Impact of Aspergillus fumigatus inoculation on the composting of wood shaving bedding for horses

Equine farming generates a significant amount of waste, prompting the need for effective management. Composting enhanced by filamentous fungi holds promise for this purpose. This study focused on inoculating Aspergillus fumigatus isolates in composting horse bedding made with wood shavings (Pinus elliottii). The experiment lasted 90 days, with two treatment groups, control and inoculated, analyzing temperature, pH, electrical conductivity, total organic carbon and nitrogen content, and cellulose, hemicellulose, and lignin contents. Both treatments entered the thermophilic phase by the fourth day, reaching temperatures above 55°C and mesophilic maturation at 35 days (41 ± 0.2°C). The inoculated treatment exhibited higher electrical conductivity after 30 days and a more pronounced reduction in the total carbon content (42.85% vs. 38.29%) compared to the control. While there was no significant nitrogen difference, the inoculated treatment had a sharper reduction in carbon/nitrogen ratio, and cellulose and hemicellulose contents. Both treatments showed low coliform counts, no Salmonella sp., and reduced Strongyloides sp. larvae. Inoculating A. fumigatus in saturated horse bedding made from wood shavings improved compost quality, providing a possibility for sustainable equine farming waste treatment.

Lignin-Modifying Enzymes in Scedosporium Species

Scedosporium species are usually soil saprophytes but some members of the genus such as S. apiospermum and S. aurantiacum have been regularly reported as causing human respiratory infections, particularly in patients with cystic fibrosis (CF). Because of their low sensitivity to almost all available antifungal drugs, a better understanding of the pathogenic mechanisms of these fungi is mandatory. Likewise, identification of the origin of the contamination of patients with CF may be helpful to propose prophylactic measures. In this aim, environmental studies were conducted demonstrating that Scedosporium species are abundant in human-made environments and associated with nutrient-rich substrates. Although their natural habitat remains unknown, there is accumulated evidence to consider them as wood-decaying fungi. This study aimed to demonstrate the ability of these fungi to utilize lignocellulose compounds, especially lignin, as a carbon source. First, the lignolytic properties of Scedosporium species were confirmed by cultural methods, and biochemical assays suggested the involvement of peroxidases and oxidases as lignin-modifying enzymes. Scedosporium genomes were then screened using tBLASTn searches. Fifteen candidate genes were identified, including four peroxidase and seven oxidase genes, and some of them were shown, by real-time PCR experiments, to be overexpressed in lignin-containing medium, thus confirming their involvement in lignin degradation.

Lignin Degradation and Modification by the Soil-Inhabiting Fungus Fusarium proliferatum

A soil-inhabiting Fusarium proliferatum strain was capable of transforming or degrading nonlabeled and (sup14)C-labeled industrial, natural, and synthetic lignin. The mineralization rate per day (expressed as the percentage of added radioactivity recovered as to (sup14)CO(inf2)) was maximal during primary metabolism.

Lignin biodegradation by the ascomycete Chrysonilia sitophila

The lignin biodegradation process has an important role in the carbon cycle of the biosphere. The study of this natural process has developed mainly with the use of basidiomycetes in laboratory investigations. This has been a logical approach since most of the microorganisms involved in lignocellulosic degradation belong to this class of fungi. However, other microorganisms such as ascomycetes and also some bacteria, are involved in the lignin decaying process. This work focuses on lignin biodegradation by a microorganism belonging to the ascomycete class, Chrysonilia sitophila. Lignin peroxidase production and characterization, mechanisms of lignin degradation (lignin model compounds and lignin in wood matrix) and biosynthesis of veratryl alcohol are outstanding. Applications of C. sitophila for effluent treatment, wood biodegradation and single-cell protein production are also discussed.