which in pure culture could exert an inhibiting effect on cellulolysis.