Effects of Methyl Cellulose on the Cellulolytic Bacterium, Ruminococcus Flavefaciens (Rumen, Anaerobe)
Rasmussen, Mark Axel
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https://hdl.handle.net/2142/71728
Description
Title
Effects of Methyl Cellulose on the Cellulolytic Bacterium, Ruminococcus Flavefaciens (Rumen, Anaerobe)
Author(s)
Rasmussen, Mark Axel
Issue Date
1986
Department of Study
Animal Science
Discipline
Dairy Science
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Microbiology
Abstract
Cellulose degradation by Ruminococcus flavefaciens and other ruminal cellulolytic bacteria was strongly inhibited by highly substituted methyl celluloses (degree of substitution > 1.5 and mol wt > 12,000). The inhibitory response was concentration dependent with 0.1% (wt/vol) or methyl cellulose required for complete inhibition. R. flavefaciens was unable to use methyl cellulose for growth and no bacterial depolymerization of methyl cellulose was observed. Bacterial adherence to cellulose also was inhibited by the cellulose derivatives. Crude mixtures of methylated cellulodextrins (average degree of polymerization (DP) = 9.4 and 8.5) prepared from methyl cellulose by mild acid hydrolysis (2 N HCl) partially inhibited cellulose degradation by R. flavefaciens. Inhibition did not occur with extended hydrolysis preparations (DP = 4.5 and 1.0) nor with the addition of 3-O-methyl-(beta)-D-glucose.
Similar inhibitory responses were observed on cellulose-grown cultures of R. flavefaciens using a p-nitrophenyl-(beta)-D-cellobioside enzyme assay. Cellulodextrins (DP = 3 - 7) synthetically methylated also inhibited enzymatic activity, however no inhibition was observed when glucose or cellobiose were similarly derivatized. A direct relationship between degree of inhibition and DP was suggested by these data. The recalcitrant nature of methyl celluloses and their inhibitory activities make these compounds important tools in the study of bacterial adherence to cellulose, cellulase enzymology and bacterial carbohydrate metabolism.
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