Characterization and in-vivo evaluation of potential probiotics of the bacterial flora within the water column of a healthy shrimp larviculture system

A thorough understanding of the normal bacterial flora associated with shrimp larviculture systems contributes to probiotic screening and disease control. The bacterial community of the water column over a commercial Litopenaeus vannamei larval rearing run was characterized with both culture-dependent and culture-independent methods. A total of 27 phylotypes at the species level were isolated and identified based on 16S rDNA sequence analysis. Denaturing gradient gel electrophoresis （DGGE） analysis of the V3-V5 region of 16S rRNA genes showed a dynamic bacterial community with major changes occurred from stages zoea to mysis during the rearing run. The sequences retrieved were affiliated to four phyla, Proteobacteria, Actinobacteria, Bacteroidetes, and Firmicutes, with the family Rhodobacteraceae being the most frequently recovered one. Subsequently, 13 representative strains conferred higher larval survival than the control when evaluated in the in-vivo experiments; in particular, three candidates, assigned to Phaeobacter sp., Arthrobacter sp., and Microbacteriurn sp., significantly improved larval survival （P〈0.05）. Therefore, the healthy shrimp larviculture system harbored a diverse and favorable bacterial flora, which contribute to larval development and are of great importance in exploiting novel probiotics.

Bacterial flora concurrent with Helicobacter pylori in the stomach of patients with upper gastrointestinal diseases

AIM： To investigate the non-He/icobacterpy/ori （H. pylori） bacterial flora concurrent with H. pylori infection.METHODS： A total of 103 gastric biopsy specimens from H. pylori positive patients were selected for bacterial culture. All the non-H, pylori bacterial isolates were identified by matrix assisted laser desorption ionization time-of-flight mass spectrometry （MALDI-TOF MS）.RESULTS： A total of 201 non-H, pyiori bacterial isolates were cultivated from 67 （65.0%） of the 103 gastric samples, including 153 isolates identified successfully at species level and 48 at genus level by MALDI-TOF MS. The dominant species were Streptococcus, Neisseria, Rothla and Staphylococcus, which differed fromthe predominantly acid resistant species reported previously in healthy volunteers. The prevalence of non-H. pylori bacteria was higher in non-ulcer dyspepsia group than in gastric ulcer group （100% vs 42.9%, P 〈 0.001）. Six bacterial species with urease activity （Staphylococcus epidermidis, Staphylococcus warneri, Staphylococcus capitis, Staphylococcus aureus, Brevibacteriurn spp. and Klebsiella pneumoniae） were also isolated.CONCLUSION： There is a high prevalence of the non-H, pylori bacteria concurrent with H. pylori infection, and the non-H, pylori bacteria may also play important as-yet-undiscovered roles in the pathogenesis of stomach disorders.

Evolution of fracture permeability due to co-colloidal bacterial transport in a coupled fracture-skin-matrix system

A numerical model is developed for investigating the evolution of fracture permeability in a coupled fracture-matrix system in the presence of fracture-skin with simultaneous colloidal and bacte- rial transport, by taking into account the effects of thermal stress and silica precipitation/dissolution, which is computed using linear reaction kinetics. The non-linear coupled equations are numerically modeled using the fully implicit finite difference method and a constant continuous source is adopted while modeling thermal, contaminant, colloidal and bacterial transport. Due to co-colloid bacterial trans- port under non-isothermal conditions, in a coupled fracture-skin-matrix system, the fracture apertures vary spatially, with a corresponding pressure variation for a constant discharge. A series of numerical experiments were conducted for analyzing the spatial variation of fracture aperture in response to the combined effects of thermal stress, silica precipitation/dissolution, and simultaneous colloidal and bacte- rial transport in the presence of the fracture-skin. The simulation results suggest that temperature and contaminant concentration of the mobile fluid within the fracture increases with reduction in initial frac- ture aperture. The pattern of variation followed by the fracture aperture is nearly the same in the presence and absence of bacterial transport but the magnitude of the fracture aperture is low under the influence of bacterial transport. The variation in the fracture aperture resulting from precipitation-dissolution and thermoelastic stress is significant when the fracture aperture is very low and reduces with increment in fracture aperture. The variation in fracture aperture and pressure remains the same for both undersaturated and supersaturated fluid entering the fracture due to the influence of bacterial transport at the inlet of the fracture.

External Bacterial Flora and Antimicrobial Susceptibility Patterns of Staphylococcus spp. and Pseudomonas spp. Isolated from Two Household Cockroaches, Blattella germanica and Blatta orientalis

A study was performed to estimate the prevalence of the external bacterial flora of two domestic cockroaches （Blattella germanica and Blatta orientalis） collected from households in Tebessa （northeast AIgeria）.Three major bacterial groups were cultured （total aerobic, enterobacteria, and staphylococci） from 14 specimens of cockroaches, and antibiotic susceptibility was tested for both Staphylococcus and Pseudomonas isolates. Culturing showed that the total bacterial load of cockroaches from different households were comparable （P〈0.001） and enterobacteria were the predominant colonizers of the insect surface, with a bacterial load of （2.1×10^5 CFU/insect）, whereas the staphylococci group was the minority. Twenty-eight bacterial species were isolated, and susceptibility patterns showed that most of the staphylococci isolates were highly susceptible to chloramphenicol, gentamycin, pristinamycin, ofloxacin, clindamycin, and vancomycin; however, Pseudomonas strains exhibited resistance to amoxicillin/clavulanic acid, imipenem, and the second-generation antibiotic cephalosporin cefuroxime.

Heterotrophic Bacterial Floras in Industrial Area and Unpolluted Marine Environments around Qingdao

From Oct. 1999 to Oct. 2000, the heterotrophic bacterial floras in the industrial marine environment around the Qingdao Power Plant (QPP) and in the unpolluted marine environments were investigated. The results showed that the numbers of the heterotrophic bacteria around QPP were much higher than those in unpolluted environments, and the average numbers in QPP Seawater, QPP Sediment, Unpolluted Seawater and Unpolluted Sediment were 5.4×104cfu(mL) -1, 5.0×105cfug -1, 3.0×102cfu(mL) -1 and 1.3×105cfug -1 respectively. Totally, 118 strains were isolated from QPP and 99 of them were Gram-negative. One hundred and twenty one strains were isolated from the unpolluted environments and 104 of them were Gram-negative. All the Gram-negative bacteria belonged to 13 genera. The distribution of the bacteria was varied in different marine environments. The results showed that the unpolluted marine environments contained much more Vibrio than seawater and sediment around QPP.

Heterotrophic Bacterial Flora in Aquaculture Area around Xuejiadao

From Oct., 1999 to Oct., 2000, the heterotrophic bacterial flora in the aquaculture area around Xuejiadao was investigated. The result shows that the populations of the heterotrophic bacteria are heavier in summer and autumn than those in winter and spring. The average populations in seawater, sediment, the surface of seaweed and the surface of fish are 1.4×10 4 cfu mL -1, 5.4×10 6 cfu g -1, 1.5×10 6 cfu g -1 and 1.8×10 3 cfu cm -2, respectively. A total of 301 strains were isolated, among them 259 were Gram-negative. All the Gram-negative bacteria belong to 13 genera and some genera of Enterobacteriaceae. The communities of bacteria are slightly different among the samples. In the body surface of fish, Genus vibrio is dominant. In the remaining samples, dominant genus is Aeromonas.

Research Progress on the Relationship between Skin Microbial Flora and Skin Health

This paper discusses the researches on human skin microbial flora in the past 50 years, including research methods, characteristics of human skin microbial flora and key influencing factors, etc. The dynamic relationship between microbial flora and skin health is further discussed. Finally, the potential application of the research in the future is put forward. This paper also points out that the microbial flora may become the inevitable and necessary future trend of daily chemical products, maximizing the balance between human skin health and beauty.

Bacterial flora of conjunctiva after death

AIM:To evaluate the frequency of bacterial flora of conjunctiva after death(cadaver eyes) which will give information about the bacterial contamination of donor eyes,and the in-vitro sensitivity of isolated bacteria to the commonly used antibiotics in ophthalmic practice.METHODS:Conjunctival swabs were taken from the cadavers(motor vehicle accident deaths and patients who died in the hospital),within 6h after death,and sent for culture and sensitivity test.Conjunctival swabs,taken from the healthy conjunctiva of patients admitted for cataract surgery,were sent for culture and sensitivity as controls(eyes in those of living status).The bacterial isolates were tested against the commonly used antibiotics(chloramphenicol,gentamicin,ciprofloxacin) in ophthalmology practice.RESULTS:Bacteria were isolated in 41 out of 100 conjunctival swabs(41%),taken from 50 cadavers(study group).Coagulase negative staphylococcus was the most common bacteria isolated(15%),followed by pseudomonas aeruginosa(5%).Gentamicin was effective against majority of the bacterial isolates(82%).Bacteria were isolated from 7 out of 100 conjunctival swabs taken as control group(eyes in living state).Coagulase negative staphylococcus was the most common organism(5%) isolated in control group;the others were staphylococcus aureus(1%) and beta hemolyticus streptococci(1%).CONCLUSION:Bacteria were isolated from 41% of the cadaver eyes.High percentage sensitivity of the bacterial isolates to gentamicin(82%) supports the practice of thorough irrigation of the eyes with gentamicin solution before starting the procedure of enucleation followed by immersion of the enucleated eyeballs in gentamycin solution,to prevent the bacterial contamination.

Bacterial Flora of Water and Rotifers in Outdoor Mass Culture Tanks Fed with Different Microalagal Diets

Investigations were carried out on the bacterial flora of water and the quality of rotifers in outdoor mass culture tanks. Brachionus plicatilis and B. rotundiformis were cultured in 10 numbers of 1 tonne tanks and the physico-chemical parameters and microbial loads of water, and total bacterial and Vibrio loads of microalgae and rotifers, during the period 2014-15, were studied. The study revealed a significant variation of the ammonia levels and total bacterial loads with different diets （P 〈 0.05）. A positive correlation was observed between the total bacterial loads of algal concentrations and loads of rotifers, but no correlation was observed between Vibrio loads of water and rotifers. The prevalence of Vibrio loads of rotifers was low in tanks fed with Nannochloropsis oculata and maximum Vibrio loads were recorded in Chaetoceros calcitrans fed rotifers. The Vibrio loads significantly varied with days of culture and also with the algal diets. A positive correlation was observed between the total Vibrio loads of water and rotifers.

Effect of artificial dermis combined with jinfu ning on skin healing and bacterial detection rate of finger abdomen

Objective: To explore the effect of artificial dermis combined with rhGM-CSF(Jinfuning) on healing of soft tissue defect of finger ventral skin and the influence of bacterial detection rate. Methods: Totally 110 patients with finger injury admitted to the rehabilitation department of our department from January 2017 to June 2018 were collected and divided into control group and observation group according to the random number table method with 55 cases in each group. The control group received direct artificial derma lrepairing after thorough debridement, while the observation group received recombinant gm-csf gel coating on the wound surface before artificial dermal repairing, Wound healing, wound inflammation, bacterial detection rate, inflammatory factor expression, follow-up and adverse reactions were compared between the two groups. Results: The wound healing rate of the observation group at 7, 14, 21 and 28 days after treatment was significantly higher than that of the control group (t= 11.211, P =0.000).( T = 14.895, P =0.000;T = 25.346, P=0.000;T =8.247, P=0.000). The wound healing time of the observation group was (19.7±2.3) d, and that of the control group was (27.4±3.3) d. The average wound healing time of the observation group was significantly shorter than that of the control group, and the difference was statistically significant (t=14.197, P= 0.000). Observation group wound inflammation at each time point score was significantly lower than the control group, the group rooms, time points, ·point interaction effect between the comparison, the differences were statistically significant (P <0.05), the observation group wound bacteria detection rate of 7.27% (4 cases) : the control bacteria detection rate was 21.81% (12 cases), difference was statistically significant (chi-square = 4.68, P= 0.0305), the observation group of bacteria detection rate was significantly lower than the control group;The bacteria detected in the two groups were mainly e. coli, tetanus bacillus and fungi. There was no significant difference in the indicators between the two groups before treatment, and the values of inflammatory cytokines il-1 and TNF- IOD in the two groups were significantly decreased after treatment, and the observation group was significantly lower than the control group, with statistically significant differences (P < 0.05). No serious adverse reactions occurred in either group during the treatment. Conclusion: the application of artificial dermals combined with jinfuning can promote wound healing of skin and soft tissue defect of finger abdomen, effectively inhibit bacterial infection of wound surface, reduce inflammation and infection,reducing bacterial detection rate.

Normal Bacterial Floras in Intestinal Tract of Ring-Necked Pheasant

The normal bacterial floras in intestinal tract of ring-necked pheasant were investigated. Eight age groups were chosen. Samples of intestines were diluted in 10 fold series and incubated on different selective media. Atter incubation. aimed bacterial colonies were counted then the number of CFU/g of gut inclusions was evaluated. The data were analyzed in statistics. The physiological values of eight main normal bacterial floras were obtained. The eubiosis of normal bacterial floras in intestinal tract of ring-necked pheasant was established from its age of 10 days old to 30 days old. The dominant bacterial floras were bifidobacterium, lactobacillus and bacteroideceae.

Characterization of the Ear Canal Bacterial Flora Present in Hearing Aids (HA) Wearing Subjects

The use of hearing aids (HA) is considered a predisposing factor for ear microbial infections. We undertook this study to compare the presence and nature of the microbial flora inhabiting of ears of HA and non-HA (nHA) users. Swab samples of the ears of HA and nHA users were collected from the Institute of Otolaryngology, “Cattolica del Sacro Cuore” University “Agostino Gemelli”, Rome, Italy. Swab samples were taken from the ear canal of 57 HA and 33 nHA users. The components of the microbial flora present on each swab sample were identified and characterized at the level of species. A total of 41 different bacterial species were identified. A statistically significant prevalence of polymicrobial communities was found in ears presenting signs of inflammation (2.5 ± 1.7 vs 2.1 ± 1.3;P = 0.02) and in HA users (2.3 ± 1.2 vs 1.7 ± 1.0;P = 0.002). Few putative pathogens were detected. Candida albicans spp. was not isolated in our study. A small number of swab samples presented no microbial growth. Bacterial species isolated from HA users with and without inflammation were assayed for the ability to form biofilm. Among gram-positive and gram-negative bacteria, S. aureus, CoNS, P. aeruginosa and K. pneumoniae were found to be strong biofilm producers. S. aureus and P. aeruginosa, isolated only from the ears of HA and nHA users presenting signs of inflammation, were further analyzed for their antibiotic-resistance profile and characterized by the Multilocus Sequence Typing (MLST) assay. The highest rates of antibacterial resistance were in S. aureus to penicillin (75.5%) and in P. aeruginosa, to amoxicillin-clavulanic acid, cefotaxime, ertapenem, tigecycline and trime-thoprim-sulfamethoxazole (100%). Moreover, three S. aureus strains (37.5%) were methicillin-resistant (MRSA). Of the eight S. aureus isolates, we identified six sequence types (ST) indicating that 75% are likely independent clones. For what it concerned P. aeruginosa, six different STs were assigned. Interestingly, two out of the six strains presented newly identified ST values. This study sheds new light on the combined effect of the presence of HA devices and signs of external ear inflammation on the composition of the ear bacterial flora. Our results reinforce the need to practice careful hygiene of HA devices to prevent serious ear canal infections.

Bio-chemical characterization of bacterial flora associated with spoilt vegetables in kaduna markets Northern Nigeria

Some vegetables such as Capsicum annum (Pepper), Lycopersicon esculentum (Tomato), Allium cepa (Onion), Cucumis sativus (Cucumber), Solanum tubero- sum (Potato) and Daucus carrota (Carrot) which are consumed more frequently in the area were obtained from Kaduna central market and Kawo market with the aim of isolating and characterizing the different bacterial flora associated with their spoilage. Four bacteriological media: Mannitol Salt Agar (MSA), MacConkey Agar (MA), Salmonella Shigella Agar (SSA) and Blood Agar (BA) were used for the isolation of the bacterial populations. The results obtained from Kaduna central market indicated the presence of two Gram positive bacteria viz: Staphylococcus and Streptococcus strains as well as three Gram negative bacteria including Escherichia coli, Citrobacter and Klebsiella spp. Staphylococcus aureus is the most abundant (with 80% relative occurrence) with Strep-tococcus spp being the least abundant (with 10% relative occurrence). Furthermore, among the Gram negative isolates, Escherichia coli, Citrobacter and Kleb- siella spp had the highest occurrence of 30% each, while Enterobacter spp had the least. Similar results were obtained of the isolates from Kawo market except that among the Gram negatives, Edwardsiella spp was found in Kawo market but E. coli is absent. More so, S. aureus and K. spp has the highest percentage of 605 each in Kawo market. The result showed that the people consuming these vegetables are at higher risk of boils, carbuncles, impetigo, infections of wounds and burns, breast abscesses, whitlow, osteomyelitis, bronchopneumonia, septicemia, bacteremia, acute endocarditis, food poisoning and scalded skin syndrome due to these bacterial populations.

Skin Cancer Treatment by Nanoskin Cellulose: Future Cancer Wound Healing

Cancer cells can be proliferating in a few months and years. It depends on cancer stage. Chemotherapy, immunotherapy and anti-metabolic drugs have been used in order to kill cancer cells and prevent immune system weakly and metastasis. However, such drugs can damage healthy cells too. Natural ways to cancer treatments may help whole body to cancer cells. In this work, it was taking off cancer nodule to skin cancer by surgery and we treat the nodule as wound, using Nanoskin® advance cell therapy (ACT), natural extra cellular matrix which releases nutrients to the skin cancer. Our result shows that the cancer nodule disappears in few weeks in skin, because of natural membrane treatment. In addition, we obtained complete wound healing due anticancer nutrients (beta-glucan) delivery to skin.

Characterization of Skin Symbiotic Bacteria of Sympatric Amphibians in Southeastern China

The fungal infection called chytridiomycosis,caused by Batrachochytrium dendrobatidis(Bd),has given rise to dramatic declines or extinctions of many amphibian species around the world;however,in Asia,this disease has shown a low zoospore load or scant mortality.One potential reason for this may be that certain unique community structures of amphibian skin symbiosis contribute to the outcome of the disease;nevertheless,we know very little about the microbiota in this region. In this study,we used skin swabs of five sympatric amphibian species that have various habitat preferences in Lishui,Zhejiang Province,a place in southeastern China,to explore the skin bacterial communities by using 16 S rRNA amplicon sequencing.We detected a total of 1020 OTUs,belonging to 17 phyla,among which Proteobacteria,Firmicutes,Actinobacteria and Bacteroidetes dominated all five host species.Enterobacteriaceae and Exiguobacteraceae and the genera Escherichia and Exiguobacterium belonging to these two families were identified as the most abundant taxa on our focal species.The alpha diversity was significantly lower on the terrestrial species,and also the highly enriched Proteobacteria was found on the terrestrial species,Rana zhenhaiensis,whereas Actinobacteria,Bacteroidetes,Cyanobacteria and Firmicutes were more abundant on aquatic species than on the terrestrial species.Our results suggest that both host species and habitat sites are important factors driving skin microbial diversity and composition and that amphibians in China may harbour unique skin bacterial communities.This study helps elucidate amphibian skin microbial ecology,and with further efforts,the specific mechanism of the interaction between Bd and host amphibians in China could be elucidated.

Human skin bacterial microbiota homeostasis:A delicate balance between health and disease

As the largest organ of the body,the skin acts as a barrier to prevent diseases and harbors a variety of beneficial bacteria.Furthermore,the skin bacterial microbiota plays a vital role in health and disease.Disruption of the barrier or an imbalance between symbionts and pathogens can lead to skin disorders or even systemic diseases.In this review,we first provide an overview of research on skin bacterial microbiota and human health,including the composition of skin bacteria in a healthy state,as well as skin bacterial microbiota educating the immune system and preventing the invasion of pathogens.We then discuss the diseases that result from skin microbial dysbiosis,including atopic dermatitis,common acne,chronic wounds,psoriasis,viral transmission,cutaneous lupus,cutaneous lymphoma,and hidradenitis suppurativa.Finally,we highlight the progress that utilizes skin microorganisms for disease therapeutics,such as bacteriotherapy and skin microbiome transplantation.A deeper knowledge of the interaction between human health and disease and the homeostasis of the skin bacterial microbiota will lead to new insights and strategies for exploiting skin bacteria as a novel therapeutic target.

Gut flora and bacterial translocation in chronic liver disease

Increasing evidence suggests that derangement of gut flora is of substantial dinical relevance to patients with cirrhosis. Intestinal bacterial overgrowth and increased bacterial translocation of gut flora from the intestinal lumen, in particular, predispose to an increased potential for bacterial infection in this group. Recent studies suggest that, in addition to their role in the pathogenesis of overt infective episodes and the clinical consequences of sepsis, gut flora contributes to the pro-inflammatory state of cirrhosis even in the absence of overt infection. Furthermore, manipulation of gut flora to augment the intestinal content of lactic acid-type bacteria at the expense of other gut flora species with more pathogenic potential may favourably influence liver function in cirrhotic patients. Here we review current concepts of the various inter-relationships between gut flora, bacterial translocation, bacterial infection, pro-inflammatory cytokine production and liver function in this group.

Microbact^TM 24E system identification and antimicrobial sensitivity pattern of bacterial flora from raw milk of apparently healthy lactating cows in Gwagwalada, Nigeria

Objective: To determine the prevalence of bacterial organisms from raw milk of cows in Gwagwalada and determine their susceptibility to commonly used antimicrobial agents. Methods: A total of 120 samples of milk were obtained from lactating cows that were at different stages of postpartum from six different locations in Gwagwalada metropolis. Samples were subjected to Microbact? 24E system identification, isolation and characterization of isolates, and antibiotics susceptibility test. Results: The most prevalent organisms were Staphylococcus aureus (34.1%), Escherichia coli (27.3%) and Bacillus species (18.2%) while the least isolated were Salmonella species (11.4%) and Pseudomonas aeruginosa (9.0%). The highest resistance patterns were shown by Staphylococcus aureus which displayed resistance to five drugs: amoxicillin, ampiclox, levofloxacin, norfloxacin, chloramphenicol and streptomycin. The least resistance was displayed by Bacillus species which were resistant to only two drugs, norfloxacin and chloramphenicol. Pseudomonas aeroginosa dissipated the highest pattern susceptibility to ciprofloxacin, norfloxacin, gentamicin and streptomycin while Salmonella species showed the lowest pattern of susceptibility to ciprofloxacin only. Other microorganisms dissipated susceptibility patterns ranging from 16.6%–100.0%. Conclusions: This study documented the occurrence of bacterial flora in raw milk of apparently healthy lactating cows in the Gwagwalada area. The variation in patterns of multidrug resistance and susceptibilities in our studies may lead to possibility of transfer of antibiotic resistance from raw milk consumers. More studies are required using higher molecular techniques to expose different species of microorganisms causing milk borne illness and their antibiotic resistant genes.

运动对大学生肠道菌群影响的系统综述

背景:运动对肠道菌群的调节与人体健康密切相关,但肠道菌群涉及多方面因素影响,国内外研究尚缺乏有关运动对大学生肠道菌群影响的较为一致的证据。目的:探讨运动对大学生肠道菌群多样性和物种组成的影响。方法:通过系统检索PubMed、Web of Science、Embase、Medline、Cochrane Library、中国知网、万方、维普数据库,筛选后纳入8篇实证研究,对其采用半定量的方法进行分析。结果与结论:①在运动改变大学生肠道菌群物种多样性方面,高强度间歇训练和太极拳运动均能显著提升大学生肠道菌群的物种多样性,而有氧运动对大学生肠道菌群多样性的提升效果不显著;②在运动影响肠道菌群物种组成方面,3种运动方式均能显著改变大学生肠道中菌群的组成结构,可以提高瘤胃球菌、普氏粪杆菌、布劳提亚菌等有益菌的丰度,降低埃希氏菌属等有害菌的丰度;相较于高强度间歇训练,有氧运动和太极拳运动引起了更多有益菌丰度的提升;③除肠道菌群特征的变化外,运动还可以改善大学生体成分、心肺功能以及执行功能等,这些健康效益与运动引起的菌群变化密切相关,这些菌群可通过代谢调节、屏障功能以及神经调节对机体产生健康效益;④虽然目前已有研究证实了运动与肠道菌群存在关联,但运动影响肠道菌群的机制尚未明确,同时定位与宿主健康相关的菌群是未来以肠道菌群为治疗靶点的关键,这些均值得学者进一步关注和探究。

Composition and immuno-stimulatory properties of extracellular DNA from mouse gut flora

AIM To demonstrate that specific bacteria might release bacterial extracellular DNA(e DNA) to exert immunomodulatory functions in the mouse small intestine.METHODS Extracellular DNA was extracted using phosphate buffered saline with 0.5 mmol/L dithiothreitol combined with two phenol extractions. TOTO-1 iodide, a cell-impermeant and high-affinity nucleic acid stain, was used to confirm the existence of e DNA in the mucus layers of the small intestineand colon in healthy Male C57 BL/6 mice. Composition difference of e DNA and intracellular DNA(i DNA) of the small intestinal mucus was studied by Illumina sequencing and terminal restriction fragment length polymorphism(T-RFLP). Stimulation of cytokine production by e DNA was studied in RAW264.7 cells in vitro.RESULTS TOTO-1 iodide staining confirmed existence of e DNA in loose mucus layer of the mouse colon and thin surface mucus layer of the small intestine. Illumina sequencing analysis and T-RFLP revealed that the composition of the e DNA in the small intestinal mucus was significantly different from that of the i DNA of the small intestinal mucus bacteria. Illumina Miseq sequencing showed that the e DNA sequences came mainly from Gram-negative bacteria of Bacteroidales S24-7. By contrast, predominant bacteria of the small intestinal flora comprised Grampositive bacteria. Both e DNA and i DNA were added to native or lipopolysaccharide-stimulated Raw267.4 macrophages, respectively. The e DNA induced significantly lower tumor necrosis factor-α/interleukin-10(IL-10) and IL-6/IL-10 ratios than i DNA, suggesting the predominance for maintaining immune homeostasis of the gut.CONCLUSION Our results indicated that degraded bacterial genomic DNA was mainly released by Gram-negative bacteria, especially Bacteroidales-S24-7 and Stenotrophomonas genus in gut mucus of mice. They decreased pro-inflammatory activity compared to total gut flora genomic DNA.