Weishuai Yu

Chaetosphaeriaceae is a group of micro-ascomycetes widely distributed in diverse ecosystems worldwide. Group members are commonly found on decaying wood, leaf litter and in moist soil. However, their diversity in soil habitats, especially in understudied bamboo forest ecosystems, remains poorly characterised. In this study, we isolated chaetosphaeriaceous fungi from soil samples collected from a bamboo forest on Xiangyun Mountain, Jiangxi Province, China. We determined their taxonomic placement using maximum likelihood (ML) and Bayesian inference (BI) analyses of concatenated sequence data from three nuclear loci: the internal transcribed spacer (ITS), the large subunit (LSU), and the translation elongation factor 1-α ( tef 1-α). Our results confirm that these isolates belong to two new species: Chloridium jiangxiense and Paragongromeriza jiangxiensis . We present detailed descriptions and micrographs of both species and compare them with other members of Chaetosphaeriaceae . Our findings not only expand the documented species richness of Chaetosphaeriaceae in Asia but also underscore the importance of bamboo forest soils as a promising niche for discovering previously unrecognised fungal diversity. Detailed descriptions, photomicrographs, and comparisons with phenotypically similar taxa are provided to facilitate future identification and ecological studies.

The Yellow River Delta is a representative coastal saline–alkaline ecosystem in China, where high salinity and complex soil properties create a distinct habitat that significantly shapes microbial community structure and function. In this study, we analyzed 34 saline–alkaline soil samples from four regions within the delta. We characterized soil physicochemical properties (salt content, electrical conductivity, and pH) and systematically assessed fungal diversity, potential ecological functions, and their relationships with environmental variables using both internal transcribed spacer high-throughput sequencing and culture-based isolation. Sequencing generated 1,137,196 sequences that clustered into 13,574 operational taxonomic units (OTUs), with Good’s coverage values ranging from 0.96 to 1.00, indicating sufficient sequencing depth. The soils were generally alkaline and exhibited pronounced spatial heterogeneity in salinity and electrical conductivity. Sequencing analyses revealed Ascomycota and Basidiomycota as the dominant fungal phyla. Alpha diversity tended to decline with increasing salt content and electrical conductivity; however, substantial within-group variability indicated strong microenvironmental influences. Beta diversity analyses revealed distinct clustering patterns in community structure among regions based on PCoA ordinations. Redundancy analysis revealed that soil pH had the only significant unique contribution to fungal community variation. However, all three measured edaphic factors together explained only 17% of the total community variation. Functional inference using the FUNGuild database identified diverse fungal trophic modes and several plant-associated taxa in several samples. Culture-based approaches yielded 347 isolates representing 52 genera. Among the isolates, the vast majority (>95%) belonged to Ascomycota, with Basidiomycota represented by only a few isolates, which is consistent with the dominance of Ascomycota observed in the high-throughput sequencing data. Comparisons between sequencing and cultivation results demonstrated complementary diversity profiles and highlighted a substantial reservoir of nonculturable fungi in these soils. Overall, this study clarifies spatial patterns and key environmental drivers of fungal diversity in the Yellow River Delta and establishes a foundational culture collection for future ecological restoration efforts.

Auxiliary activity 9 (AA9) lytic polysaccharide monooxygenases (LPMOs) are copper-dependent oxidoreductases that use O₂ or H₂O₂ to perform oxidative cleavage of cellulose in the presence of an electron donor. Combined with cellulases, they can assist in a more efficient cleavage of cellulose. AA9 LPMOs have therefore attracted considerable attention in recent years for use in biotechnological applications. Here, a native AA9 LPMO (nTaAA9A) from the thermophilic fungus Thermoascus aurantiacus was purified and characterized. The enzyme was shown to be active and able to cleave cellulose and xylan to produce C1- and C4-oxidized products. It was also found to retain about 84.3, 63.7, and 35.3% of its activity after incubation for 30 min at 60, 70, and 80 °C, respectively, using quantitative activity determination. The structure was determined to 1.36 Å resolution and compared with that of the recombinant enzyme expressed in Aspergillus oryzae. Structural differences in the glycosylated Asn138 and in solvent-exposed loops were identified.