• IMMUNE NETWORK
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• v.14 no.1
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• pp.38-44
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• 2014

K/BxN serum can transfer arthritis to normal mice owing to the abundant autoantibodies it contains, which trigger innate inflammatory cascades in joints. Little is known about whether gut-residing microbes affect host susceptibility to autoantibody-mediated arthritis. To address this, we fed C57BL/6 mice with water containing a mixture of antibiotics (ampicillin, vancomycin, neomycin, and metronidazol) for 2 weeks and then injected them with K/BxN serum. Antibiotic treatment significantly reduced the amount of bacterial genomic DNA isolated from fecal samples, in particular a gene encoding 16S ribosomal RNA derived from segmented filamentous bacteria. Arthritic signs, as indicated by the arthritic index and ankle thickness, were significantly attenuated in antibiotic-treated mice compared with untreated controls. Peyer's patches and mesenteric lymph nodes from antibiotic-treated mice contained fewer IL-17-expressing cells than those from untreated mice. Antibiotic treatment reduced serum C3 deposition in vitro via the alternative complement pathway. IL-$17^{-/-}$ congenic C57BL/6 mice were less susceptible to K/BxN serum-transferred arthritis than their wild-type littermates, but were still responsive to treatment with antibiotics. These results suggest that gut-residing microbes, including segmented filamentous bacteria, induce IL-17 production in GALT and complement activation via the alternative complement pathway, which cause the host to be more susceptible to autoantibody-mediated arthritis.

• Journal of Microbiology and Biotechnology
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• v.30 no.9
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• pp.1321-1334
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• 2020

Beef, pork, chicken and milk are considered representative protein sources in the human diet. Since the digestion of protein is important, the role of intestinal microflora is also important. Despite this, the pure effects of meat and milk intake on the microbiome are yet to be fully elucidated. To evaluate the effect of beef, pork, chicken and milk on intestinal microflora, we observed changes in the microbiome in response to different types of dietary animal proteins in vitro. Feces were collected from five 6-week-old pigs. The suspensions were pooled and inoculated into four different media containing beef, pork, chicken, or skim milk powder in distilled water. Changes in microbial communities were analyzed using 16S rRNA sequencing. The feces alone had the highest microbial alpha diversity. Among the treatment groups, beef showed the highest microbial diversity, followed by pork, chicken, and milk. The three dominant phyla were Proteobacteria, Firmicutes, and Bacteroidetes in all the groups. The most abundant genera in beef, pork, and chicken were Rummeliibacillus, Clostridium, and Phascolarctobacterium, whereas milk was enriched with Streptococcus, Lactobacillus, and Enterococcus. Aerobic bacteria decreased while anaerobic and facultative anaerobic bacteria increased in protein-rich nutrients. Functional gene groups were found to be over-represented in protein-rich nutrients. Our results provide baseline information for understanding the roles of dietary animal proteins in reshaping the gut microbiome. Furthermore, growth-promotion by specific species/genus may be used as a cultivation tool for uncultured gut microorganisms.

• Food Science and Industry
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• v.52 no.3
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• pp.261-271
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• 2019

Gut microbiome have recently provided evidence that the gut microbiota are capable of greatly influencing all aspects of physiology and immunology. Although a number of recent studies have shown that probiotics can modulate gut microbiota structure, the mechanism underlying this effect remains to be elucidated. In a disease state, the relative abundances of beneficial gut bacteria are generally reduced, which is restored by constant probiotic supplementation. Oral administration of probiotics improved the disease state by (1) inducing differentiation and function of regulatory T cells, (2) reducing inflammatory response, (3) modulating the gut environment, and (4) increasing the proportions of short-chain fatty acid- or beneficial metabolite-producing gut microbiota including the genera Bifidobacterium, Faecalibacterium, Akkermansia, etc. In this review, current knowledge on how probiotics can influence host's health by altering gut microbiota structure and on how probiotics and beneficial gut bacteria can be applied as next-generation probiotics will be discussed.

• Asian-Australasian Journal of Animal Sciences
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• v.31 no.11
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• pp.1781-1794
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• 2018

Objective: This meta-analysis was conducted to evaluate the overall effect of direct-fed microbial (DFM) or probiotic supplementation on the log concentrations of culturable gut microbiota in broiler chickens. Methods: Relevant studies were collected from PubMed, SCOPUS, Poultry Science Journal, and Google Scholar. The studies included controlled trials using DFM supplementation in broiler chickens and reporting log concentrations of the culturable gut microbiota. The overall effect of DFM supplementation was determined using standardized mean difference (SMD) with a random-effects model. Subgroups were analyzed to identify pre-specified characteristics possibly associated with the heterogeneity of the results. Risk of bias and publication bias were assessed. Results: Eighteen taxa of the culturable gut microbiota were identified from 42 studies. The overall effect of DFM supplementation on the log concentrations of all 18 taxa did not differ significantly from the controls (SMD = -0.06, 95% confidence interval [-0.16, 0.04], p = 0.228, $I^2=85%$, n = 699 comparisons), but the 18 taxa could be further classified into three categories by the direction of the effect size: taxa whose log concentrations did not differ significantly from the controls (category 1), taxa whose log concentrations increased significantly with DFM supplementation (category 2), and taxa whose log concentrations decreased significantly with DFM supplementation (category 3). Category 1 comprised nine taxa, including total bacterial counts. Category 2 comprised four taxa: Bacillus, Bifidobacterium, Clostridium butyricum, and Lactobacillus. Category 3 comprised five taxa: Clostridium perfringens, coliforms, Escherichia coli, Enterococcus, and Salmonella. Some characteristics identified by the subgroup analysis were associated with result heterogeneity. Most studies, however, were present with unclear risk of bias. Publication bias was also identified. Conclusion: DFM supplementation increased the concentrations of some beneficial bacteria (e.g. Bifidobacterium and Lactobacillus) and decreased those of some detrimental bacteria (e.g. Clostridium perfringens and Salmonella) in the guts of broiler chickens.

• Journal of Microbiology and Biotechnology
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• v.24 no.7
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• pp.888-897
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• 2014

A bacterial community analysis of the gut of Tenebrio molitor larvae was performed using pyrosequencing of the 16S rRNA gene. A predominance of genus Spiroplasma species in phylum Tenericutes was observed in the gut samples, but there was variation found in the community composition between T. molitor individuals. The gut bacteria community structure was not significantly affected by the presence of antibiotics or by the exposure of T. molitor larvae to a highly diverse soil bacteria community. A negative relationship was identified between bacterial diversity and ampicillin concentration; however, no negative relationship was identified with the addition of kanamycin. Ampicillin treatment resulted in a reduction in the bacterial community size, estimated using the 16S rRNA gene copy number. A detailed phylogenetic analysis indicated that the Spiroplasma-associated sequences originating from the T. molitor larvae were distinct from previously identified Spiroplasma type species, implying the presence of novel Spiroplasma species. Some Spiroplasma species are known to be insect pathogens; however, the T. molitor larvae did not experience any harmful effects arising from the presence of Spiroplasma species, indicating that Spiroplasma in the gut of T. molitor larvae do not act as a pathogen to the host. A comparison with the bacterial communities found in other insects (Apis and Solenopsis) showed that the Spiroplasma species found in this study were specific to T. molitor.

• Microbiology and Biotechnology Letters
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• v.49 no.1
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• pp.57-64
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• 2021

Lactic acid bacteria (LAB), belonging to the Firmicutes phylum, lack heme biosynthesis and, thus, are characterized as fermentative and catalase-negative organisms. To verify the hypothesis that heme-rich-nutrients might compensate the heme-biosynthesis incapability of non-respiratory LAB in animal gut, a heme-rich-nutrient was fed to a dog and its fecal microbiome was analyzed. Firmicutes abundance in the feces from the heme-rich-nutrient-fed dog was 99%, compared to 92% in the control dog. To clarify the reason of increased Firmicutes abundance in the feces from the heme-rich-nutrient-fed dog, Lacobacillus gasseri were used as model anerobic LAB to study a purified heme (hemin). The anaerobic growth of L. gasseri in the medium with 25 µM hemin supplementation was faster than that in the medium without hemin, while the growth in the 50 µM hemin-supplemented medium did not vary. Cellular activities of the cytochrome bd complex were 1.55 ± 0.19, 2.11 ± 0.14, and 2.20 ± 0.08 U/gcell in the cells from 0, 25, and 50 µM hemin-supplemented medium, while intracellular ATP concentrations were 7.90 ± 1.12, 11.95 ± 0.68, and 12.56 ± 0.58 µmol_ATP/g_cell, respectively. The ROS-scavenging activities of the L. gasseri cytosol from 25 µM and 50 µM hemin-supplemented medium were 68% and 82% greater than those of the cytosol from no hemin supplemented-medium, respectively. These findings indicate that external hemin could compensate the heme-biosynthesis incapability of L. gasseri by increasing the cytosolic ROS-scavenging and extra ATP generation, possibly through increasing the electron transfer. Increase in the number of anaerobic bacteria in heme-rich-nutrient-fed animal gut is discussed based on the results.

• Korean Journal of Agricultural Science
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• v.45 no.4
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• pp.655-663
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• 2018

The insect gut microbiome is known to have important roles in host growth, development, digestion, and resistance against pathogens. In addition, the genetic diversity of the insect gut microbiota has recently been recognized as potential genetic resources for industrial bioprocessing. However, there is limited information regarding the insect gut microbiota to better help us understand their potential benefits for enhanced pig production. With the development of next-generation sequencing methods, whole genome sequence analysis has become possible beyond traditional culture-independent methods. This improvement makes it possible to identify and characterize bacteria that are not cultured and located in various environments including the gastrointestinal tract. Insect intestinal microorganisms are known to have an important role in host growth, digestion, and immunity. These gut microbiota have recently been recognized as potential genetic resources for livestock farming which is using the functions of living organisms to integrate them into animal science. The purpose of this literature review is to emphasize the necessity of research on insect gut microbiota and their applicability to pig production or bioindustry. In conclusion, bacterial metabolism of feed in the gut is often significant for the nutrition intake of animals, and the insect gut microbiome has potential to be used as feed additives for enhanced pig performance. The exploration of the structure and function of the insect gut microbiota needs further investigation for their potential use in the swine industry particularly for the improvement of growth performance and overall health status of pigs.

• Development and Reproduction
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• v.26 no.4
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• pp.145-153
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• 2022

The gut microbiota is involved in the maintenance of physiological homeostasis and is now recognized as a regulator of many diseases. Although germ-free mouse models are the standard for microbiome studies, mice with antibiotic-induced sterile intestines are often chosen as a fast and inexpensive alternative. Pathophysiological changes in the gut microbiome have been demonstrated, but there are no reports so far on how such alterations affect the bacterial composition of the uterus. Here we examined changes in uterine microbiota as a result of gut microbiome disruption in an antibiotics-based sterile-uterus mouse model. Sterility was induced in 6-week-old female mice by administration of a combination of antibiotics, and amplicons of a bacteria marker gene (16S rRNA) were sequenced to decipher bacterial community structures in the uterus. At the phylum-level, Proteobacteria, Firmicutes, and Actinobacteria were found to be dominant, while Ralstonia, Escherichia, and Prauserella were the major genera. Quantitative comparisons of the microbial contents of an antibiotic-fed and a control group revealed that the treatment resulted in the reduction of bacterial population density. Although there was no significant difference in bacterial community structures between the two animal groups, β-diversity analysis showed a converged profile of uterus microbiotain the germ-free model. These findings suggest that the induction of sterility does not result in changes in the levels of specific taxa but in a reduction of individual variations in the mouse uterus microbiota, accompanied by a decrease in overall bacterial population density.

• Journal of Microbiology and Biotechnology
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• v.30 no.7
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• pp.1067-1071
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• 2020

To understand the formation of initial gut microbiota, three initial fecal samples were collected from two groups of two breast milk-fed (BM1) and seven formula milk-fed (FM1) infants, and the compositional changes in gut microbiota were determined using metagenomics. Compositional change analysis during week one showed that Bifidobacterium increased from the first to the third fecal samples in the BM1 group (1.3% to 35.1%), while Klebsiella and Serratia were detected in the third fecal sample of the FM1 group (4.4% and 34.2%, respectively), suggesting the beneficial effect of breast milk intake. To further understand the compositional changes during progression from infancy to childhood (i.e., from three weeks to five years of age), additional fecal samples were collected from four groups of two breast milk-fed infants (BM2), one formula milk-fed toddler (FM2), three weaning food-fed toddlers (WF), and three solid food-fed children (SF). Subsequent compositional change analysis and principal coordinates analysis (PCoA) revealed that the composition of the gut microbiota changed from an infant-like composition to an adult-like one in conjunction with dietary changes. Interestingly, overall gut microbiota composition analyses during the period of progression from infancy to childhood suggested increasing complexity of gut microbiota as well as emergence of a new species of bacteria capable of digesting complex carbohydrates in WF and SF groups, substantiating that diet type is a key factor in determining the composition of gut microbiota. Consequently, this study may be useful as a guide to understanding the development of initial gut microbiota based on diet.

• Journal of Animal Science and Technology
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• v.48 no.1
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• pp.77-90
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• 2006

The purpose of this study was to isolate cellulolytic and hemicellulolytic anaerobic bacteria inhabiting from gut of ruminants and investigate their hydrolytic enzyme activities. Extracellular CMCase activities of H-strains isolated from the rumen of a Holstein dairy cow were higher than those of D- and DC- strains from the rumen and large intestine of Korean spotted deer. Most isolated bacteria utilized more efficiently Dehority's artificial medium containing starch, glucose and cellobiose (DAS) than those in Dehority's artificial medium containing cellulose only (DAC). The results of biochemical reactions and sugar fermentation indicated that the isolated bacteria belong to one of bacterial strains of Peptostreptococcus spp., Bifidobacterium spp., Prevotela ruminicola/buccae, Clostridium beijer/butyricum and Streptococcus intermedis which are not highly cellulolytic. Activities of Avicelase, xylanase, β-D-glucosidase, α-L-arabinofuranosidase and β-xylosidase of the isolated anaerobic bacteria in DAS were higher than those in DAC. In conclusion, the results indicated the higher enzyme activities of the isolated strains cultured in DAS medium were mainly caused by their specific carbohydrate utilization for enzyme production and growth rate. The highly cellulolytic bacteria were not isolated in the present experiment. Thus further research is required to investigate characteristics of gut bacteria from Korean spotted deer.