BMC Microbiology最新文献

The composition of gut microbiota is jointly determined by the host's food habit, ecological niche, and genetic background, serving as a direct reflection of the host's adaptation to its environment and evolutionary pressures. To investigate the distinct adaptation mechanisms of four sympatric small mammal species in the Hengduan Mountains region, this study compared the environmental adaptation strategies of endemic and alien species. This study collected ten wild specimens each of the Eothenomys miletus, Eothenomys oliter, Tupaia belangeri, and Apodemus chevrieri from Yunlong County, Yunnan Province. Using 16SrRNA gene sequencing technology, we analyzed the gut microbial composition, abundance, and community structure across species, investigating the distinct gut microbial community characteristics between the endemic species (E. miletus and E. oliter) and the alien species (T. belangeri and A. chevrieri.). Results indicate: E. miletus and E. oliter possess complex and diverse gut microbial communities with plant-degrading functions. These communities with sparse interactions are capable of utilizing multiple plant sources for nutrition and exhibit strong resilience against environmental disturbances. In contrast, T. belangeri and A.chevrieri exhibit simple, specialized, yet tightly cooperative omnivorous gut microbial communities. While capable of utilizing diverse food resources within specific adaptive environments, they demonstrate extreme specificity in adaptation to particular habitats or survival strategies and are relatively sensitive to external disturbances. Furthermore, the E. miletus, widely distributed across the Hengduan Mountains, its gut bacterial community is dominated by stochastic processes. In contrast, the T. belangeri shows a positive correlation with various gut bacteria associated with omnivorous characteristics. The distinction between these two distinct environmental adaptation strategies is particularly pronounced. In summary, Among these four sympatric small mammal species in the Hengduan Mountains, the gut microbiota of endemic and alien species showed high similarity respectively and exhibited convergence.

Background: Pseudomonas aeruginosa is an opportunistic pathogen responsible for severe infections in immunocompromised individuals, including burn patients and those with cystic fibrosis. β-Ketoacyl-ACP synthases play essential roles in bacterial fatty acid metabolism, influencing both cellular function and pathogenicity. Two types of long-chain β-ketoacyl-ACP synthases have been identified: FabB and FabF. This study aims to elucidate the roles of the fabF1 and fabF2 genes in fatty acid biosynthesis and virulence of P. aeruginosa PAO1.

Results: Complementation assays in Escherichia coli revealed that fabF2 could functionally replace E. coli FabB, whereas FabF1 exhibited FabF-like activity. In P. aeruginosa PAO1, deletion of fabF1 significantly reduced cis-vaccenic acid levels while increasing palmitoleic acid, whereas deletion of fabF2 had no measurable effect. The double mutant exhibited a pronounced reduction in cis-vaccenic acid levels. Virulence assays demonstrated that the ΔfabF1 strain exhibited a 63% decrease in rhamnolipid production, while the ΔfabF2 strain showed a 45% reduction. The double mutant retained only 28% of wild-type rhamnolipid levels. Furthermore, pyoverdine secretion was markedly reduced in the double mutant, and pyocyanin production was impaired. Motility assays indicated diminished swimming, twitching, and swarming abilities in the mutants. Additionally, proper expression levels of fabF2 were required to genetically complement fabF2 deletion in the mutant strain, as both overexpression and insufficient expression failed to restore the mutant phenotype effectively.

Conclusions: These findings highlight the critical roles of fabF1 and fabF2 in fatty acid biosynthesis, virulence factor production, and motility in P. aeruginosa. This study provides new insights into the functional divergence of FabF homologs and identifies potential targets for antimicrobial development.

Early diagnosis and treatment of Candidozyma auris improve survival. At Cho Ray Hospital, the organism was successfully identified using Vitek 2 and Vitek MS systems. However, antifungal susceptibility testing remains challenging due to the lack of Clinical and Laboratory Standards Institute (CLSI) standards. The Microbiology Department follows provisional United States Centers for Disease Control and Prevention (U.S. CDC) guidelines and uses the broth microdilution method with the Sensititre YeastOne panel for testing. Candidozyma auris showed susceptibility rates of 81.6% to caspofungin, 94.7% to fluconazole, and 71.1% to amphotericin B. No isolates were resistant to all three antifungal classes, while 7.9% were resistant to two classes and 36.8% to one. Susceptibility patterns of 38 isolates were evaluated using both Sensititre YeastOne (microdilution with color) and Etest (agar diffusion), following CDC guidelines, to support method selection based on lab resources.

This study focused on the antimicrobial resistance (AMR) and virulence genes as well as plasmid replicons in three enterococci isolated from Bongo, a fermented dairy beverage from Uganda. They included Enterococcus (E.) faecium BM01, BM55 and BM70. They were tested against seventeen antibiotics using the disk diffusion and epsilon tests. Additionally, the DNA of the three isolates was extracted and subjected to Whole Genome Sequencing (WGS). AMR and virulence genes as well as plasmid replicons were determined by comparing the WGS data with the ResFinder database. Results indicated that the three isolates were resistant to all the antibiotics investigated. They all showed minimum inhibitory concentrations (MICs) at and above the highest concentrations tested (≥ 256 mg/mL for most antibiotics; ≥ 32 mg/mL for ciprofloxacin and levofloxacin). All isolates had the aac(6')-li and msrC AMR genes, the acm and efaAfm virulence genes as well as the repUS15 plasmid replicon. Additionally, a stress gene, CIpL was observed in the three isolates. The results call for the need to strictly control food microbial contamination as well regulate the use of antibiotics both in human and veterinary use so as to improve food safety. This study provides preliminary evidence that a Ugandan fermented dairy beverage can harbor multidrug-resistant E. faecium carrying intrinsic AMR determinants, virulence-associated genes, and a plasmid replicon linked to plasmid replication, underscoring a potential food-safety concern that warrants broader surveillance.

The giant kelp Macrocystis pyrifera forms abundant underwater forests that hosts diverse and dynamic bacterial communities. In the sub-Antarctic Strait of Magellan, while spatial variability is known to influence these associations, the combined effects of temporal variability and intra-thallus differentiation remains poorly understood. In this study, 16S rRNA gene metabarcoding was used to characterize bacterial diversity and composition by comparing communities across two sampling dates (March, late austral summer, and August, austral winter), two different kelp blade types (apical vegetative and basal reproductive sporophylls), and three sampling sites along the Strait of Magellan (Bahía Buzo, San Gregorio and Buque Quemado) which differ in their environmental settings. Bacterial communities were primarily structured by spatial variation among sites, both in terms of richness and composition. Beta diversity analyses revealed strong site-level differentiation in both sampling periods, while blade-type effects on community composition were only evident in August, indicating a date-related modulation of host-associated bacterial assemblages. Alpha diversity showed few differences related with blade types, whereas spatial variation, particularly in bacterial richness, was more pronounced and varied across dates. Furthermore, the global core microbiota was very small, consisting of only a few ubiquitous taxa consistently associated with Macrocystis pyrifera: Persicirhabdus (Verrucomicrobiia), Thalassotalea (Gammaproteobacteria), and an unclassified member of the family Flavobacteriaceae. Beyond this minimal shared core, core composition varied with blade type, sampling site and date, highlighting the combined influence of these factors on kelp-associated bacterial communities from a remote and understudied sub-Antarctic region.

Background: Prior research has demonstrated sex-specific differences in hypertension (HTN). The gut microbiota (GM) and its metabolic functions have emerged as key players in the development of HTN. To explore potential sex-based heterogeneity in gut bacteria among hypertensive patients, we conducted this study with the aim of validating sex differences in the gut flora associated with HTN.

Methods: Here, we leveraged a metagenomic dataset comprising 106 fecal samples from a Chinese cohort of individuals with essential HTN to systematically analyze and compare alterations in the gut microbiome between male and female patients, as well as relative to a healthy control group.

Results: Our study confirmed a statistically significant difference in the β-diversity of GM between hypertensive patients and healthy controls. When the subjects were further stratified by sex, significant differences in the distribution of gut flora were observed exclusively in females, whereas none was noted between groups in males. It was observed that certain genera of GM exhibit negative correlations with blood pressure. Notably, the relative abundance of these bacterial genera, including Lachnospira, Faecalibacterium, and Roseburia, was significantly diminished in female hypertensive patients. These organisms are primarily involved in the biosynthesis of short-chain fatty acids (SCFAs), with a notable emphasis on butyrate production. Ruminococcus gnavus was specifically enriched in hypertensive males, whereas certain bacteria, such as Lactobacillus, were notably depleted. The abnormality of the SCFAs-producing flora in female hypertensive patients may be related to that women are more likely to develop hypertensive organ damage.

Conclusions: The findings of our study indicate that GM dysbiosis is more significantly associated with HTN in females. Consequently, sex constitutes a critical factor in evaluating the role of intestinal flora in the pathogenesis of HTN.