Environmentally relevant fungicide levels modify fungal community composition and interactions but not functioning

Aquatic hyphomycetes (AHs), a group of saprotrophic fungi adapted to submerged leaf litter, play key functional roles in stream ecosystems as decomposers and food source for higher trophic levels. Fungicides, controlling fungal pathogens, target evolutionary conserved molecular processes in fungi and contaminate streams via their use in agricultural and urban landscapes. Thus fungicides pose a risk to AHs and the functions they provide. To investigate the impacts of fungicide exposure on the composition and functioning of AH communities, we exposed four AH species in monocultures and mixed cultures to increasing fungicide concentrations (0, 5, 50, 500, and 2500 mg/L). We assessed the biomass of each species via quantitative real-time PCR. Moreover, leaf decomposition was investigated. In monocultures, none of the species was affected at environmentally relevant fungicide levels (5 and 50 mg/L). The two most tolerant species were able to colonize and decompose leaves even at very high fungicide levels (>= 500 mg/L), although less efficiently. In mixed cultures, changes in leaf decomposition reflected the response pattern of the species most tolerant in monocultures. Accordingly, the decomposition process may be safeguarded by tolerant species in combination with functional redundancy. In all fungicide treatments, however, sensitive species were displaced and interactions between fungi changed from complementarity to competition. As AH community composition determines leaves' nutritional quality for consumers, the data suggest that fungicide exposures rather induce bottom-up effects in food webs than impairments in leaf decomposition. (C) 2021 The Author(s). Published by Elsevier Ltd

Molecular techniques for pathogen identification and fungus detection in the environment

Many species of fungi can cause disease in plants, animals and humans. Accurate and robust detection and quantification of fungi is essential for diagnosis, modeling and surveillance. Also direct detection of fungi enables a deeper understanding of natural microbial communities, particularly as a great many fungi are difficult or impossible to cultivate. In the last decade, effective amplification platforms, probe development and various quantitative PCR technologies have revolutionized research on fungal detection and identification. Examples of the latest technology in fungal detection and differentiation are discussed here

A unique fungal strain collection from Vietnam characterized for high performance degraders of bioecological important biopolymers and lipids

Fungal strains are abundantly used throughout all areas of biotechnology and many of them are adapted to degrade complex biopolymers like chitin or lignocellulose. We therefore assembled a collection of 295 fungi from nine different habitats in Vietnam, known for its rich biodiversity, and investigated their cellulase, chitinase, xylanase and lipase activity. The collection consists of 70 isolates from wood, 55 from soil, 44 from rice straw, 3 found on fruits, 24 from oil environments (butchery), 12 from hot springs, 47 from insects as well as 27 from shrimp shells and 13 strains from crab shells. These strains were cultivated and selected by growth differences to enrich phenotypes, resulting in 211 visually different fungi. DNA isolation of 183 isolates and phylogenetic analysis was performed and 164 species were identified. All were subjected to enzyme activity assays, yielding high activities for every investigated enzyme set. In general, enzyme activity corresponded with the environment of which the strain was isolated from. Therefore, highest cellulase activity strains were isolated from wood substrates, rice straw and soil and similar substrate effects were observed for chitinase and lipase activity. Xylanase activity was similarly distributed as cellulase activity, but substantial activity was also found from fungi isolated from insects and shrimp shells. Seven strains displayed significant activities against three of the four tested substrates, while three degraded all four investigated carbon sources. The collection will be an important source for further studies. Therefore representative strains were made available to the scientific community and deposited in the public collection of the Leibniz-Institute DSMZ–German Collection of Microorganisms and Cell Cultures, Braunschweig

Stream-dwelling fungal decomposer communities along a gradient of eutrophication unraveled by 454 pyrosequencing

Microbial decomposers, especially a fungal group called aquatic hyphomycetes, play a critical role in processing plant litter in freshwaters by increasing its palatability to invertebrate shredders. Traditionally, communities of aquatic hyphomycetes have been assessed through the identification of spores, which misses non-sporulating taxa. Among new technologies, 454 pyrosequencing stands out as most promising for large-scale species identification. However, very few attempts have been made to validate its effectiveness for assessing the diversity of stream-dwelling fungal communities. We attempted to gain greater insight into the diversity of aquatic fungal communities in streams exposed to various degrees of eutrophication by using the 454 pyrosequencing technology. A total of 173,889 ITS2 pyrosequencing reads with hits for fungi were obtained from the 5 investigated streams. The majority of operational taxonomic units (OTUs) belonged to Ascomycota and the identification to the genus level was achieved for 169 OTUs. Of the total, 135,257 reads (ca. 78%) showed close affinities to aquatic hyphomycete species. Pyrosequencing showed declining fungal diversity in the most eutrophic streams, which was congruent with a reduced diversity found through spore identification. Dominance patterns revealed by connecting representative OTUs to ITS sequences from aquatic hyphomycetes were similar to those determined by traditional spore identification techniques. However, 454 pyrosequencing provided a more comprehensive view of fungal diversity; it captured almost twice as many taxa as spore counts. This study validates the effectiveness of 454 pyrosequencing for surveying the diversity of stream-dwelling fungal decomposer communities. Its application may accelerate the use of these communities for monitoring the integrity of freshwaters.The European Regional Development Fund - Operational Competitiveness Programme (FEDER-POFC-COMPETE) (FCOMP-01-0124-FEDER-013954) and the Portuguese Foundation for Science and Technology supported this study (PEst-OE/BIA/UI4050/2014 and PTDC/AACAMB/113746/2009) and S. Duarte (SFRH/BPD/47574/2008). The authors want also to thank to Conceicao Egas from Biocant for the help during interpretation of data from pyrosequencing.info:eu-repo/semantics/publishedVersio