Microorganism of decomposition cellulose - Several microorganisms are capable of decomposing cellulose in the total absence of molecular oxygen and the polysaccharide disappears under anaero-biosis whether supplied as the purified chemical or in the form of plant materials. The production of large quantities of ethanol and organic acids such as acetic, formic, lactic and butyric is typical of the anaerobic cleavage of the cellulose molecule. When a soil becomes anaerobic, the decomposition proceeds through the action of bacteria that do not require O2.
Fungi or Actinomycetes are not significant in anaerobic environments. Differing from the transformation in air, the anaerobic conversion is not detectably affected by added inorganic nitrogen. Since anaerobic decomposition supplies little energy, the bacteria must degrade large quantities of the substrate in order to assimilate a small amount of carbon. Consequently, there is a proportionally small demand for nitrogen for assimilation into microbial cells, less than the amount usually present in plant residues.
The isolation and maintenance of pure cultures of cellulolytic anaerobic is difficult and many early investigators undoubtedly never had pure cultures. At present, several types of anaerobic cellulose decomposer are known, spore-forming mesophiles, spore-forming thermophiles, non-spore-forming rods, cocci and several actinomycetes and fungi that grow anaerobically.
The isolation and maintenance of pure cultures of cellulolytic anaerobic is difficult and many early investigators undoubtedly never had pure cultures. At present, several types of anaerobic cellulose decomposer are known, spore-forming mesophiles, spore-forming thermophiles, non-spore-forming rods, cocci and several actinomycetes and fungi that grow anaerobically.
At best, cellulolysis without O2 is slow, regardless of the group concerned. The anaerobic bacteria are rarely numerous in unamended, well drained soils although peats, marshes and manure often support a sizable population. Commonly, from 10^2 to 10^3 anaerobic cellulose fermenting bacteria are found per gram of nonflooded soil. On the other hand, the presence of a fermentable substrate or the exclusion of air stimulates this flora. The low number detected in well-drained soil probably represent the spore of the predominant bacteria. Differing from the aerobic bacteria, these organisms are not too sensitive to acidity and they have been found in soil of pH 4.3.
Anaerobic Cellulose Fermenters
The most common anaerobic cellulose fermenters in nature appear to be members of the genus Clostridium. These bacteria are found in soil, compost, manure, river mud and sewage. Many Clostridium species are cellulolytic, a capacity not too rare in the genus. To isolate such clostridia, a soil suspension is heated at 80oC for 10 minutes and dilutions are introduced into cellulose media that are then incubation anaerobically. The method takes advantage of the heat resistance of the spores and the anaerobic and cellulolytic nature of the vegetative cell. The technique is, therefore, a relatively specific means of obtaining isolate of the genus.
Non-spore-forming cellulolytic anaerobes can be demonstrated in soil or in sewage sludge, but they are not abundant. Certain fungi such as Merulius and Fomes have the capacity to develop slowly on cellulose in the absence of O2 and these may play some role in the soil. An occasional actinomycete may grow anaerobically, albeit slowly, in cellulosic media.
Anaerobic Cellulose Fermenters
The most common anaerobic cellulose fermenters in nature appear to be members of the genus Clostridium. These bacteria are found in soil, compost, manure, river mud and sewage. Many Clostridium species are cellulolytic, a capacity not too rare in the genus. To isolate such clostridia, a soil suspension is heated at 80oC for 10 minutes and dilutions are introduced into cellulose media that are then incubation anaerobically. The method takes advantage of the heat resistance of the spores and the anaerobic and cellulolytic nature of the vegetative cell. The technique is, therefore, a relatively specific means of obtaining isolate of the genus.
Non-spore-forming cellulolytic anaerobes can be demonstrated in soil or in sewage sludge, but they are not abundant. Certain fungi such as Merulius and Fomes have the capacity to develop slowly on cellulose in the absence of O2 and these may play some role in the soil. An occasional actinomycete may grow anaerobically, albeit slowly, in cellulosic media.
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