Influence of dietary fiber on xylanolytic and cellulolytic bacteria of adult pigs.

Xylanolytic and cellulolytic bacteria were enumerated over an 86-day period from fecal samples of 10 8-month-old gilts that were fed either a control or a 40% alfalfa meal (high-fiber) diet. Fecal samples were collected from all pigs on days 0, 3, 5, 12, 25, 37, 58, and 86. Overall, the numbers of xylanolytic bacteria producing greater than 5-mm-diameter zones of clearing on 0.24% xylan roll tube medium after 24 to 36 h of incubation were 1.6 X 10(8) and 4.2 X 10(8)/g (dry weight) of feces for the control pigs and those fed the high-fiber diet, respectively. After 1 week of incubation, a large number of smaller zones of clearing (1 to 2 mm) appeared. Besides Bacteroides succinogenes and Ruminococcus flavefaciens, which produced faint zones of clearing in xylan roll tubes, three strains which closely resembled B. ruminicola hydrolyzed and used xylan for growth. The overall numbers of cellulolytic bacteria producing zones of clearing in 0.5% agar roll tube medium were 0.36 X 10(8) and 4.1 X 10(8)/g for the control pigs and those fed the high-fiber diet, respectively. B. succinogenes was the predominant cellulolytic isolate from both groups of pigs, and R. flavefaciens was found in a ratio of approximately 1 to 15 with B. succinogenes. Degradation of xylan and cellulose, measured by in vitro dry matter disappearance after inoculation with fecal samples, was significantly greater for pigs fed the high-fiber diet than that for the controls. These data suggest that the number of fibrolytic microorganisms and their activity in the large intestine of the adult pig can be increased by feeding pigs high-alfalfa-fiber diets and that these organisms are similar to those found in the rumen.     

Enumeration and activity of cellulolytic bacteria from gestating swine fed various levels of dietary fiber.

Cellulolytic bacteria were enumerated and cellulase activity was determined over a 98-day period from fecal samples of gestating swine fed various levels and sources of fiber. The diets, each fed to five pigs, were a corn-soybean control, 20% corn cobs, and 40 and 96% alfalfa meal. Fecal samples were collected from all pigs on days 0, 5, 14, 21, 35, 49, 70, and 98. Overall, the most probable number of cellulolytic bacteria from pigs fed the control, 20% corn cobs, and 40 and 96% alfalfa meal was 23.3 X 10(8), 15.2 X 10(8), 45.1 X 10(8), and 52.5 X 10(8) per g (dry weight) of fecal sample, respectively. Enumeration of cellulolytic bacteria by counting zones of clearing in roll tubes, as compared with the most probable number procedure, accounted for only 1.1 and 17.0% of the cellulolytic bacteria, respectively, from pigs fed the control or 96% alfalfa meal diet. Cellulolytic bacteria (most probable number) on days 70 and 98 accounted for 4.1 and 10.0% of the viable count for the pigs fed the control and 96% alfalfa meal diets, respectively. The viable count was not different between pigs fed the control and 96% alfalfa meal diets. The overall mean cellulolytic activity (milligrams of glucose released from carboxymethyl cellulose per gram [dry weight] fecal sample per 30 min was 17.0, 19.9, 23.8, and 20.6, respectively, for the control, 20% corn cobs, and 40 and 96% alfalfa meal diets. The results indicate that the cellulolytic flora can be increased by prolonged feeding of high-fiber diets and may represent 10% of the culturable flora.     

Enumeration and activity of cellulolytic bacteria from gestating swine fed various levels of dietary fiber

Cellulolytic bacteria were enumerated and cellulase activity was determined over a 98-day period from fecal samples of gestating swine fed various levels and sources of fiber. The diets, each fed to five pigs, were a corn-soybean control, 20% corn cobs, and 40 and 96% alfalfa meal. Fecal samples were collected from all pigs on days 0, 5, 14, 21, 35, 49, 70, and 98. Overall, the most probable number of cellulolytic bacteria from pigs fed the control, 20% corn cobs, and 40 and 96% alfalfa meal was 23.3 X 10(8), 15.2 X 10(8), 45.1 X 10(8), and 52.5 X 10(8) per g (dry weight) of fecal sample, respectively. Enumeration of cellulolytic bacteria by counting zones of clearing in roll tubes, as compared with the most probable number procedure, accounted for only 1.1 and 17.0% of the cellulolytic bacteria, respectively, from pigs fed the control or 96% alfalfa meal diet. Cellulolytic bacteria (most probable number) on days 70 and 98 accounted for 4.1 and 10.0% of the viable count for the pigs fed the control and 96% alfalfa meal diets, respectively. The viable count was not different between pigs fed the control and 96% alfalfa meal diets. The overall mean cellulolytic activity (milligrams of glucose released from carboxymethyl cellulose per gram [dry weight] fecal sample per 30 min was 17.0, 19.9, 23.8, and 20.6, respectively, for the control, 20% corn cobs, and 40 and 96% alfalfa meal diets. The results indicate that the cellulolytic flora can be increased by prolonged feeding of high-fiber diets and may represent 10% of the culturable flora.     

Cellulolytic bacteria from pig large intestine.

An anaerobic, cellulose-degrading, gram-negative rod and a gram-positive coccus, identified as Bacteroides succinogenes and Ruminococcus flavefaciens, respectively, were isolated from pig fecal samples. These organisms were isolated from cellulolytic most-probable-number dilutions which represented 4 or 6% of the viable bacterial count when pigs were fed a low- or high-fiber diet, respectively.     

Cellulolytic bacteria from pig large intestine

An anaerobic, cellulose-degrading, gram-negative rod and a gram-positive coccus, identified as Bacteroides succinogenes and Ruminococcus flavefaciens, respectively, were isolated from pig fecal samples. These organisms were isolated from cellulolytic most-probable-number dilutions which represented 4 or 6% of the viable bacterial count when pigs were fed a low- or high-fiber diet, respectively.     

Influence of high-fiber diet on bacterial populations in gastrointestinal tracts of obese- and lean-genotype pigs

Bacterial populations from gastrointestinal tracts of genetically lean and obese pigs fed a low- or high-fiber diet (0 or 50% alfalfa meal, respectively) were enumerated with rumen fluid media and specific energy sources. Total culture counts in rectal samples declined 56 (P greater than 0.05) and 63% (P less than 0.05) in lean and obese animals, respectively, 3 weeks after feeding the high-fiber diet. After 8 weeks, culture counts had risen and were similar to those obtained before alfalfa was fed (0 week). At slaughter, 12 to 17 weeks after feeding the high-fiber diet, total counts from rectal samples of lean pigs continued to rise and were 13% greater than the 0-week counts, whereas counts from obese animals declined 37% (P greater than 0.05). The number of cellulolytic bacteria in rectal samples of lean-genotype pigs fed the high-fiber diet increased 80 and 71% from 0 to 3 weeks and 3 to 8 weeks, respectively. This overall increases from 0 to 8 weeks in lean pigs was significant (P less than 0.05); however, these increases were not seen in obese pigs. These data suggest that the microflora is initially suppressed when exposed to a high-fiber diet and that later some adaptation takes place, apparently more so in lean than in obese pigs. When specific energy sources were used to delineate the distribution of different bacterial populations in the cecum, colon, and rectum, trends could be detected between high- and low-fiber diets. These data also support the concept that bacteria populations from different sites in the large bowel differ.     

Influence of high-fiber diet on bacterial populations in gastrointestinal tracts of obese- and lean-genotype pigs.

Bacterial populations from gastrointestinal tracts of genetically lean and obese pigs fed a low- or high-fiber diet (0 or 50% alfalfa meal, respectively) were enumerated with rumen fluid media and specific energy sources. Total culture counts in rectal samples declined 56 (P greater than 0.05) and 63% (P less than 0.05) in lean and obese animals, respectively, 3 weeks after feeding the high-fiber diet. After 8 weeks, culture counts had risen and were similar to those obtained before alfalfa was fed (0 week). At slaughter, 12 to 17 weeks after feeding the high-fiber diet, total counts from rectal samples of lean pigs continued to rise and were 13% greater than the 0-week counts, whereas counts from obese animals declined 37% (P greater than 0.05). The number of cellulolytic bacteria in rectal samples of lean-genotype pigs fed the high-fiber diet increased 80 and 71% from 0 to 3 weeks and 3 to 8 weeks, respectively. This overall increases from 0 to 8 weeks in lean pigs was significant (P less than 0.05); however, these increases were not seen in obese pigs. These data suggest that the microflora is initially suppressed when exposed to a high-fiber diet and that later some adaptation takes place, apparently more so in lean than in obese pigs. When specific energy sources were used to delineate the distribution of different bacterial populations in the cecum, colon, and rectum, trends could be detected between high- and low-fiber diets. These data also support the concept that bacteria populations from different sites in the large bowel differ.     

Ruminal cellulolytic bacteria and protozoa from bison, cattle-bison hybrids, and cattle fed three alfalfa-corn diets.

Ruminal cellulolytic bacteria and protozoa and in vitro digestibility of alfalfa fiber fractions were compared among bison, bison hybrids, and crossbed cattle (five each) when they were fed alfalfa and corn in a ratio of 100:0, 75:25, and 50:50, respectively. The total number of viable bacteria (2.16 x 10(9) to 5.44 x 10(9)/ml of ruminal fluid) and the number of cellulolytic bacteria (3.74 x 10(7) to 10.9 x 10(7)/ml) were not different among groups of animals fed each diet. The genera of protozoa in all of the animal groups were similar; however, when either the 100:0 or 50:50 diet was used the percentage of Entodinium sp. was lower and the percentage of Diplodiniinae was higher (P less than 0.05) in bison than in bison hybrids or cattle. Bacteroides succinogenes made up the largest number of cellulolytic isolates from bison (58 and 36%, respectively, on the 100:0 and 75:25 diets), which were more numerous (P less than 0.05) than those from bison hybrids (36 and 12%) and cattle (33 and 18%). This was offset by a lower number of cellulolytic Butyrivibrio isolates. The numbers of Ruminococcus albus and R. flavefaciens isolates, in general, were similar among the bovid species, although R. flavefaciens generally made up less than 10% of the cellulolytic isolates. In vitro digestibility coefficients were greater (P less than 0.05) for the bison when the 75:25 diet was used and similar for the other two diets. The concentration of ruminal volatile fatty acids was larger (P less than 0.05) in bison than in bison hybrids and cattle when the 50:50 diet was used.(ABSTRACT TRUNCATED AT 250 WORDS)     

Enumeration and isolation of cellulolytic and hemicellulolytic bacteria from human feces

The fibrolytic microbiota of the human large intestine was examined to determine the numbers and types of cellulolytic and hemicellulolytic bacteria present. Fecal samples from each of five individuals contained bacteria capable of degrading the hydrated cellulose in spinach and in wheat straw pretreated with alkaline hydrogen peroxide (AHP-WS), whereas degradation of the relatively crystalline cellulose in Whatman no. 1 filter paper (PMC) was detected for only one of the five samples. The mean concentration of cellulolytic bacteria, estimated with AHP-WS as a substrate, was 1.2 X 10(8)/ml of feces. Pure cultures of bacteria isolated on AHP-WS were able to degrade PMC, indicating that interactions with other microbes were primarily responsible for previous low success rates in detecting fecal cellulolytic bacteria with PMC as a substrate. The cellulolytic bacteria included Ruminococcus spp., Clostridium sp., and two unidentified strains. The mean concentration of hemicellulolytic bacteria, estimated with larchwood xylan as a substrate, was 1.8 X 10(10)/ml of feces. The hemicellulose-degrading bacteria included Butyrivibrio sp., Clostridium sp., Bacteroides sp., and two unidentified strains, as well as four of the five cellulolytic strains. This work demonstrates that many humans harbor intestinal cellulolytic bacteria and that a hydrated cellulose source such as AHP-WS is necessary for their consistent detection and isolation.     

Enumeration and isolation of cellulolytic and hemicellulolytic bacteria from human feces.

The fibrolytic microbiota of the human large intestine was examined to determine the numbers and types of cellulolytic and hemicellulolytic bacteria present. Fecal samples from each of five individuals contained bacteria capable of degrading the hydrated cellulose in spinach and in wheat straw pretreated with alkaline hydrogen peroxide (AHP-WS), whereas degradation of the relatively crystalline cellulose in Whatman no. 1 filter paper (PMC) was detected for only one of the five samples. The mean concentration of cellulolytic bacteria, estimated with AHP-WS as a substrate, was 1.2 X 10(8)/ml of feces. Pure cultures of bacteria isolated on AHP-WS were able to degrade PMC, indicating that interactions with other microbes were primarily responsible for previous low success rates in detecting fecal cellulolytic bacteria with PMC as a substrate. The cellulolytic bacteria included Ruminococcus spp., Clostridium sp., and two unidentified strains. The mean concentration of hemicellulolytic bacteria, estimated with larchwood xylan as a substrate, was 1.8 X 10(10)/ml of feces. The hemicellulose-degrading bacteria included Butyrivibrio sp., Clostridium sp., Bacteroides sp., and two unidentified strains, as well as four of the five cellulolytic strains. This work demonstrates that many humans harbor intestinal cellulolytic bacteria and that a hydrated cellulose source such as AHP-WS is necessary for their consistent detection and isolation.     

Fibrolytic activities and cellulolytic bacterial community structure in the solid and liquid phases of rumen contents.

Four sheep were fed an alfalfa hay diet. Rumen content samples were collected three hours after feeding in order to total microorganism population (TP), solid attached population (SAP) and solid attached firmly population (SAFP). Fibrolytic specific activities (xylanase, CMCase and beta-glycosidases) were estimated by the amount of reducing sugars or p-nitrophenol released from the appropriate substrate. The distribution of the three main cellulolytic bacterial species (Fibrobacter succinogenes, Ruminococcus albus and Ruminococcus flavefaciens) was quantified by dot-blot hybridisation using specific 16S-rRNA-targeting probes. Specific activities of polysaccharidase enzymes were higher in SAP than in TP, and in SAFP than in SAP. The sum of RNA of the three cellulolytic bacterial species represented on average 9% of the total bacterial RNA, and increased after filtration. In all samples, the relative population size of F. succinogenes was higher than that of R. albus and of R. flavefaciens. These results demonstrate that the most active enzymes are secreted by the particle-associated microorganisms. The differences in composition of the microflora between the solid and liquid phase suggest that bacteria are not equally distributed throughout the rumen content: the cellulolytic species are present in a higher proportion in the solid phase of rumen contents.     

Adhesion of cellulolytic ruminal bacteria to barley straw

Adhesion of the cellulolytic ruminal bacteria Ruminococcus flavefaciens and Fibrobacter succinogenes to barley straw was measured by incubating bacterial suspensions with hammer-milled straw for 30 min, filtering the mixtures through sintered glass filters, and measuring the optical densities of the filtrates. Maximum adhesion of both species occurred at pH 6.0 and during mid- to late-exponential phase. Adhesion was saturable at 33 and 23 mg (dry weight) g of straw for R. flavefaciens and F. succinogenes, respectively. Methyl cellulose and carboxymethyl cellulose inhibited adhesion by 24 to 33%. Competition between species was determined by measuring characteristic cell-associated enzyme activities in filtrates of mixtures incubated with straw; p-nitrophenyl-beta-d-lactopyranoside hydrolysis was used as a marker for F. succinogenes, while either beta-xylosidase or carboxymethyl cellulase was used for R. flavefaciens, depending on the other species present. R. flavefaciens had no influence on F. succinogenes adhesion, and F. succinogenes had only a minor (<20%) effect on R. flavefaciens adhesion. The noncellulolytic ruminal bacteria Bacteroides ruminicola and Selenomonas ruminantium had no influence on adhesion of either cellulolytic species, although these organisms also adhered to the straw. We concluded that R. flavefaciens and F. succinogenes have separate, specific adhesion sites on barley straw that are not obscured by competition with non-cellulolytic species.     

Effect of high-fiber and high-oil diets on the fecal flora of swine

Six pairs of pigs were fed a basal diet, a high-fiber diet, and a diet high in corn oil in different sequences to minimize the carry-over effect of diet. After 2 months on each diet, a fecal specimen from each pig was cultured on nonselective medium in roll tubes. Fifty colonies were randomly selected from each fecal sample, and isolates were characterized to identify a representative cross section of the fecal flora. The bacterial composition of the fecal flora differed between basal and high-fiber diets (P = 0.002) and between high-fiber and high-oil diets (P = 0.015). However, the floras were not significantly different between the basal and the high-oil diets (P = 0.135), nor were the floras of the 12 individual pigs (each on all three diets) statistically different (P = 0.103). Only 14 of the 160 observed taxa have been detected in the human fecal flora, and only 159 of 1,871 total isolates (8.5%) were members of described species. The most common isolate was a Streptococcus species similar to that reported by Robinson et al. (I. M. Robinson, S. C. Whipp, J. A. Bucklin, and M. J. Allison, Appl. Environ. Microbiol. 48:964-969, 1984), which was found in 34 of 36 samples and which represented 27.5% of all isolates. Lactobacillus, Fusobacterium, Eubacterium, Bacteroides, and Peptostreptococcus species were the next most common bacteria. Escherichia coli represented 1.7% of all fecal isolates, which is somewhat higher than the 0.1 to 0.6% observed in human feces cultured similarly with prereduced anaerobically sterilized media.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of high-fiber and high-oil diets on the fecal flora of swine.

Six pairs of pigs were fed a basal diet, a high-fiber diet, and a diet high in corn oil in different sequences to minimize the carry-over effect of diet. After 2 months on each diet, a fecal specimen from each pig was cultured on nonselective medium in roll tubes. Fifty colonies were randomly selected from each fecal sample, and isolates were characterized to identify a representative cross section of the fecal flora. The bacterial composition of the fecal flora differed between basal and high-fiber diets (P = 0.002) and between high-fiber and high-oil diets (P = 0.015). However, the floras were not significantly different between the basal and the high-oil diets (P = 0.135), nor were the floras of the 12 individual pigs (each on all three diets) statistically different (P = 0.103). Only 14 of the 160 observed taxa have been detected in the human fecal flora, and only 159 of 1,871 total isolates (8.5%) were members of described species. The most common isolate was a Streptococcus species similar to that reported by Robinson et al. (I. M. Robinson, S. C. Whipp, J. A. Bucklin, and M. J. Allison, Appl. Environ. Microbiol. 48:964-969, 1984), which was found in 34 of 36 samples and which represented 27.5% of all isolates. Lactobacillus, Fusobacterium, Eubacterium, Bacteroides, and Peptostreptococcus species were the next most common bacteria. Escherichia coli represented 1.7% of all fecal isolates, which is somewhat higher than the 0.1 to 0.6% observed in human feces cultured similarly with prereduced anaerobically sterilized media.(ABSTRACT TRUNCATED AT 250 WORDS)     

Ruminal cellulolytic bacteria and protozoa from bison, cattle-bison hybrids, and cattle fed three alfalfa-corn diets

Ruminal cellulolytic bacteria and protozoa and in vitro digestibility of alfalfa fiber fractions were compared among bison, bison hybrids, and crossbed cattle (five each) when they were fed alfalfa and corn in a ratio of 100:0, 75:25, and 50:50, respectively. The total number of viable bacteria (2.16 x 10(9) to 5.44 x 10(9)/ml of ruminal fluid) and the number of cellulolytic bacteria (3.74 x 10(7) to 10.9 x 10(7)/ml) were not different among groups of animals fed each diet. The genera of protozoa in all of the animal groups were similar; however, when either the 100:0 or 50:50 diet was used the percentage of Entodinium sp. was lower and the percentage of Diplodiniinae was higher (P less than 0.05) in bison than in bison hybrids or cattle. Bacteroides succinogenes made up the largest number of cellulolytic isolates from bison (58 and 36%, respectively, on the 100:0 and 75:25 diets), which were more numerous (P less than 0.05) than those from bison hybrids (36 and 12%) and cattle (33 and 18%). This was offset by a lower number of cellulolytic Butyrivibrio isolates. The numbers of Ruminococcus albus and R. flavefaciens isolates, in general, were similar among the bovid species, although R. flavefaciens generally made up less than 10% of the cellulolytic isolates. In vitro digestibility coefficients were greater (P less than 0.05) for the bison when the 75:25 diet was used and similar for the other two diets. The concentration of ruminal volatile fatty acids was larger (P less than 0.05) in bison than in bison hybrids and cattle when the 50:50 diet was used.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cereal supplementation modified the fibrolytic activity but not the structure of the cellulolytic bacterial community associated with rumen solid digesta

4 ruminally cannulated cows were fed a forage diet (93% hay + 7% straw) and a mixed diet (33 % hay + 7% straw + 40% barley) in a 2 x 2 crossover experimental design. In sacco degradation of forage, fibrolytic activities (polysaccharidases and glycosidases) of the solid-associated bacteria (SAB), and distribution of the 3 main cellulolytic bacterial species (Fibrobacter succinogenes, Ruminococcus albus, Ruminococcus flavefaciens) were determined for both diets. Barley supplementation decreased the hay degradation rate and mainly the polysaccharidase activities of the SAB (30% on average). The sum of rRNA of the 3 cellulolytic bacterial species represented on average 17% of the total bacterial signal and R. albus was the dominant cellulolytic bacterial species of the 3 studied. Barley supplementation did not modify the proportion of the 3 cellulolytic bacteria attached to plant particles. The negative effect of barley on the ruminal hay degradation rate is due to a decrease in fibrolytic activity of the SAB, and not to a modification of the balance of the three cellulolytic bacterial species examined.     

Gas-liquid chromatography for evaluating polysaccharide degradation by Ruminococcus flavefaciens C94 and Bacteroides succinogenes S85.

Two predominant rumen cellulolytic bacteria, Ruminococcus flavefaciens C94 and Bacteroides succinogenes S85, were incubated with ground filter paper (Whatman no. 1), cattle manure fiber, wheat straw, Kentucky bluegrass, alfalfa, and corn silage as substrates. Analyses of the initial substrate and the recovered residue after 48 h of static incubation showed that R. flavefaciens C94 was quantitatively more effective than B. succinogenes S85 in degrading total dry matter (32.3% versus 16.1%). However, B. succinogenes S85 demonstrated a qualitative advantage in degrading the hemicellulose and hemicellulosic sugars of particular substrates. R. flavefaciens degraded a mean 29.7% of the cellulose and 35.6% of the hemicellulose in the various substrates, whereas B. succinogenes degraded a mean 17.9 and 31.6% of these fractions, respectively. Gas-liquid chromatography was an important aid in characterizing the polysaccharide-degrading capabilities of these rumen species.     

Quantification by real-time PCR of cellulolytic bacteria in the rumen of sheep after supplementation of a forage diet with readily fermentable carbohydrates: effect of a yeast additive

AIM: To examine the effect of concentrate and yeast additive on the number of cellulolytic bacteria in the rumen of sheep. METHODS AND RESULTS: Fibrobacter succinogenes, Ruminococcus albus and Ruminococcus flavefaciens were quantified using real-time PCR (targeting 16S rDNA) in parallel to cellulolytic flora enumeration with cultural techniques. Whatever the conditions tested, R. flavefaciens was slightly more abundant than F. succinogenes, with both species outnumbering R. albus. Before feeding, the shift from hay to hay plus concentrate diet had no effect on rumen pH and on the number of the three specie; while after feeding, the concentrate-supplemented diet induced a decrease (-1 log) of the number of the three species concomitant with the rumen acidification. Overall, the presence of the live yeast resulted in a significant increase (two- to fourfold) of the Ruminococci. CONCLUSION: The use of real-time PCR allowed us to show changes in the number of cellulolytic bacterial species in vivo in response to diet shift and additives that could not be as easily evidenced by classical microbial methods. SIGNIFICANCE AND IMPACT OF THE STUDY: This study contributes to the understanding of the negative impact of readily fermentable carbohydrates on rumen cellulolysis and the beneficial effect of yeast on rumen fermentation.     

Interactions between rumen bacterial strains during the degradation and utilization of the monosaccharides of barley straw cell-walls

Pure cultures and pair-combinations of strains representative of the rumen cellulolytic species Ruminococcus flavefaciens, Fibrobacter succinogenes and Butyrivibrio fibrisovens were grown on cell-wall materials from barley straw. Of the pure cultures, R. flavefaciens solubilized straw most rapidly. The presence of B. fibrisolvens , which was unable to degrade straw extensively in pure culture, increased the solubilization of dry matter by R. flavefaciens and the solubilization of cell-wall carbohydrates by both R. flavefaciens and F. succinogenes. During fermentation, both R. flavefaciens and F. succinogenes released bound glucose and free and bound arabinose and xylose into solution. The accumulation of these sugars, especially arabinose and xylose, was greatly reduced in co-cultures containing B. fibrisolvens , suggesting that significant interspecies cross feeding of the products of hemicellulose hydrolysis (particularly soluble bound xylose released by F. succinogenes ) occurs during straw degradation by mixed cultures containing this species.     

Adhesion of Bacteroides succinogenes in pure culture and in the presence of Ruminococcus flavefaciens to cell walls in leaves of perennial ryegrass (Lolium perenne).

Bacteroides succinogenes and Ruminococcus flavefaciens are two of the most important cellulolytic bacteria in the rumen. Adhesion of B. succinogenes in pure culture, and in mixed culture with R. flavefaciens, to the various types of cell walls in sections of perennial ryegrass (Lolium perenne L. cultivar S24) leaves was examined by transmission and scanning electron microscopy. B. succinogenes adhered to the cut edges of most plant cell walls except those of the meta- and protoxylem. It also adhered, though in much smaller numbers, to the uncut surfaces of mesophyll, epidermal, and phloem cell walls. In mixed culture, both species adhered in significant numbers to the cut edges of most types of plant cell wall, but R. flavefaciens predominated on the epidermis, phloem, and sclerenchyma cell walls. B. succinogenes predominated on the cut edges and on the uncut surfaces of the mesophyll cell walls, and its ability to adhere to uncut surfaces of other cell walls was not affected by the presence of the ruminococcus. Both organisms rapidly digested the epidermal, mesophyll, and phloem cell walls. Zones of digestion were observed around bacteria of both species when attached to the lignified cell walls of the sclerenchyma, but not when attached to the lignified xylem vessels.