Amino acid and soluble protein cocktail from waste keratin hydrolysed by a fungal keratinase of Paecilomyces marquandii

Waste bovine hooves and horns were enzymatically hydrolysed into soluble products intended for foliar fertilizer. With the powdered keratin at 50°C and pH 8 between 34 to nearly 60% of nitrogen was solubilized in 5 h, depending on the enzyme concentration. The reaction could further be improved by steam pretreatment of the keratin, resulting in 98% solubilisation of the nitrogen. The products of hydrolysis consisted of a mixture of soluble proteins, peptides, and free amino acids. Among the latter, 18 common amino acids were detected. Several of them were previously recognized to have a positive effect on plants. Nonpolar neutral, basic, and sulphur amino acids were present in relatively large amounts, while proline and tryptophan were not found. Comparison with other protein hydrolysates aimed for fertilizer suggests that keratin degradation products, obtained by enzymatic hydrolysis, have potential to be used for foliar fertilization, alone or in a combination with another complementary hydrolysate of a different source, such as skin or plant proteins.     

Elastase activity of fungi with anamorphs similar to Coccidioides immitis

The elastin digestion assay was examined to determine if it would facilitate the identification of Coccidioides immitis when non-pathogenic fungi resembling C. immitis are encountered. Fungal isolants tested have anamorphs that closely resemble the macroscopic or microscopic morphology of C. immitis. Elastin hydrolysis was measured by elastin-agar plate assays. Approximately 80% of the isolants hydrolyzed elastin; thus, the elastin digestion assay as a differential test appears to have little value.     

Response of fungal, bacterial and ureolytic communities to synthetic sheep urine deposition in a grassland soil

In grazed pastures, soil pH is raised in urine patches, causing dissolution of organic carbon and increased ammonium and nitrate concentrations, with potential effects on the structure and functioning of soil microbial communities. Here we examined the effects of synthetic sheep urine (SU) in a field study on dominant soil bacterial and fungal communities associated with bulk soil and plant roots (rhizoplane), using culture-independent methods and a new approach to investigate the ureolytic community. A differential response of bacteria and fungal communities to SU treatment was observed. The bacterial community showed a clear shift in composition after SU treatment, which was more pronounced in bulk soil than on the rhizoplane. The fungal community did not respond to SU treatment; instead, it was more affected by the time of sampling. Redundancy analysis of data indicated that the variation in the bacterial community was related to change in soil pH, while fungal community was more responsive to dissolution of organic carbon. Like the universal bacterial community, the ureolytic community was influenced by the SU treatment. However, different taxa within the ureolytic bacterial community responded differentially to the treatment. The ureolytic community comprised of members from a range of phylogenetically different taxa and could be used to measure the effect of environmental perturbations on the functional diversity of natural ecosystems.     

Beetle grazing reduces natural infection of Rumex obtusifolius by fungal pathogens

In previously reported laboratory experiments, infection of Rumex obtusifolius by the rust fungus Uromyces rumicis was decreased on leaves which had prior herbivory by the beetle Gastrophysa viridula . In this paper we investigate whether this interaction is robust for natural infection by a variety of fungi in field experiments carried out in spring and autumn with plants given different levels of nitrogen fertilization. Grazing by G. viridula led to a decrease in lesion density of Ramularia rubella and Venturia rumicis in the spring and V. rumicis and U. rumicis in the autumn experiment. For V. rumicis and U. rumicis significant reductions in lesion density occurred on the undamaged leaves of damaged plants, compared with similar leaves on undamaged plants, suggesting systemic induced resistance. This induced resistance was usually independent of the amount of nitrogen fertilization, although the inhibitory effect of grazing on R. rubella in the spring and V. rumicis in the autumn experiment was enhanced by increasing nitrogen fertilization and was inhibited by increasing nitrogen fertilization for V. rumicis in the spring. In both experiments, the lesion density of V. rumicis was greater on leaves on which R. rubella was also present, and the presence of U. rumicis in the autumn experiment was linked to a similar but greater effect on V. rumicis lesion density. We found no evidence of induced resistance by fungi against fungi in these experiments. We highlight the complex interactions between inhibitory and facilitatory processes acting on leaf fungal infection. These results are compared with the proposed molecular mechanisms of induced resistance(s) and we consider the benefits of closer integration between molecular and ecological investigations of induced resistances that occur in the field.     

Alien plants associate with widespread generalist arbuscular mycorrhizal fungal taxa: evidence from a continental‐scale study using massively parallel 454 sequencing

Aim The biogeography of arbuscular mycorrhizal (AM) fungi is poorly understood, and consequently the potential of AM fungi to determine plant distribution has been largely overlooked. We aimed to describe AM fungal communities associating with a single host‐plant species across a wide geographical area, including the plant’s native, invasive and experimentally introduced ranges. We hypothesized that an alien AM plant associates primarily with the geographically widespread generalist AM fungal taxa present in a novel range. Location Europe, China. Methods We transplanted the palm Trachycarpus fortunei into nine European sites where it does not occur as a native species, into one site where it is naturalized (Switzerland), and into one glasshouse site. We harvested plant roots after two seasons. In addition, we sampled palms at three sites in the plant’s native range (China). Roots were subjected to DNA extraction, polymerase chain reaction (PCR) and 454 sequencing of AM fungal sequences. We analysed fungal communities with non‐metric multidimensional scaling (NMDS) ordination and cluster analysis and studied the frequency of geographically widespread fungal taxa with log‐linear analysis. We compared fungal communities in the roots of the palm with those in resident plants at one site in the introduced range (Estonia) where natural AM fungal communities had previously been studied. Results We recorded a total of 73 AM fungal taxa. AM fungal communities in the native and introduced ranges differed from one another, while those in the invasive range contained taxa present in both other ranges. Geographically widespread AM fungal taxa were over‐represented in palm roots in all regions, but especially in the introduced range. At the Estonian site, the palm was colonized by the same community of widespread AM fungal taxa as associate with resident habitat‐generalist plants; by contrast, resident forest‐specialist plants were colonized by a diverse community of widespread and other AM fungal taxa. Main conclusions AM fungal communities in the native, invasive and experimentally introduced ranges varied in taxonomic composition and richness, but they shared a pool of geographically widespread, non‐host‐specific taxa that might support the invasion of a generalist alien plant. Our dataset provides the first geographical overview of AM taxon distributions obtained using a single host‐plant species.     

Communities of fungal endophytes in tropical forest grasses: highly diverse host- and habitat generalists characterized by strong spatial structure

Plant-symbiotic fungi influence the structure and function of all terrestrial ecosystems, but factors shaping their distributions in time and space are rarely well understood. Grasses (Poaceae), which first arose and diversified in tropical forests, harbor diverse but little-studied endophytes in the lowland forests of Panama. We used sequence data for 402 isolates from two sampling years, 11 host species, and 55 microsites at Barro Colorado Island, Panama to investigate the influence of host and habitat (soil type, forest age) in shaping endophyte diversity and composition. In contrast to previous studies, we found no evidence for host- or habitat specificity. Instead, endophytes demonstrated strong spatial structure consistent with dispersal limitation, with community similarity decaying markedly over a scale of hundreds of meters. Spatial structure that is independent of host species and habitat reveals remarkable heterogeneity of endophyte–host associations at small geographic scales and adds an important spatial component to extrapolative estimates of fungal diversity.