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PubMed2002

Distribution of genes encoding the trypsin-dependent lantibiotic ruminococcin A among bacteria isolated from human fecal microbiota.

Fourteen bacterial strains capable of producing a trypsin-dependent antimicrobial substance active against Clostridium perfringens were isolated from human fecal samples of various origins (from healthy adults and children, as well as from adults with chronic pouchitis). Identification of these strains showed that they belonged to Ruminococcus gnavus, Clostridium nexile, and Ruminococcus hansenii species or to new operational taxonomic units, all from the Clostridium coccoides phylogenetic group. In hybridization experiments with a probe specific for the structural gene encoding the trypsin-dependent lantibiotic ruminococcin A (RumA) produced by R. gnavus, seven strains gave a positive response. All of them harbored three highly conserved copies of rumA-like genes. The deduced peptide sequence was identical to or showed one amino acid difference from the hypothetical precursor of RumA. Our results indicate that the rumA-like genes have been disseminated among R. gnavus and phylogenetically related strains that can make up a significant part of the human fecal microbiota.

Bacteria↗

PubMed2003

Effects of alternative dietary substrates on competition between human colonic bacteria in an anaerobic fermentor system.

Duplicate anaerobic fermentor systems were used to examine changes in a community of human fecal bacteria supplied with different carbohydrate energy sources. A panel of group-specific fluorescent in situ hybridization probes targeting 16S rRNA sequences revealed that the fermentors supported growth of a greater proportion of Bacteroides and a lower proportion of gram-positive anaerobes related to Faecalibacterium prausnitzii, Ruminococcus flavefaciens-Ruminococcus bromii, Eubacterium rectale-Clostridium coccoides, and Eubacterium cylindroides than the proportions in the starting fecal inoculum. Nevertheless, certain substrates, such as dahlia inulin, caused a pronounced increase in the number of bacteria related to R. flavefaciens-R. bromii and E. cylindroides. The ability of three strictly anaerobic, gram-positive bacteria to compete with the complete human fecal flora was tested in the same experiment by using selective plating to enumerate the introduced strains. The Roseburia-related strain A2-183(F) was able to grow on all substrates despite the fact that it was unable to utilize complex carbohydrates in pure culture, and it was assumed that this organism survived by cross-feeding. In contrast, Roseburia intestinalis L1-82(R) and Eubacterium sp. strain A2-194(R) survived less well despite the fact that they were able to utilize polysaccharides in pure culture, except that A2-194(R) was stimulated 100-fold by inulin. These results suggest that many low-G+C-content gram-positive obligate anaerobes may be selected against during in vitro incubation, although several groups were stimulated by inulin. Thus, considerable caution is necessary when workers attempt to predict the in vivo effects of probiotics and prebiotics from their effects in vitro.

Anaerobiosis↗

PubMed1971

Carbon dioxide requirement of various species of rumen bacteria.

The carbon dioxide requirement of 32 strains of rumen bacteria, representing 11 different species, was studied in detail. Increasing concentrations of CO(2) were added as NaHCO(3) to a specially prepared CO(2)-free medium which was tubed and inoculated under nitrogen. Prior depletion of CO(2) in the inoculum was found to affect the level of requirement; however, the complexity and buffering capacity of the medium did not appear to be involved. An absolute requirement for CO(2) was observed for eight strains of Bacteroides ruminicola, three strains of Bacteroides succinogenes, four strains of Ruminococcus flavefaciens, two strains of Lachnospira multiparus, one strain of Succinimonas amylolytica, and two strains of Butyrivibrio fibrisolvens. Inconsistent growth responses were obtained in CO(2)-free media with one strain each of B. fibrisolvens, Ruminococcus albus, and Selenomonas ruminantium. Growth of six additional strains of B. fibrisolvens, and single strains of Eubacterium ruminantium and Succinivibrio dextrinosolvens was markedly increased or stimulated by increasing concentrations of CO(2). Peptostreptococcus elsdenii B159 was the only organism tested which appeared to have no requirement, either absolute or partial, for CO(2). Higher concentrations of CO(2) were required for the initiation of growth, as well as for optimal growth, by those species which produce succinic acid as one of their primary end products.

Agar↗

PubMed1977

Studies on some characteristics of hydrogen production by cell-free extracts of rumen anaerobic bacteria.

Hydrogen production was studied in the following rumen anaerobes: Bacteroides clostridiiformis, Butyrivibrio fibrisolvens, Enbacterium limosum, Fusobacterium necrophorum, Megasphaera elsdenii, Ruminococcus albus, and Ruminococcus flavefaciens. Clostridium pasteurianum and Escherichia coli were included for comparative purposes. Hydrogen production from dithionite, dithionite-reduced methyl viologen, pyruvate, and formate was determined. All species tested produced hydrogen from dithionite-reduce methyl viologen, but only C. pasteurianum, B. clostridiiformis, E. limosum, and M. elsdenii produced hydrogen from dithionite. All species except E. coli produced hydrogen from pyruvate, but activity was low or absent in extracts of E. limosum, F. necrophorum, R. albus, and R. flavefaciens unless methyl viologen was added. Hydrogen was produced from formate only by E. coli, B. clostridiiformis, E. limosum, F. necrophorum, and R. flavefaciens. Extracts were subjected to ultracentrifugation in an effort to determine the solubility of hydrogenase. The hydrogenase of all species except E. coli appeared to be soluble, although variable amounts of hydrogenase activity were detected in the pellet. Treatment of extracts of the rumen microbial species with DEAE-cellulose resulted in loss ofhydrogen production from pyruvate. Activity was restored by the addition of methyl viologen. It is concluded that hydrogen production in these rumen microorganisms is similar to that in the saccharolytic clostridia.

Anaerobiosis↗

PubMed1987

Electron microscopic study of the methylcellulose-mediated detachment of cellulolytic rumen bacteria from cellulose fibers.

The presence of methylcellulose prevents the attachment of cellulolytic rumen bacteria to cellulose fibers. The addition of methylcellulose to pure cultures of these organisms in which the cells are already adherent to cellulose causes their detachment from this insoluble substrate and the inhibition of their growth. Methylcellulose is not used as a carbon source by these organisms and has no effect on their growth when glucose and cellobiose are the carbon sources. Attached cells of Bacteroides succinogenes orient themselves in the plane of the individual cellulose fibers and their methylcellulose-induced detachment, which is complete (almost 100%), leaves grooves where the cellulose has been digested. Attached cells of Ruminococcus albus colonize the cellulose in a looser and less regular pattern and their almost complete methylcellulose-induced detachment leaves less regular pits in the cellulose surface. On the other hand, attached cells of Ruminococcus flavefaciens colonize the cellulose surface in a random orientation by means of a discernible exopolysaccharide network, and their less complete methylcellulose-induced detachment leaves no residual impressions on the cellulose surface. These data support the suggestion that bacterial attachment is necessary for the digestion of highly ordered crystalline cellulose, and that cellulolytic species differ in the nature of their attachment to this insoluble substrate and in the nature of their enzymatic attack. Methylcellulose is an effective agent for detaching major rumen cellulolytic bacteria from their cellulosic substrate.

Animals↗

PubMed2025

Influence of creatine pyruvate on newly received cattle: insights from metagenomics and metabolomics.

Transport stress is a critical factor affecting the health and growth performance of beef cattle, potentially leading to oxidative stress, inflammation, and metabolic disorders. Creatine pyruvate (CrPyr), as a potential stress alleviator, has unclear mechanisms of action. We monitored the growth of 17 Simmental calves (control, n = 8; CrPyr, n = 9) over 30 days post-transportation, collecting rumen and blood samples on days 1/4, and 30. This study aims to investigate the effects of CrPyr on the growth performance, rumen microbiome, and metabolome of calves subjected to transport stress. Results showed that CrPyr increased average daily gain and antioxidant capacity, while reducing the level of stress hormones and inflammation. In the 4 days post-transport, CrPyr mainly increases Ruminococcus abundance to boost ruminal nitrogen metabolism, providing substrates for microbial protein synthesis. CrPyr also provides energy for the proliferation of Ruminococcus by regulating ATP synthesis genes (ATPVC) and enriching purine metabolism products. Meanwhile, it strengthens the host's amino acid metabolism, especially aspartate, to enhance antioxidative capacity. By day 30, CrPyr primarily boosts Prevotella abundance to regulate VFA synthesis, supplying host energy. It regulates the ATP synthesis gene ATPF0A and enriches purine metabolism products, supporting Prevotella growth. Increased citric acid and ATP levels further aid host growth. The findings distinctly demonstrate that the mechanisms by which CrPyr alleviates transport stress through the regulation of the rumen microbiome and metabolome, and confirms that its effects are time-dependent. These findings provide a theoretical basis for the development of stress-alleviation strategies based on CrPyr and hold significant implications for enhancing the health and production performance of beef cattle.

Animals↗

PubMed1997

Microbial perspective on fiber utilization by swine.

Dietary fiber may contribute up to 30% of the maintenance energy needs of growing pigs. Higher energy contributions may be obtained from dietary fiber fed to sows, along with some improvements in reproduction, health, and well-being. As long as cereal grain supplies and high-quality protein supplements are abundant, the use of fibrous feeds for swine most likely will be limited. However, as the human demand for cereal grains increases, swine producers, especially those with reproductive animals, may be economically forced to incorporate alternative feedstuffs. These feedstuffs might include lignified plant cell wall material such as grasses and legumes, and feed-milling and distillery by-products that contain a high level of fiber residues. The microflora in swine large intestine will be able to adapt to these lignified forages and by-product feeds much better than the microflora in humans. Swine microflora contain highly active ruminal cellulolytic and hemicellulolytic bacterial species, which include Fibrobacter succinogenes (intestinalis), Ruminococcus albus, Ruminococcus flavefaciens, Butyrivibrio spp., and Prevotella ruminicola. Additionally, a new highly active cellulolytic bacterium, Clostridium herbivorans, has been recently isolated from pig large intestine. The populations of these microorganisms are known to increase in response to the ingestion of diets high in plant cell wall material. The numbers of cellulolytic bacteria from adult animals are approximately 6.7 times greater than those found in growing pigs. None of these highly active cellulolytic bacterial species are found in the human large intestine. Thus, the pig large intestinal fermentation of fiber seems to more closely resemble that of ruminants than that of humans.

Animals↗

PubMed1999

Feasibility of using total purines as a marker for ruminal bacteria.

A procedure for measuring total purine content of mixed ruminal bacteria was adapted for use in the determination of purines in pure cultures of ruminal bacteria. Recovery of adenine and guanine, alone or in mixture, was quite variable. The problem was traced to solubility of the silver salt of adenine in the acid wash solution. When the precipitating solution was used as the wash, recovery of the purines was over 97%. Recovery of a 1:1 mixture of adenine and guanine added to yeast RNA was 100.6+/-3.2%. Purine, protein, and bacterial concentrations were determined for 10 pure cultures of ruminal bacteria: Butyrivibrio fibrisolvens, D16f, H10b, and H17c; Fibrobacter succinogenes B21a; Lachnospira multiparus D25e; Lactobacillus lactis ARD26e; Prevotella ruminicola H15a; Ruminococcus albus 7; Ruminococcus flavefaciens B34b; and Streptococcus bovis ARD5d. The CV for the most-probable-number (MPN) assay (bacterial concentrations), purine analysis, and protein analysis were 55.86, 5.25 and 6.52%, respectively. Considerable variation was found among bacterial species and strains when purine and protein concentrations were compared as the amount per individual cell. More consistent values were obtained when these components were expressed on a dry matter basis. Purine:protein ratios for the 10 pure cultures ranged from .023 to .1299, with a mean value of .0883. For samples of mixed bacteria separated from ruminal fluid, this ratio was found to average .0306, which is approximately one-third of the value for the pure cultures. The value determined for the mixed bacterial sample is similar to previously reported values. Based on the ratio obtained with the pure cultures, the microbial protein flow out of the rumen has probably been overestimated in most previous reports. Limited studies suggest that the samples of mixed ruminal bacteria used as a standard are probably contaminated with feed particles containing protein, which results in lower purine:protein ratios.

Animals↗

PubMed2002

A comparison of enzymatic and molecular approaches to characterize the cellulolytic microbial ecosystems of the rumen and the cecum.

We used RNA probes and enzyme activities to compare the cellulolytic microbial ecosystems of the rumen and the cecum. Four rumen- and cecum-cannulated wethers were fed a diet of barley plus hay (60:40). Digesta samples were collected 1 h before feeding and 3, 6, and 9 h after feeding for measurements on microbial populations, and 1 h before feeding and 3 and 6 h after feeding for digestion measurements, pH, and VFA. Polysaccharidase and glycosidase specific activities of solid-adherent microorganisms were measured respectively by the amount of reducing sugars released from xylan or avicel or p-nitrophenol from the p-nitrophenol derivatives of xylose and glucose. The distribution and amounts of the three main cellulolytic bacterial species (Fibrobacter succinogenes, Ruminococcus albus, and Ruminococcus flavefaciens) were determined by dot-blot hybridization using specific 16SrRNA-targeting probes. Enzyme activities were higher in the rumen than in the cecum and before feeding than at 3 h after feeding. The sum of the three cellulolytic bacterial species represented, on average, 4.5% of the total bacterial RNA in the two compartments and did not vary with sampling time. The cellulolytic bacterial community structure was different in the two compartments, with F. succinogenes as the main species in the rumen and R. flavefaciens in the cecum. The lower cellulolytic activity in the cecum than in the rumen could not be ascribed to any difference in the structure of the cellulolytic bacterial community between these two compartments, and other hypotheses related to digestion are proposed.

Animal Feed↗

PubMed2006

In vitro bacterial growth and in vivo ruminal microbiota populations associated with bloat in steers grazing wheat forage.

The role of ruminal bacteria in the frothy bloat complex common to cattle grazing winter wheat has not been previously determined. Two experiments, one in vitro and another in vivo, were designed to elucidate the effects of fresh wheat forage on bacterial growth, biofilm complexes, rumen fermentation end products, rumen bacterial diversity, and bloat potential. In Exp. 1, 6 strains of ruminal bacteria (Streptococcus bovis strain 26, Prevotella ruminicola strain 23, Eubacterium ruminantium B1C23, Ruminococcus albus SY3, Fibrobacter succinogenes ssp. S85, and Ruminococcus flavefaciens C94) were used in vitro to determine the effect of soluble plant protein from winter wheat forage on specific bacterial growth rate, biofilm complexes, VFA, and ruminal H2 and CH4 in mono or coculture with Methanobrevibacter smithii. The specific growth rate in plant protein medium containing soluble plant protein (3.27% nitrogen) was measured during a 24-h incubation at 39 degrees C in Hungate tubes under a CO2 gas phase. A monoculture of M. smithii was grown similarly, except under H2:CO2 (1:1), in a basal methanogen growth medium supplemented likewise with soluble plant protein. In Exp. 2, 6 ruminally cannulated steers grazing wheat forage were used to evaluate the influence of bloat on the production of biofilm complexes, ruminal microbial biodiversity patterns, and ruminal fluid protein fractions. In Exp. 1, cultures of R. albus (P < 0.01) and R. flavefaciens (P < 0.05) produced the most H2 among strains and resulted in greater (P < 0.01) CH4 production when cocultured with M. smithii than other coculture combinations. Cultures of S. bovis and E. ruminantium + M. smithii produced the most biofilm mass among strains. In Exp. 2, when diets changed from bermudagrass hay to wheat forage, biofilm production increased (P < 0.01). Biofilm production, concentrations of whole ruminal content (P < 0.01), and cheesecloth filtrate protein fractions (P < 0.05) in the ruminal fluid were greater on d 50 for bloated than for nonbloated steers when grazing wheat forage. The molecular analysis of the 16S rDNA showed that 2 different ruminal microbiota populations developed between bloated and nonbloated animals grazing wheat forage. Bloat in cattle grazing wheat pastures may be caused by increased production of biofilm, resulting from a diet-influenced switch in the rumen bacterial population.

Acetates↗

PubMed2003

Kinetics of in sacco fiber-attachment of representative ruminal cellulolytic bacteria monitored by competitive PCR.

Stems of orchardgrass hay in nylon bags were incubated in the rumens of three ruminally fistulated sheep to monitor the rate and extent of fiber attachment by the representative ruminal cellulolytic bacteria via competitive polymerase chain reaction. After incubation for 5 min, the numbers of Fibrobacter succinogenes and the two ruminococcal species attached to stems were 10(5) and 10(4)/g dry matter (DM) of stem, respectively. At 10 min, the numbers of all three species attached to stems increased 10-fold. Thereafter, attached cell numbers of the three species gradually increased and peaked at 24 h (10(9)/g DM for F. succinogenes and 10(7)/g DM for Ruminococcus flavefaciens) or 48 h (10(6)/g DM for Ruminococcus albus). On the other hand, cell numbers of all three species in the whole digesta were constant over 24 h. Changes in the rate of in sacco neutral detergent fiber disappearance of hay stem, which showed a linear increase up to 96 h, were not synchronized with changes in cellulolytic bacterial mass. These results suggest that sufficient numbers of cells of the three cellulolytic species to move to new plant fragments are present at the start of incubation, the initial attachment to new plant matter is mostly accomplished within 10 min and then bacterial growth and fibrolytic action follow. F. succinogenes was most dominant, both in the whole rumen digesta and on the suspended hay stems, demonstrating the ecological and functional significance of this species in ruminal fiber digestion.

Animals↗

PubMed1994

Response to various amounts of Aspergillus oryzae fermentation extract on ruminal metabolism in cattle.

The objective of this study was to determine whether Aspergillus oryzae fermentation extract stimulated or inhibited ruminal fermentation when fed at higher than recommended doses (3 g/d). Four dietary treatments of A. oryzae fermentation extract were fed daily to six cows fitted with ruminal cannulas. For each of four periods, bromegrass hay (6% CP) with and without extract was fed for 28 d. Dacron bags containing bromegrass cell walls were ruminally incubated to determine ruminal fiber degradation. The A. oryzae fermentation extract did not affect degradation of cell walls, cellulose, or hemicellulose. Total ruminal anaerobic or cellulolytic bacteria were not different among treatments; neither were the proportions of cellulolytic species, Butyrivibrio sp., Ruminococcus albus, or Ruminococcus flavefaciens. Ruminal ammonia was not different; however, total VFA were higher, and pH tended to be lower, when 27 g/d of A. oryzae fermentation extract was fed. The proportion of VFA was not different among treatments. The A. oryzae fermentation extract fed at nine times the recommended dosage did not produce any stimulatory effects, except for total VFA, and was not inhibitory or toxic to ruminal metabolism and forage fiber degradation.

Ammonia↗

PubMed1996

Why don't ruminal bacteria digest cellulose faster?

The bacteria Fibrobacter succinogenes, Ruminococcus flavefaciens, and Ruminococcus albus generally are regarded as the predominant cellulolytic microbes in the rumen. Comparison of available data from the literature reveals that these bacteria are the most actively cellulolytic of all mesophilic organisms described to date from any habitat. In light of numerous proposals to improve microbial cellulose digestion in ruminants, it is instructive to examine the characteristics of these species that contribute to their superior cellulolytic capabilities and to identify the factors that prevent them from digesting cellulose even more rapidly. As a group, these species have extreme nutritional specialization. They are able to utilize cellulose (or in some cases xylan) and its hydrolytic products as their nearly sole energy sources for growth. Moreover, each species apparently has evolved to similar maximum rates of cellulose digestion (first-order rate constants of 0.05 to 0.08 h-1). Active cellulose digestion involves adherence of cells to the fibers via a glycoprotein glycocalyx, which protects cells from protozoal grazing and cellulolytic enzymes from degradation by ruminal proteases while it retains-at least temporarily-the cellodextrin products for use by the cellulolytic bacteria. These properties result in different ecological roles for the adherent and nonadherent populations of each species, but overall provide an enormous selective advantage to these cellulolytic bacteria in the ruminal environment. However, major constraints to cellulose digestion are caused by cell-wall structure of the plant (matrix interactions among wall biopolymers and low substrate surface area) and by limited penetration of the nonmotile cellulolytic microbes into the cell lumen. Because of these constraints and the highly adapted nature of cellulose digestion by the predominant cellulolytic bacteria in the rumen, transfer of cellulolytic capabilities to noncellulolytic ruminal bacteria (e.g., by genetic engineering) that display other desirable properties offers limited opportunities to improve ruminal digestion of cellulose.

Animals↗

PubMed1997

Effects of a Saccharomyces cerevisiae culture on ruminal bacteria that utilize lactate and digest cellulose.

The objective of this study was to determine the effects of a yeast (Saccharomyces cerevisiae) culture on lactate utilization and cellulose digestion by ruminal bacteria. Growth of Selenomonas ruminantium HD4 in medium that contained 5 g/L of DL-lactate, Trypticase, and yeast extract was stimulated 7 and 15% by 1 and 5% (vol/vol) yeast culture filtrate respectively. The 1 and 5% yeast culture filtrate stimulated growth of Selenomonas ruminantium H18 and Megasphaera elsdenii B159 and T81 on 5 g/L of DL-lactate in medium without Trypticase or yeast extract. Growth of Fibrobacter succinogenes S85 and Ruminococcus albus B199 on 6 g/L of cellobiose was stimulated by the addition of yeast culture filtrate to medium without Trypticase or yeast extract. The yeast culture filtrate increased the concentrations of acetate and total volatile fatty acids that were produced by Sel. ruminantium HD4 and increased the concentrations of propionate and total volatile fatty acids that were produced by Sel. ruminantium H18 but did not alter end-product formation of M. elsdenii or cellulolytic bacteria. Treatment with yeast culture increased the initial rate but not the extent of cellulose digestion by F. succinogenes S85 and Ruminococcus flavefaciens FD1. Collectively, these results suggest that yeast culture provides soluble growth factors (i.e., organic acids, B vitamins, and amino acids) that stimulate growth of ruminal bacteria that utilize lactate and digest cellulose.

Acetates↗

PubMed1999

Effect of diet on populations of three species of ruminal cellulolytic bacteria in lactating dairy cows.

The effects of four contrasting diets were determined on populations of three species of ruminal cellulolytic bacteria (Ruminococcus albus, Ruminococcus flavefaciens, and Fibrobacter succinogenes) using oligonucleotide probes to rRNA. Diets based on alfalfa silage or corn silage as the primary fiber source were formulated to contain either 24 or 32% neutral detergent fiber measured after alpha-amylase treatment. The diets were fed twice daily to four ruminally fistulated, lactating Holstein cows in a trial using a Latin square design. The cows fed the alfalfa silage diets had higher dry matter intakes and milk production and smaller pH fluctuations than did cows fed the corn silage diets (0.3 vs. 0.8 units). The total populations of the three cellulolytic species at 3 h after feeding ranged from 0.3 to 3.9% of the bacterial domain; R. albus was generally the most abundant of the three species. The data are in general agreement with population assessments obtained by some traditional methods of culture enumeration. Although diet and individual cows had major effects on ruminal pH and volatile fatty acid concentrations and on milk production and composition, differences in cellulolytic populations that were attributable to individual cows were larger than those attributable to diet, suggesting that each cow maintained a unique assemblage of cellulolytic species.

Animals↗

PubMed2026

Brucellar spondylitis is associated with disturbance in gut microbiota and histamine metabolism associated inflammation.

BACKGROUND: The pathogenesis of brucellar spondylitis (BLS) has traditionally been considered to be primarily limited to local osteoarticular lesions. With the proposal of the "gut-spine axis" concept, the role of intestinal microecological dysbiosis in inflammatory spinal diseases has attracted in an increase of attention. The overactivated inflammatory cytokine network not only mediates bone destruction and intervertebral disc damage, but also forms a bidirectional interaction with gut microbiota dysbiosis through the "gut-spine axis," collectively driving disease progression. However, the inflammatory mechanism by which gut microbiota participates in the pathological process of BLS remains largely unclear. METHODS: This study recruited 20 BLS patients and 20 healthy donors. Multi-omics analysis including metagenomics, untargeted metabolomics, and targeted short-chain fatty acids (SCFAs) analysis, were used to compare the structural differences in gut microbiota between the two groups and screen for signature differential bacterial species. Plasma levels of histamine and histidine decarboxylase were measured by ELISA to clarify the role of differential histidine metabolic pathway in the disease. Additionally, plasma levels of lipopolysaccharide (LPS) and inflammatory cytokines (IL-1β, IL-6, IL-10, IL-17A, TNF-α) were detected by ELISA. The correlation between gut microbiota and inflammatory indicators was further analyzed. RESULTS: Compared to the healthy control group, the α-diversity of the gut microbiota in BLS patients was significantly reduced, with the microbial community structure exhibiting increased homogeneity. Beta diversity analysis revealed significant differences, suggesting that disease progression is associated with an overall imbalance in the gut microbiota and the deterioration of its specific structural composition. At the phylum level, the abundances of Actinomycetota, unclassified_d_Viruses, and Fusobacteriota were significantly increased in the gut microbiota of BLS patients compared to the control group, while the abundances of Bacillota and Pseudomonadota were significantly decreased. Further analysis revealed that, compared to the control group, the generic abundance of Enterococcus was significantly increased, while the proportions of Blautia, Faecalibacterium, Ruminococcus, Agathobacter, Roseburia, Clostridium, Eubacterium, Alistipes and Anaerobutyricum were significantly decreased. At the species level, the abundances of Enterococcus sp and Enterococcus-faecium were increased, whereas Blautia sp, Ruminococcus sp, Faecalibacterium sp, Faecalibacterium prausnitzii, Agathobacter rectalis, Eubacterium sp, Agathobacter sp, and Roseburia sp were decreased. Furthermore, untargeted metabolomics revealed that metabolites were enriched in the histidine metabolic pathway, and the levels of SCFAs including butyrate, isobutyrate, valerate, and 4-methylvalerate in the intestinal contents were reduced in BLS. Functional KEGG profiling revealed that key KOs involved in butyrate synthesis (e.g., K00074, K00172, K01640) and transport were globally downregulated in the patient group, whereas histidine decarboxylase KOs (K01693, K11755, K19787) that convert histidine to pro-inflammatory histamine were significantly enriched. The loss of butyrate-producing symbionts led to SCFAs deficiency and mucosal barrier disruption, creating ecological niches for facultatively anaerobic Enterococcus, which further exacerbated local inflammation via proteolytic fermentation and histamine production. Compared with the control group, BLS patients showed decreased plasma levels of IL-10, while levels of IL-1β, IL-6, IL-17A, and TNF-α were increased, and LPS levels were elevated. In addition, significantly elevated plasma pro-inflammatory LPS levels in patients with BLS suggest disruption of intestinal integrity and permeability. Correlation analysis indicated a close relationship between gut microbiota and inflammation. CONCLUSION: BLS is associated with gut microbiota dysbiosis and alterations in microbial metabolites, which may be linked to inflammatory responses and histamine metabolism. The differential microbial taxa identified in this study could be developed into a stool-based non-invasive diagnostic panel to facilitate early differentiation of BLS from other spinal disorders. Furthermore, restoring gut microbial balance through probiotic supplementation or dietary modulation may represent a promising adjunctive strategy to enhance the efficacy of standard antibiotic therapy and reduce disease recurrence.

Humans↗

PubMed1988

Degradation of human intestinal glycosphingolipids by extracellular glycosidases from mucin-degrading bacteria of the human fecal flora.

Certain normal strains of human fecal bacteria are unique in producing extracellular glycosidases that degrade the oligosaccharide chains of gut mucin glycoproteins. We have studied the action of such glycosidases partially purified from the cell-free supernates of five of these strains on intestinal glycosphingolipids isolated from human meconium. The glycolipids were sialosyl-lactosylceramide, lactosylceramide, and fucolipids with A, B, H, Lea, or Leb blood group determinants. In addition to the strain-specific high blood group A-degrading activities (Ruminococcus torques strains VIII-239 and IX-70), B-degrading activity (Ruminococcus AB strain VI-268), and H-degrading activities (all strains) corresponding to alpha 1-3-N-acetylgalactosaminidase, alpha 1-3-galactosidase and alpha 1-2-fucosidase, respectively, all strains also degraded sialosyl-lactosylceramide and Lea and Leb antigenic glycolipids, indicating the presence of alpha 2-3-neuraminidases and alpha 1-4-fucosidases. Enzyme preparations from Bifidobacterium infantis strain VIII-240 and R. torques strain VIII-239 hydrolyzed the Lea active glycolipid directly to lactosylceramide, suggesting the presence of endo-beta 1-3-N-acetylglucosaminidase activities. Similar endo-beta-N-acetylglucosaminidase activities were identified in four of the five enzyme preparations. The enzymes produced by R. AB strain VI-268 lacked this activity as well as beta 1-3-galactosidase, and thus degradation stopped at lactotetraosylceramide. With enzyme preparations from the other strains lactosylceramide was the single major degradation product from complex glycosphingolipids with less than 30% further degradation to glucosylceramide within 48 h. We conclude that glycosidases from mucin-degrading strains of human enteric bacteria degrade oligosaccharide chains of lactoseries fucolipids and gangliosides of intestinal origin primarily to lactosylceramide. Since several genera of enteric bacteria bind preferentially to lactosylceramide in vitro, mucin-degrading strains may have an important ecological role in host-microbial associations in the human gut.

Bacteria↗

PubMed2004

Detection of cellulolytic bacteria from the human colon.

The main representatives of bacteria in the human colon were investigated by specific PCR and denaturing gradient gel electrophoresis (DGGE). Prevalent in both cases were species of Bifidobacterium, Clostridium, Bacteroides, Faecalibacterium and Eubacterium. Simultaneously, cellulolytic bacteria were isolated from the human feces. The largest proportion was represented by ruminococcus-like isolates. Their presence was confirmed both by PCR and DGGE methods; the latter one was able to give more comprehensive data about the composition of bacterial population in the human colon chyme.

Bacteria↗