BMC Microbiology最新文献

Background: Cylindrocladium black rot of peanut is caused by the fungus Calonectria ilicicola (anamorph: Cylindrocladium parasiticum). This quarantined plants pathogen, causes this diseasethat threatens the healthy production of peanuts. The objective of this study was to screen andexplore the extracts of biocontrol bacteria against C. ilicicola.

Results: A bacterial strain XYDY-1 was isolated from saline-alkali soil samples collected near peanut plants and identified as Bacillus velezensis based on morphological characteristics, 16S rDNA, and gyrB sequence analyses. The bacterial suspension of XYDY-1 exhibited significant inhibitory effects on the growth of eight pathogenic fungi, including C. ilicicola, Aspergillus niger, Fusarium pseudograminearum, F. oxysporum, F. neocosmosporiellum, Sclerotium rolfsii, Rhizoctonia solanikühn, and Sclerotinia sclerotiorum. Extracellular enzyme assays revealed that XYDY-1 possessed protease, cellulase, amylase, chitinase, and β-1,3-glucanase activities. Furthermore, genomic analysis confirmed the presence of genes srfAD, fenB, ituA, and bmyA, which encode surfactin, fengycin, iturin, and bacillomycin D, respectively, all of which contribute to the inhibition of hyphal growth. Ultra-high-performance liquid chromatography coupled with quadrupole-electrostatic field orbitrap high-resolution tandem mass spectrometry (UPLC-QE Orbitrap MS/MS) analysis detected antifungal compounds in B. velezensis metabolites, including 8-hydroxyquinoline, tunicamycin, Validamycin A, chloramphenicol palmitate, pyocyanin, and Surfactin C. 8-Hydroxyquinoline, tunicamycin, Surfactin C and Validamycin A exhibited significant antifungal activity in assays conducted with pure compounds. Of these, 8-hydroxyquinoline at a concentration of 10 mg/mL displayed the highest efficacy, yielding an inhibition rate of 98.31%. Additionally, greenhouse pot experiments demonstrated that the culture filtrate of XYDY-1 significantly promoted peanut plant growth, increasing fresh and dry biomass by 39.02% and 39.09%, respectively, compared to control treatments with culture medium alone. Moreover, the culture filtrate enhanced peanut resistance to C. ilicicola, achieving a biocontrol efficacy exceeding 56.41%.

Conclusion: B. velezensis XYDY-1, a plant-growth-promoting rhizobacterium, was able to protect peanuts from C. ilicicola infection and is a promising biocontrol agent.It can provide scientific basis for the development of new biological control pesticides, reduce the use of chemical pesticides, and promote the sustainable development of agriculture.

Potato common scab, incited by pathogenic Streptomyces species, poses a significant threat to agriculture. The biocontrol agent Streptomyces sp. strain PBSH9 has shown remarkable field efficacy, yet its underlying antibacterial mechanisms remain unclear. To bridge this knowledge gap, we employed an integrated transcriptomic, proteomic, and metabolomic approach to compare PBSH9 under high (8-day) and low (2-day) antibacterial activity conditions. Transcriptomics identified 2,653 differentially expressed genes (DEGs), primarily enriched in oxidative phosphorylation and β-lactam resistance pathways. Proteomics quantified 32 differentially abundant proteins (DAPs), which were also predominantly involved in energy metabolism. Critically, metabolomic profiling of 1,299 differential metabolites (DAMs) revealed the core of the antibacterial activity: a massive > 28-fold accumulation of the antibiotics L-anticapsin and bacilysin, coupled with a significant 1.08- to 2.85-fold increase in several aminoglycoside antibiotics, including neomycin B and kanamycin. This enhanced antibiotic production was supported by the systematic upregulation of energy metabolism pathways, such as oxidative phosphorylation and the TCA cycle. Multi-dimensional correlation networks linked antibiotic accumulation to DEGs (st, phzF) and DAPs. Our findings demonstrate that the potent biocontrol activity of PBSH9 stems from a metabolic reprogramming that fuels the synergistic accumulation of a diverse antibiotic arsenal. This study provides a comprehensive molecular blueprint for optimizing and engineering this promising biocontrol strain.

Myxobolus bengalensis is a significant fish parasite responsible for disease and economic losses in aquaculture; however, information on its pathogenicity and impact on fish health remains limited. This study aimed to identify the morphological and molecular features of Myxobolus bengalensis and investigate the immunological changes in infected Labeo catla. Symptomatic fish showed signs of disease, including extreme lethargy, a slender body with a large head (growth retardation), and pale gills with the presence of whitish cysts in the gill lamellae. The Myxozoan parasite was isolated from infected L. catla tissue samples and preliminarily identified as M. bengalensis based on morphology, 18S rRNA PCR sequencing, and phylogenetic analysis. Tissue specimens were collected and underwent examination of immune-related gene expression (in the liver and kidney). The M. bengalensis spores isolated from the gills were ellipsoidal, with ovoid polar capsules. Sequencing and phylogenetic analysis of the 18S rRNA region revealed a ~ 1700 bp fragment, confirming the parasite's identity and placing it within the same clade as other M. bengalensis isolates. The transcription analysis of genes associated with inflammation (TNF-α, IL-1β, iNOS), immune activation (TLR 4, C3, MYD88, NOD 1), and both innate and adaptive immune responses (IFN-γ, Hsp70, Mx, IgM) further highlights that M. bengalensis modulates the expression of genes in the liver and kidney tissue samples of infected L. catla. There is limited data available on the host-pathogen response during M. bengalensis infection; thus, this study provides key insights into the morphology, pathogenicity, and immunological impacts of M. bengalensis in L. catla.

Background: Xizang (formerly known as Tibet in English) has one of the highest tuberculosis (TB) incidence rates in China. The region's extreme altitudes (≥ 3000 m) and hypoxic environment present substantial challenges for conventional diagnostic methods. Additionally, the clinical and biological characteristics of TB at high altitudes remain poorly understood.

Method: TB-seq, a third-generation nanopore-targeted sequencing method, was used to analyze sputum samples from 158 confirmed pulmonary TB patients in Xizang. Bacterial load was quantified, a drug-resistance gene landscape was generated, and these findings were correlated with clinical phenotypes. A matched low-altitude group (< 1000 m) was included to investigate the effects of altitude on Mycobacterium tuberculosis biology.

Result: In Xizang, retreatment cases accounted for the majority of TB patients (58.23%). Type I TB was the most common form (79.75%), while non-type I forms were observed only in retreatment patients (P < 0.01). Bacterial load decreased significantly with increasing age (P < 0.001), was higher in retreatment cases (P = 0.013), and positively correlated with white blood cell and neutrophil counts (P < 0.05). Drug-resistant mutations were identified in 22.78% of patients, primarily as mono-resistance (63.9%), with key resistance-associated genes being rpsL (47.2%), rpoB (38.9%), and katG (33.3%). Compared to low-altitude controls, the high-altitude group had a significantly lower bacterial load (P < 0.01), reduced overall drug resistance (23.7% vs. 38.2%, P < 0.01), no rrs mutations, and a significantly lower pncA mutation rate (P < 0.05).

Conclusion: Tuberculosis in Xizang is marked by a high proportion of retreatment cases, low pathogen burden, and a reduced rate of drug resistance-associated gene mutations. Altitude appears to suppress bacterial quantity and may select for specific resistance mechanisms. These findings support the need for targeted TB control strategies in Xizang and underscore the complex interactions among the environment, the pathogen, and the host.