Selection and acclimatization of strains of edible mycorrhizal fungi for improved field persistence

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Growth dynamic of dual culture systems comprising ectomycorrhizal fungi and mycorrhiza helper bacteria

Ectomycorrhizal fungi are ubiquitous root symbionts that associate with the majority of forest trees and often have a crucial role on plant survival and growth in impoverished soils. Within the vast community of soil microorganisms, the mycorrhiza helper bacteria (MHB) are recognizably one of the groups that most directly affect fungal growth and mycorrhiza establishment. Although their positive effect on the mycorrhizal partnership has been previously reported, the specificity of such association is high and the dynamics not yet fully understood. Many studies evaluated the impact of bacteria on fungal growth but the reciprocal has received little attention. The present study aimed to evaluate the growth dynamics of co-culturing fungi and bacteria, under both perspectives. Bacillus pumilus was chosen for its capability to promote the growth of Suillus granulatus in a dual culture system with a low nutrient medium. To assess the impact of fungal exudates on bacterial growth, different quantities of fungal culture medium were added to MMN medium containing a Bacillus pumilus inoculum and bacterial growth was monitored. To evaluate the influence of Bacillus pumilus on fungal growth, an experiment was setup where the bacterium was added at two different phases of fungal growth, lag phase and exponential phase. A control without bacteria was also performed. Bacterial growth was monitored through OD readings and fungal growth was assessed through dry weight and ergosterol content. The experience was held for 33 days, with sampling every three days. Triplicates for each treatment were performed. Results from the first experiment showed that fungal exudates influenced the growth of bacteria with a pronounced extension of the lag phase. In the second experiment, fungal growth was completely inhibited when bacteria was added at the fungal lag phase. A different outcome was observed when the bacterium was added in the exponential phase. Results suggest that the regulation of the concentration at which the bacterium is present may be a key factor to optimization of the use of bacteria as MHB

The use of multiple correspondence analysis to explore associations between categories of qualitative variables in healthy ageing

In pressPopulation studies are often characterized by a plethora of data that includes quantitative to qualitative variables. The main focus of this study was to illustrate the applicability of multiple correspondence analysis (MCA) in detecting and representing underlying structures in large datasets used to investigate cognitive ageing. Principal component analysis (PCA) was used to obtain main cognitive dimensions (based on the continuous neurocognitive test variables) and MCA to detect and explore relationships of cognitive, clinical, physical and lifestyle categorical variables across the low-dimensional space. Altogether the technique allows to not only simplify complex data, providing a detailed description of the data and yielding a simple and exhaustive analysis, but also to handle a large and diverse dataset comprised of quantitative, qualitative, objective and subjective data. Two PCA dimensions were identified (general cognition/executive function and memory) and two main MCA dimensions were retained. As expected, poorer cognitive performance was associated with older age, less school years, unhealthier lifestyle indicators and presence of pathology. Interestingly, the first MCA dimension indicated the clustering of general/executive function and lifestyle indicators and education, while the second association between memory and clinical parameters and age. The clustering analysis with object scores method was used to identify groups sharing similar characteristics within each of the identified dimensions. Following MCA findings, the weaker cognitive clusters in terms of memory and executive function comprised individuals with characteristics contributing to a higher MCA dimensional mean score (age, less education and presence of indicators of unhealthier lifestyle habits and/or clinical pathologies). MCA provided a powerful tool to explore complex ageing data, covering multiple and diverse variables, showing not only if a relationship exists between variables but also how they are related, offering at the same time statistical results can be seen both analytically and visually.EC -European Commissio

The use of canonical correlation analysis to assess the relationship between executive functioning and verbal memory in older adults

Executive functioning (EF), which is considered to govern complex cognition, and verbal memory (VM) are constructs assumed to be related. However, it is not known the magnitude of the association between EF and VM, and how sociodemographic and psychological factors may affect this relationship, including in normal aging. In this study, we assessed different EF and VM parameters, via a battery of neurocognitive/psychological tests, and performed a Canonical Correlation Analysis (CCA) to explore the connection between these constructs, in a sample of middle- aged and older healthy individuals without cognitive impairment (N = 563, 50+ years of age). The analysis revealed a positive and moderate association between EF and VM independently of gender, age, education, global cognitive performance level, and mood. These results confirm that EF presents a significant association with VM performance.This work was funded by the European Commission (FP7): “SwitchBox” (Contract HEALTH-F2-2010-259772) and co-financed by the Portuguese North Regional Operational Program (ON.2–O Novo Norte) under the National Strategic Reference Framework (QREN), through the European Regional Development Fund (FEDER). P.S.M. is supported by a “MyHealth” project (Contract DoIT-13853) doctoral fel- lowship and N.C.S. by a “SwitchBox” project post-doctoral fellowship

Structural basis of proton-coupled potassium transport in the KUP family

Potassium homeostasis is vital for all organisms, but is challenging in single-celled organisms like bacteria and yeast and immobile organisms like plants that constantly need to adapt to changing external conditions. KUP transporters facilitate potassium uptake by the co-transport of protons. Here, we uncover the molecular basis for transport in this widely distributed family. We identify the potassium importer KimA from Bacillus subtilis as a member of the KUP family, demonstrate that it functions as a K+/H+ symporter and report a 3.7 Å cryo-EM structure of the KimA homodimer in an inward-occluded, trans-inhibited conformation. By introducing point mutations, we identify key residues for potassium and proton binding, which are conserved among other KUP proteins

Selection of high performance strains of edible mycorrhizal fungi for improved abiotic stress resistance

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Non-invasive monitoring of stress response of urban trees inoculated with EcM

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Bioremediation on anthropogenic affected areas: Ectomycorrhizal and plant growth bacteria as promoters of pine establishment

The recovery of damaged areas due to inadequate farming policies and increased industrial sediment deposition, have contaminated not only soil and surrounding areas but also other natural resources. The potential use of disturbed sites for agriculture and forestry is jeopardised and their remediation is critical and expensive. The utilization of biotechnological tools, such as plant growth promoting bacteria (PGPB) and ectomycorrhizal fungi (ECM) could help remediation of such soils as they can be used as plant facilitators for land recovery. The aim of this study was to assess the potential of PGPB and ECM to enhance the growth of Pinus pinaster in antropogenic sediments and forest soil. Pine seedlings were inoculated with Suillus bovinus, Pisolithus tinctorius and Paxillus involutus, and co-inocualted with Bacillus spp. and Mesorhizobium spp. Plants were harvested after 6 month growth and parametric and nutritional data determined. Results show that P. involutus increased seedling growth(height) in industrial sediments soil, whereas in forest soil, plant performance was higher with S. bovinus. The effect of inoculation on the fungal communityin seedling roots and bacterial rhizosphere was also analysed by PCR-DGGE and differences arose between inoculated and uninoculated soil, indicating that PGPB and ECM may significantly influence the plant growth performance over a period of time. The study shows that PGPB and ECM fungi may be used as a biotechnology tool contributing to the successful plant establishment in disturbed environments

Benefits of ectomycorrhizal inoculation of tilia tomentosa seedlings on plant growth and vigor depends on substrate pH

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