A Comparison of Two Techniques for Counting Cellulolytic Rumen Bacteria

Abstract

S U M M A R YCellulolytic bacteria were counted by the ' direct' method; estimated from the number of clearings produced in films of cellulose-containing agar medium inoculated with high dilutions of rumen ingesta and by the 'indirect' method; numbers were calculated from 'total culturable' counts on films of a non-specific agar medium and from the percentages of bacteria found to be cellulolytic after isolation in pure culture. The two methods yielded similar results.

Ecology of Microbial Cellulose Degradation

“…Since cellulose is the major part of the ruminant diet, cellulolytic bacteria have been the targets of much interest. Several methods have been developed to determine the number of cellulolytic microorganisms in the rumen (Bryant and Robinson, 1961;van Gylswyk, 1970;Teather and Wood, 1982). Their nutritional requirements have been discussed in many papers [see the above-mentioned reviews and Bryant (1973)].…”

Enumeration ofBacteroides succinogenesin the rumen of sheep fed maize-straw diets

“…In an earlier study [8] no appreciable differences were found when numbers of cellulolytic rumen bacteria were estimated by either a direct or an indirect counting method. However, it was subsequently shown that with the direct method the number of cellulolytic bacteria is underestimated because B. succinogenes, an important component of the cellulolytic flora, does not produce clearings in cellulose agar medium [5].…”

“…We also present the results of an experiment on longevity of newly isolated strains of B. succinogenes in agar medium which could explain why we did not find appreciable differences in cellulolytic counts in the rumen of sheep when using 2 different counting techniques in another study [8].…”

“…One medium contained glucose and cellobiose (0.2% of each; RGCA medium) while the other contained glucose, cellobiose, starch and xylan (0.05% of each; GSCX medium). Roll bottles were incubated for 7 days as was done before [8]. After this period, 5 colonies from each strain and each medium were picked and stabbed into RGCA slopes which were incubated for up to 10 days.…”

“…In that work we obtained estimates of different cellulolytic species by identifying bacteria that gave rise to clearings in thin layers of cellulose agar medium and we were, therefore, not able to assess numbers of B. succinogenes. In the present study we used a method essentially similar to one that has often been used by American researchers when examining the bovine rumen [7].We also present the results of an experiment on longevity of newly isolated strains of B. succinogenes in agar medium which could explain why we did not find appreciable differences in cellulolytic counts in the rumen of sheep when using 2 different counting techniques in another study [8].0168o6496/86/$03.50…”