Metagenomic Next-Generation Sequencing as an Effective Diagnostic Tool for Talaromycosis in HIV-Negative Patients.

The diagnosis of Talaromyces marneffei infection in HIV-negative patients remains challenging. There is an urgent need for rapid and convenient methods to diagnose this complicated disease. The aim of this study was to evaluate the diagnostic efficiency of metagenomic next-generation sequencing (mNGS) for talaromycosis in non-HIV-infected patients by comparing mNGS with traditional microbial culture. In total, 66 samples from 57 patients were analyzed via both mNGS and microbial culture. The ROC curve showed a sensitivity for mNGS of 97.22%, which was greater than that of microbial culture (61.11%). Samples from the respiratory tract, infectious skin lesions, and lymph nodes are recommended as routine samples for talaromycosis detection via mNGS. Furthermore, mNGS significantly reduced the diagnostic time compared to microbial culture. Overall, our study demonstrated that mNGS is a promising tool for rapid and accurate pathogenic detection in HIV-negative patients with talaromycosis.

Biocontrol potential and growth-promoting effect of endophytic fungus Talaromyces muroii SD1-4 against potato leaf spot disease caused by Alternaria alternata.

BACKGROUND: Alternaria alternata is the primary pathogen of potato leaf spot disease, resulting in significant potato yield losses globally. Endophytic microorganism-based biological control, especially using microorganisms from host plants, has emerged as a promising and eco-friendly approach for managing plant diseases. Therefore, this study aimed to isolate, identify and characterize the endophytic fungi from healthy potato leaves which had great antifungal activity to the potato leaf spot pathogen of A. alternata in vitro and in vivo. RESULTS: An endophytic fungal strain SD1-4 was isolated from healthy potato leaves and was identified as Talaromyces muroii through morphological and sequencing analysis. The strain SD1-4 exhibited potent antifungal activity against the potato leaf spot pathogen A. alternata Lill, with a hyphal inhibition rate of 69.19%. Microscopic and scanning electron microscope observations revealed that the strain SD1-4 grew parallel to, coiled around, shrunk and deformed the mycelia of A. alternata Lill. Additionally, the enzyme activities of chitinase and ß-1, 3-glucanase significantly increased in the hyphae of A. alternata Lill when co-cultured with the strain SD1-4, indicating severe impairment of the cell wall function of A. alternata Lill. Furthermore, the mycelial growth and conidial germination of A. alternata Lill were significantly suppressed by the aseptic filtrate of the strain SD1-4, with inhibition rates of 79.00% and 80.67%, respectively. Decrease of leaf spot disease index from 78.36 to 37.03 was also observed in potato plants treated with the strain SD1-4, along with the significantly increased plant growth characters including plant height, root length, fresh weight, dry weight, chlorophyll content and photosynthetic rate of potato seedlings. CONCLUSION: The endophyte fungus of T. muroii SD1-4 isolated from healthy potato leaves in the present study showed high biocontrol potential against potato leaf spot disease caused by A. alternata via direct parasitism or antifungal metabolites, and had positive roles in promoting potato plant growth.

Activation of a Silent Gene Cluster from the Endophytic Fungus Talaromyces sp. Unearths Cryptic Azaphilone Metabolites.

Fungal azaphilones have attracted widespread attention due to their significant potential as sources of food pigments and pharmaceuticals. Genome mining and gene cluster activation represent powerful tools and strategies for discovering novel natural products and bioactive molecules. Here, a putative azaphilone biosynthetic gene cluster lut from the endophytic fungus Talaromyces sp. was identified through genome mining. By overexpressing the pathway-specific transcription factor LutB, five new sclerotiorin-type azaphilones (1, 6, 8, and 10-11) together with seven known analogues (2-5, 7, 9, 12) were successfully produced. Compounds 8 and 9 exhibited antibacterial activity against Bacillus subtilis with MIC values of 64 and 16 µg/mL, respectively. Compound 11 showed cytotoxic activity against HCT116 and GES-1 with IC50 values of 10.9 and 4.9 µM, respectively, while 1, 4, 5, and 7-10 showed no obvious cytotoxic activity. Gene inactivation experiments confirmed the role of the lut cluster in the production of compounds 1-12. Subsequent feeding experiments unveiled the novel functional diversity of the dual megasynthase system. Furthermore, a LutC-LutD binary oxidoreductase system was discovered, and in combination with DFT calculations, the basic biosynthetic pathway of the sclerotiorin-type azaphilones was characterized. This study provided a good example for the discovery of new azaphilones and further uncovered the biosynthesis of these compounds.

Three-Step Enzymatic Remodeling of Chitin into Bioactive Chitooligomers.

Here we describe a complex enzymatic approach to the efficient transformation of abundant waste chitin, a byproduct of the food industry, into valuable chitooligomers with a degree of polymerization (DP) ranging from 6 to 11. This method involves a three-step process: initial hydrolysis of chitin using engineered variants of a novel fungal chitinase from Talaromyces flavus to generate low-DP chitooligomers, followed by an extension to the desired DP using the high-yielding Y445N variant of ß-N-acetylhexosaminidase from Aspergillus oryzae, achieving yields of up to 57%. Subsequently, enzymatic deacetylation of chitooligomers with DP 6 and 7 was accomplished using peptidoglycan deacetylase from Bacillus subtilis BsPdaC. The innovative enzymatic procedure demonstrates a sustainable and feasible route for converting waste chitin into unavailable bioactive chitooligomers potentially applicable as natural pesticides in ecological and sustainable agriculture.

Clinical usefulness of metagenomic next-generation sequencing for Talaromyces marneffei diagnosis in China: a retrospective study.

PURPOSE: Metagenomic next-generation sequencing (mNGS) has been widely used in the diagnosis of infectious diseases. However, studies on Talaromyces marneffei detection using mNGS remain scarce. Therefore, this study aimed to explore the diagnostic performance of mNGS in T. marneffei. METHODS: Between March 2021 and June 2023, patients who were discharged with a final diagnosis of talaromycosis, or confirmed T. marneffei infection by mNGS, culture or pathological examination were included in the study. Culture and mNGS were performed simultaneously for all patients. Clinical data were retrieved for analysis. RESULTS: A total of 78 patients were enrolled, with 40 in the talaromycosis group and 38 in the suspected-talaromycosis group. In the talaromycosis group, mNGS showed a higher positivity rate(40/40, 100.0%) compared to culture(34/40, 85.0%)(P = 0.111). All patients in the suspected-talaromycosis group tested negative via culture, while mNGS yielded positive results. The T. marneffei reads in the talaromycosis group were significantly higher than in the suspected-talaromycosis group (4399 vs. 28, P < 0.001). In the suspected-talaromycosis group, of the four patients with low reads who did not receive antifungal therapy, one died and one lung lesion progressed; most patients(31/34, 91.2%) recovered after receiving appropriate antifungal therapy. CONCLUSION: mNGS proves to be a rapid and highly sensitive method for detecting T. marneffei. Higher reads of T. marneffei correspond to a higher likelihood of infection. However, cases with low reads necessitate a comprehensive approach, integrating clinical manifestations, laboratory tests, and imaging examinations to confirm T. marneffei infection.

Pulmonary dimorphic fungal infections among HIV/AIDS non-TB patients with chronic cough in Kampala, Uganda.

INTRODUCTION: Dimorphic fungi cause infection following the inhalation of spores into the pulmonary system. In the lower respiratory tract, the conidia transform into yeasts, which are engulfed by alveolar macrophages and may be destroyed without disease manifestation. However, in some immunocompromised individuals, they may persist and cause active fungal disease characterized by formation of granulomas in the infected tissues, which may mimic Mycobacterium tuberculosis (MTB). OBJECTIVE: To determine the prevalence of pulmonary dimorphic fungal infections among HIV/AIDS patients with non-TB chronic cough at Mulago National Referral and Teaching Hospital in Kampala, Uganda. METHODS: Sputum samples were collected from 175 consented HIV/AIDS patients attending the immuno-suppression syndrome (ISS) clinic at the hospital. Upon Xpert MTB/RIF sputum testing, 21 patients tested positive for MTB, and these were excluded from further analysis. The other 154 sputum negative samples were then subjected to PCR for dimorphic fungi at MBN Clinical Laboratories. Singleplex PCR was used to detect the target sequences in selected respective genes of each dimorphic fungal species of interest. DNA amplicons were detected based on gel electrophoresis. RESULTS: Dimorphic fungi were detected in 16.2% (25/154) of the studied population. Of these 9.1% (14/154) had Blastomyces dermatitidis and 7.1% (11/154) had Talaromyces marneffei. The remaining 84% of the studied participants had no dimorphic fungi. Histoplasma capsulatum, Coccidioides immitis and Paracoccidioides brasiliensis were not detected in any of the participants. CONCLUSION: Dimorphic fungi (B. dermatitidis and T. marneffei) were found in 16.2% of the HIV/AIDS patients with non-TB chronic cough in Kampala, Uganda. We recommend routine testing for these pathogens among HIV/AIDS patients with chronic cough.

Molecular and biological characterization of a novel partitivirus from Talaromyces pinophilus.

Talaromyces spp. have a worldwide distribution, are ecologically diverse and have been isolated from numerous different substrates. Talaromyces spp. are considered biotechnologically important due to their ability to produce a range of enzymes and pigments. Talaromyces pinophilus, belonging to genus Talaromyces and family Trichocomaceae, is known for producing several important bioactive metabolites. Here we report the isolation and characterisation of a partitivirus from T. pinophilus which we have nominated Talaromyces pinophilus partitivirus-1 (TpPV-1). TpPV-1 possesses a genome consisting of three double stranded (ds) RNA segments i.e., dsRNAs1-3, 1824 bp, 1638 bp and 1451 bp respectively, which are encapsidated in icosahedral particles 35 nm in diameter. Both dsRNA1 and dsRNA2 contain a single open reading frame (ORF) encoding respectively a 572 amino acid (aa) protein of 65 kDa and a 504 aa protein of 50 kDa. The third segment (dsRNA3) is potentially a satellite RNA. Phylogenetic analysis revealed that the TpPV-1 belongs to the family Partitiviridae in the proposed genus Zetapartitivirus. TpPV-1 infection decreases the mycelial growth rate of the host fungus and alters pigmentation as indicated by time course experiments performed on a range of different solid media comparing virus-infected and virus-free isogenic lines. This is the first report of mycovirus infection in T. pinophilus and may provide insights into understanding the effect of the mycovirus on the production of enzymes and pigments by the host fungus.

Engineering of glycoside hydrolase family 7 cellobiohydrolases directed by natural diversity screening.

Protein engineering and screening of processive fungal cellobiohydrolases (CBHs) remain challenging due to limited expression hosts, synergy-dependency, and recalcitrant substrates. In particular, glycoside hydrolase family 7 (GH7) CBHs are critically important for the bioeconomy and typically difficult to engineer. Here, we target the discovery of highly active natural GH7 CBHs and engineering of variants with improved activity. Using experimentally assayed activities of genome mined CBHs, we applied sequence and structural alignments to top performers to identify key point mutations linked to improved activity. From ∼1500 known GH7 sequences, an evolutionarily diverse subset of 57 GH7 CBH genes was expressed in Trichoderma reesei and screened using a multiplexed activity screening assay. Ten catalytically enhanced natural variants were identified, produced, purified, and tested for efficacy using industrially relevant conditions and substrates. Three key amino acids in CBHs with performance comparable or superior to Penicillium funiculosum Cel7A were identified and combinatorially engineered into P. funiculosum cel7a, expressed in T. reesei, and assayed on lignocellulosic biomass. The top performer generated using this combined approach of natural diversity genome mining, experimental assays, and computational modeling produced a 41% increase in conversion extent over native P. funiculosum Cel7A, a 55% increase over the current industrial standard T. reesei Cel7A, and 10% improvement over Aspergillus oryzae Cel7C, the best natural GH7 CBH previously identified in our laboratory.

In vivo assembly of genetic constructs in filamentous fungus Talaromyces cellulolyticus.

In the filamentous fungus Talaromyces cellulolyticus, similar to other filamentous fungi, non-homologous recombination predominates over homologous recombination. For instance, to achieve an acceptable integration frequency of a genetic construct into a target site on the intact chromosome, the flanking sequences directing this integration should be approximately 2.5 kb in length. However, despite the requirement of long flanks for integration into the intact chromosome, we found that homologous recombination between linear DNA fragments in T. cellulolyticus effectively occurs when these fragments overlap by just 50 bp. This allows for the assembly of full-sized genetic constructs in vivo from relatively small blocks, eliminating the need for in vitro assembly, similar to the approach previously developed for the yeast Saccharomyces cerevisiae. To validate this possibility, we replaced the native promoter of the target gene by transforming the recipient strain with five DNA fragments: two flanks for recombination with the target locus, two parts of the marker gene, and a donor promoter. This discovery significantly expedites the genetic engineering of T. cellulolyticus and potentially other fungi.

Talaromyces mellisjaponici sp. nov., a xerophilic species isolated from honey in Japan.

Five isolates of a xerophilic Talaromyces species were obtained from honey in Japan. Molecular phylogenetic analysis based on a combined dataset for four regions (rRNA internal transcribed spacer, ß-tubulin, calmodulin and RNA polymerase II second largest subunit) revealed that the strains formed an independent clade in section Trachyspermi, which is sister to Talaromyces affinitatimellis, Talaromyces basipetosporus and Talaromyces speluncarum. The strains and their relatives have different growth on creatine agar, yeast extract sucrose agar and dichloran 18 % glycerol agar, different branching patterns (mostly monoverticillate or biverticillate, less frequently divaricate or terverticillate), and different sizes and surface structures of conidia. Xerotolerance tests were also conducted using media adjusted to five different sucrose concentrations (0, 20, 40, 60 and 80 %). The colony diameters of the strains were larger than those of T. affinitatimellis, T. basipetosporus and T. speluncarum at each sucrose concentration. Altogether, the obtained morphological, molecular and physiological data allowed the proposal of Talaromyces mellisjaponici sp. nov. for this novel species, with NBRC 116048T as the type strain.