Genomic and functional diversity of the human-derived isolates of Faecalibacterium.

Introduction: Faecalibacterium is one of the most abundant bacteria in the gut microbiota of healthy adults, highly regarded as a next-generation probiotic. However, the functions of Faecalibacterium genomes from cultured strains and the distribution of different species in populations may differ among different sources. Methods: We here performed an extensive analysis of pan-genomes, functions, and safety evaluation of 136 Faecalibacterium genomes collected from 10 countries. Results: The genomes are clustered into 11 clusters, with only five of them were characterized and validly nomenclated. Over 80% of the accessory genes and unique genes of Faecalibacterium are found with unknown function, which reflects the importance of expanding the collection of Faecalibacterium strains. All the genomes have the potential to produce acetic acid and butyric acid. Nine clusters of Faecalibacterium are found significantly enriched in the healthy individuals compared with patients with type II diabetes.. Discussion: This study provides a comprehensive view of genomic characteristic and functions and of culturable Faecalibacterium bacterium from human gut, and enables clinical advances in the future.

Nickel oxide nanoparticles decrease the accumulation of atrazine in earthworms.

Nickel oxide nanoparticles (NiO-NPs) are common nanomaterials that may be released into the environment, affecting the toxicity of other contaminants. Atrazine (ATZ) is a commonly used herbicide that can harm organisms due to its persistence and bioaccumulation in the environment. Although the toxicity of ATZ to earthworms is well-documented, the risk of co-exposure with NiO-NPs increases as more nanoparticles accumulate in the soil. In this study, we investigated the effects and mechanisms of NiO-NPs on the accumulation of ATZ in earthworms. The results showed that after day 21, the antioxidant system of the cells under ATZ treatment alone was adversely affected, with ROS content 36.05 % higher than that of the control (CK) group. However, the addition of NiO-NPs reduced the ROS contents in the earthworms by 0.6 %- 32.3 %. Moreover, analysis of earthworm intestinal sections indicates that NiO-NPs mitigated cellular and tissue damage caused by ATZ. High-throughput sequencing revealed that NiO-NPs in earthworm intestines increased the abundance of Pseudomonas aeruginosa and Aeromonas aeruginosa. Additionally, the enhanced function of the ABC transport system in the gut resulted in lower accumulation of ATZ in earthworms. In summary, NiO-NPs can reduce the accumulation and thus the toxicity of ATZ in earthworms. Our study contributes to a deeper understanding of the effects of NiO-NPs on co-existing pollutants.

Qi Huang Fang improves intestinal barrier function and intestinal microbes in septic mice through NLRP3 inflammasome-mediated cellular pyroptosis.

OBJECTIVE: Sepsis has a high incidence, morbidity, and mortality rate and is a great threat to human safety. Gut health plays an important role in sepsis development. Qi Huang Fang (QHF) contains astragalus, rhubarb, zhishi, and atractylodes. It is used to treat syndromes of obstructive qi and deficiency of righteousness. This study aimed to investigate whether QHF improves intestinal barrier function and microorganisms in mice through NLRP3 inflammatory vesicle-mediated cellular focal death. METHODS: A mouse model of sepsis was constructed by cecal ligation and puncture (CLP) of specific pathogen-free (SPF)-grade C57BL/6 mice after continuous gavage of low, medium, and high doses of astragalus formula or probiotics for 4 weeks. Twenty-four hours postoperatively, the mechanism of action of QHF in alleviating septic intestinal dysfunction and restoring intestinal microecology, thereby alleviating intestinal injury, was evaluated by pathological observation, immunohistochemistry, western blotting, ELISA, and 16S rDNA high-throughput sequencing. RESULTS: Different doses of QHF and probiotics ameliorated intestinal injury and reduced colonic apoptosis in mice to varying degrees (P < 0.05). Meanwhile, different doses of QHF and probiotics were able to reduce the serum levels of IL-6, IL-1ß, and TNF-α (P < 0.05); down-regulate the protein expression of NLRP3, caspase-1, and caspase-11 (P < 0.05); and up-regulate the protein expression of zonula occluden-1 (ZO-1) and occludin (P < 0.05), which improved the intestinal barrier function in mice. In addition, QHF decreased the relative abundance of harmful bacteria (Firmicutes, Muribaculaceae, Campilobacterota, Helicobacter, and Alistipes) and increased the relative abundance of beneficial bacteria (Bacteroidetes and Actinobacteria) (P < 0.05). CONCLUSION: QHF improves intestinal barrier function and gut microbiology in mice via NLRP3 inflammasome-mediated cellular pyroptosis.

Discussion of factors influencing preclinical studies based on fecal bacteria transplantation in mice / 中国实验动物学报

Fecal microbiota transplantation(FMT)is a therapeutic approach that targets intestinal microorganisms by transplanting fecal microorganisms from healthy individuals into the gastrointestinal tract of diseased individuals,thus restoring the recipient's disordered gastrointestinal microbiota by restructuring the intestinal flora.However,the mechanism of action and adverse effects of FMT in different diseases have not yet been clarified,thus limiting its wide clinical application.Its use still relies on in-depth preclinical studies;however,highly inconsistent or incomplete experimental details provided in current reports,coupled with a lack of authoritative standards and recommendations,seriously affect the interpretation of the study findings and replication of the experimental procedures,as well as hindering the clinical translation of the result.We therefore review and discuss the key steps of recipient selection and graft sample collection,storage,graft material preparation,and grafting route,with the aim of improving the utilization of experimental animals,consumables,and labor,and providing method ological recommendations and references to achieve replicability and standardization of preclinical FMT studies.

The role of chicken eggs in modulating sarcopenic obesity and gut microbiota in db/db mice.

Background: Sarcopenia obesity, in which loss of muscle mass and fat accumulation occur simultaneously, is the pathological basis of type 2 diabetes mellitus. The usefulness of chicken eggs in sarcopenia prevention has been reported in several previous studies. The purpose of this study was to determine the beneficial effects of chicken eggs in the prevention of sarcopenic obesity in db/db mice. Methods: We raised 8-week-old db/db male mice, a model of sarcopenia obesity, for 8 weeks and fed them a diet mixed with dried whole eggs. The fecal microbiota transplant (FMT) group was treated with antibiotics for 2 weeks, starting at 6 weeks of age, followed by FMT twice a week until 16 weeks of age. Results: Eggs administered to db/db mice showed increased grip strength (p = 0.022) and muscle mass (p = 0.013), decreased visceral fat mass (p = 0.005), and significantly increased physical activity (p < 0.001). The FMT group of egg-fed mice showed a significant improvement in glucose intolerance and sarcopenic obesity. Sequencing of gene expression in the small intestine showed that the gene expression of amino acid transporters such as Slc6a18, Slc6a19, and Slc38a6 was increased in egg-fed mice. 16S rRNA sequencing of the gut microbiota showed an increase in the genus Vampirovibrio in both the egg-fed and FMT groups compared to that in egg-fed mice. Conclusion: The results of this study indicate that egg consumption not only increases the intake of amino acids and other nutrients but also alters the intestinal microbiota and increases amino acid absorption from the intestinal tract, suggesting that eggs might contribute to the ameliorative mechanism of sarcopenic obesity.

Effects of Dietary Supplementation of Lacticaseibacillus Chiayiensis AACE3 on Hepatic Antioxidant Capacity, Immune Factors and Gut Microbiology in Nandan Yao Chicks.

The growing issue of antibiotic resistance has restrained the utilization of antibiotics as growth enhancers in the poultry industry. Probiotics are candidates for replacing antibiotics in the poultry industry. However, probiotics are strain-specific and their efficacy needs to be investigated before applying them. The aim of this study was to assess the positive effects of Lacticaseibacillus chiayiensis AACE3 on the health and gut microbiota of Nandan Yao chicks. The results showed that compared with the blank control (NC) and aureomycin (PC) groups, L. chiayiensis AACE3 increased final body weight (BW), villus height and improved the ratio of villus height to crypt depth in chicken jejunal tissues. L. chiayiensis AACE3 also increased the activity of hepatic antioxidant enzymes (SOD, CAT and T-AOC) and reduced hepatic oxidative damage (MDA). Furthermore, compared to NC, L. chiayiensis AACE3, the activity of intestinal digestive enzymes (i.e., α-amylase, lipase and trypsin) was increased. L. chiayiensis AACE3 upregulated the production of IgA and IgG and downregulated the production of IL-6, IL-1ß and TNF-α in chicken serum. Moreover, supplementation of L. chiayiensis AACE3 enhances the diversity of gut microbes. At the phylum level, the abundance of Actinobacteriota and Proteobacteria decreased with L. chiayiensis AACE3 supplementation, while the abundance of Verrucomicrobiota and Bacteroidetes increased. At the genus level, there was an increase in the abundance of potential probiotics Akkermansia, Romboutsia, Subdoligranulum, and Lactobacillus. This study confirms that L. chiayiensis AACE3 is an excellent feed additive as an alternative to aureomycin and offers various advantages for the healthy growth of chickens during the brooding period by positively affecting their gut microbiome.

Gut microbiology of UK care home residents: a cross-sectional analysis from a randomised controlled trial.

OBJECTIVE: To describe the prevalence of potentially clinically relevant gut pathogens and associations with the carriage of resistant organisms in UK care home residents. METHODS: Stool samples were collected pre-randomisation from care home residents participating in a randomised placebo-controlled trial. Cultivable clinically relevant bacteria were analysed. Antimicrobial susceptibility testing was performed by agar dilution (amoxicillin, co-amoxiclav, gentamicin, trimethoprim, nitrofurantoin, and ciprofloxacin). We also aimed to detect resistance to third-generation cephalosporins, carbapenems, and vancomycin. RESULTS: Stool samples were available for 159/310 residents participating in the trial (51%) from 23 care homes between 2016 and 2018. In total, 402 bacterial isolates were cultured from 158 stool samples and 29 different species were cultured. The five most common species were Escherichia coli (155/158, 98%), Pseudomonas aeruginosa (40/158, 25%), Enterococcus faecalis (35/158, 22%), Enterococcus faecium (30/158, 19%), and Proteus mirabilis (25/158, 16%). Enterobacterales isolates were cultured from 157 samples (99%), and resistance to at least one of the tested antimicrobials was found in 119 of these (76%). There were high levels of variation in outcomes by care home. DISCUSSION: We demonstrated that care home residents harbour significant levels of antimicrobial-resistant organisms in their stool. This work emphasises the importance of both enhanced infection control practices and antimicrobial stewardship programmes to support the appropriate use of antimicrobials in this setting.

Mechanism of Metabolic Response to Hepatectomy by Integrated Analysis of Gut Microbiota, Metabolomics, and Proteomics.

Hepatectomy is a common clinical procedure for the treatment of many liver diseases, and the successful recovery of a patient's liver metabolism and function after surgery is crucial for a good prognosis. The objective of this study was to elucidate the metabolic response to hepatectomy using high-throughput sequencing analysis of 16S rRNA gene, metabolomics, and proteomics data. Fecal and serum samples from beagle dogs were collected on day 0 (LH0), day 7 (LH7), and day 28 (LH28) after laparoscopic partial hepatectomy. Liver tissue samples were taken on LH0 and LH7. Dysbiosis in the fecal microbiota was explored, and host-microbiome interactions based on global metabolic and protein profiles and inflammatory processes were determined. Results showed that the relative abundance of Allobaculum and Turicibacter was decreased and that of Escherichia-Shigella was increased after hepatectomy (P < 0.05); the phenylalanine, tyrosine, and tryptophan biosynthetic pathway, along with the phenylalanine and aminoacyl-tRNA biosynthetic pathway, was significantly associated with liver injury. The serum metabolites l-phenylalanine and l-arginine were useful as biomarkers, and the fecal metabolite l-threonine was a signature target monitor for liver recovery. The proteomics profile revealed 412 significantly different proteins and further highlighted two key signaling pathways (mitogen-activated protein kinase [MAPK] and peroxisome proliferator-activated receptor [PPAR]) involved in the response to liver injury. We systematically explored the metabolic mechanism of liver injury and recovery, providing new insights into effective ways to promote recovery after hepatectomy and improve liver function and long-term survival. These fundamental studies on hepatectomy will provide the basis for future advances in treatment and recovery from common liver diseases. IMPORTANCE As the largest parenchymal organ, the liver is a target for bacterial and viral infections, nonalcoholic fatty liver disease (NAFLD), cirrhosis, cancer, and many other diseases, constituting a serious worldwide problem. The treatment for many of these diseases involves hepatectomy. Here, we show that aberrant inflammatory processes after hepatectomy of the liver as reflected in the association between liver metabolism and gut microbiota create a grave risk. This study investigated the mechanisms of gut microbiota and host metabolism involved in liver injury and recovery after hepatectomy, using proteomics to reveal the mechanisms of postoperative liver injury and a comprehensive multi-omics approach to identify changes in metabolism after hepatectomy.

Preventive effect of Ya'an Tibetan tea on obesity in rats fed with a hypercaloric high-fat diet revealed by gut microbiology and metabolomics studies.

Ya'an Tibetan Tea (YATT) is a classic dark tea variety fermented with a unique geographical environment and traditional craftsmanship. Previous research indicates that it is beneficial for obesity and related metabolic disorders, but no systematic research currently reveals its precise mechanisms. This work investigated the preventive effect of YATT on obesity and the corresponding potential mechanisms by performing 16S rRNA gene sequencing and metabolomics studies. Our results demonstrated that YATT could significantly improve the body weight and fat deposition in hypercaloric high-fat diet (HFD)-induced obese rats, enhance antioxidant enzymes activity and reduce inflammation, and reverse the liver damage caused by an HFD. Moreover, 16S rRNA analysis showed that YATT could improve the intestinal microbial disorders caused by the HFD by significantly reversing the increase in Firmicutes/Bacteroidetes（F/B）ratio and the relative abundance of flora associated with the HFD, such as unclassified_Lachnospiraceae and Romboutsia flora. In addition, metabolomic analysis of cecum contents identified 121 differential metabolites, of which 19 were common to all experimental rats fed with and without a high-fat diet. Strikingly, 17 of the most prevalent 19 differential metabolites, including Theobromine, L-Valine, and Diisobutyl phthalate, were considerably reversed by YATT. Enrichment analysis of the metabolic pathways of these differential metabolites indicated that Caffeine metabolism, Phenylalanine metabolism, and Lysine degradation are the potential metabolic pathways responsible for the obesity prevention effect of YATT. Collectively, this work revealed that YATT has good potential for obesity prevention and the improvement of intestinal microbial communities, potentially due to the YATT-induced alterations in the metabolic pathways and functional metabolite levels of caffeine and amino acids. These results inform the material basis of YATT for obesity prevention and its mechanisms and provide essential insights for developing YATT as a healthy beverage for obesity prevention.

MiR155 Disrupts the Intestinal Barrier by Inducing Intestinal Inflammation and Altering the Intestinal Microecology in Severe Acute Pancreatitis.

BACKGROUND: Intestinal dysfunction is a common complication of acute pancreatitis. MiR155 may be involved in the occurrence and development of intestinal dysfunction mediated by acute pancreatitis, but the specific mechanism is not clear. AIMS: To investigate the effect of miR155 on severe acute pancreatitis (SAP)-associated intestinal dysfunction and its possible mechanism in a mice model. METHODS: In this study, SAP mice model was induced by intraperitoneal injection of caerulein and LPS in combination. Adeno-associated virus (AAV) was given by tail vein injection before the SAP model. The pancreatic and intestinal histopathology changes were analyzed. Cecal tissue was collected for 16S rRNA Gene Sequencing. Intestinal barrier proteins ZO-1 and E-cad were measured by Immunohistochemistry Staining and Western Blot, respectively. Intestinal tissue miR155 and inflammatory factors TNF-α, IL-1ß, and IL-6 were detected by Q-PCR. The expression levels of protein associated with TNF-α and TLR4/MYD88 pathway in the intestinal were detected. RESULTS: In miR155 overexpression SAP group, the levels of tissue inflammatory factor were significantly increased, intestinal barrier proteins were significantly decreased, and the injury of intestinal was aggravated. Bacterial 16S rRNA sequencing was performed, showing miR155 promotes gut microbiota dysbiosis. The levels of TNF-α, TLR4, and MYD88 in the intestinal were detected, suggesting that miR155 may regulate gut microbiota and activate the TLR4/MYD88 pathway, thereby affecting the release of inflammatory mediators and regulating SAP-related intestinal injury. After application of miR155-sponge, imbalance of intestinal flora and destruction of intestinal barrier-related proteins have been alleviated. The release of inflammatory mediators decreased, and the histopathology injury of intestinal was improved obviously. CONCLUSION: MiR155 may play an important role in SAP-associated intestinal dysfunction. MiR155 can significantly alter the intestinal microecology, aggravated intestinal inflammation through TLR4/MYD88 pathway, and disrupts the intestinal barrier in SAP mice.

Probiotic supplementation affects IGF-1 and leptin levels in Nile tilapia hepatopancreatic tissue / Suplementação com probiótico afeta os níveis de IGF-1 e leptina no tecido hepatopancreático de tilápias-do-nilo

This work aimed to assess the effect of the probiotic strain, Lactobacillus plantarum, on the levels of leptin, IGF-1 and their receptors on the hepatopancreatic tissues of Nile tilapia (Oreochromis niloticus) and then correlate fish growth performance and gut microbiological parameters. Fish juveniles (±23g) were reared in a recirculation system with constant aeration and temperature (25°C). They were distributed into six polyethylene tanks (45L) and fed twice a day at 5% of the tank biomass with the respective diets: control (commercial diet without probiotic) and supplemented with L. plantarum inoculum (1 x 108 CFU mL-1), both in triplicate. After 30 days of feeding, L. plantarum-fed fishes showed greater weekly growth rate, final weight, and feed conversion rate, in addition to higher count of lactic-acid bacteria and lower count of pathogenic bacteria in the intestinal tract, when compared to the control group. The immunostaining intensity for IGF-1 and leptin hormones was lower after L. plantarum supplementation than in the control group, with no change in the level for receptors. This reduction could implicate important changes in fish metabolism and homeostasis.(AU)

O presente trabalho teve como objetivo avaliar o efeito da cepa probiótica Lactobacillus plantarum sobre os níveis de leptina, IGF-1 e seus receptores no tecido hepatopancreático de tilápia-do-nilo (Oreochromis niloticus) e correlacionar com o desempenho zootécnico e os parâmetros microbiológicos intestinais dos peixes. Juvenis de tilápia-do-nilo (±23g) foram distribuídos em seis tanques de polietileno (45L) conectados a um sistema de recirculação, com aeração e temperatura constantes (25°C). Os peixes foram alimentados duas vezes ao dia, a 5% da biomassa do tanque, com as respectivas dietas: controle (dieta comercial sem probiótico) e suplementada com L. plantarum (1 x 108 UFC mL-1), ambas em triplicata. Após 30 dias de cultivo, os peixes alimentados com L. plantarum apresentaram maiores ganho de peso semanal, peso final e conversão alimentar, bem como maior contagem de bactérias ácido-láticas e menor contagem de bactérias patogênicas no trato intestinal das tilápias alimentadas com dieta probiótica, em comparação ao grupo controle. A intensidade da imunomarcação para os hormônios IGF-1 e leptina foi menor com a suplementação de L. plantarum do que no grupo controle, sem alterar os níveis de seus receptores. Essa redução pode implicar mudanças importantes no metabolismo e na homeostase dos peixes.(AU)

Phylogenomic analysis of 589 metagenome-assembled genomes encompassing all major prokaryotic lineages from the gut of higher termites.

"Higher" termites have been able to colonize all tropical and subtropical regions because of their ability to digest lignocellulose with the aid of their prokaryotic gut microbiota. Over the last decade, numerous studies based on 16S rRNA gene amplicon libraries have largely described both the taxonomy and structure of the prokaryotic communities associated with termite guts. Host diet and microenvironmental conditions have emerged as the main factors structuring the microbial assemblages in the different gut compartments. Additionally, these molecular inventories have revealed the existence of termite-specific clusters that indicate coevolutionary processes in numerous prokaryotic lineages. However, for lack of representative isolates, the functional role of most lineages remains unclear. We reconstructed 589 metagenome-assembled genomes (MAGs) from the different gut compartments of eight higher termite species that encompass 17 prokaryotic phyla. By iteratively building genome trees for each clade, we significantly improved the initial automated assignment, frequently up to the genus level. We recovered MAGs from most of the termite-specific clusters in the radiation of, for example, Planctomycetes, Fibrobacteres, Bacteroidetes, Euryarchaeota, Bathyarchaeota, Spirochaetes, Saccharibacteria, and Firmicutes, which to date contained only few or no representative genomes. Moreover, the MAGs included abundant members of the termite gut microbiota. This dataset represents the largest genomic resource for arthropod-associated microorganisms available to date and contributes substantially to populating the tree of life. More importantly, it provides a backbone for studying the metabolic potential of the termite gut microbiota, including the key members involved in carbon and nitrogen biogeochemical cycles, and important clues that may help cultivating representatives of these understudied clades.

Effect of dietary saponin rich soapnut (Sapindus mukorossi) shell powder on growth performance, immunity, serum biochemistry and gut health of broiler chickens.

This study was conducted to evaluate the effects of dietary soapnut (Sapindus mukorossi) shell powder (SSP), a cheap source of saponins, on growth performance, immunity, serum biochemistry and gut health of broiler chickens. The experimental design was 4×2, employing four saponin levels (0, 100, 150 and 200 mg/kg diet), each provided for two time durations (0-42 day and 21-42 day) resulting into eight dietary treatments. Results revealed no significant effect of dietary saponins on body weight gain, feed intake and feed conversion ratio of birds. The abdominal fat percentage, heterophil to lymphocyte ratio, serum cholesterol and triglyceride levels, faecal total plate count, coliform count and E. coli count decreased (p < .05) progressively with increasing saponin levels and lower values were observed at 150 mg and 200 mg saponin levels. Significant improvement of cell-mediated and humoral immune response was observed in birds fed 150 mg and 200 mg saponin compared to control. The serum glucose concentration was significantly (p < .05) higher in control group compared to other groups. No significant effects of dietary saponin were observed on carcass characteristics, faecal Lactobacillus count, intestinal histomorphometry and cost economics of broiler chicken production. Thus, dietary saponins at 150 mg/kg diet as SSP for three weeks (21-42 days) was optimum for better immunity and welfare of birds without adverse effects on the growth performance.

The effect of feeding system and sex on the performance and selected gastrointestinal features of fattening pigs.

The aim of the study was to evaluate the efficiency of two feeding systems for fattening pigs (wet and dry), taking into account their sex, on performance, nutrient digestibility, and some histological and microbiological parameters of the gut. The study was conducted on 450 fattening pigs, divided into 6 groups (n = 75) and housed in pens with 15 pigs per pen. The first three groups, divided according to sex, i.e. gilts, barrows and boars subjected to immunocastration (B-I), received complete dry feed, while the next three, divided in the same manner according to sex, were fed a fermented liquid diet. The nutritional value of the feeds, calculated on a dry weight basis, was similar for the two feeding systems in both stages of the fattening period. The best weight gains were observed in the group B-I pigs which received the liquid diet, and the poorest in the gilts fed the dry feeds. The best feed conversion ratio (FCR) was observed in the boars treated with Improvac®, especially those receiving the liquid diet. The feeding system significantly influenced the digestibility of nutrients, with higher apparent digestibility coefficients for crude protein, fat and fibre noted in the animals fed in the wet system. The liquid feeding system caused an increase in crypt depth in the colon in all groups of pigs, as well as an increase in the width of the muscular layer. A significant decrease in the total bacterial count was observed in the calcium, especially in the animals fed in the wet system.

Gram-negative intestinal indigenous microbiota from two Siluriform fishes in a tropical reservoir

The Gram-negative intestinal microbiota of Hypostomus auroguttatus and Pimelodus maculatus, a detritivorous and an omnivorous fish species, respectively, were compared between fishes from the reservoir and the stretch of the river below the dam of the Funil hydroelectric plant, Rio de Janeiro, Brazil. Four selective culture media were used under aerobic and two under anaerobic conditions. The omnivorous species had microbiota with higher population levels compared to the detritivorous species. The number of morphotypes and population levels of total bacteria, vibrio and Bacteroides tended to be higher in summer and autumn in the reservoir, and not different in the river. The number of morphotypes of enterobacteria and total bacteria were higher in the lotic environment compared with the lentic one. The bacteria Aeromonas hydrophila and Plesiomonas shigelloides and the obligate anaerobic Fusobacterium mortiferum were the most frequently identified microorganisms in the intestine of both H. auroguttatus and P. maculatus. Both season and habitat influenced the Gram-negative intestinal microbiota of H. auroguttatus and P. maculatus. Environmental factors influenced the Gram-negative intestinal microbiota of both species with possible impact on the interrelationship between the fishes and their digestive ecosystem, although the gut microbiota composition of fishes may result from host-specific selective pressures within the gut.

Altered egos: antibiotic effects on food animal microbiomes.

The human food chain begins with upwards of 1,000 species of bacteria that inhabit the intestinal tracts of poultry and livestock. These intestinal denizens are responsible for the health and safety of a major protein source for humans. The use of antibiotics to treat animal diseases was followed by the surprising discovery that antibiotics enhanced food animal growth, and both led to six decades of antibiotic use that has shaped food animal management practices. Perhaps the greatest impact of antibiotic feeding in food animals has been as a selective force in the evolution of their intestinal bacteria, particularly by increasing the prevalence and diversity of antibiotic resistance genes. Future antibiotic use will likely be limited to prudent applications in both human and veterinary medicine. Improved knowledge of antibiotic effects, particularly of growth-promoting antibiotics, will help overcome the challenges of managing animal health and food safety.

Gram-negative intestinal indigenous microbiota from two Siluriform fishes in a tropical reservoir.

The Gram-negative intestinal microbiota of Hypostomus auroguttatus and Pimelodus maculatus, a detritivorous and an omnivorous fish species, respectively, were compared between fishes from the reservoir and the stretch of the river below the dam of the Funil hydroelectric plant, Rio de Janeiro, Brazil. Four selective culture media were used under aerobic and two under anaerobic conditions. The omnivorous species had microbiota with higher population levels compared to the detritivorous species. The number of morphotypes and population levels of total bacteria, vibrio and Bacteroides tended to be higher in summer and autumn in the reservoir, and not different in the river. The number of morphotypes of enterobacteria and total bacteria were higher in the lotic environment compared with the lentic one. The bacteria Aeromonas hydrophila and Plesiomonas shigelloides and the obligate anaerobic Fusobacterium mortiferum were the most frequently identified microorganisms in the intestine of both H. auroguttatus and P. maculatus. Both season and habitat influenced the Gram-negative intestinal microbiota of H. auroguttatus and P. maculatus. Environmental factors influenced the Gram-negative intestinal microbiota of both species with possible impact on the interrelationship between the fishes and their digestive ecosystem, although the gut microbiota composition of fishes may result from host-specific selective pressures within the gut.

Isolation and identification of cellulolytic bacteria from the gut of Holotrichia parallela larvae (Coleoptera: Scarabaeidae).

In this study, 207 strains of aerobic and facultatively anaerobic cellulolytic bacteria were isolated from the gut of Holotrichia parallela larvae. These bacterial isolates were assigned to 21 genotypes by amplified ribosomal DNA restriction analysis (ARDRA). A partial 16S rDNA sequence analysis and standard biochemical and physiological tests were used for the assignment of the 21 representative isolates. Our results show that the cellulolytic bacterial community is dominated by the Proteobacteria (70.05%), followed by the Actinobacteria (24.15%), the Firmicutes (4.35%), and the Bacteroidetes (1.45%). At the genus level, Gram-negative bacteria including Pseudomonas, Ochrobactrum, Rhizobium, Cellulosimicrobium, and Microbacterium were the predominant groups, but members of Bacillus, Dyadobacter, Siphonobacter, Paracoccus, Kaistia, Devosia, Labrys, Ensifer, Variovorax, Shinella, Citrobacter, and Stenotrophomonas were also found. Furthermore, our results suggest that a significant amount of bacterial diversity exists among the cellulolytic bacteria, and that Siphonobacter aquaeclarae, Cellulosimicrobium funkei, Paracoccus sulfuroxidans, Ochrobactrum cytisi, Ochrobactrum haematophilum, Kaistia adipata, Devosia riboflavina, Labrys neptuniae, Ensifer adhaerens, Shinella zoogloeoides, Citrobacter freundii, and Pseudomonas nitroreducens are reported to be cellulolytic for the first time in this study. Our results indicate that the scarab gut is an attractive source for the study of novel cellulolytic microorganisms and enzymes useful for cellulose degradation.