Gastrointestinal Tract Of Animals Research Articles

The potential role of galectin-4 in protecting the intestinal barrier in the lined seahorse Hippocampus erectus

Galectin-4 is a prominent antimicrobial peptide primarily expressed in the gastrointestinal tract of animals. It plays crucial roles in antimicrobial defense and in regulating the repair of intestinal epithelial cells. Given the unique immune system in seahorses, which are known for male pregnancy, the function of galectin-4 in their intestinal tract, which lack gut-associated lymphoid tissues, remains unknown. In this study, we identified a galectin-4 gene (HeGal-4) in the lined seahorse (Hippocampus erectus). The sequence length of the open reading frame (ORF) was 1041 bp, encoding 346 amino acids. The mRNA expression of HeGal-4 in the intestine was significantly higher than that in other internal organs. However, the synthesized peptide fragment (HeGal-4(302–315)) from the functional domain of HeGal-4 only showed moderate inhibitory effects against Escherichia coli, Klebsiella pneumoniae, and Micrococcus luteus. Interestingly, in situ hybridization showed that HeGal-4 was predominantly expressed in seahorse intestinal epithelial cells, while genes associated with galectin-4 in the repair of intestinal epithelium, such as β-catenins, were highly expressed in their intestines. Therefore, our results suggest that HeGal-4 may be crucial for regulating the repair of intestinal epithelial cells in seahorse intestinal epithelial cells, and that it possesses significant potential for the prevention and control of intestinal diseases in seahorse aquaculture.

Gut Microbiota Diversity of Local Egyptian Cattle Managed in Different Ecosystems.

The animal gastrointestinal tract contains a complex microbiome whose composition ultimately reflects the co-evolution of microorganisms with their animal host and their host's environment. This study aimed to gain insights into the adaptation of the microbiota of local Egyptian cattle to three different ecosystems (Upper Egypt, Middle Egypt, and Lower Egypt) distributed across 11 governorates (with an average of 12 animals per governorate) using amplicon sequencing. We analyzed the microbiota from 136 fecal samples of local Egyptian cattle through a 16S rRNA gene sequencing approach to better understand the fecal microbial diversity of this breed which developed under different ecosystems. An alpha diversity analysis showed that the fecal microbiota of the Egyptian cattle was not significantly diverse across areas, seasons, sexes, or farm types. Meanwhile, microbiota data revealed significant differences in richness among age groups (p = 0.0018). The microbial community differed significantly in the distribution of its relative abundance rather than in richness across different ecosystems. The taxonomic analysis of the reads identified Firmicutes and Actinobacteriota as the dominant phyla, accounting for over 93% of the total bacterial community in Egyptian cattle. Middle Egypt exhibited a different microbial community composition compared to Upper and Lower Egypt, with a significantly higher abundance of Firmicutes and Euryarchaeota and a lower abundance of Actinobacteriota in this region than the other two ecosystems. Additionally, Middle Egypt had a significantly higher relative abundance of the Methanobacteriaceae family and the Methanobrevibacter genera than Lower and Upper Egypt. These results suggest a difference in the adaptation of the fecal microbial communities of Egyptian cattle raised in Middle Egypt. At the genus level, eleven genera were significantly different among the three ecosystems including Bacillus, DNF00809, Kandleria, Lachnospiraceae_NK3A20_group, Methanobrevibacter, Mogibacterium, Olsenella, Paeniclostridium, Romboutsia, Turicibacter, and UCG-005. These significant differences in microbiota composition may impact the animal's adaptation to varied environments.

Novel feed additive delivers antimicrobial copper and influences fecal microbiota in pigs.

Dehydrated alginate beads formulated with copper were synthesized and tested as a feed additive to influence the microbiota in finishing pigs and potentially use them as a preharvest intervention to reduce fecal pathogen shedding. The efficacy of the copper beads was tested in vitro and in vivo. In vitro, Salmonella was significantly (P < 0.05) reduced when in contact with the copper beads solution for up to 6 h, with a 5.4 log CFU/mL reduction over the first hour. Chemical analysis of the soak solutions demonstrated the beads delivered their copper payload gradually over the same period the bactericidal effect was observed. For the in vivo experiments, pigs (n = 48) supplemented with the copper beads experienced significant shifts in their microbiota. Enterobacteriaceae (EB) increased by 1.07 log CFU/g (P < 0.05), while lactic acid bacteria (LAB) decreased by 1.22 log CFU/g (P < 0.05) during the treatment period. When beads were removed from the feed, EB and LAB concentrations returned to baseline, indicating copper beads led to measurable and significant changes in microbial loads. Fecal microbiome analysis conducted to explore additional changes by copper bead supplementation demonstrated that, at the phylum level, there was an increase in Firmicutes, Euryarchaeota, and Acidobacteriota, while at the genus level, an increase in Methanosphaera and Pseudomonas was observed. Measures of copper in swine feces showed values ~20 times higher in the treatment group than in the control group during the treatment period, suggesting that dehydrated alginate copper beads were effective in delivering antimicrobial copper to the animal hindgut.IMPORTANCECopper has long been known to have antimicrobial properties. However, when water-soluble salts are fed to livestock, the copper may rapidly dissolve in gastric contents and fail to reach the gut. Here, specially formulated copper beads are seamlessly incorporated into feed and allow copper to remain longer in the gastrointestinal tract of animals, reach deep into both the foregut and hindgut, and shift microbial populations. The technology delivers antimicrobial copper to the animal hindgut and potentially reduces pathogenic microorganisms before animal slaughter.

The efficiency of mycotoxin binding by sorbents in the in vitro model using a naturally contaminated animal feed.

The productivity of domestic animals and the safety of food products derived from them are jeopardised by mycotoxins in animal feed. To control them, feed additives are used, which limit the absorption of mycotoxins in the gastrointestinal tract of animals by binding to them. The study aimed to evaluate the effectiveness of a new in vitro model in experiments on the binding of mycotoxins from buffers and contaminated feed and to confirm the effect of a single sorbent or mixture in binding them. Nine mineral sorbents were tested for their efficiency binding eight mycotoxins. Two in vitro experiments were conducted to indicate the mycotoxin-binding capacity of sorbents, each specifying a buffer with one of two different pH levels reflecting gastrointestinal conditions (pH 3.5 and 7.0). The first investigated the sorbent with only the buffer and mycotoxin standards, while the second did so with the sorbent, buffer and feed naturally contaminated with mycotoxins (deoxynivalenol, zearalenone, and ochratoxin A). The sorption was significantly lower in the trial with feed. In the first experiment at gastric pH (pH 3.5), activated charcoal bound deoxynivalenol and sepiolite bound zearalenone at 70% and 96%, respectively, whereas in the second experiment with feed, the binding was only 3% and 6%. The study underlines the challenge of finding a feed additive that would work comprehensively, binding all mycotoxins regulated by law.

Critical complex network structures in animal gastrointestinal tract microbiomes

BackgroundLiving things from microbes to their hosts (plants, animals and humans) interact with each other, and their relationships may be described with complex network models. The present study focuses on the critical network structures, specifically the core/periphery nodes and backbones (paths of high-salience skeletons) in animal gastrointestinal microbiomes (AGMs) networks. The core/periphery network (CPN) mirrors nearly ubiquitous nestedness in ecological communities, particularly dividing the network as densely interconnected core-species and periphery-species that only sparsely linked to the core. Complementarily, the high-salience skeleton network (HSN) mirrors the pervasive asymmetrical species interactions (strictly microbial species correlations), particularly forming heterogenous pathways in AGM networks with both “backbones” and “rural roads” (regular or weak links). While the cores and backbones can act as critical functional structures, the periphery nodes and weak links may stabilize network functionalities through redundancy.ResultsHere, we build and analyze 36 pairs of CPN/HSN for the AGMs based on 4903 gastrointestinal-microbiome samples containing 473,359 microbial species collected from 318 animal species covering all vertebrate and four major invertebrate classes. The network analyses were performed at host species, order, class, phylum, kingdom scales and diet types with selected and comparative taxon pairs. Besides diet types, the influence of host phylogeny, measured with phylogenetic (evolutionary) timeline or “age”, were integrated into the analyses. For example, it was found that the evolutionary trends of three primary microbial phyla (Bacteroidetes/Firmicutes/Proteobacteria) and their pairwise abundance-ratios in animals do not mirror the patterns in modern humans phylogenetically, although they are consistent in terms of diet types.ConclusionsOverall, the critical network structures of AGMs are qualitatively and structurally similar to those of the human gut microbiomes. Nevertheless, it appears that the critical composition (the three phyla of Bacteroidetes, Firmicutes, and Proteobacteria) in human gut microbiomes has broken the evolutionary trend from animals to humans, possibly attributable to the Anthropocene epoch and reflecting the far-reaching influences of agriculture and industrial revolution on the human gut microbiomes. The influences may have led to the deviations between modern humans and our hunter-gather ancestors and animals.

Pojavnost tiouracila u svinjećim i goveđim urinima prikupljenih na hrvatskim farmama

Thyrostats are a group of forbidden substances in food producing animals that increase water absorption in muscle tissue and the gastrointestinal tract of animals. These substances can be abused as illegal growth promoters as oral drugs on farms before slaughtering. The consequences of their illegal use on farm animals include higher yield though inferior meat quality, while these substances also pose a potential risk to human health, and so their application is banned in European Union Member States. Thiouracil (2-thiouracil) (TU) is the representative, and belongs to the group of thyrostats but also can be naturally present in the urine of farm animals fed with feed containing Brassicaceae species. The aim of this study was to monitor TU concentrations in pig and bovine urine in the period from 2015 to 2023. For this purpose, 391 urine samples were collected as a part of the National Residue Control Plan (NRCP) and TU concentrations were determined by liquid chromatography tandem mass spectrometry. TU was detected in 89 of 391 samples, or 22.76%. TU concentration ranged from 1.66 to 28.30 μg/L, and a statistically significant difference (P &amp;lt; 0.05) was determined in urine TU concentrations between pigs and bovines. Mean concentrations of TU varied by year, and ranged from 1.66 to 8.06 μg/L in pig urine and from 5.92 to 13.68 μg/L in bovine urine. None of the analysed urine samples contained TU concentration in excess of 30 μg/L, which is the cut-off value to distinguish potentially natural origin resulting from a cruciferous diet (Brassicaceae species). The results exclude the possibility of abuse of this substances in the livestock industry in the Republic of Croatia.

Spore-Based Probiotic Bacillus subtilis: Current Applications in Humans and Future Perspectives

Bacillus subtilis has been used for more than 50 years in many different industrial applications, including farming, precision fermentation, and probiotic supplements. It is particularly attractive as a probiotic because of its ability to form shelf-stable, acid-resistant spores that lend to diverse applications in the food system. B. subtilis is the most ubiquitous species of the genus and can be isolated from a broad variety of environments including animal and human gastrointestinal (GI) tracts. This is a comprehensive review of human intervention studies utilizing B. subtilis as a probiotic for supporting gastrointestinal health, as well as the reported impacts of B. subtilis use on the human gut microbiota and other biomarkers of health. It briefly covers the fate of ingested spores in the GI tract, summarizes the observed effects of different probiotic B. subtilis strains, and offers a perspective for the continued and future uses of B. subtilis in human applications.

Unraveling the phylogenomic diversity of Methanomassiliicoccales and implications for mitigating ruminant methane emissions

BackgroundMethanomassiliicoccales are a recently identified order of methanogens that are diverse across global environments particularly the gastrointestinal tracts of animals; however, their metabolic capacities are defined via a limited number of cultured strains.ResultsHere, we profile and analyze 243 Methanomassiliicoccales genomes assembled from cultured representatives and uncultured metagenomes recovered from various biomes, including the gastrointestinal tracts of different animal species. Our analyses reveal the presence of numerous undefined genera and genetic variability in metabolic capabilities within Methanomassiliicoccales lineages, which is essential for adaptation to their ecological niches. In particular, gastrointestinal tract Methanomassiliicoccales demonstrate the presence of co-diversified members with their hosts over evolutionary timescales and likely originated in the natural environment. We highlight the presence of diverse clades of vitamin transporter BtuC proteins that distinguish Methanomassiliicoccales from other archaeal orders and likely provide a competitive advantage in efficiently handling B12. Furthermore, genome-centric metatranscriptomic analysis of ruminants with varying methane yields reveal elevated expression of select Methanomassiliicoccales genera in low methane animals and suggest that B12 exchanges could enable them to occupy ecological niches that possibly alter the direction of H2 utilization.ConclusionsWe provide a comprehensive and updated account of divergent Methanomassiliicoccales lineages, drawing from numerous uncultured genomes obtained from various habitats. We also highlight their unique metabolic capabilities involving B12, which could serve as promising targets for mitigating ruminant methane emissions by altering H2 flow.

Clinical use of tigecycline may contribute to the widespread dissemination of carbapenem-resistant hypervirulent Klebsiella pneumoniae strains

ABSTRACT The emergence of carbapenem-resistant hypervirulent Klebsiella pneumoniae (CR-hvKP) poses grave threats to human health. These strains increased dramatically in clinical settings in China in the past few years but not in other parts of the world. Four isogenic K. pneumoniae strains, including classical K. pneumoniae, carbapenem-resistant K. pneumoniae (CRKP), hypervirulent K. pneumoniae (hvKP) and CR-hvKP, were created and subjected to phenotypic characterization, competition assays, mouse sepsis model and rat colonization tests to investigate the mechanisms underlying the widespread nature of CR-hvKP in China. Acquisition of virulence plasmid led to reduced fitness and abolishment of colonization in the gastrointestinal tract, which may explain why hvKP is not clinically prevalent after its emergence for a long time. However, tigecycline treatment facilitated the colonization of hvKP and CR-hvKP and reduced the population of Lactobacillus spp. in animal gut microbiome. Feeding with Lactobacillus spp. could significantly reduce the colonization of hvKP and CR-hvKP in the animal gastrointestinal tract. Our data implied that the clinical use of tigecycline to treat carbapenem-resistant K. pneumoniae infections facilitated the high spread of CR-hvKP in clinical settings in China and demonstrated that Lactobacillus spp. was a potential candidate for anticolonization strategy against CR-hvKP.

Heme utilization by the enterococci.

Heme consists of a tetrapyrrole ring ligating an iron ion and has important roles in biological systems. While well-known as the oxygen-binding molecule within hemoglobin of mammals, heme is also cofactor for several enzymes and a major iron source for bacteria within the host. The enterococci are a diverse group of Gram-positive bacteria that exist primarily within the gastrointestinal tract of animals. However, some species within this genus can transform into formidable opportunistic pathogens, largely owing to their extraordinary adaptability to hostile environments. Although enterococci cannot synthesize heme nor depend on heme to grow, several species within the genus encode proteins that utilize heme as a cofactor, which appears to increase their fitness and ability to thrive in challenging environments. This includes more efficient energy generation via aerobic respiration and protection from reactive oxygen species. Here, we review the significance of heme to enterococci, primarily the major human pathogen Enterococcus faecalis, use bioinformatics to assess the prevalence of hemoproteins throughout the genus, and highlight recent studies that underscore the central role of the heme-E. faecalis relationship in host-pathogen dynamics and interspecies bacterial interactions.

MICROENCAPSULATION OF FEED ADDITIVES WITH POTENTIAL IN LIVESTOCK AND POULTRY PRODUCTION: A SYSTEMATIC REVIEW

The expected population growth will increase global food consumption, particularly meat consumption, which is estimated to increase 14% by 2030. Hence, the efficient utilization of all the resources involved in meat production, predominantly feed additives in livestock, is important due to economic costs and the high environmental in terms of gas production and ammonia excretion. Efforts have been made to increase efficiency in livestock production and improve the absorption and utilization of nutrients. Nevertheless, advances in technology in the chemical, pharmaceutical, and food industries have barely been used by the livestock and poultry industry. The micro/nano encapsulation process has been used in animal nutrition to protect bioactive compounds or to control the release of feed additives into the animal gastrointestinal tract, avoiding rumen microbes attack, or monogastric digestion in swine and poultry, to be available in the small intestine. However, not all the encapsulation techniques are suitable for applications in animal feeding. For example, spray drying, emulsion and coacervation can be used to control the release of feed additives in ruminants. In this sense, micro encapsulation of different feed additives such as amino acids, fatty acids, and probiotics may face enormous challenges to help improve livestock and poultry nutrition. The objective of this review is to highlight and discuss the techniques, compounds, and key aspects involved in the encapsulation of feed additives and nutrients with potential applications in the livestock and poultry production

Chlortetracycline Concentration Impact on Salmonella Typhimurium Sustainability in the Presence of Porcine Gastrointestinal Tract Bacteria Maintained in Continuous Culture.

Concern exists that the continued use of antibiotics in animal feeds may lead to an increased prevalence of resistant bacteria within the host animal's gastrointestinal tract. To evaluate the effect of chlortetracycline on the persistence of Salmonella enterica serotype Typhimurium within a diverse population of porcine cecal bacteria, we cultured a mixed population of cecal bacteria without or with added chlortetracycline. When grown at a 24 h vessel turnover rate, chlortetracycline-susceptible S. Typhimurium exhibited more than 2.5 times faster (p < 0.05) disappearance rates than theoretically expected (0.301 log10 colony-forming unit/mL per day) but did not differ whether treated or not with 55 mg of chlortetracycline/L. Chlortetracycline-resistant S. Typhimurium was not recovered from any of these cultures. When the mixed cultures were inoculated with a chlortetracycline-resistant S. Typhimurium, rates of disappearance were nearly two times slower (p < 0.05) than those observed earlier with chlortetracycline-susceptible S. Typhimurium, and cultures persisted at >2 log10 colony-forming units/mL for up to 14 days of treatment with 110 mg of chlortetracycline/L. Under the conditions of this study, chlortetracycline-resistant S. Typhimurium was competitively enabled to persist longer within the mixed populations of porcine gut bacteria than chlortetracycline-susceptible S. Typhimurium, regardless of the presence or absence of added chlortetracycline.

Novel chitinolytic Bacillus spp. increase feed efficiency, feed digestibility, and survivability to Vibrio anguillarum in European seabass fed with diets containing Hermetia illucens larvae meal

Insect meals (IM) are being pointed out as a promising sustainable protein source. However, chitin in IM may negatively interfere with fish performance and nutrient availability. Given that carnivorous fish have a low or inexistent ability to digest chitin, novel strategies are needed to overcome chitin-imposed bottlenecks. Carbohydrolytic sporeforming probiotics offer a competitive industrial approach, being able to resist the harsh feed manufacturing process, transport, storage, and animal's gastrointestinal tract, while being able to increase the digestibility of otherwise indigestible components. Aiming to increase IM chitin digestibility, two chitinolytic sporeforming fish isolates (Fish isolates 645 (FI645) and 658 (FI658)), closely related to Bacillus licheniformis, were isolated from European sea bass (ESB) gastrointestinal tract, and incorporated (individually or as a mixture) in ESB diets with high defatted Hermetia illucens larvae meal (HM) levels (30% inclusion). FI were evaluated regarding their effects on ESB growth performance and digestibility. The spores were able to maintain their viability throughout the 180 days of diet storage at room temperature. Dietary inclusion of FI645 led to higher chitin digestibility. Concomitantly, the digestibility of dry matter, protein, and energy increased, overall leading to higher feed efficiency and protein efficiency ratio. Dietary inclusion of FI645 led to increased plasma N-acetylglucosamine (GlcNAc) levels. This is the first evidence for diet-mediated modulation of plasma GlcNAc concentrations. Dietary inclusion of FI645 also increased the expressions of the genes coding for N-acetylglucosamine kinase (nagk) and GlcNAc phosphomutase (pgm3), key enzymes from the GlcNAc salvage pathway and the hexosamine biosynthetic pathway (HBP). On the other hand, no differences were found for the expression of N-acetyl-D-glucosamine-6-phosphate deacetylase (amdhd2), a precursor enzyme for GlcNAc redirection to glycolysis. These results hint that free GlcNAc resulting from increased chitin digestibility might be preferentially redirected to protein O-GlcNAcylation processes through HBP in fish cells. Additionally, when challenged with Vibrio anguillarum, and after being feed for one month with the same diets, D645 also increased ESB survival from 52.5% to 77.5%, when compared to the control. Together, these results establish the potential of using FI645 as a probiotic for enhancing chitin digestion and acting as a prophylactic agent for ESB protection against V. anguillarum infection. This strategy opens novel possibilities for using commodities, including high chitin levels in aquafeeds, and reducing the use of antibiotics in aquaculture.

A-251 Comparison of Antimicrobial Susceptibility Profiles of Enterobacteriaceae spp. Isolates from Retail Meat Products Imported from USA and Brazil or Domestically Produced on Caribbean Islands of St. Kitts and Grenada

Abstract Background Enterobacteriaceae species, including Escherichia coli, Klebsiella and Salmonella, are endogenous colonizers of gastrointestinal tract of livestock animals, which pose potential health threats to humans, particularly for individuals with compromised immune systems (Guentzel 1996). The emergence of drug-resistant strains due to the overuse of antibiotics in agricultural practices have increased the urgency to evaluate zoonotic bacteria and to assess potential impact on human and animal health (Llor 2014). Project Aim and Methods The aim of this study is to compare the microbial prevalence and antimicrobial resistance profiles of Enterobacteriaceae isolates present on pork and poultry products domestically produced in the Caribbean Islands, St. Kitts and Grenada as compared to poultry imported from USA and Brazil. This study was conducted over a 4-year time period at University of Medicine and Health Sciences (UMHS) in St Kitts and at St. George’s University (SGU), Grenada. Microbial colonies were isolated on MacConkey agar after 24-hour incubation at 36°C in Buffered Peptone Water and identified using standard biochemical assays and API-20E test kit. Antimicrobial susceptibility was evaluated using the Kirby-Bauer disc diffusion on Mueller-Hinton plates. Results A total of 44 meat products from Caribbean Islands and 49 meat samples from Brazil and USA were processed to yield 64 and 60 bacterial isolates, respectively. Bacterial colonies isolated from imported meat products displayed higher incidence of antibiotic susceptibility to multiple classes of drugs (MDR = Multiple Drug Resistant) as compared to domestically produced meats. The prevalence of MDR bacteria was 45% MDR isolates from USA-imported chicken as compared to 13% MDR bacteria isolated from chicken domestically raised. Conclusions Imported meats exhibit a higher prevalence of antimicrobial resistance, particularly in the beta-lactam class of antibiotics, including amoxicillin and cephalosporins and fluroquinolones. The overuse of subtherapeutic antibiotics in mass scale livestock production is likely creating selective pressure for the overabundance of MDR strains in the gastrointestinal tract of animals. The findings of this study will be communicated to relevant community leaders and organizations in order to inform the development of strategies aimed at reducing the prevalence of antimicrobial resistance and identifying appropriate treatment options for associated infections.

Negative chemotaxis of Ligilactobacillus agilis BKN88 against gut-derived substances

Ligilactobacillus agilis is a motile lactic acid bacterium found in the gastrointestinal tracts of animals. The findings of our previous study suggest that the motility of L. agilis BKN88 enables gut colonization in murine models. However, the chemotactic abilities of motile lactobacilli remain unknown. This study aimed to identify the gut-derived chemoeffectors and their corresponding chemoreceptors in L. agilis BKN88. Chemotaxis assays with chemotactic and non-chemotactic (ΔcheA) L. agilis strains revealed that low pH, organic acids, and bile salts served as repellents. L. agilis BKN88 was more sensitive to bile and acid than the gut-derived non-motile lactobacilli, implying that L. agilis might utilize motility and chemotaxis instead of exhibiting stress tolerance/resistance. L. agilis BKN88 contains five putative chemoreceptor genes (mcp1–mcp5). Chemotaxis assays using a series of chemoreceptor mutants revealed that each of the five chemoreceptors could sense multiple chemoeffectors and that these chemoreceptors were functionally redundant. Mcp2 and Mcp3 sensed all tested chemoeffectors. This study provides further insights into the interactions between chemoreceptors and ligands of motile lactobacilli and the unique ecological and evolutionary features of motile lactobacilli, which may be distinct from those of non-motile lactobacilli.

Evolution of the T4 phage virion is driven by selection pressure from non-bacterial factors.

Bacteriophages colonize animal and human bodies, propagating on sensitive bacteria that are symbionts, commensals, or pathogens of animals and humans. T4-like phages are dependent on abundant symbionts such as Escherichia coli, commonly present in animal and human gastrointestinal (GI) tracts. Bacteriophage T4 is one of the most complex viruses, and its intricate structure, particularly the capsid head protecting the phage genome, likely contributes substantially to the overall phage fitness in diverse environments. We investigated how individual head proteins-gp24, Hoc, and Soc-affect T4 phage survival under pressure from non-bacterial factors. We constructed a panel of T4 phage variants defective in these structural proteins: T4∆Soc, T4∆24byp24, T4∆Hoc∆Soc, T4∆Hoc∆24byp24, T4∆Soc∆24byp24, and T4∆Hoc∆Soc∆24byp24 (byp = bypass). These variants were investigated for their sensitivity to selected environmental conditions relevant to the microenvironment of the GI tract, including pH, temperature, and digestive enzymes. The simple and "primitive" structure of the phage capsid (∆24byp24) was significantly less stable at low pH and more sensitive to inactivation by digestive enzymes, and the simultaneous lack of gp24 and Soc resulted in a notable decrease in phage activity at 37°C. Gp24 was also found to be highly resistant to thermal and chemical denaturation. Thus, gp24, which was acquired relatively late in evolution, seems to play a key role in T4 withstanding environmental conditions, including those related to the animal/human GI tract, and Soc is a molecular glue that enhances this protective effect. IMPORTANCE Bacteriophages are important components of animal and human microbiota, particularly in the gastrointestinal tract, where they dominate the viral community and contribute to shaping microbial balance. However, interactions with bacterial hosts are not the only element of the equation in phage survival-phages inhabiting the GI tract are constantly exposed to increased temperature, pH fluctuations, or digestive enzymes, which raises the question of whether and how the complex structure of phage capsids contributes to their persistence in the specific microenvironment of human/animal bodies. Here we address this phage-centric perspective, identifying the role of individual head proteins in T4 phage survival in GI tract conditions. The selection pressure driving the evolution of T4-like phages could have come from the external environment that affects phage virions with increased temperature and variable pH; it is possible that in the local microenvironment along the GI tract, the phage benefits from stability-protecting proteins.

Virulence and Resistance Factors Associated with the Specie of Proteus vulgaris

Proteus vulgaris belongs to the Enterobacteriaceae family, colonizing mainly the gastrointestinal tract of animals, including humans. However, when there is some deregulation in the host's immune system, this pathogen spreads, causing several clinical manifestations. Currently in the literature little is discussed about the virulence and resistance profile of this species. Thus, the study aimed, through a literature review, to describe the main virulence factors and resistance of this strain. Studies have shown that P. vulgaris is associated with most Urinary Tract Infections (UTIs), despite being less isolated from P. mirabilis, exhibiting high motility ability related to its fimbriae, enzyme and endotoxin secretion, ability to produce urease and biofilm formation. As for resistance, the pathogen is intrinsically resistant to several antibiotics, requiring further studies for the development of new therapeutic alternatives.

Bile Carriage of optrA-Positive Enterococcus faecium in a Patient with Choledocholith.

We isolated one Enterococcus faecium isolate SZ21B15 from a bile sample of a patient with choledocholith in Shenzhen, China in 2021. It was positive for oxazolidinone resistance gene optrA and was intermediate to linezolid. The whole genome of E. faecium SZ21B15 was sequenced by Illumina Hiseq. It belonged to ST533 within the clonal complex 17. The optrA gene and additional two resistance genes fexA and erm(A) were located within a 25,777-bp multiresistance region, which was inserted into the chromosomal radC gene, being chromosomal intrinsic resistance genes. The chromosomal optrA gene cluster found in E. faecium SZ21B15 was closely related to the corresponding regions of multiple optrA-carrying plasmids or chromosomes from Enterococcus, Listeria, Staphylococcus, and Lactococcus strains. It further highlights the ability of the optrA cluster that transfers between plasmids and chromosomes and evolves by a series of molecular recombination events. IMPORTANCE Oxazolidinone are effective antimicrobial agents for the treatment of infections caused by multidrug-resistant Gram-positive bacteria, including vancomycin-resistant enterococci. The emergence and global spread of transferable oxazolidinone resistance genes such as optrA is worrisome. Enterococcus spp. can become causes of hospital-associated infections and are also widely distributed in the gastrointestinal tracts of animals and the natural environment. In this study, one E. faecium isolate from bile sample carried chromosomal optrA, being intrinsic resistance gene. optrA-positive E. faecium in bile not only makes the treatment of gallstones difficult, but also may become a reservoir of resistance genes in the body.

Adsorptive removal of aflatoxin B1 from simulated animal gastrointestinal tract using sugarcane bagasse fly ash

Adsorptive removal of aflatoxin B1 from simulated animal gastrointestinal tract using sugarcane bagasse fly ash

Microplastic occurrence in finfish and shellfish from the mangroves of the northern Gulf of Oman

This study was conducted to assess microplastic (MP) pollution in some aquatic animals inhabiting planted and natural mangrove swamps in the northern Gulf of Oman. The KOH-NaI solution was used to retrieve MPs from the gastrointestinal tracts of animals. The highest MP prevalence was recorded in crabs (41.65 %) followed by fish (33.89 %) and oysters (20.8 %). The abundance of MPs in examined animals varied from zero in Sphyraena putnamae to 11 particles in a Rhinoptera javanica specimen. When polluted-only animals were considered, the mean abundance of MPs significantly varied among species and between locations. The mean density of ingested MPs was higher in the planted mangrove animals (1.79 ± 2.89 vs. 1.21 ± 2.25 n/individual; mean ± SD). Among the examined fish species, R. javanica ingested the highest number of MPs (3.83 ± 3.93 n/individual; mean ± SD). The polyethylene/ polypropylene fragments or fibers of average 1900 μm size were recorded as predominant (>50 % occurrence) MP particles.