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1.
Curr Issues Mol Biol ; 46(6): 6069-6084, 2024 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-38921033

RESUMEN

Candida auris was reported by the WHO as second to Cryptococcus neoformans, in the list of nineteen fungal priority pathogens, along with two species with a new nomenclature, Nakaseomyces glabrata (Candida glabrata) and Pichia kudriavzevii (Candida krusei). This novel classification was based on antifungal resistance, the number of deaths, evidence-based treatment, access to diagnostics, annual incidence, and complications and sequelae. We assessed which molecular assays have been used to diagnose Candida auris outbreaks in the last five years. Using "Candida auris; outbreak; molecular detection" as keywords, our search in PubMed revealed 32 results, from which we selected 23 original papers published in 2019-2024. The analyzed studies revealed that the detection methods were very different: from the VITEK® 2 System to MALDI TOF (Matrix-Assisted Laser Desorption Ionization-Time of Flight), NGS (Next-Generation Sequencing), WGS (Whole Genome Sequencing), and commercially available real-time PCR (Polymerase Chain Reaction) assays. Moreover, we identified studies that detected antifungal resistance genes (e.g., FKS for echinocandins and ERG11 for azoles). The analyzed outbreaks were from all continents, which confirms the capability of this yeast to spread between humans and to contaminate the environment. It is important that real-time PCR assays were developed for accurate and affordable detection by all laboratories, including the detection of antifungal resistance genes. This will allow the fast and efficient implementation of stewardship programs in hospitals.

2.
Int J Biol Macromol ; 274(Pt 1): 132879, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38838899

RESUMEN

The base of Flammulina velutipes (F. velutipes) stipe are agricultural wastes generated during the cultivation of edible fungus F. velutipes with high amount of chitin. Herein, this study firstly prepared chitosan from the base of F. velutipes stipe (FVC) and its structure was identified. It was confirmed that FVC acted as an antigenic substance to activate the immune system in vivo and in vitro, drive T cells to differentiate into Th-17 cells, and establish an effective mucosal immune barrier in the oral cavity, thus inhibited C. albicans infection; On the other hand, FVC maintained the oral flora stability and significantly reduced the abundance of Streptococcus spp., which was closely related to C. albicans infection. On this basis, the inhibitory effects of FVC on oral pathogens Streptococcus mutans and Lactobacillus casei associated with C. albicans infection were further verified, and it was demonstrated that FVC effectively interfered with the growth of pathogenic bacteria by inducing the production of intracellular ROS to damage bacterial cells. Therefore, FVC may be potentially exploited as a novel approach to the prevention and treatment of oral C. albicans infection.


Asunto(s)
Candida albicans , Diferenciación Celular , Quitosano , Flammulina , Streptococcus mutans , Células Th17 , Streptococcus mutans/efectos de los fármacos , Quitosano/química , Quitosano/farmacología , Flammulina/química , Candida albicans/efectos de los fármacos , Animales , Diferenciación Celular/efectos de los fármacos , Células Th17/inmunología , Ratones , Candidiasis Bucal/tratamiento farmacológico , Candidiasis Bucal/microbiología , Boca/microbiología
3.
ISME Commun ; 4(1): ycae057, 2024 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-38812718

RESUMEN

Microbial communities are diverse biological systems that include taxa from across multiple kingdoms of life. Notably, interactions between bacteria and fungi play a significant role in determining community structure. However, these statistical associations across kingdoms are more difficult to infer than intra-kingdom associations due to the nature of the data involved using standard network inference techniques. We quantify the challenges of cross-kingdom network inference from both theoretical and practical points of view using synthetic and real-world microbiome data. We detail the theoretical issue presented by combining compositional data sets drawn from the same environment, e.g. 16S and ITS sequencing of a single set of samples, and we survey common network inference techniques for their ability to handle this error. We then test these techniques for the accuracy and usefulness of their intra- and inter-kingdom associations by inferring networks from a set of simulated samples for which a ground-truth set of associations is known. We show that while the two methods mitigate the error of cross-kingdom inference, there is little difference between techniques for key practical applications including identification of strong correlations and identification of possible keystone taxa (i.e. hub nodes in the network). Furthermore, we identify a signature of the error caused by transkingdom network inference and demonstrate that it appears in networks constructed using real-world environmental microbiome data.

4.
Front Plant Sci ; 15: 1384431, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38751834

RESUMEN

Vascular wilt disease, caused by the soil-borne fungus Fusarium oxysporum (Fo), poses a threat to many crop species. Four different tomato resistance (R) genes (I-1, I-2, I-3, and I-7) have been identified to confer protection against Fo f.sp. lycopersici (Fol). These I genes are root-expressed and mount an immune response upon perception of the invading fungus. Despite immune activation, Fol is still able to colonize the xylem vessels of resistant tomato lines. Yet, the fungus remains localized in the vessels and does not colonize adjacent tissues or cause disease. The molecular mechanism constraining Fol in the vascular system of the stem remains unclear. We here demonstrate that an I-2-resistant rootstock protects a susceptible scion from Fusarium wilt, notwithstanding fungal colonization of the susceptible scion. Proteomic analyses revealed the presence of fungal effectors in the xylem sap of infected plants, showing that the lack of fungal pathogenicity is not due to its inability to express its virulence genes. To identify mobile root-derived proteins, potentially involved in controlling fungal proliferation, comparative xylem sap proteomics was performed. We identified distinct pathogenesis-related (PR) protein profiles in xylem sap from Fol-inoculated I-1, I-2, I-3, and I-7 resistant lines. Despite structural diversity, all four immune receptors trigger the accumulation of a common set of four PR proteins: PR-5x, PR-P2, and two glucan endo-1,3-ß-D-glucosidases. This research provides insights into Fusarium resistance mechanisms and identifies a core set of proteins whose abundance correlates with defense against Fusarium wilt.

6.
Afr J Infect Dis ; 18(2): 8-18, 2024.
Artículo en Inglés | MEDLINE | ID: mdl-38606189

RESUMEN

Background: Infectious diseases due to antibiotic resistant pathogens are a global public health problem. This study aimed at determining the potential effect of bacterial-fungal interaction on the antibiotic susceptibility profile of Alcaligenes faecalis. Materials and Methods: Alcaligenes faecalis was isolated from water samples. The isolate was identified using the conventional biochemical tests and the 16S rRNA molecular sequencing technique. Additionally, Penicillium species was isolated and identified based on colony morphological characteristics and microscopic features. Standardized isolates were co-cultured in broth medium. Antibiotic susceptibility evaluation of the Alcaligenes faecalis from the co-culture and the original Alcaligenes faecalis was carried out using the Kirby bauer disk diffusion method. Results: The antibiotic susceptibility profile of Alcaligenes faecalis before and after co-culture remained largely unchanged except in the case of chloramphenicol, where the isolate showed reduced susceptibility. Molecular analysis of resistance gene revealed the absence of tested gene encoding antibiotic resistance, including the streptomycin resistance (str) genes (stra and strb) and the erythromycin resistance methylase (erm) gene. Conclusion: The result of this study showed that there is a minimal influence of Penicillium cultures on the susceptibility of A. faecalis. Further research involving a wide spectrum of microorganisms and their interactions should be conducted to acquire a thorough understanding of the influence of microbial interactions on antibiotic susceptibility profiles in order to pave way for novel strategies to combat antimicrobial resistance.

7.
Plants (Basel) ; 13(7)2024 Apr 08.
Artículo en Inglés | MEDLINE | ID: mdl-38611573

RESUMEN

Stem rust, caused by Puccinia graminis f.sp. tritici, is one of the most dangerous rust diseases on wheat. Through physiological, biochemical, and molecular analysis, the relationship between the change in resistance of 15 wheat cultivars to stem rust disease and the response of 41 stem rust resistance genes (Sr,s) as well as TTKSK, TTKST, and TTTSK races was explained. Some cultivars and Sr genes, such as Gemmeiza-9, Gemmeiza-11, Sids-13, Sakha-94, Misr-1, Misr-2, Sr31, and Sr38, became susceptible to infection. Other new cultivars include Mir-3 and Sakha-95, and Sr genes 13, 37, 40, GT, and FR*2/SRTT3-SRTT3-SR10 remain resistant. Some resistance genes have been identified in these resistant cultivars: Sr2, Sr13, Sr24, Sr36, and Sr40. Sr31 was not detected in any cultivars. Reactive oxygen species such as hydrogen peroxide and superoxide, enzymes activities (catalase, peroxidase, and polyphenoloxidase), and electrolyte leakage were increased in the highly susceptible cultivars, while they decreased in the resistant ones. Anatomical characteristics such as the thickness of the epidermis, ground tissue, phloem tissue and vascular bundle diameter in the midrib were decreased in susceptible cultivars compared with resistant cultivars. Our results indicated that some races (TTKSK, TTKST, and TTTSK) appeared for the first time in Egypt and many other countries, which broke the resistant cultivars. The wheat rust breeding program must rely on land races and pyramiding genes in order to develop new resistance genes that will survive for a very long time.

8.
Arch Microbiol ; 206(4): 170, 2024 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-38491263

RESUMEN

There are many available reports of secondary metabolites as bioactive molecules from culturable endophytes, nevertheless, there are scarce research pertaining to the levels of metabolites in plants with respect to the incidence and colonisation of fungal endophytes in the same foliar tissues. Therefore, the study was focussed to examine whether fungal endophyte colonisation and the accumulation of secondary metabolites, such as flavonoids and phenols, in the plants are related in any way. For this reason, the study aims to analyse phenols and flavonoids from the fronds of eleven pteridophytes along with the culture-dependent isolation of fungal endophytes from the host plants subsequently assigning them to morphological category and their quantitative analysis and further resolving its identities through molecular affiliation. The results revealed that nine morpho-categories of fungal endophytes were allotted based on culture attributes, hyphal patterns and reproductive structural characters. Highest numbers of species were isolated from Adiantum capillus-veneris and least was recorded from Pteris vittata and Dicranopteris linearis. Maximum phenol content was analysed from the fronds of P. vittata and lowest was recorded in A. capillus-veneris. Highest flavonoid content was measured in D. linearis and lowest was detected in Christella dentata. Significant negative correlation was observed between phenol content of ferns and species richness of fungi. Moreover, significant positive correlation was observed with the relative abundance of Chaetomium globosum and flavonoid content of ferns and negative significant relation was found between relative abundance of Pseudopestalotiopsis chinensis and phenol content of pteridophytes. The occurrence and the quantitative aspects of endophytes in ferns and their secondary metabolites are discussed.


Asunto(s)
Endófitos , Helechos , Endófitos/metabolismo , Fenoles/metabolismo , Fenol/metabolismo , Helechos/metabolismo , Plantas , Flavonoides/metabolismo , Hongos/genética
9.
J Exp Bot ; 75(10): 3153-3170, 2024 May 20.
Artículo en Inglés | MEDLINE | ID: mdl-38394357

RESUMEN

Endophytic symbioses between plants and fungi are a dominant feature of many terrestrial ecosystems, yet little is known about the signaling that defines these symbiotic associations. Hydrogen peroxide (H2O2) is recognized as a key signal mediating the plant adaptive response to both biotic and abiotic stresses. However, the role of H2O2 in plant-fungal symbiosis remains elusive. Using a combination of physiological analysis, plant and fungal deletion mutants, and comparative transcriptomics, we reported that various environmental conditions differentially affect the interaction between Arabidopsis and the root endophyte Phomopsis liquidambaris, and link this process to alterations in H2O2 levels and H2O2 fluxes across root tips. We found that enhanced H2O2 efflux leading to a moderate increase in H2O2 levels at the plant-fungal interface is required for maintaining plant-fungal symbiosis. Disturbance of plant H2O2 homeostasis compromises the symbiotic ability of plant roots. Moreover, the fungus-regulated H2O2 dynamics modulate the rhizosphere microbiome by selectively enriching for the phylum Cyanobacteria, with strong antioxidant defenses. Our results demonstrated that the regulation of H2O2 dynamics at the plant-fungal interface affects the symbiotic outcome in response to external conditions and highlight the importance of the root endophyte in reshaping the rhizosphere microbiota.


Asunto(s)
Arabidopsis , Endófitos , Homeostasis , Peróxido de Hidrógeno , Microbiota , Raíces de Plantas , Rizosfera , Simbiosis , Arabidopsis/microbiología , Arabidopsis/fisiología , Endófitos/fisiología , Peróxido de Hidrógeno/metabolismo , Raíces de Plantas/microbiología , Raíces de Plantas/fisiología , Ascomicetos/fisiología
10.
Environ Res ; 247: 118269, 2024 Apr 15.
Artículo en Inglés | MEDLINE | ID: mdl-38246293

RESUMEN

Investigating the quality of the subway environment, especially regarding antibiotic resistance genes (ARGs) and xenobiotics, conveys ecological and health impacts. In this study, compositions and relations of microorganisms harboring ARGs and xenobiotic degradation and metabolism genes (XDGs) in the Sukhumvit subway station (MRT-SKV) in Bangkok was assessed by analyzing the taxonomic and genetic diversity of the microbiome in the air and on the surfaces of floor and handrail. The major bacteria in the MRT-SKV (including Moraxella, which was abundant in the bioaerosol and handrail samples, and Staphylococcus, which was abundant in the bioaerosol samples) were found to contain both ARGs and XDGs. The co-abundance correlation network revealed notable relationships among bacteria harboring antibiotic resistance genes (ARGs) and xenobiotic degradation genes (XDGs). Significant associations were observed between ARGs linked to glycopeptide and fluoroquinolone resistance and genes associated with benzoate, styrene, and atrazine degradation pathways, as well as between ARGs related to cephamycin, cephalosporin, and MLS resistance and XDGs associated with the cytochrome P450-dependent drug metabolism pathway. These correlations suggested that selective pressure exerted by certain xenobiotics and antibiotics can simultaneously affect both ARGs and XDGs in the environment and should favor correlations and co-survival among ARG- and XDG-containing bacteria in the environments. The correlations may occur via shared mechanisms of resistance to both xenobiotics and antibiotics. Finally, different correlation pairs were seen in different niches (air, handrail, floor) of the subway environment or different geolocations. Thus, the relationship between ARG and XDG pairs most likely depends on the unique characteristics of the niches and on the prominent types of xenobiotics and antibiotics in the subway environment. The results indicated that interactions and connections between microbial communities can impact how they function. These microorganisms can have profound effects on accumulation of xenobiotics and ARGs in the MRT-SKV.


Asunto(s)
Microbiota , Vías Férreas , Antibacterianos/farmacología , Antibacterianos/análisis , Genes Bacterianos , Xenobióticos , Tailandia , Bacterias/genética
11.
Cell Host Microbe ; 32(1): 93-105.e6, 2024 Jan 10.
Artículo en Inglés | MEDLINE | ID: mdl-38103543

RESUMEN

Cross-kingdom small RNA trafficking between hosts and microbes modulates gene expression in the interacting partners during infection. However, whether other RNAs are also transferred is unclear. Here, we discover that host plant Arabidopsis thaliana delivers mRNAs via extracellular vesicles (EVs) into the fungal pathogen Botrytis cinerea. A fluorescent RNA aptamer reporter Broccoli system reveals host mRNAs in EVs and recipient fungal cells. Using translating ribosome affinity purification profiling and polysome analysis, we observe that delivered host mRNAs are translated in fungal cells. Ectopic expression of two transferred host mRNAs in B. cinerea shows that their proteins are detrimental to infection. Arabidopsis knockout mutants of the genes corresponding to these transferred mRNAs are more susceptible. Thus, plants have a strategy to reduce infection by transporting mRNAs into fungal cells. mRNAs transferred from plants to pathogenic fungi are translated to compromise infection, providing knowledge that helps combat crop diseases.


Asunto(s)
Arabidopsis , Vesículas Extracelulares , ARN Mensajero/genética , ARN Mensajero/metabolismo , ARN , Arabidopsis/genética , Arabidopsis/microbiología , Plantas/genética , Enfermedades de las Plantas/microbiología
12.
J Appl Microbiol ; 134(12)2023 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-38086610

RESUMEN

AIMS: Aspergillus fungi are common members of the soil microbiota. Some physiological and structural characteristics of Aspergillus species make them important participants in soil ecological processes. In this study, we aimed to evaluate the impact of 2,4-diacetylphloroglucinol (2,4-DAPG), a common metabolite of soil and rhizosphere bacteria, on the physiology of Aspergillus fumigatus. METHODS AND RESULTS: Integrated analysis using microscopy, spectrophotometry, and liquid chromatography showed the following effects of 2,4-DAPG on Aspergillus physiology. It was found that A. fumigatus in the biofilm state is resistant to high concentrations of 2,4-DAPG. However, experimental exposure led to a depletion of the extracellular polymeric substance, changes in the structure of the cell wall of the mycelium (increase in the content of α- and ß-glucans, chitin, and ergosterol), and conidia (decrease in the content of DHN-melanin). 2,4-DAPG significantly reduced the production of mycotoxins (gliotoxin and fumagillin) but increased the secretion of proteases and galactosaminogalactan. CONCLUSIONS: Overall, the data obtained suggest that 2,4-DAPG-producing Pseudomonas bacteria are unlikely to directly eliminate A. fumigatus fungi, as they exhibit a high level of resistance when in the biofilm state. However, at low concentrations, 2,4-DAPG significantly alters the physiology of aspergilli, potentially reducing the adaptive and competitive capabilities of these fungi.


Asunto(s)
Aspergillus fumigatus , Matriz Extracelular de Sustancias Poliméricas , Humanos , Aspergillus fumigatus/metabolismo , Matriz Extracelular de Sustancias Poliméricas/metabolismo , Floroglucinol/farmacología , Floroglucinol/metabolismo , Suelo
13.
Curr Biol ; 33(23): 5071-5084.e7, 2023 12 04.
Artículo en Inglés | MEDLINE | ID: mdl-37977140

RESUMEN

Cell walls are important interfaces of plant-fungal interactions, acting as robust physical and chemical barriers against invaders. Upon fungal colonization, plants deposit phenolics and callose at the sites of fungal penetration to prevent further fungal progression. Alterations in the composition of plant cell walls significantly impact host susceptibility. Furthermore, plants and fungi secrete glycan hydrolases acting on each other's cell walls. These enzymes release various sugar oligomers into the apoplast, some of which activate host immunity via surface receptors. Recent characterization of cell walls from plant-colonizing fungi has emphasized the abundance of ß-glucans in different cell wall layers, which makes them suitable targets for recognition. To characterize host components involved in immunity against fungi, we performed a protein pull-down with the biotinylated ß-glucan laminarin. Thereby, we identified a plant glycoside hydrolase family 81-type glucan-binding protein (GBP) as a ß-glucan interactor. Mutation of GBP1 and its only paralog, GBP2, in barley led to decreased colonization by the beneficial root endophytes Serendipita indica and S. vermifera, as well as the arbuscular mycorrhizal fungus Rhizophagus irregularis. The reduction of colonization was accompanied by enhanced responses at the host cell wall, including an extension of callose-containing cell wall appositions. Moreover, GBP mutation in barley also reduced fungal biomass in roots by the hemibiotrophic pathogen Bipolaris sorokiniana and inhibited the penetration success of the obligate biotrophic leaf pathogen Blumeria hordei. These results indicate that GBP1 is involved in the establishment of symbiotic associations with beneficial fungi-a role that has potentially been appropriated by barley-adapted pathogens.


Asunto(s)
Hordeum , Micorrizas , beta-Glucanos , Hordeum/metabolismo , Simbiosis/fisiología , Hongos , Micorrizas/fisiología , Plantas , beta-Glucanos/metabolismo , Raíces de Plantas/metabolismo
14.
Heliyon ; 9(9): e19954, 2023 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-37810154

RESUMEN

Objective: Elucidating the concurrence and interdependence of three precipitating factors as contributors of a subset of secondary burning mouth syndrome (BMS), which is defined having detectable precipitating factors. Design: 47 secondary BMS and 15 non-BMS cases were sourced from medical records of an Oral Pathology Specialty Clinic in Canada (2017-2021). Each case had Cytology, Hematology, and Sialometry tests to detail the state of three precipitating factors (the presence of fungal hyphae, hypovitaminosis D, and objective oral dryness). Three factors were compared between secondary BMS and non-BMS groups independently, in pairs, and as a triple-factor by Fisher's exact tests, Contingency Coefficients, and Logistic Regressions. Results: Rates of objective oral dryness (89.36%) and hypovitaminosis D (74.47%) in the secondary BMS group significantly differ from the non-BMS group (p = 0.0013, p = 0.0016). No difference was found in the incidence of fungal hyphae between BMS (91.49%) and non-BMS groups (p = 0.0881). Rates of three precipitating factors in pairs and as a triple-factor within the secondary BMS group significantly differ from the non-BMS group (p-values from 0.0011 to <0.0001). Their significant correlations with secondary BMS are found independently (excluding fungal hyphae), in pairs, and as a triple-factor (C-values from 0.371 to 0.461, p-values from 0.002 to <0.001). The highest C-value belongs to the triple-factor. Objective oral dryness (p = 0.009) and hypovitaminosis D (p = 0.008) are confirmed as significant predictors for secondary BMS. Conclusions: The presence of fungal hyphae contribute to a subset of secondary BMS only when coinciding with objective oral dryness, hypovitaminosis D, or both. This interdependent relationship leads to a hypothesis that hypovitaminosis D, which is commonly called "a low value of vitamin D", and objective oral dryness make an oral environment conducive to insidious Candida invasion, which is an intermediate status of the host-fungal interaction staying between healthy oral mucosa (non-infection) and oral candidiasis (infection).

15.
Mycopathologia ; 188(5): 603-621, 2023 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-37289362

RESUMEN

Aspergillus fumigatus is one the most ubiquitous airborne opportunistic human fungal pathogens. Understanding its interaction with host immune system, composed of cellular and humoral arm, is essential to explain the pathobiology of aspergillosis disease spectrum. While cellular immunity has been well studied, humoral immunity has been poorly acknowledge, although it plays a crucial role in bridging the fungus and immune cells. In this review, we have summarized available data on major players of humoral immunity against A. fumigatus and discussed how they may help to identify at-risk individuals, be used as diagnostic tools or promote alternative therapeutic strategies. Remaining challenges are highlighted and leads are given to guide future research to better grasp the complexity of humoral immune interaction with A. fumigatus.


Asunto(s)
Aspergilosis , Aspergillus fumigatus , Humanos , Inmunidad Humoral , Aspergilosis/microbiología
16.
Front Microbiol ; 14: 1160631, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37125154

RESUMEN

Interactions between plants and arbuscular mycorrhizal fungi (AMF) are strongly affected by soil phosphorus (P) availability. However, how P forms impact rhizosphere AMF diversity, community composition, and the co-occurrence network associated with native and invasive plants, and whether these changes in turn influence the invasiveness of alien species remain unclear. In this work, we performed a greenhouse experiment with the invasive species Solidago canadensis and its native congener S. decurrens to investigate how different forms of P altered the AMF community and evaluate how these changes were linked with the growth advantage of S. canadensis relative to S. decurrens. Plants were subjected to five different P treatments: no P addition (control), simple inorganic P (sodium dihydrogen phosphate, NaP), complex inorganic P (hydroxyapatite, CaP), simple organic P (adenosine monophosphate, AMP) and complex organic P (myo-inositol hexakisphosphate, PA). Overall, invasive S. canadensis grew larger than native S. decurrens across all P treatments, and this growth advantage was strengthened when these species were grown in CaP and AMP treatments. The two Solidago species harbored divergent AMF communities, and soil P treatments significantly shifted AMF community composition. In particular, the differences in AMF diversity, community composition, topological features and keystone taxa of the co-occurrence networks between S. canadensis and S. decurrens were amplified when the dominant form of soil P was altered. Despite significant correlations between AMF alpha diversity, community structure, co-occurrence network composition and plant performance, we found that alpha diversity and keystone taxa of the AMF co-occurrence networks were the primary factors influencing plant growth and the growth advantage of invasive S. canadensis between soil P treatments. These results suggest that AMF could confer invasive plants with greater advantages over native congeners, depending on the forms of P in the soil, and emphasize the important roles of multiple AMF traits in plant invasion.

17.
Microbiol Spectr ; 11(3): e0445722, 2023 06 15.
Artículo en Inglés | MEDLINE | ID: mdl-37014254

RESUMEN

Burkholderia gladioli strain NGJ1 exhibits mycophagous activity on a broad range of fungi, including Rhizoctonia solani, a devastating plant pathogen. Here, we demonstrate that the nicotinic acid (NA) catabolic pathway in NGJ1 is required for mycophagy. NGJ1 is auxotrophic to NA and it potentially senses R. solani as a NA source. Mutation in the nicC and nicX genes involved in NA catabolism renders defects in mycophagy and the mutant bacteria are unable to utilize R. solani extract as the sole nutrient source. As supplementation of NA, but not FA (fumaric acid, the end product of NA catabolism) restores the mycophagous ability of ΔnicC/ΔnicX mutants, we anticipate that NA is not required as a carbon source for the bacterium during mycophagy. Notably, nicR, a MarR-type of transcriptional regulator that functions as a negative regulator of the NA catabolic pathway is upregulated in ΔnicC/ΔnicX mutant and upon NA supplementation the nicR expression is reduced to the basal level in both the mutants. The ΔnicR mutant produces excessive biofilm and is completely defective in swimming motility. On the other hand, ΔnicC/ΔnicX mutants are compromised in swimming motility as well as biofilm formation, potentially due to the upregulation of nicR. Our data suggest that a defect in NA catabolism alters the NA pool in the bacterium and upregulates nicR which in turn suppresses bacterial motility as well as biofilm formation, leading to mycophagy defects. IMPORTANCE Mycophagy is an important trait through which certain bacteria forage over fungal mycelia and utilize fungal biomass as a nutrient source to thrive in hostile environments. The present study emphasizes that nicotinic acid (NA) is important for bacterial motility and biofilm formation during mycophagy by Burkholderia gladioli strain NGJ1. Defects in NA catabolism potentially alter the cellular NA pool, upregulate the expression of nicR, a negative regulator of biofilm, and therefore suppress bacterial motility as well as biofilm formation, leading to mycophagy defects.


Asunto(s)
Burkholderia gladioli , Niacina , Burkholderia gladioli/metabolismo , Niacina/metabolismo , Bacterias/metabolismo , Biopelículas , Mutación , Proteínas Bacterianas/genética , Proteínas Bacterianas/metabolismo , Regulación Bacteriana de la Expresión Génica
18.
Insects ; 14(3)2023 Mar 14.
Artículo en Inglés | MEDLINE | ID: mdl-36975969

RESUMEN

The dubas bug (Ommatissus lybicus) (Hemiptera: Tropiduchidae) is a serious pest in date palms in several date-producing countries, including Oman. Infestation results in a severe reduction in yield and a weakening of date palm growth. In addition, egg laying, which causes injuries to date palm leaves, results in the development of necrotic lesions on the leaves. This study aimed at investigating the role of fungi in the development of necrotic leaf spots following dubas bug infestation. Leaf samples developing leaf spot symptoms were collected from dubas-bug-infested leaves, as the leaf spot symptoms were not observed on the non-infested leaves. Isolation from date palm leaves collected from 52 different farms yielded 74 fungal isolates. Molecular identification of the isolates revealed that they belonged to 31 fungal species, 16 genera, and 10 families. Among the isolated fungi, there were five Alternaria species, four species each of Penicillium and Fusarium, three species each of Cladosporium and Phaeoacremonium, and two species each of Quambalaria and Trichoderma. Out of the thirty-one fungal species, nine were pathogenic on date palm leaves and induced varying levels of leaf spot symptoms. The pathogenic species were Alternaria destruens, Fusarium fujikuroi species complex, F. humuli, F. microconidium, Cladosporium pseudochalastosporoides, C. endophyticum, Quambalaria cyanescens, Phaeoacremonium krajdenii, and P. venezuelense, which were reported for the first time as leaf spot causal agents in date palms. The study provided novel information on the effect of dubas bug infestation in date palms on the development of fungal infection and associated leaf spot symptoms.

19.
Mycotoxin Res ; 39(1): 57-66, 2023 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-36633770

RESUMEN

Mycotoxin co-occurrence compromises the safety of food crops worldwide. Environmental factors, as well as fungal interaction, can substantially influence the infectivity of mycotoxigenic fungi and their subsequent production of multi-mycotoxin. Here, we investigated the mutual effects of the co-culture of ochratoxigenic and aflatoxigenic Aspergillus strains on the co-production of ochratoxin A (OTA) and aflatoxin B1 (AFB1). Single cultures of ochratoxigenic A. carbonarius and A. alliaceus grew optimally at 25 °C, whereas aflatoxigenic A. flavus grew optimally at 35 °C. The maximum levels of OTA and AFB1 were achieved at 25 °C, whereas mycotoxin production decreased at 35 °C. During competitive growth of the ochratoxigenic and aflatoxigenic isolates, inhibition or stimulation of mycotoxin production was dependent on the fungal strain, temperature, and the ratio of the spore concentration. Aspergillus carbonarius and A. alliaceus generally produced OTA, with similar patterns of relative OTA levels at all temperatures. AFB1 production by A. flavus in the presence of ochratoxigenic Aspergillus species was inhibited at 25 °C and stimulated at 35 °C. These results indicated that the temperature, presence of other mycotoxigenic Aspergillus species, and ratio of the initial spore concentration significantly contributed to the co-production of OTA and AFB1.


Asunto(s)
Micotoxinas , Ocratoxinas , Técnicas de Cocultivo , Aspergillus , Hongos , Aflatoxina B1
20.
Environ Sci Pollut Res Int ; 30(15): 44112-44120, 2023 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-36689116

RESUMEN

The aim of the study was to compare the succession of fungal community and their interaction with bacterial community during pig manure composting with different phosphate additives and further to identify microbial roles on the transformation of carbon and nitrogen (C&N) components and compost maturity. The results showed that the composition of fungal community was significantly affected by pH in composting and acidic phosphate might postpone the C&N degradation process. Network analysis showed that phosphate additives, especially acidic additives, could increase the interaction of microbial community but acidic phosphate decreased the core fungi:bacteria ratio. Redundancy analysis indicated that the interactions between bacterial and fungal communities played more roles than individual contribution of bacteria or fungi for C&N conversion of composting. Structural equation modeling suggested that bacterial community was positively directly correlated to C&N loss and the participation of fungal community significantly benefited the maturity of composting. pH exhibited a great intermediated role for driving C&N conversion, maturity, and safety of composts by regulating bacterial and fungal community in composting with phosphate addition, which suggested a fast-composting way based on pH regulation by additives.


Asunto(s)
Compostaje , Micobioma , Animales , Porcinos , Carbono/metabolismo , Compostaje/métodos , Nitrógeno/análisis , Fosfatos , Hongos/metabolismo , Bacterias/metabolismo , Estiércol/microbiología , Suelo
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