Frontiers in Microbiology最新文献

Poultry lacks carbamoyl phosphate synthetase, which is a key enzyme in the endogenous synthesis of arginine, thus poultry must obtain arginine from their diet. Citrulline (L-Cit), as a precursor of arginine, produces the same biological effects as arginine, and may even be more effective. In these experiments, we discovered that the addition of L-Cit significantly increased production performance, antioxidant and immune properties, and modulated the intestinal microbiota. The study involved 240 1-day-old male yellow-feathered broilers randomly assigned to one of four treatment groups: control (CON), 0.5% L-Cit, 1% L-Cit, and 1.5% L-Cit, with 10 replicates per group and six birds per replicate. The feeding trial lasted for 63 days. The body weight at 42 days and 63 days, as well as the average daily weight gain from day 1 to 63, increased linearly and quadratically with the addition of L-citrulline. The plasma concentrations of citrulline, ornithine, and arginine increased linearly with the dose of L-Cit. L-citrulline increased total antioxidant capacity (T-AOC) and superoxide dismutase (SOD) levels and decreased interleukin-1β (IL-1β), IL-6, and tumor necrosis factor alpha (TNF-α). Dietary addition of 1% L-Cit also significantly altered the overall composition of the broiler intestinal microbiota, increasing the relative abundance of Prevotellaceae_UCG-001 while reducing the relative abundance of Synergistota and Campylobacterota. This indicates that L-Cit can enhance the production performance of broilers, and improve antioxidant activity and immune functions, thereby protecting intestinal health. The optimum dietary amount of L-Cit is 1 to 1.5%.

Garlic is an important spice crop used for flavoring food and has a long history of use in traditional medicine. However, black mold is a common fungal disease affecting garlic, which was caused by an Aspergillus infection. This disease significantly impacts both the production and quality of garlic. Therefore, this study aimed to evaluate the antifungal activity of novel green-synthesized zinc oxide nanoparticles (ZnO-NPs) against black mold diseases in garlic. An environmentally friendly green synthesis technique was used to produce ZnO-NPs using zinc-tolerant bacteria Serratia sp. (ZTB24). In the present study the experimental analysis viz. UV-Vis spectroscopy at 380 nm, transmission electron microscopy (TEM), dynamic light scattering (DLS), and zeta potential confirmed the successful biosynthesis of green ZnO-NPs from Serratia sp. The poisoned food technique and spore germination test revealed the antifungal activities of ZnO-NPs against A. niger under in vitro conditions. The presence of disease-causing A. niger fungus was confirmed through its isolation from infected garlic bulbs, and it was further identified at the molecular level using inter-transcribed sequence (ITS) rDNA sequencing. ZnO-NPs reduced the mycelial growth up to 90% and the 73% spore germination at 250 μg ml^-1 concentration of ZnO-NPs. The ZnO-NPs were further used in vivo at different concentrations (50, 100, 250, and 500 ppm) in the post-harvest treatment of garlic. The percentage of disease severity was assessed after 7 and 14 days, and the application of 500 ppm of ZnO-NPs exhibited 0% disease severity in the pre-inoculation method, while disease severity of black mold disease in garlic plant was recorded at 1.10% after 7 days and 0.90% after 14 days in the post-inoculation method, compared to the control group. Hence, the antifungal activity of ZnO-NPs synthesized using the green technique paves the way for the development of natural fungicides, offering a sustainable and renewable alternative to traditional chemical control methods.

Developing new antibiotics poses a significant challenge in the fight against antimicrobial resistance (AMR), a critical global health threat responsible for approximately 5 million deaths annually. Finding new classes of antibiotics that are safe, have acceptable pharmacokinetic properties, and are appropriately active against pathogens is a lengthy and expensive process. Therefore, high-throughput platforms are needed to screen large libraries of synthetic and natural compounds. In this review, we present bacterial cytological profiling (BCP) as a rapid, scalable, and cost-effective method for identifying antibiotic mechanisms of action. Notably, BCP has proven its potential in drug discovery, demonstrated by the identification of the cellular target of spirohexenolide A against methicillin-resistant Staphylococcus aureus. We present the application of BCP for different bacterial organisms and different classes of antibiotics and discuss BCP's advantages, limitations, and potential improvements. Furthermore, we highlight the studies that have utilized BCP to investigate pathogens listed in the Bacterial Priority Pathogens List 2024 and we identify the pathogens whose cytological profiles are missing. We also explore the most recent artificial intelligence and deep learning techniques that could enhance the analysis of data generated by BCP, potentially advancing our understanding of antibiotic resistance mechanisms and the discovery of novel druggable pathways.

The emergence of multidrug-resistant (MDR) Salmonella is recognized as a significant public health problem worldwide. This study investigated the occurrence of MDR Salmonella serovars in chicken meat from wet markets in Metro Manila, Philippines from February to July 2022. Using whole genome sequencing (WGS) and phenotypic antimicrobial resistance (AMR) testing, the serovar, drug resistance, and virulence profiles of Salmonella isolates were characterized. Out of 253 chicken cut samples, 95 S. enterica isolates representing 15 distinct serovars were recovered. The most common was S. enterica serovar Infantis (51.58%), followed by S. Brancaster (9.47%), S. Anatum (7.37%), S. London (7.37%), S. Uganda (6.32%), and S. Derby (4.21%). Phenotypic AMR testing revealed that 73.68% of the isolates were resistant to at least one drug class, and 45.26% were MDR. A wide array of antimicrobial resistance genes (ARGs) associated with resistance to 12 different drug classes was identified, including three β-lactamase gene variants: bla _CTX-M-65, bla _TEM-1, and bla _TEM-176. Some of these ARGs were located on MDR plasmids, such as those on IncFIB(K)_1_Kpn3, IncFIA(HI1)_1_HI1, and IncX1_1. A total of 131 virulence genes were detected, some of which conferred pESI-like characteristics to S. Infantis. These findings highlight a potential public health risk posed by pathogenic MDR Salmonella in chicken meat and underscore the urgent need for further research and coordinated AMR surveillance in the Philippines, aiming to stimulate national efforts to combat AMR.

Objective: Bacillus cereus (B. cereus) can be used as a probiotic or produce a variety of toxins that are pathogenic to humans and animals. Environmental stressors can affect the growth process of B. cereus and the expression of its virulence genes. Due to the limitations of methods such as pharmacological disinfection methods (there are limits to the use of antibiotics) and chemical disinfection methods (chemical methods may produce residues), attempts can be made to remove and reduce B. cereus infections through environmental stress factors.

Methods: In this study, the expression of four virulence genes (nheA, hblD, cytK, and entFM) of bovine-origin lethal B. cereus was investigated by qPCR under the effect of different environmental stressors. The extent of pathological damage to various organs of mice by B. cereus was observed by pathological sections.

Results: The results showed that high temperature could inhibit the expression of B. cereus virulence genes. Expression of B. cereus virulence genes was affected under the influence of pH. Different salt concentrations could make the B. cereus virulence genes show low expression. Under a single environmental stressors, nheA, hblD, cytK, and entFM had the lowest expression at 40°C, pH 8.0, and were lowly expressed at all salt concentrations except the control group. The action of multiple environmental stressors affect the expression of virulence genes. Under multiple environmental stressors, nheA, hblD and cytK were least expressed at a temperature of 40°C, pH 6.0, and salt concentration of 3.0%, and entFM was least expressed at a temperature of 20°C, pH 8.0, and salt concentration of 1.5%. Animal pathogenicity tests have shown that environmental stressors affect the virulence of B. cereus.

Conclusion: The level of virulence gene expression in B. cereus can be reduced by environmental stress factors, thus further reducing the risk of B. cereus to human health. This study provides some reference for the prevention and control of B. cereus disease.

Introduction: Norovirus, a leading cause of acute gastroenteritis worldwide, is notably stable in the environment due to its non-enveloped nature. In the absence of effective vaccines or treatments, disinfection remains the primary prevention strategy, highlighting the importance of virucidal efficacy in household care products. Conventional effective disinfectants are predominantly alcohol-based, but alcohol is known to pose health risks, such as skin irritation. This study investigates a non-alcohol-based alternative, specifically a combination of Arginine and Zinc chloride (ZnCl₂).

Methods: Utilizing MS2 bacteriophage as a surrogate, we identified a robust combination of arginine and ZnCl₂ that is effective against Feline Calicivirus (FCV), a mammalian virus surrogate model for Norovirus.

Results: Our results determined a 5 min contact time at pH 11 as optimal, achieving significant virucidal activity against FCV without pH-induced reversibility. Dynamic Light Scattering (DLS) and transmission electron microscopy (TEM) analyses suggested that the mechanism of action for the Arg-Zn²⁺-Arg complex does not involve capsid disruption. Further insights from molecular modeling studies revealed that the complex potentially inhibits FCV by occupying a key capsid binding pocket essential for Junctional Adhesion Molecule (JAM) receptor engagement, thereby preventing viral entry.

Conclusion: These findings allow us to propose a novel and non-alcohol-based virucidal approach against viruses from the Caliciviridae family, highlighting the potential of Arg-Zn²⁺-Arg complexes in public health protection.

Bloodstream infection (BSI) is a systemic infectious disease that can lead to shock, disseminated intravascular coagulation, multiorgan failure, and even death. Blood culture is considered the gold standard for the etiological diagnosis of BSI; however, blood culture is time-consuming and has a low positivity rate, which has limited its utility for early and rapid clinical diagnosis. Nanopore sequencing technology (NST), a third-generation sequencing method, offers rapid detection, real-time single-molecule sequencing, and ultra-long reads. These features enable the prompt detection of pathogens and the analysis of drug-resistant genes and genomic characteristics, thereby optimizing the clinical diagnosis and treatment of BSI. In this article, we summarize the application of NST in the etiological diagnosis of BSI.

Soil microbial species diversity and distribution of microbial communities are vital for soil and crop health, nutrient cycling, availability, and subsequent plant growth. These soil dynamics are highly influenced and altered by various soil management practices, inputs, and agricultural techniques. In the present study, the effects of chemical and organic management practices on soil microbial diversity and community structure were examined and compared using amplicon sequencing of the 16S and ITS regions. Two contrasting soil samples were selected from each crop fields at the International Rice Research Institute-South Asia Regional Centre (IRRI-SARC) in Varanasi: one field followed conventional chemical fertilizer inputs, while the other implemented natural farming practices, including tillage, on-farm crop residue management, and water management. Soil samples from each field were analyzed for bacterial and fungal diversity. Our findings showed that the two differently managed soils exhibited distinct microbial community compositions, with the organically managed soil exhibiting a higher diversity of decomposer bacteria and fungi, showing 40 unique elements in organic soil samples and 19 in chemically managed soil. Natural farming practices also demonstrated a higher relative abundance of bacterial and fungal phyla. Our results emphasize the significance of sustainable soil management techniques, suggesting that organic inputs can increase soil microbial diversity and richness. The functional roles of these microbial communities in soil ecosystems and their potential impact on crop yield and nutrient cycling warrant further study.

Background: Autism spectrum disorder (ASD) is an early-onset neurodevelopmental disorder, usually accompanied by gut microbiota dysregulation. Gut microbiota homeostasis is considered effective for ASD. Reportedly, Dachaihu decoction (DCHD) can efficiently regulate gut microbiota and inflammation. However, the mechanisms underlying the effects of DCHD in the treatment of ASD remain unclear.

Objective: This study investigated the potential effects and mechanisms of DCHD in treating ASD.

Methods: In the animal experiment, propionic acid was administered to construct an ASD rat model. The ASD rats were treated with DCHD, and the efficacy was assessed using the behavioral detections, such as open field test, elevated plus maze test, novel object recognition test. Additionally, the levels of IL-6, TNF-α, IL-10, T-SOD, MDA, GSH and CAT were determined using kits, and histological staining was used to evaluate brain morphology. Moreover, tight junction proteins (ZO-1 and occludin) expression levels were evaluated using RT-qPCR, whereas Iba1 expression level was assessed by immunofluorescence staining. The 16S rRNA sequencing and metabolomic analysis of feces revealed the potential targets of DCHD against ASD. In a small human trail, the clinical scales ADOS-2 and Autism Behavior Checklist (ABC) assessed autism severity. Gastrointestinal problems and brain function were evaluated based on food intolerance and event-related potential, respectively.

Results: DCHD significantly improved autism-like behaviors and increased antioxidant enzyme activity, decreased inflammation and enhanced the intestinal barrier by the animal experiment. Furthermore, the DCHD treatment altered the gut microbiota profile, with increased probiotics Adlercreutzia, Parvibacter, Turicibacter, and Christensenellaceae. Further, DCHD increased the beneficial metabolite indole-3-acetate and decreased the cognitive impairment-related metabolites asymmetric dimethylarginine and homogentisic acid. Meanwhile, the small clinical trial revealed that DCHD significantly alleviated the core symptoms of ASD, with decreased ADOS-2 and ABC scale scores. DCHD also decreased the levels of specific egg white/yolk and milk IgG antibodies and shortened the MMN and P3b latencies.

Conclusion: This study demonstrated that DCHD may alleviate ASD via inhibiting oxidative stress, reducing inflammation, and modulating the gut microbiota in rats. Combined with human trial, DCHD may be a promising drug for treating ASD. This study provides a scientific rationale for treating mental disorders related to gut microbiota dysbiosis.