Search Results (399)

Rusty root rot of ginseng (Panax ginseng) caused by Ilyonectria spp. infection is a devastating soil-borne disease restricting the sustainable production of garden-cultivated ginseng (GCG) in Northeast China and causes severe yield and economic losses; GCG is far more susceptible to this pathogen than forest-cultivated ginseng (Lin-Xia-Shan-Shen, LXSS). Ginsenosides, the signature triterpenoid saponin defensive metabolites of ginseng, are characteristic dammarane-type triterpenoid defensive saponins represented by Re, Rg₂, Rb₁, Rd, and Rg₁. These compounds are continuously secreted into the rhizosphere and widely participate in plant–microbe interactions, yet their functional roles in mediating Ilyonectria infection remain poorly clarified. This study aimed to clarify how rhizospheric ginsenosides regulate the infection process of pathogenic Ilyonectria strains. Two pathogenic strains, Ilyonectria sp. SYM-1 and Ilyonectria sp. SYM-2, were found isolated from diseased GCG roots and verified as causal agents via morphological observation, molecular ITS identification and artificial inoculation infection experiments. Interestingly, the concentrations of five ginsenosides, Re, Rg₂, Rb₁, Rd, and Rg₁, in the rhizospheric soil of GCG with rusty root rot were significantly higher than those in the rhizospheric soil of healthy LXSS plants. In addition, the concentrations of ginsenosides in the LXSS rhizospheric soils decreased with increasing age of plants. Non-nutritive suspension co-culture assays showed that high concentrations of the ginsenosides Rg₁ and Rd significantly promoted spore germination of the strains SYM-1 and SYM-2. However, Rb₁ had a certain inhibitory effect on the growth of Ilyonectria sp. SYM-2. Host inoculation experiments further indicated that infection with either fungus significantly reduced the concentrations of ginsenosides produced in ginseng roots. These results demonstrate that the pathogenic fungi SYM-1 and SYM-2 of Ilyonectria can adapt to and utilize ginsenosides. Collectively, these findings prove that the two pathogenic Ilyonectria strains have evolved the capacity to adapt to and exploit rhizospheric ginsenosides to facilitate their infectivity. From an application perspective, reducing rhizospheric ginsenoside release may represent a promising theoretical strategy for ginseng cultivation and germplasm improvement, which warrants further verification by field or greenhouse experiments for validation. Full article

Black spot disease caused by Ceratocystis fimbriata (C. fimbriata)is a severe postharvest disease of sweet potatoes. This study evaluated the biocontrol potential of Bacillus velezensis (B. velezensis) L33a against this pathogen. Confrontation assays showed that L33a inhibited mycelial growth by 82.83%. FDA/PI staining and scanning electron microscopy revealed that L33a disrupted cell membrane integrity and caused severe mycelial deformation. Co-culture experiments indicated that L33a altered the expression of key pathogenic genes in C. fimbriata. Volatile organic compounds (VOCs) from L33a inhibited the pathogen by 77.78%, outperforming cell-free supernatant (CFS). VOCs primarily suppressed spore germination, with phenylethanol (PEA) and octanoic acid achieving 100% inhibition. In planta tests on sweet potato tubers showed that both L33a culture and VOCs significantly reduced lesion expansion. Using qPCR analysis, we found that L33a activated defense-related genes in tissues around wounds, particularly those involved in the jasmonic acid (JA) signaling pathway. In summary, B. velezensis L33a effectively controls sweet potato black rot through multiple mechanisms: direct antifungal activity, inhibition of spore germination, modulation of pathogen gene expression, and induction of host defense responses. It represents a promising natural inhibitor for postharvest disease management. Full article

The gut microbiota of fish plays a crucial role in nutrition, metabolism and immune regulation, and is highly sensitive to environmental stressors such as pesticide exposure. This study investigated the effects of emamectin benzoate (EMB) exposure on Asian stinging catfish (Heteropneustes fossilis) gut microbiota using an integrated culture-dependent and culture-independent approach to assess functional and taxonomic dysbiosis. Gut smear samples from control and EMB-treated fish at two sublethal concentrations (0.5 µg/L and 5 µg/L) were analyzed for major functional bacterial groups, including heterotrophic, lipid-hydrolysing, starch-hydrolysing, spore-forming, and Gram-negative bacteria and Pseudomonas spp., using standard plate count techniques. In parallel, microbial community composition and diversity were examined through 16S rRNA (V3–V4 region) gene amplicon sequencing followed by bioinformatic analysis. Culture-based results showed a significant decline in total heterotrophic bacteria and key functional groups in EMB-treated fish, indicating suppression of microbial metabolic activity and functional imbalance. Lipid-hydrolysing and starch-hydrolysing bacteria showed pronounced sensitivity to pesticide exposure, while spore-forming bacteria exhibited a marked reduction, suggesting compromised microbial resilience. Although Gram-negative bacteria declined overall, Pseudomonas spp. displayed a non-linear response, with an initial decrease, followed by partial recovery under higher exposure. Culture-independent analysis demonstrated reduced alpha diversity, altered community structure, and taxonomic shifts in EMB-treated fish. Pseudomonadota exhibited a distinct pattern characterized by decline at 0.5 µg/L and partial recovery at 5 µg/L, reflecting adaptive tolerance rather than restoration of microbial homeostasis. Overall, the combined evidence indicates pronounced EMB-induced gut dysbiosis at both functional and compositional levels. This study highlights the fish gut microbiome as a sensitive biomarker of stress and underscores the ecological risks associated with EMB in aquatic environments. Full article

Green mold disease caused by Trichoderma species represents one of the most serious threats to the cultivation of Ganoderma lingzhi. In this study, a rapid molecular detection system was developed for the identification of green mold caused by Trichoderma longibrachiatum. The pathogen was first identified based on morphological characteristics and pathogenicity tests. Species-specific primers were then designed targeting the RPB2 gene region, and their specificity and sensitivity were evaluated using polymerase chain reaction (PCR). The results confirmed that the causal pathogen was T. longibrachiatum. The designed primers exhibited high specificity and produced amplification only with genomic DNA from the target strain. Sensitivity assays demonstrated that the minimum detectable DNA concentration was 10⁻² ng/µL. In soil inoculation experiments, the target DNA could be detected in soil containing 4.28 × 10⁶ spores/g using the developed primers. Compared with conventional culture-based detection methods, the molecular detection system established in this study is faster, more accurate, and highly sensitive. This method provides a practical diagnostic tool for the early detection and management of green mold disease in G. lingzhi cultivation. Full article

Pine gall rust has emerged as a serious threat to Pinus taiwanensis (Huangshan pine) in Huangshan Mountain, a UNESCO World Heritage site in China. This study systematically investigated the etiology, host range, and epidemiological characteristics of the disease through field surveys, morphological observations, molecular phylogenetic analyses, and inoculation tests. The pathogen was identified as Cronartium orientale based on multi-locus sequencing (SSU, LSU, and ITS) and distinct basidiospore morphology. Quercus stewardii and Castanea seguinii were confirmed as alternate hosts, with Q. stewardii showing higher susceptibility. Microscopic examination revealed detailed spore morphology, and germination assays demonstrated that aeciospores and urediniospores germinate optimally at 12 °C and under near-saturated humidity. Aeciospore dispersal peaked from late April to early May, with spores detected up to 8 m from infected trees, under nearly windless conditions. The life cycle of C. orientale in this region involves annual production of pycnia and aecia on pine, followed by uredinia and telia on alternate hosts, enabling repeated infections. These findings clarify the etiology and epidemiology of pine gall rust on Huangshan pine, providing a scientific basis for disease monitoring and management strategies to protect the ecologically and culturally valuable Huangshan pine forests. Full article

Rice (Oryza sativa L.) production is severely threatened by rice blast disease caused by the hemibiotrophic fungus Magnaporthe oryzae. Chemical fungicides, although effective, cause environmental pollution, disrupt soil microbiomes, and select for resistant pathogen populations, creating an urgent need for sustainable alternatives. In this study, we isolated Kitasatospora hibisci strain 21007 from mangrove soil and evaluated its biocontrol potential through integrated phenotypic and transcriptomic analyses. The cell-free culture filtrate (CFCF) extract showed potent antifungal activity, inhibiting M. oryzae mycelial growth and suppressing conidial germination as well as appressorium formation in a concentration-dependent manner via antibiosis. Fermentation optimization identified Gauze’s Synthetic Medium No. 1 as optimal for metabolite production. Both inoculation of M. oryzae spores with 21007 CFCF extract and pre-treatment of rice seedlings with 21007 CFCF significantly reduced disease severity under greenhouse conditions. Transcriptomic analysis revealed extensive reprogramming of gene expression in leaves of rice seedlings cultured with 21007 CFCF extract. KEGG pathway enrichment analysis indicated activation of the plant–pathogen interaction and MAPK signaling pathways in rice seedlings cultured with 5% and 10% CFCF extract, suggesting that 21007 CFCF induces host defense signaling. These results support the potential of K. hibisci 21007 as a candidate for sustainable biocontrol of rice blast disease and establish a foundation for future metabolomic and genomic investigations. Full article

A microbial community study using a culture-dependent method was conducted on dehydrated sludge collected from a steel factory’s wastewater treatment plant. One isolate, designated QWL-01^T, was a strictly anaerobic, Gram-stain-negative, non-motile, non-spore-forming bacterium with coccoid cells measuring 0.6–0.9 μm in diameter. The growth of strain QWL-01^T was observed at 4–40 °C (optimum at 28–35 °C), pH 5.5–8.0 (optimum at pH 7.1), and a range of 0–3% NaCl (optimum at 0.5%). An analysis of the Biolog AN plate revealed positive carbon source utilization only for palatinose, α-ketovaleric acid, and pyruvic acid. The predominant fatty acids were iso-C_13:0 (17.0%), C_16:0 dimethyl acetal (12.0%), and anteiso-C_13:0 (9.2%). A 16S rRNA gene sequence analysis through BLASTN demonstrated that the nearest phylogenetic neighbors of the novel strain were Youngiibacter multivorans DSM 6139^T (93.82%) and Proteiniclasticum ruminis JCM 14817^T (93.75%). The genome size of strain QWL-01^T was 3.69 Mbp, with a G+C content of 50.8 mol%. Comparing strain QWL-01^T with closely related species of genera Proteiniclasticum and Youngiibacter, the digital DNA-DNA hybridization (dDDH), average nucleotide identity (ANI), and average amino acid identity (AAI) values ranged from 26.60% to 36.80%, 65.89% to 68.30%, and 49.27% to 51.58%, respectively. Based on phenotypic, physiological, phylogenetic, and genomic relatedness evidence, strain QWL-01^T represents a novel genus in the family Clostridiaceae, for which the name Anaerococcoides asporogena gen. nov. sp. nov. is proposed. Strain QWL-01^T (=BCRC 81396^T = CICC 25258^T = NBRC 117088^T) is the type strain of the proposed novel species. Full article

Background: Fungal infections pose a significant threat to public health, with over 6.55 million cases and 2.55 million deaths annually. Exposure to fungal spores in indoor environments primarily occurs through inhalation or direct contact with surfaces. Monitoring is critical for early detection and prevention of outbreaks, yet routine airborne fungal testing is not universally mandated across healthcare settings. Methods: A systematic review of peer-reviewed articles from four databases was conducted to identify current airborne fungal monitoring guidelines and best practices for sample collection, culture media, incubation conditions, and results interpretation. Results: Eighteen articles met the inclusion criteria, and four studies discussed potential guidelines for acceptable airborne fungal levels in healthcare environments. Guidelines ranged from <1 CFU/m³ for HEPA-filtered environments to >1000 CFU/m³ for non-filtered areas. The most common fungi identified were Aspergillus, Penicillium, Alternaria, Cladosporium, and Rhizopus, with six WHO-listed critical fungal pathogens found. Impaction was the sole sampling method used, with most studies employing Sabouraud dextrose or malt extract agar with chloramphenicol, incubation for 2–7 days at 25–30 °C, and morphological identification. Conclusions: The need for globally recognized fungal monitoring standards is pressing. Without them, preventable fungal exposure will persist, risking severe, potentially fatal infections for patients and healthcare workers. Full article

Phthorimaea operculella is a globally distributed pest of solanaceous crops and represents one of the most critical constraints on potato production worldwide. The overuse of chemical insecticides has led to widespread resistance in pest populations, making entomopathogenic fungi a promising alternative strategy for sustainable agricultural pest management. In this study, a fungal strain designated ML-2 was isolated from naturally infected P. operculella larvae collected from a potato field in Yunnan province, China. Through morphological characteristics and ITS sequence analysis, strain ML-2 was identified as M. robertsii. The growth rate and sporulation yield on PDA and SDAY media were assessed, the virulence of ML-2 against eggs, larvae, and pupae of P. operculella were determined using the dipping method, and the data were analyzed via the time-concentration-mortality (TCM) model. The results showed that there were no significant differences in the growth rate of strain ML-2 on the two culture media (p > 0.05), whereas the sporulation yield on PDA medium was significantly higher than that on SDAY medium (p < 0.01). The highest corrected cumulative mortality rates for P. operculella larvae and pupae were 94.50% and 83.07% on day 7 after inoculation, respectively, while the highest cumulative mortality rate for eggs was relatively low at only 20.28%. Additionally, at a concentration of 1 × 10⁸ spores/mL, the LT₅₀ values of strain ML-2 against P. operculella larvae and pupae were 2.34 days and 2.72 days, respectively. On day 7 post-inoculation, the LC₅₀ values for larvae and pupae were 3.24 × 10⁷ conidia/mL and 9.64 × 10⁵ conidia/mL, respectively. In conclusion, M. robertsii ML-2 exhibits high potential as a candidate biopesticide and can be used in the sustainable integrated management of P. operculella. Full article

The potential of Trichoderma nordicum (Hypocreales, Ascomycota), a recently described species, for antagonism and use in the biocontrol of oomycete-caused plant diseases is unknown. Trichoderma is a well-known genus for containing microbial antagonists and biocontrol agents. The T. nordicum in this study was isolated from decomposing wood, and rpb2 and tef1 barcode sequencing demonstrated that the isolates were a match to the reference T. nordicum and T. nigricans strains. Since T. nordicum was described before T. nigricans, the isolates were assigned to T. nordicum, although taxonomic uncertainty between these species requires future clarification. In dual-culture confrontation assays, T. nordicum overgrew five economically important oomycete plant pathogens (Phytophthora capsici, P. sojae, Pythium aphanidermatum, P. myriotylum, and Globisporangium ultimum). The inability to recover viable P. aphanidermatum and P. capsici from the parts of the plate overgrown by T. nordicum, coupled with protease and endo-cellulase activities, correlates with T. nordicum having antagonistic abilities. Inoculation with T. nordicum preventively reduced the levels of cucumber seedling damping-off caused by P. aphanidermatum by up to 70%. The T. nordicum biocontrol effects against pepper blight caused by P. capsici were greater than 80%, compared to an autoclaved T. nordicum spore control. T. nordicum could also significantly promote the growth of pepper, with plant weight increased by up to 40%, compared to an autoclaved-spore control. In contrast, T. nordicum could not be used to control Pythium soft rot of ginger caused by P. myriotylum, even though P. myriotylum was overgrown by T. nordicum, suggesting host- or pathosystem-specific factors influence biocontrol efficacy. In summary, T. nordicum is a promising biocontrol agent for use in the control of pepper blight caused by P. capsici, and also has potential for use in the control of other oomycete-caused plant diseases in vegetable production systems. Full article

Muskmelon (Cucumis melo L.) is an economically important crop that remains highly susceptible to destructive fungal diseases, including gummy stem blight, downy mildew, Fusarium wilt, and anthracnose. Although fungicides and resistant cultivars are widely used, reliance on chemical control raises concerns regarding environmental safety, food quality, and the emergence of fungicide-resistant pathogen populations. Consequently, microbial biopesticides, particularly Bacillus species, have attracted increasing attention as sustainable alternatives. In this study, muskmelon plants exhibiting leaf wilting, chlorosis, and stem yellowing were collected from Guangming Farm in Wufeng, Taichung, Taiwan, and associated pathogens were isolated from stem tissues and identified to determine the causal agent of these symptoms. In addition, the biocontrol efficacy of Bacillus subtilis strain MCLB2 against melon fruit rot, as well as its underlying mechanisms, was evaluated. Pathogenicity assays confirmed that isolate F01 was the causal agent. Based on morphological characteristics and internal transcribed spacer (ITS) sequence analysis, this isolate showed 99.8% identity to Fusarium pernambucanum URM 7559 (GenBank accession no. NR_163754), and phylogenetic analysis further placed it within the Fusarium incarnatum-equiseti species complex (FIESC). Antagonistic assays demonstrated that B. subtilis MCLB2 significantly inhibited mycelial growth and suppressed the spore germination of F. pernambucanum. In addition, culture filtrates of strain MCLB2 effectively reduced Fusarium-induced fruit rot in melon and disrupted fungal cellular respiration. Liquid chromatography–tandem mass spectrometry (LC–MS/MS) analysis revealed that the strain produced surfactin-family lipopeptides. In conclusion, B. subtilis MCLB2 exhibits potential as a sustainable biocontrol agent for managing Fusarium fruit rot in melon, likely through surfactin-mediated disruption of fungal cellular respiration. Full article

Pasteuria penetrans (Pp) is a mycelial and endospore-forming bacterium that parasitizes Meloidogyne spp. A single Pp population may contain multiple genotypes that differ in their spore-attachment specificity. Consequently, a subpopulation within a Pp isolate, which can attach to one Meloidogyne species, may fail to attach to another. Repeated culturing of that Pp isolate, on different Meloidogyne species, may therefore lead to shifts in host specificity. We tested this hypothesis using M. luci and M. arenaria, both of which are quite poor hosts of the Pp3 isolate maintained on M. javanica. Using relatively high spore concentrations (10⁶ spores/mL), low levels of attachment and infection were obtained, and after three successive selection cycles, Pp3 sub-isolates adapted to M. luci and M. arenaria were generated. This selection process was associated with a fitness cost, expressed as reduced spore attachment on M. javanica. The shift in host specificity proved reversible. When the adapted Pp3 M. arenaria and Pp3 M. luci sub- isolates were subsequently selected on M. javanica, for two generations, they regained the ability to attach on M. javanica but with a corresponding fitness cost, of spore attachment on M. arenaria and M. luci. These results demonstrate that Pp host specificity is plastic and capable of rapid selection-driven changes in attachment patterns, although such shifts are accompanied by fitness trade-offs. Full article

Actinomycetes are among the richest sources of bioactive secondary metabolites in biotechnology, owing to their remarkable metabolic diversity. Although the genus Streptomyces has been extensively explored and has yielded many clinically important antibiotics, rare actinomycetes remain comparatively underinvestigated. In this study, Kitasatospora sp. SeTe27, isolated from uncontaminated soil in Sicily (Italy), was investigated for its antibacterial activity and fermentation-driven enhancement of secondary metabolite production. The strain inhibited Staphylococcus aureus ATCC 25923, prompting physiological and genomic analyses. Spore conditioning was evaluated in four media (R5A, GYM, TSB, and YEME) to enhance antibiotic production. Conditioned cultures exhibited markedly increased antibacterial activity in TSB and YEME, moderate production in R5A, and no detectable activity in GYM. Whole-genome sequencing revealed an 8.5 Mb genome (73.5% GC) containing 48 biosynthetic gene clusters (BGCs), including NRPS, PKS, terpene, and hybrid pathways. Several clusters showed high similarity to known antibiotic-associated BGCs, such as clifednamide- and phenazine-related pathways, while numerous orphan clusters indicated significant unexplored biosynthetic potential. These findings identify Kitasatospora sp. SeTe27 as a promising antimicrobial producer and demonstrate that spore conditioning in complex media is an effective strategy to enhance antibiotic production in rare actinomycetes. Full article

To explore microbial resources for ester production in sub-high-temperature Daqu, this study first established that the esterifying enzyme activity in Daqu predominantly originated from fungi, with Rhizopus being the dominant fungal genus. Six Rhizopus strains capable of decomposing esters were isolated and purified from Daqu. Following secondary screening, strain M1 exhibited the highest esterification activity (40.26 U/mL) and was identified as Rhizopus oryzae based on morphological characteristics and molecular biological analyses. This strain was subsequently designated as Rhizopus oryzae M1 (R. oryzae M1). Using mycelial powder of strain M1 as the inoculum and sterilized wheat bran as the substrate, a pure-culture Fuqu was prepared. Orthogonal array design experiments were conducted to optimize the preparation process of this Fuqu, using esterifying enzyme activity as the evaluation index. Under the optimal conditions, the spore count and esterification activity of the pure-culture Fuqu reached 1.73 × 10⁹ CFU/g and 80.13 U/g, respectively. This pure-culture Fuqu was subsequently used as an inoculum to produce fortified Daqu. Following orthogonal optimization of the Daqu preparation process, the esterification activity of the fortified Daqu reached 103.22 U/g, and its key physicochemical indices met the requirements for high-quality sub-high-temperature Daqu. Analysis of the microbial community structure revealed that Rhizopus was the dominant fungal genus in the fortified Daqu, with its relative abundance increased by 35% compared to the non-fortified Daqu. Consistent with this, the esterifying enzyme activity of the fortified Daqu was 51.79% higher, suggesting that Rhizopus may have been largely responsible for the increase in esterification capacity. In laboratory-scale Baijiu brewing trials, this fortified Daqu produced a base Baijiu with a total ester content of 2.74 g/L, representing a 40.5% increase over the non-fortified Daqu and further confirming the pivotal role of Rhizopus in driving the esterifying enzyme activity. This study successfully screened a high esterifying enzyme-producing strain, R. oryzae M1, systematically optimized its enzyme production and Qu-making processes, and provides an excellent microbial strain and process reference for the preparation of fortified Daqu and the enhancement of Baijiu flavor. Full article

Sparassis latifolia is an edible and medicinal mushroom with significant economic value, now commercially cultivated on a large scale in China. However, current cultivars face challenges, including an extended mycelial growth period and unstable fruiting body yields. Advances in molecular breeding and functional genomics for this species are hindered by the absence of a reliable genetic transformation system. In this study, we first determined that S. latifolia is highly sensitive to carboxin and hygromycin, two selective agents commonly used in fungal genetics. We subsequently constructed a novel binary vector, pCbxHyg, harboring a carboxin resistance cassette driven by its native Pleurotus eryngii promoter and a hygromycin resistance cassette under the control of the P. eryngii Glycerol 3-phosphate dehydrogenase (GPD) gene promoter. Initial transformation attempts using Agrobacterium-mediated transformation of liquid-cultured mycelial pellets were unsuccessful. During microscopic examination, we discovered that S. latifolia mycelia produce abundant asexual chlamydospores. Using these chlamydospores as recipient material, we efficiently and reproducibly obtained transformants with the pCbxHyg vector under both carboxin and hygromycin selection. This method highlights the advantage of using asexual spores of Basidiomycetes as recipients for genetic transformation. PCR analysis confirmed the stable integration of the exogenous resistance genes into the fungal genome. The functionality of the system was further validated by transforming chlamydospores with a vector carrying a β-glucuronidase (GUS) reporter gene, whose expression was confirmed via histochemical staining of the resulting transformant mycelia. This work establishes the first successful Agrobacterium-mediated genetic transformation system for S. latifolia, providing a foundational platform for future gene function studies and molecular breeding efforts. Full article