Frontiers in Microbiology最新文献

The increasing use of plastics globally has generated serious environmental and human health problems, particularly in the agricultural sector where low-density polyethylene (LDPE) and other plastics are widely used. Due to its low recycling rate and slow degradation process, LDPE is a major source of pollution. This paper addresses the problem of plastic accumulation in agriculture, focusing on LDPE biodegradation strategies. The studies reviewed include recent data and the methodologies used include state-of-the-art technologies and others that have been used for decades, to monitor and measure the degree of biodegradation that each treatment applied can have, including SEM, GCMS, HPLC, and microscopy. The countries investigating these biodegradation methodologies are identified, and while some countries have been developing them for some years, others have only begun to address this problem in recent years. The use of microorganisms such as bacteria, fungi, algae, and insect larvae that influence its decomposition is highlighted. A workflow is proposed to carry out this type of research. Despite the advances, challenges remain, such as optimizing environmental conditions to accelerate the process and the need for further research that delves into microbial interactions in various environmental contexts.

Background: Despite the advantages of endoscopic surgery in reducing trauma and enhancing recovery for breast cancer patients, its impact on gut microbiota, which is crucial for health and estrogen metabolism, remains unclear. Further investigation is necessary to fully understand this impact and its implications.

Materials and methods: Between June and December 2022, fecal samples were collected from 20 patients who underwent endoscopic surgery. The gut microbiota composition was determined using 16S rRNA sequencing, while the metabolites were analyzed through liquid chromatography-tandem mass spectrometry (LC-MS/MS). Bioinformatics and statistical analyses were employed to identify significant alterations in microbial taxa abundance and to assess intergroup differences. These analyses included t-tests for pairwise comparisons, one-way ANOVA for multiple group comparisons, and chi-square tests for categorical data analysis.

Results: Endoscopic surgery in breast cancer patients subtly changed gut microbiota diversity and composition. Post-surgery, there was a reduction in Lachnospiraceae, Monoglobaceae and Firmicutes to Bacteroides ratios. Shifts in metabolites were also observed, the changed metabolites impacted pathways such as primary bile biosynthesis and Ascorbate and aldarate metabolism, with PE(PGD1/18:1(9Z)) identified as a key differential metabolite that increased post-surgery. Azasetron, tyramine glucuronide, DL-DOPA, phthalide, acetophenazine, aciclovir, creatinine bicarbonate, and 4-oxo-L-proline being associated with distinct bacterial taxa.

Conclusion: Breast cancer patients undergoing endoscopic surgery experience a shift in their gut microbiota and metabolic profiles. Therefore, postoperative management, with a particular focus on the adjustment of the gut microbiota, is crucial for enhancing patient recovery and health outcomes.

Anaplasma phagocytophilum, the etiologic agent of human granulocytic anaplasmosis (HGA), is an obligate intracellular Gram-negative bacterium. During infection, A. phagocytophilum transfers its type IV secretion system (T4SS) effector proteins into host cells to manipulate cellular processes. AFAP (an actin filament-associated Anaplasma phagocytophilum protein) was identified as a T4SS effector protein and found to interact with the host nucleolin, as described in a previous study. In this study, proteomic analysis was performed to extensively identify AFAP-interacting proteins in host cells and analyze the potential role of AFAP in modulating host cellular processes. A total of 586 host proteins were identified interacting with AFAP by data-independent acquisition mass spectrometry and annotated to 501 Gene Ontology (GO) terms, with the significantly over-represented ones related to ribosomes, nucleolus, DNA binding, and rRNA metabolic process. Given the role of the nucleolus in cellular stress response, the targeting of AFAP to the nucleolus, and the identification of dozens of AFAP-interacting proteins that were annotated to the GO term (GO:0072331, signal transduction by p53 class mediator), the role of AFAP in modulating host apoptosis was determined. AFAP was found capable of inhibiting induced apoptosis. Thus, the proteomic analysis of AFAP-interacting proteins and determination of AFAP with anti-apoptotic activity may help elucidate the role of this T4SS effector protein in HGA pathogenesis.

Strain LCG007, isolated from Lu Chao Harbor's intertidal water, phylogenetically represents a novel genus within the family Rhodobacteraceae. Metabolically, it possesses a wide array of amino acid metabolic genes that enable it to thrive on both amino acids or peptides. Also, it could hydrolyze peptides containing D-amino acids, highlighting its potential role in the cycling of refractory organic matter. Moreover, strain LCG007 could utilize various carbohydrates, including mannopine and D-apiose-compounds primarily derived from terrestrial plants-demonstrating its capacity to degrade terrestrial organic matter. It could assimilate ammonia, nitrate and nitrite, and utilizes organic nitrogen sources such as polyamines, along with diverse organic and inorganic phosphorus and sulfur sources. Importantly, unlike very limited Sulfitobacter species that possess photosynthetic genes, the genomes of strain LCG007-affiliated genus and all Roseobacter species harbor photosynthetic gene clusters. This conservation was further supported by the significant impact of light on the growth and cell aggregation of strain LCG007, suggesting that acquirement of photosynthetic genes could play a crucial role in the speciation of their common ancestor. In terms of environmental adaptability, the genes that encode for DNA photolyase, heat and cold shock proteins, and enzymes responsible for scavenging reactive oxygen species, along with those involved in the uptake and biosynthesis of osmoprotectants such as betaine, γ-aminobutyric acid (GABA), and trehalose collectively enable strain LCG007 to survive in the dynamic and complex intertidal zone environment. Besides, the capacity in biofilm formation is crucial for its survival under conditions of oligotrophy or high salinity. This study enhances our comprehension of the microbial taxonomy within the Roseobacter clade affiliated cluster, their survival strategies in intertidal ecosystems, and underscores the significance of their role in nutrient cycling. It also highlights the crucial importance of photosynthetic metabolism for the speciation of marine bacteria and their ecological resilience.

Introduction: Glaesserella parasuis causes Glässer's disease in pigs, a leading cause of death in swine herds and a major contributor to economic losses in the global swine industry. Although several studies have investigated antimicrobial resistance in G. parasuis, the correlation between phenotypic and genotypic resistance remains unclear due to incomplete genetic resistance mechanisms detection.

Methods: The susceptibility of 117 clinical G. parasuis isolates to 7 antimicrobials was determined using a broth microdilution method. The sequences of 48 resistant isolates were obtained by whole-genome sequencing. Resistance genes, mutations, and group 1 vtaAs were detected based on whole-genome sequence data. Sequence types (STs) were identified by multilocus sequence typing (MLST).

Results: Phenotypic analysis showed that most isolates were susceptible to the tested antibiotics; resistance was most common against tetracycline (27%) and enrofloxacin (20%). All isolates were susceptible to ceftiofur. Analysis of whole-genome sequences revealed that resistance to tetracycline, amoxicillin, erythromycin, florfenicol, and chloramphenicol was frequently associated with the resistance genes tet(B) or tet(H), bla _ROB-1 , erm(T), floR, and catA3, and enrofloxacin resistance was associated with mutations in GyrA, ParC, and ParE. MLST identified 25 STs, of which, 14 were novel. The sequenced strains were divided into two primary lineages, LI and LII. Group 1 vtaA genes were detected in 87.5% (n = 42) of the isolates.

Conclusion: This study provides comprehensive insights into the molecular mechanisms responsible for drug resistance in G. parasuis, the characteristics of molecular epidemiology, and the virulence of resistant groups. Our findings can aid in the development of G. parasuis-specific clinical breakpoints and inform strategies for managing antimicrobial resistance in swine herds.

The application of antimicrobial surfaces requires proof of their effectivity by in vitro methods in laboratories. One of the most common test methods is ISO 22196:2011, which represents a simple and inexpensive protocol by applying the bacterial suspension with known volume and concentration covered under a polyethylene film on the surfaces. The incubation is then conducted under defined humidity conditions for 24 h. Another approach for testing non-porous surfaces is the newly published ISO 7581:2023. With this protocol, a "dry test" is achieved by spreading and drying 1 μL of a bacterial suspension on the surfaces. A comprehensive evaluation of both standard protocols was conducted. This showed that they have some limitations and often do not include realistic test conditions that refer to the final product. Accordingly, the objective of this study was to develop a novel testing procedure that uses the spraying of a suspension inside of a chamber to generate aerosols with a precisely defined bacterial or yeast load. The samples to be analyzed are covered with small droplets that dry up within a few minutes and thus enable very reproducible contamination of the surfaces. The test series was carried out with low-alloyed carbon steel and glass without antimicrobial substances against two different Escherichia coli and Staphylococcus epidermidis strains and one Candida albicans strain to evaluate the new method. The results provided reproducible and reliable results in the setup carried out. This test method represents a valuable alternative for the assessment of non-porous surfaces in a manner that more closely reflects real-world conditions (e.g., simulation of aerosol formation by sneezing).

Influenza A viruses have been a threat to human health for the past 100 years. Understanding the dynamics and pathogenicity of the influenza viruses in vivo is of great value in controlling the influenza pandemic. Fluorescent protein-carrying recombinant influenza virus is a substantially useful tool for studying viral characteristics in vivo and high-throughput screening in vitro. In this study, we generated a recombinant pdmH1N1 CA04 influenza virus carrying a Venus reporter gene in the non-structural (NS) segment using reverse genetics. After passaging the recombinant influenza virus carrying Venus from lung to lung in mice, we found that virulence of the passaged pdmH1N1 CA04-Venus significantly increased and was lethal to the mice. We finally isolated one mouse-adapted pdmH1N1 CA04-Venus with bigger plaques expressing the amount of Venus proteins by using the ninth passage lung homogenate with plague purification. We found three different amino acids (PB2 T340K, PA I21M, and F175L) between WT-CA04-Venus and MA-CA04-Venus using whole-genome sequencing. Interestingly, the polymerase activity of MA-CA04-Venus was significantly lower than that of WT-CA04-Venus in a minigenome assay. Further investigation demonstrates that PA I21M and PA I21M + PB2 T340K significantly enhanced the polymerase activity of WT-CA04-Venus; however, PA F175L + PB2 T340K significantly decreased the polymerase activity of MA-CA04-Venus. Therefore, PA I21M mutation may determine the increased virulence in mice, and PA F175L + PB2 T340K may be involved in the stability of Venus insertion. Above all, we generated a mouse-adapted pdmH1N1 CA04-Venus virus with high virulence and stable green fluorescent Venus protein. It is a useful tool for high-throughput screening of antiviral drugs and for investigating the interaction between the influenza virus and host in vivo.

The NOD-like receptor family pyrin domain-containing 3 (NLRP3) is a key pattern recognition receptor in the innate immune system. Its overactivation leads to the production of pro-inflammatory cytokines, such as IL-1β and IL-18, which contribute to the development and progression of various diseases. In recent years, evidence has shown that gut microbiota plays an important role in regulating the activation of NLRP3 inflammasome. Variations in the function and composition of gut microbiota can directly or indirectly influence NLRP3 inflammasome activation by influencing bacterial components and gut microbiota metabolites. Additionally, exercise has been shown to effectively reduce NLRP3 inflammasome overactivation while promoting beneficial changes in gut microbiota. This suggests that gut microbiota may play a key role in mediating the effects of exercise on NLRP3 inflammasome regulation. This review explores the impact of exercise on gut microbiota and NLRP3 inflammasome activation, and examines the mechanisms through which gut microbiota mediates the anti-inflammatory effects of exercise, providing new avenues for research.