Abstract The growth of endophytic bacteria is influenced by the host plants and their secondary metabolites and activities. In this study, P. megaterium P-NA14 and P. megaterium D-HT207 were isolated from potato tuber and dendrobium stem respectively. They were both identified as Priestia megaterium . The antimicrobial activities and metabolites of both strains were explored. For antimicrobial activities, results showed that P. megaterium P-NA14 exhibited a stronger inhibition effect on the pathogen of dendrobium, while P. megaterium D-HT207 exhibited a stronger inhibition effect on the pathogen of potato. The supernatant of P. megaterium P-NA14 showed an inhibition effect only on Staphylococcus aureus , while the sediment of P. megaterium D-HT207 showed an inhibition effect only on Escherichia coli . For metabolomic analysis, the content of L -phenylalanine in P. megaterium P-NA14 was higher than that of P. megaterium D-HT207, and several key downstream metabolites of L -phenylalanine were associated with inhibition of S. aureus including tyrosine, capsaicin, etc. Therefore, we speculated that the different antimicrobial activities between P. megaterium P-NA14 and P. megaterium D-HT207 were possibly related to the content of L -phenylalanine and its metabolites. This study preliminarily explored why the same strains isolated from different hosts exhibit different activities from the perspective of metabolomics.
Herpes simplex virus type 1 (HSV-1) is a ubiquitous human pathogen that can cause significant morbidity, primarily facial cold sores and herpes simplex encephalitis. Previous studies have shown that a variety of viruses can reprogram the metabolic profiles of host cells to facilitate self-replication. In order to further elucidate the metabolic interactions between the host cell and HSV-1, we used liquid chromatography-tandem mass spectrometry (LC-MS/MS) to analyze the metabolic profiles in human lung fibroblasts KMB17 infected with HSV-1. The results showed that 654 and 474 differential metabolites were identified in positive and negative ion modes, respectively, and 169 and 114 metabolic pathways that might be altered were screened. These altered metabolites are mainly involved in central carbon metabolism, choline metabolism, amino acid metabolism, purine and pyrimidine metabolism, cholesterol metabolism, bile secretion, and prolactin signaling pathway. Further, we confirmed that the addition of tryptophan metabolite kynurenine promotes HSV-1 replication, and the addition of 25-Hydroxycholesterol inhibits viral replication. Significantly, HSV-1 replication was obviously enhanced in the ChOKα (a choline metabolic rate-limiting enzyme) deficient mouse macrophages. These results indicated that HSV-1 induces the metabolic reprogramming of host cells to promote or resist viral replication. Taken together, these observations highlighted the significance of host cell metabolism in HSV-1 replication, which would help to clarify the pathogenesis of HSV-1 and identify new anti-HSV-1 therapeutic targets.
Abstract Background Allostatic load (AL) reflects the cumulative burden of chronic stress throughout life, potentially influencing the onset and prognosis of cancer. However, the associations between AL, colorectal cancer (CRC) risk and all-cause mortality in patients with CRC remain unclear. Methods We analyzed the association between AL and CRC risk in 304,959 adults and all-cause mortality in 1,794 patients with CRC from the UK Biobank, using Cox proportional hazards regression models. Results Compared to the AL level in the first quartile, individuals in the second to fourth quartiles had a respective 20%, 29%, and 43% increased risk of CRC; 15%, 24%, and 42% increased risk for colon cancer; and 30%, 38%, and 45% increased risk for rectal cancer. We identified a positive dose-gradient association of AL score with CRC risk, including colon and rectal cancer. Additionally, the association between AL and increased risk of CRC was observed across different strata of genetic susceptibility for CRC. Eliminating AL exposures could prevent nearly 39.24% (95% CI: 36.16-42.32) of CRC incident cases. Meanwhile, a significant association between the AL and all-cause mortality in patients with CRC was found, with a HR of 1.71 (95% CI: 1.16-2.50) for the fourth quartile compared to the AL score in the first quartile, demonstrating a positive dose-response relationship. Conclusion High AL was associated with increased CRC risk and all-cause mortality in CRC patients. Future research should prioritize the development of cognitive or behavioral intervention strategies to mitigate the adverse effects of AL on CRC incidence and prognosis.
ABSTRACT The Pelagibacterales order (SAR11) in Alphaproteobacteria dominates marine surface bacterioplankton communities, where it plays a key role in carbon and nutrient cycling. SAR11 phages, known as pelagiphages, are among the most abundant phages in the ocean. Four pelagiphages that infect Pelagibacter HTCC1062 have been reported. Here we report 11 new pelagiphages in the Podoviridae family. Comparative genomic analysis revealed that they are all closely related to previously reported pelagiphages HTVC011P and HTVC019P, in the HTVC019Pvirus genus. HTVC019Pvirus pelagiphages share a core genome of 15 genes, with a pan-genome of 234 genes. Phylogenomic analysis clustered these pelagiphages into three subgroups. Integrases were identified in all but one pelagiphage genomes. Evidence of site-specific integration was obtained by high-throughput sequencing and sequencing PCR amplicons containing predicted integration sites, demonstrating the capacity of these pelagiphages to propagate by both lytic and lysogenic infection. HTVC019P, HTVC021P, HTVC022P, HTVC201P and HTVC121P integrate into tRNA-Cys genes. HTVC011P, HTVC025P, HTVC105P, HTVC109P, HTVC119P and HTVC200P target tRNA-Leu genes, while HTVC120P integrates into the tRNA-Arg. Evidence of pelagiphage integration was also retrieved from Global Ocean Survey (GOS) database, suggesting the occurrence of pelagiphage integration in situ . The capacity of HTVC019Pvirus pelagiphages to integrate into host genomes suggests they could impact SAR11 populations by a variety of mechanisms, including mortality, genetic transduction, and prophage-induced viral immunity. HTVC019Pvirus pelagiphages are a rare example of a lysogenic phage that can be implicated in ecological processes on broad scales, and thus have potential to become a useful model for investigating strategies of host infection and phage-dependent horizontal gene transfer. IMPORTANCE Pelagiphages are ecologically important because of their extraordinarily high census numbers, which makes them potentially significant agents in the viral shunt, a concept that links viral predation to the recycling of dissolved organic matter released from lysing plankton cells. Lysogenic Pelagiphages, such as the HTVC019Pvirus pelagiphages we investigate here, are also important because of their potential to contribute to the hypothesized processes such as the “Piggy-Back-the-Winner” and “King-of-the-Mountain”. The former explains nonlinearities in virus to host ratios by postulating increased lysogenization of successful host cells, while the latter postulates host-density dependent propagation of defensive alleles. Here we report multiple Pelagiphage isolates, and provided detailed evidence of their integration into SAR11 genomes. The development of this ecologically significant experimental system for studying phage-dependent processes is progress towards the validation of broad hypotheses about phage ecology with specific examples based on knowledge of mechanisms.
The SAR11 Alphaproteobacteria are the most abundant heterotrophs in the oceans and are believed to play a major role in mineralizing marine dissolved organic carbon. Their genomes are among the smallest known for free-living heterotrophic cells, raising questions about how they successfully utilize complex organic matter with a limited metabolic repertoire. Here we show that conserved genes in SAR11 subgroup Ia (Candidatus Pelagibacter ubique) genomes encode pathways for the oxidation of a variety of one-carbon compounds and methyl functional groups from methylated compounds. These pathways were predicted to produce energy by tetrahydrofolate (THF)-mediated oxidation, but not to support the net assimilation of biomass from C1 compounds. Measurements of cellular ATP content and the oxidation of 14C-labeled compounds to 14CO2 indicated that methanol, formaldehyde, methylamine, and methyl groups from glycine betaine (GBT), trimethylamine (TMA), trimethylamine N-oxide (TMAO), and dimethylsulfoniopropionate (DMSP) were oxidized by axenic cultures of the SAR11 strain Ca. P. ubique HTCC1062. Analyses of metagenomic data showed that genes for C1 metabolism occur at a high frequency in natural SAR11 populations. In short term incubations, natural communities of Sargasso Sea microbial plankton expressed a potential for the oxidation of 14C-labeled formate, formaldehyde, methanol and TMAO that was similar to cultured SAR11 cells and, like cultured SAR11 cells, incorporated a much larger percentage of pyruvate and glucose (27–35%) than of C1 compounds (2–6%) into biomass. Collectively, these genomic, cellular and environmental data show a surprising capacity for demethylation and C1 oxidation in SAR11 cultures and in natural microbial communities dominated by SAR11, and support the conclusion that C1 oxidation might be a significant conduit by which dissolved organic carbon is recycled to CO2 in the upper ocean.
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