Clostridium cellulovorans
Classification
Bacteria; Firmicutes; Clostridia; Clostridiales; Clostridiaceae; Clostridium
Species
Clostridium cellulovorans
Description and Significance
Describe the appearance, habitat, etc. of the organism, and why you think it is important.
Clostridium cellulovorans (ATCC 35296) is anaerobic, spore forming and stain gram negative non-motile rods originally isolated from a batch methanogenic fermentation of hybrid poplar wood 1. C. Cellulovorans is a mesophilic bacterium with optimum growth temperature of 37°C, though it can grow in a temperature range of 20 to 40°C. Optimum pH is 7.0, and the pH range of growth is 6.4 to 7.8. This organism produces extracellular enzyme complex known as cellulosome, which can degrade plant cell walls. As most abundantly available potential source of fermentable sugars in the world are the higher plants’ cell walls2, utilization of such a vast resource for energy production would reduce the dependency on non-renewable fossil fuel. Hence, C. cellulovorans have potential industrial application for energy production.
Genome Structure
Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence? Genome sequencing of C. cellulovorans has been completed. C. Cellulovorans contains circular chromosomes containing 5,262,222 bp genomes which is about 1 Mbp larger than the genomes from other cellulosomal clostridia; 57 cellulosomal genes were reported in C. Cellulovorans 3. Number of predicted genes was the largest in C. cellulovorans as compared to other cellulosomal clostridia. C. Cellulovorans contains large number of genes encoding non-cellulosomal enzymes which are more associated with polysaccharides (such as hemicelluloses and pectins) degradation than to cellulose4.
Cell Structure, Metabolism and Life Cycle
Interesting features of cell structure; how it gains energy; what important molecules it produces.
C. Cellulovorans are 0.7 to 0.9 by 2.5 to 3.5 µm in size and are non-motile rods, though peritrichous flagella were detected under electron microscopy 1. Apart from cellulose, it ferments various carbon sources, such as xylan, pectin, cellobiose, glucose, fructose, galactose, sucrose, lactose and mannose to produce hydrogen, carbon dioxide, acetate, butyrate, formate and lactate 1. It produces plant cell wall degrading extracellular multienzyme complex called cellulosome5. Cellulosomal components synergistically interact to catalyze the degradation of cellulose and hence, cellulosome acts as a macromolecular machine 6. Cellulosome’s molecular weight is about 1 million and is able to hydrolyze crystalline cellulose7.
Ecology and Pathogenesis
Habitat; symbiosis; biogeochemical significance; contributions to environment.
If relevant, how does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.
References
Author
Page authored by Umesh Adhikari and Joe Araiz, student of Prof. Jay Lennon at Michigan State University.
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