Phosphorus is one of the main nutrients necessary for plant growth and development. Phosphorus-dissolving microorganisms may convert insoluble phosphorus in soil into available phosphorus that plants can easily absorb and utilize. In this study, four phosphorus-solubilizing fungi (L3, L4, L5, and L12) were isolated from the rhizosphere soil of a poplar plantation in Dongtai, Jiangsu Province, China. Phylogenetic analysis based on the internal transcribed spacer (ITS) and large subunit (LSU) of the ribosomal DNA sequences showed that the ITS and 28S sequences of isolates were the most similar to those of Mortierella. Morphological observation showed that most colonies grew in concentric circles and produced spores under different culture conditions. These results and further microscopic observations showed that these isolated fungi belonged to the genus Mortierella. Pikovskaya (PKO) medium, in which tricalcium phosphate was the sole phosphorus source, was used to screen strain L4 with the best phosphorus-solubilizing effect for further study. When the carbon source was glucose, the nitrogen source was ammonium chloride, the pH was 5, and the available phosphorus content was the highest. By exploring the possible mechanism of phosphorus release by phosphorus-solubilizing fungi, it was found that strain L4 produces several organic acids, such as oxalic acid, lactic acid, acetic acid, succinic acid, tartaric acid, malic acid, and citric acid. At 24 h, the alkaline phosphatase and acid phosphatase activities reached 154.72 mol/(L·h) and 120.99 mol/(L·h), respectively.

Low density polyethylene (LDPE) has been widely used commercially for decades; however, as a non-degradable material, its continuous accumulation has contributed to serious environmental issues. A fungal strain, Cladosporium sp. CPEF-6 exhibiting a significant growth advantage on MSM-LDPE (minimal salt medium), was isolated and selected for biodegradation analysis. LDPE biodegradation was analyzed by weight loss percent, change in pH during fungal growth, environmental scanning electron microscopy (ESEM), and Fourier transformed infrared spectroscopy (FTIR). Inoculation with the strain Cladosporium sp. CPEF-6 resulted in a 0.30 ± 0.06% decrease in the weight of untreated LDPE (U-LDPE). After heat treatment (T-LDPE), the weight loss of LDPE increased significantly and reached 0.43 ± 0.01% after 30 days of culture. The pH of the medium was measured during LDPE degradation to assess the environmental changes caused by enzymes and organic acids secreted by the fungus. The fungal degradation of LDPE sheets was characterized by ESEM analysis of topographical alterations, such as cracks, pits, voids, and roughness. FTIR analysis of U-LDPE and T-LDPE revealed the appearance of novel functional groups associated with hydrocarbon biodegradation as well as changes in the polymer carbon chain, confirming the depolymerization of LDPE. This is the first report demonstrating the capacity of Cladosporium sp. to degrade LDPE, with the expectation that this finding can be used to ameliorate the negative impact of plastics on the environment.

Aspergillus, a genus of filamentous fungi, is extensively distributed in nature and plays crucial roles in the decomposition of organic materials as an important environmental microorganism as well as in the traditional fermentation and food processing industries. Furthermore, due to their strong potential to secrete a large variety of hydrolytic enzymes and other natural products by manipulating gene expression and/or introducing new biosynthetic pathways, several Aspergillus species have been widely exploited as microbial cell factories. In recent years, with the development of next-generation genome sequencing technology and genetic engineering methods, the production and utilization of various homo-/heterologous-proteins and natural products in Aspergillus species have been well studied. As a newly developed genome editing technology, the clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) system has been used to edit and modify genes in Aspergilli. So far, the CRISPR/Cas9-based approach has been widely employed to improve the efficiency of gene modification in the strain type Aspergillus nidulans and other industrially important and pathogenic Aspergillus species, including Aspergillus oryzae, Aspergillus niger, and Aspergillus fumigatus. This review highlights the current development of CRISPR/Cas9-based genome editing technology and its application in basic research and the production of recombination proteins and natural products in the Aspergillus species.

Studies on the degradation of plant cell wall polysaccharides by fungal extracellular enzymes have attracted recent attention from researchers. Xylan, abundant in hemicellulose, that play great role in connection between cellulose and lignin, has seen interest in its hydrolytic enzymatic complex. In this study, dozens of fungus species spanning genera were isolated from rotting leaves based on their ability to decompose xylan. Among these isolates, a strain with strong xylanase-producing ability was selected for further investigation by genome sequencing. Based on phylogenetic analysis of ITS (rDNA internal transcribed spacer) and LSU (Large subunit 28S rDNA) regions, the isolate was identified as Penicillium oxalicum. Morphological analysis also supported this finding. Xylanase activity of this isolated P. oxalicum 5-18 strain was recorded to be 30.83 U/mL using the 3,5-dinitro-salicylic acid (DNS) method. Further genome sequencing reveals that sequenced reads were assembled into a 30.78 Mb genome containing 10,074 predicted protein-encoding genes. In total, 439 carbohydrate-active enzymes (CAZymes) encoding genes were predicted, many of which were associated with cellulose, hemicellulose, pectin, chitin and starch degradation. Further analysis and comparison showed that the isolate P. oxalicum 5-18 contains a diverse set of CAZyme genes involved in degradation of plant cell wall components, particularly cellulose and hemicellulose. These findings provide us with valuable genetic information about the plant biomass-degrading enzyme system of P. oxalicum, facilitating a further exploration of the repertoire of industrially relevant lignocellulolytic enzymes of P. oxalicum 5-18.

The majority of terrestrial plants are symbiotic with arbuscular mycorrhizal fungi (AMF). Plants supply carbohydrates to microbes, whereas AMF provide plants with water and other necessary nutrients—most typically, phosphorus. Understanding the response of the AMF community structure to biogas slurry (BS) fertilization is of great significance for sustainable forest management. This study aimed to look into the effects of BS fertilization at different concentrations on AMF community structures in rhizospheric soil in poplar plantations. We found that different fertilization concentrations dramatically affected the diversity of AMF in the rhizospheric soil of the poplar plantations, and the treatment with a high BS concentration showed the highest Shannon diversity of AMF and OTU richness (Chao1). Further analyses revealed that Glomerales, as the predominant order, accounted for 36.2–42.7% of the AMF communities, and the relative abundance of Glomerales exhibited negligible changes with different BS fertilization concentrations, whereas the order Paraglomerales increased significantly in both the low- and high-concentration treatments in comparison with the control. Furthermore, the addition of BS drastically enhanced the relative abundance of the dominant genera, Glomus and Paraglomus. The application of BS could also distinguish the AMF community composition in the rhizospheric soil well. An RDA analysis indicated that the dominant genus Glomus was significantly positively correlated with nitrate reductase activity, while Paraglomus showed a significant positive correlation with available P. Overall, the findings suggest that adding BS fertilizer to poplar plantations can elevate the diversity of AMF communities in rhizospheric soil and the relative abundance of some critical genera that affect plant nutrient uptake.

The efficient hydrolysis of lignocellulosic biomass relies on the action of enzymes, which are crucial for the development of economically feasible cellulose bioconversion processes. However, low hydrolysis efficiency and the inhibition of cellulase production by carbon catabolite repression (CCR) have been significant obstacles in this process. The aim of this study was to identify the patterns of cellulose degradation and related genes through the genome analysis of a newly isolated lignocellulose-degrading fungus Flavodon sp. x-10. The whole-genome sequencing showed that the genome size of Flavodon sp. x-10 was 37.1 Mb, with a GC content of 49.48%. A total of 11,277 genes were predicted, with a total length of 18,218,150 bp and an average length of 1615 bp. Additionally, 157 tRNA genes responsible for transporting different amino acids were predicted, and the repeats and tandem repeats accounted for only 0.76% of the overall sequences. A total of 5039 genes were annotated in the Kyoto Encyclopedia of Genes and Genomes (KEGG) database, representing 44.68% of all genes, and 368 metabolic pathways were involved. Of the 595 genes annotated in the carbohydrate-active enzyme (CAZy) database, 183 are associated with plant cell wall-degrading enzymes (PCWDEs), surpassing those of Aspergillus niger (167), Trichoderma reesei (64), and Neurospora crassa (86). Compared to these three fungi, Flavodon sp. x-10 has a higher number of enzyme genes related to lignin degradation in its genome. Transporters were further identified by matching the whole-genome sequence to the Transporter Classification Database (TCDB), which includes 20 sugar transporters (STs) closely linked to sugar utilization. Through the comprehensive exploration of the whole-genome sequence, this study uncovered more vital lignocellulase genes and their degradation mechanisms, providing feasible strategies for improving the strains to reduce the cost of biofuel production.