A new H2 / CO2-using acetogenic bacterium from the rumen: Description of Ruminococcus schinkii sp. nov.

Abstract Two strains of H2 / CO2-using acetogenic bacteria were isolated from the rumen of suckling lambs. Both strains displayed a coccobacillar morphology and possessed a Gram-positive type cell wall. Numerous organic substrates, including some O-methylated aromatic compounds, were used heterotrophically. 16S rRNA gene sequencing demonstrated that the two acetogenic isolates were phylogenetically identical and represent a new subline within Clostridium cluster XIVa. Based on phenotypic and phylogenetic considerations a new species, Ruminococcus schinkii sp. nov., is proposed.     

Isolation of Ureolytic Peptostreptococcus productus from Feces Using Defined Medium; Failure of Common Urease Tests

Colony counts of fecal samples from three persons, obtained by using a chemically defined anaerobic roll-tube medium (containing glucose, maltose, glycerol, minerals, hemin, B-vitamins, methionine, volatile fatty acids, sulfide, bicarbonate, agar, carbon dioxide (gas phase), and 1 mM NH(4) (+) as main nitrogen source), averaged 60% of the 8.8 x 10(10) bacteria per g obtained when 0.2% Trypticase and 0.05% yeast extract were added to the otherwise identical medium. When 0.2% vitamin-free Casitone replaced Trypticase and yeast extract, counts were 94% those of the more complex medium. When urea-nitrogen was added to the defined medium as the main nitrogen source in place of NH(4) (+), counts of relatively large colonies averaged 1.0 x 10(9) per g of feces from five persons-1.1% of counts on the medium containing Trypticase and yeast extract. All of the organisms from the large colonies in the urea roll tubes were morphologically similar, and all six representative strains isolated were identified as urease-forming Peptostreptococcus productus, a species not previously known to produce urease. Ureolytic strains of Selenomonas ruminantium and P. productus were negative for urease activity in three assay media when inocula were from media containing complex nitrogen sources. The study documents that P. productus is the most numerous ureolytic species so far found in human feces and suggests that NH(4) (+) and more complex organic nitrogen sources strongly repress its production of urease. The study also indicates the efficacy of chemically defined media for direct selective isolation of nutritional groups of bacteria from feces.     

Dominant bacterial communities in the rumen of Gayals (Bos frontalis), Yaks (Bos grunniens) and Yunnan Yellow Cattle (Bos taurs) revealed by denaturing gradient gel electrophoresis

The dominant rumen bacteria in Gayals, Yaks and Yunnan Yellow Cattle were investigated using PCR-DGGE approach. The analysis of DGGE profiles, identification of dominant bands and phylogenetic analysis 16S rDNA sequences in DGGE profiles were combined to reveal the dominant bacterial communities and compared the differences between those cattle species. DGGE profiles revealed that Gayals had the most abundant dominant bacteria and the lowest similarity of intraspecies between individuals than other two cattle species. A total of 45 sequences were examined and sequence similarity analysis revealed that Gayals had the most sequences appeared to uncultured bacteria, accounting for 85.0% of the total sequences, Yaks and Yunnan Yellow Cattle had 44.4 and 68.8% uncultured bacterial sequences, respectively. According to phylogenetic analysis, the rumen dominant bacteria of Gayals were mainly phylogenetically placed within phyla firmicutes and bacteroidetes, and the known bacteria were mainly belonged to the genera Lachnospiraceae bacterium, Ruminococcus flavefaciens and Clostridium celerecrescens. Moreover, the dominant bacteria of Yaks were also mainly belonged to phyla firmicutes and bacteroidetes, and the known dominant bacteria were including Ruminococcus flavefaciens, Butyrivibrio fibrisolvens, Pseudobutyrivibrio ruminis, Schwartzia succinivorans and Clostridiales bacterium, most of them are common rumen bacteria. In addition, the dominant bacteria in Yunnan Yellow Cattle were belonged to phyla firmicutes, bacteroidetes and Actinobacteria, and the known dominant bacteria containing Prevotella sp., Staphylococci lentus, Staphylococcus xylosus and Corynebacterium casei. Present study first detected Staphylococcus lentus and Staphylococcus xylosus in the rumen of cattle.     

Effects of disodium fumarate on ruminal fermentation and microbial communities in sheep fed on high-forage diets

This study was conducted to investigate effects of disodium fumarate (DF) on fermentation characteristics and microbial populations in the rumen of Hu sheep fed on high-forage diets. Two complementary feeding trials were conducted. In Trial 1, six Hu sheep fitted with ruminal cannulae were randomly allocated to a 2 × 2 cross-over design involving dietary treatments of either 0 or 20 g DF daily. Total DNA was extracted from the fluid- and solid-associated rumen microbes, respectively. Numbers of 16S rDNA gene copies associated with rumen methanogens and bacteria, and 18S rDNA gene copies associated with rumen protozoa and fungi were measured using real-time PCR, and expressed as proportion of total rumen bacteria 16S rDNA. Ruminal pH decreased in the DF group compared with the control (P < 0.05). Total volatile fatty acids increased (P < 0.001), but butyrate decreased (P < 0.01). Addition of DF inhibited the growth of methanogens, protozoa, fungi and Ruminococcus flavefaciens in fluid samples. Both Ruminococcus albus and Butyrivibrio fibrisolvens populations increased (P < 0.001) in particle-associated samples. Trial 2 was conducted to investigate the adaptive response of rumen microbes to DF. Three cannulated sheep were fed on basal diet for 2 weeks and continuously for 4 weeks with supplementation of DF at a level of 20 g/day. Ruminal samples were collected every week to analyze fermentation parameters and microbial populations. No effects of DF were observed on pH, acetate and butyrate (P > 0.05). Populations of methanogens and R. flavefaciens decreased in the fluid samples (P < 0.001), whereas addition of DF stimulated the population of solid-associated Fibrobacter succinogenes. Population of R. albus increased in the 2nd to 4th week in fluid-associated samples and was threefold higher in the 4th week than control week in solid samples. Analysis of denaturing gradient gel electrophoresis fingerprints revealed that there were significant changes in rumen microbiota after adding DF. Ten of 15 clone sequences from cut-out bands appearing in both the 2nd and the 4th week were 94% to 100% similar to Prevotella-like bacteria, and four sequences showed 95% to 98% similarity to Selenomonas dianae. Another 15 sequences were obtained from bands, which appeared in the 4th week only. Thirteen of these 15 sequences showed 95% to 99% similarity to Clostridium sp., and the other two showed 95% and 100% similarity to Ruminococcus sp. In summary, the microorganisms positively responding to DF addition were the cellulolytic bacteria, R. albus, F. succinogenes and B. fibrisolvens as well as proteolytic bacteria, B. fibrisolvens, P. ruminicola and Clostridium sp.     

Anaerobic ureolytic bacteria from caecal content and soft faeces of rabbit

Forty strains of ureolytic bacteria were isolated from the caecal content and soft faeces of seven rabbits by the anaerobic roll tube method and were characterized. The isolates were identified with Clostridium coccoides, Cl. innocuum, Peptostreptococcus productus, P. micros, Peptococcus magnus, Fusobacterium russii and Fusobacterium sp. Urease activity of representative strains of the various species was also determined. The study indicated that strongly-ureolytic anaerobic bacteria are present in the caecum of the rabbit.     

Anaerobic ureolytic bacteria from caecal content and soft faeces of rabbit

Forty strains of ureolytic bacteria were isolated from the caecal content and soft faeces of seven rabbits by the anaerobic roll tube method and were characterized. The isolates were identified with Clostridium coccoides, Cl. innocuum, Peptostreptococcus productus, P. micros, Peptococcus magnus, Fusobacterium russii and Fusobacterium sp. Urease activity of representative strains of the various species was also determined. The study indicated that strongly-ureolytic anaerobic bacteria are present in the caecum of the rabbit.     

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.     

Cellulolytic cocci isolated from the cecum of guinea pigs (Cavia porcellus).

Five strains of anaerobic, gram-variable cellulolytic cocci, belonging to the genus Ruminococcus, were isolated from the cecum of a guinea pig. They differed from most previously described strains of cellulolytic ruminococci as follows. (i) Lactate was the major fermentation product; lesser amounts of formate and ethanol and a trace of succinate were also produced, along with an uptake of acetate. (ii) No growth occurred at 30 degrees C; however, good growth was observed at 38 and 45 degrees C, (iii) Glucose, cellobiose, cellulose, xylose, arabinose, xylan, sucrose, and lactose were fermented by all strains. Rumen fluid was required for growth in a complete medium containing all nutrients previously found to be required by species in this genus. Limited growth occurred when rumen fluid was replaced by yeast extract, and maximum, but delayed, growth occurred when a water extract of alfalfa was added to the complete medium. No qualitative differences were found in the cell wall amino acids and sugar composition of these strains as compared to Ruminococcus flavefaciens and Ruminococcus albus; however, cell walls of the guinea pig strains appeared to contain a higher proportion of glucose.     

Occurrence and activity of human intestinal bacteria involved in the conversion of dietary lignans

The human intestinal microbiota is necessary for the production of enterolignans from the dietary lignan secoisolariciresinol diglucoside (SDG). However, little is known about the bacteria that contribute to SDG conversion. Therefore, we aimed at describing the occurrence and activity of SDG metabolising bacteria. The data showed differences in conversion efficiency between SDG deglycosylating species, but SDG was completely deglycosylated within 20 h by five of six strains. The strain Clostridium sp. SDG-Mt85-3Db showed the highest initial rate of SDG deglycosylation. Furthermore, we found that Bacteroides distasonis and B. fragilis made up 0.5% and 3.3% of total faecal bacteria, respectively. However, Clostridium sp. SDG-Mt85-3Db was detected within the dominant microbiota of only two out of 20 faecal samples. Bacteria involved in the demethylation step of SDG conversion also demethylated a variety of compounds other than SDG. In particular, Peptostreptococcus productus demethylated the lignans pinoresinol, lariciresinol and matairesinol. Finally, Eggerthella lenta catalysed the reduction of pinoresinol and lariciresinol to secoisolariciresinol.     

1,4-Naphthoquinone and other nutrient requirements of Succinivibrio dextrinosolvens.

Three strains of Succinivibrio dextrinosolvens isolated from the rumen of cattle or sheep under diverse conditions grew well in a minimal medium containing glucose, minerals, cysteine, methionine, leucine, serine, ammonia, 1,4-naphthoquinone, p-aminobenzoic acid, and bicarbonate-carbonic acid buffer, pH 6.7. When menadione or vitamin K5 was substituted for 1,4-naphthoquinone, the growth rate was somewhat depressed. Growth was poor with vitamin K1 and ammonia, further addition of the amino acids aspartic acid, arginine, histidine, and tryptophan was necessary for good growth of type strain 24, but the other two strains grew well only in media containing ammonia. Strains C18 and 22B produced urease and grew well when ammonia replaced urea. When urea replaced ammonia, strain 24 grew poorly and urease activity could not be detected. Strain 24 required no B-vitamins, but the other two strains were stimulated by p-aminobenzoic acid. The methionine requirement was not placed by vitamin B12, betaine, or homocysteine. Cysteine was replaced by sulfide in strain 24 but less well in the other two strains. Very poor growth was obtained when sulfate replaced cysteine. The half-saturation constant for ammonia during growth of S. dextrinosolvens is more than 500 microM, a much higher value than that of many rumen bacteria.     

Isolation and identification of fecal bacteria from adult swine.

An examination of the fecal microflora of adult swine was made with regard to the efficiency of several roll tube media in enumeration and recovery of anaerobes, the effects of medium constituents on recovery, and the isolation and identification of the predominant kinds of bacteria. Total number of organisms by microscopic bacterial counts varied among fecal samples from 4.48 X 10(10) to 7.40 X 10(10) bacteria/g (wet weight). Comparison of different nonselective roll tube media indicated that about 30% of the fecal bacteria could be recovered with a rumen fluid (40%, vol/vol) medium (M98-5). Recoveries of 21 and 15%, respectively, were obtained with M10 and rumen fluid-glucose-cellobiose agar (RGCA) media. Rumen fluid, Trypticase, sugars, and CO2 gas phase were important components required for maximum recovery with this medium. Similar high recoveries of anaerobes were also obtained with M98-5 containing swine cecal extract of place in rumen fluid or M10 plus swine cecal extract. Significantly lower recoveries were observed with RCGA, media supplemented with swine fecal extracts, reinforced clostridial medium, brain heart infusion agar, and prereduced blood agar. Ninety percent of the bacteria isolated from roll tube media were gram positive and consisted of facultatively anaerobic streptococci, Eubacterium sp., Clostridium sp., and Propionibacterium acnes. The remainder of the flora (8%) included several other species of anaerobes and Escherichia coli. Rumen fluid (or volatile fatty acids), Trypticase, and yeast extract additions to basal media stimulated the growth of anaerobic strains. Variation in the relative proportions of the predominant fecal microflora was observed. This work indicates that satisfactory enumeration, isolation and cultivation of the predominant microflora in swine feces can be obtained when strict anaerobic culture methods and a rumen fluid medium are used.     

Tetrahydrofolate and other growth requirements of certain strains of Ruminococcus flavefaciens.

Two strains of Ruminococcus flavefaciens were studied. Each grew in a chemically defined minimal medium containing: minerals; ammonium sulfate as a nitrogen source; amino acids as a nitrogen source, a growth promotant(s) or as both; cellobiose as an energy and carbon source; isobutyric acid, isovaleric acid, carbonic acid, and bicarbonate as additional carbon sources; and biotin, thiamine, and tetrahydrofolic acid as vitamins. Tetrahydrofolic acid (5 ng/ml) served as a replacement for rumen fluid that was required in previous media tested for the growth of these bacteria. The present bacteria differ from many of the ruminococci previously studied in that they do not require either p-amino-benzoic acid or folic acid but do require tetrahydrofolic acid for maximum growth. Dihydrofolic acid and 5-methyltetrahydrofolic acid can substitute for tetrahydrofolic acid in minimal chemically defined medium. Thus, there must be extensive metabolic interaction between the microbes inhabitating the rumen, because the R. flavefaciens isolated had complex requirements for growth and yet was among the predominant bacteria in the rumen of cattle fed a simple vitamin B-deficient, nonprotein nitrogen, high-fiber, purified diet.     

The Occurence and Properties of Uric Acid Decomposing Anaerobic Bacteria in the Avian Caecum

S ummary . Anaerobic bacteria which decompose uric acid have been found in the caeca of chickens, turkeys, ducks, pheasants and guinea-fowl at levels between 5.4 × 10⁸ and 1.8 × 10¹⁰/g of caecal material (wet weight). A study has been made of the properties and identity of 35 strains which were present in high numbers in the chicken caecum. The isolates included strains of Bacteroides clostridiiformis var. clostridiiformis, Fusobacterium plauti, Clostridium malenominatum, Peptostreptococcus productus and a number of types which could not be identified with known species. Of these 3 were Bacteroides spp., 3 Eubacterium spp., 2 Peptostreptococcus spp. and 1 was an anaerobic Streptococcus . None of the strains had an absolute requirement for uric acid.     

Cellulolytic bacteria in buffalo rumen

The influence of three different feeds, wheat straw, sorghum and berseem, on total and cellulolytic bacterial counts in the buffalo rumen at different time intervals from 0 to 8 h after feeding was studied. Berseem feeding supported maximum growth of rumen bacteria in general and cellulolytic bacteria in particular. Wheat straw supported the poorest growth.
The types of cellulolytic bacteria recovered from the rumen of adult buffaloes were Ruminococcus albus, R. flavefaciens, Bacteroides succinogenes, Butyrivibrio fibrisolvens, Clostridium lochheadii, Cl. longisporum and other Clostridium spp. Cellulolytic cocci were present in smaller numbers than rod forms in the rumen of wheat-straw-fed buffaloes, whereas the cocci outnumbered rod forms in sorghum-and berseem-fed buffaloes.     

Development and use of competitive PCR assays for the rumen cellulolytic bacteria: Fibrobacter succinogenes, Ruminococcus albus and Ruminococcus flavefaciens

Competitive PCR assays were developed for the enumeration of the rumen cellulolytic bacterial species: Fibrobacter succinogenes, Ruminococcus albus and Ruminococcus flavefaciens. The assays, targeting species-specific regions of 16S rDNA, were evaluated using DNA from pure culture and rumen digesta spiked with the relevant cellulolytic species. Minimum detection levels for F. succinogenes, R. albus and R. flavefaciens were 1-10 cells in pure culture and 10(3-4) cells per ml in mixed culture. The assays were reproducible and 11-13% inter- and intra-assay variations were observed. Enumeration of the cellulolytic species in the rumen and alimentary tract of sheep found F. succinogenes dominant (10(7) per ml of rumen digesta) compared to the Ruminococcus spp. (10(4-6) per ml). The population size of the three species did not change after the proportion of dietary alfalfa hay was increased. All three species were detected in the rumen, omasum, caecum, colon and rectum. Numbers of the cellulolytic species at these sites varied within and between animals.     

Studies on the Cecal Microflora of Commercial Broiler Chickens

A study was made of the cecal microflora isolated from broilers (5-week-old) reared under typical commercial husbandry conditions. Three hundred and twenty-five bacterial strains (randomly isolated from colonies representing 49 to 81% of the microscopic count) were isolated from cecal digesta of six animals on a rumen fluid roll tube medium (M98-5). Seventy-seven percent of these strains consisted of strict anaerobes: gram-negative, pleomorphic cocci (5.2%), Peptostreptococcus (1.5%), gram-positive rods (36.1% as Propionibacterium acnes and Eubacterium sp.), gram-negative rods (18.6% as Bacteroides clostridiiformis, B. hypermegas and B. fragilis) and sporeforming rods (15.7% as Clostridium sp.). Two types of facultatively anaerobic bacteria (gram-positive cocci and Escherichia coli) were also isolated and constituted 17.5% of the remaining flora. The distribution of the bacterial groups isolated from six cecal samples varied considerably. Data on the growth requirements of anaerobic strains indicated that many could be cultured in a simple medium consisting of an energy source, minerals, reducing agent, Trypticase, and yeast extract (or a vitamin mixture in place of yeast extract). The growth of some of these bacteria was also enhanced by CO(2) and rumen fluid. These preliminary data suggest that some of the more numerous anaerobes isolated from the chicken cecum may not require complex nutrients for growth and, in fact, may be nutritionally similar to rumen anaerobes.     

Effects of potassium ion concentrations on the antimicrobial activities of ionophores against ruminal anaerobes.

The antimicrobial activities of monensin and lasalocid against representative strains of ruminal bacteria were evaluated in medium containing three different concentrations of potassium (1.3, 7.9, or 23.3 mM). The growth of Eubacterium ruminantium was inhibited by low concentrations of ionophores (less than or equal to 0.16 mg/liter), while the strain of Streptococcus bovis tested was resistant to high concentrations of ionophores (40 mg/liter) at all potassium concentrations tested. The MICs of the ionophores for strains of Bacteroides succinogenes, Butyrivibrio fibrisolvens, Ruminococcus albus, and Ruminococcus flavefaciens and for one strain of Bacteroides ruminicola increased with increasing potassium concentrations in the medium. High concentrations of ionophores (40 mg/liter) decreased the maximum cell yields or increased the lag times or both in cultures of one strain of Bacteroides ruminicola and two strains of Selenomonas ruminantium but did not completely inhibit the growth of these organisms. Increased potassium concentrations in the medium (from 7.9 to 23.3 mM) decreased the lag times or increased the cell yields or both when these three strains were grown in ionophore-containing medium, while the activities of lasalocid and monensin against these organisms were enhanced in the medium containing low potassium concentrations (1.3 mM). The data from this study suggest that extracellular potassium concentrations may influence the antimicrobial activities of ionophores in the rumen.     

Effects of potassium ion concentrations on the antimicrobial activities of ionophores against ruminal anaerobes

The antimicrobial activities of monensin and lasalocid against representative strains of ruminal bacteria were evaluated in medium containing three different concentrations of potassium (1.3, 7.9, or 23.3 mM). The growth of Eubacterium ruminantium was inhibited by low concentrations of ionophores (less than or equal to 0.16 mg/liter), while the strain of Streptococcus bovis tested was resistant to high concentrations of ionophores (40 mg/liter) at all potassium concentrations tested. The MICs of the ionophores for strains of Bacteroides succinogenes, Butyrivibrio fibrisolvens, Ruminococcus albus, and Ruminococcus flavefaciens and for one strain of Bacteroides ruminicola increased with increasing potassium concentrations in the medium. High concentrations of ionophores (40 mg/liter) decreased the maximum cell yields or increased the lag times or both in cultures of one strain of Bacteroides ruminicola and two strains of Selenomonas ruminantium but did not completely inhibit the growth of these organisms. Increased potassium concentrations in the medium (from 7.9 to 23.3 mM) decreased the lag times or increased the cell yields or both when these three strains were grown in ionophore-containing medium, while the activities of lasalocid and monensin against these organisms were enhanced in the medium containing low potassium concentrations (1.3 mM). The data from this study suggest that extracellular potassium concentrations may influence the antimicrobial activities of ionophores in the rumen.     

Effects of ingestion of difructose anhydride III (DFA III) and the DFA III-assimilating bacterium Ruminococcus productus on rat intestine

We have isolated a difructose anhydride III (DFA III)-assimilating bacterium, Ruminococcus productus AHU1760, from human. After an acclimation period of 1 week, male Sprague-Dawley rats (5 weeks old) were divided into four groups (control diet, R. productus diet, DFA III diet, and R. productus + DFA III diet; n = 8) and fed the assigned test diets for 2 weeks. The viable count of administered R. productus was 4.9 x 10(7) CFU/d in R. productus-fed rats and 4.7 x 10(7) CFU/d in R. productus + DFA III-fed rats. Survival in cecal content of this strain was confirmed by randomly amplified polymorphic DNA. The ratio of secondary bile acids in feces in R. productus + DFA III-fed rats decreased the same as that in rats fed only DFA III. The viable count of lactobacilli and bifidobacteria, known as beneficial bacteria, increased more in R. productus + DFA III-fed rats than in control or R. productus-fed rats. A combination of R. productus and DFA III might improve the balance of intestinal microbiota to a healthier condition.