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Symbiotic associations with arbuscular mycorrhizal fungi (AMF) offer an effective indirect mechanism to reduce heavy metal (HM) stress; however, it is still not clear which AMF species are more efficient as bioremediating agents. We selected different species of AMF: Rhizoglomus custos (Custos); Rhizoglomus sp. (Aznalcollar); and Rhizophagus irregularis (Intraradices), in order to study their inoculation in wheat grown in two soils contaminated with two levels of HMs; we tested the phytoprotection potential of the different AMF symbioses, as well as the physiological responses of the plants to HM stress. Plants inoculated with indigenous Aznalcollar fungus exhibited higher levels of accumulation, mainly in the shoots of most of the HM analyzed in heavily contaminated soil. However, the plants inoculated with the non-indigenous Custos and Intraradices showed depletion of some of the HM. In the less-contaminated soil, the Custos and Intraradices fungi exhibited the greatest bioaccumulation capacity. Interestingly, soil enzymatic activity and the enzymatic antioxidant systems of the plant increased in all AMF treatments tested in the soils with both degrees of contamination. Our results highlight the different AMF strategies with similar effectiveness, whereby Aznalcollar improves phytoremediation, while both Custos and Intraradices enhance the bioprotection of wheat in HM-contaminated environments.

Drought is a major threat to plant growth in many parts of the world. During periods of drought, multiple aspects of plant physiology are negatively affected. For instance, water shortages induce osmotic imbalance, inhibit photosynthesis, decrease nutrient uptake, and increases the production of reactive oxygen species (ROS). In this context, it is necessary to develop sustainable strategies for crops that would help mitigate these conditions. In previous studies, endophytic Zopfiella erostrata strains were found to extensively colonize plant roots, forming a profuse melanized mycelium in the rhizosphere, which could be involved in improving water uptake and nutrient mineralization in plants. The aim of this study is to evaluate the effect of different strains of Z. erostrata on stress mitigation in wheat and tomato plants grown under water deficit conditions. General plant growth variables, as well as physiological and biochemical parameters, related to oxidative status were determined. Our data demonstrate that inoculation with both Zopfiella strains had a very significant effect on plant growth, even under water deficit conditions. However, we observed an even more pronounced impact, depending on the plant and strain involved, suggesting a certain degree of plant/strain compatibility. The biochemical aspects, the accumulation of proline, the oxidative damage to lipids, and the activity of antioxidant enzymes varied considerably depending on the endophyte and the plant evaluated.

La inoculación de hongos saprobios principalmente Trichoderma harzianum podrían ser utilizados como parte de una estrategia en la restauración de suelos con una alta contaminación en metales pesados, debido a su capacidad para aumentar la actividad biológica del suelo y disminuir la concentración de plomo y arsénico. Teniendo en cuenta las características físico químicas del suelo estudiado (pH inferior a 4 y conductividad inferior a 3.5 mS) se piensa que es necesario realizar la inoculación de estos microrganismos con la adición de alguna enmienda que incrementen las condiciones nutricionales necesarias para el crecimiento de la planta modelo.

This study aims to evaluate the role of the extraradical mycelium of arbuscular mycorrhizal fungi in Pb transport. We also investigate how these fungi, alone or combined with the mycoremediated dry olive residue (MDOR), provide protection against Pb. We established a container system consisting of a central compartment and two lateral compartments separated by a hydrophobic membrane. The central compartment was filled with sterilized soil in which wheat plants, inoculated and non-inoculated with Funneliformis mosseae, were grown. The lateral compartments were filled with sterile, Pb-contaminated or MDOR-amended soil or combinations of both. In contrast to shoots and grains, wheat roots accumulated larger amounts of Pb with or without applications of MDOR. The extraradical mycelium (ERM) and the glomalin related protein content were significantly boosted by adding MDOR to Pb-contaminated soil samples. Wheat root biomass was decreased as the result of Pb contamination with no increases in plant phosphorous (P) uptake. However, MDOR, when added to Pb-contaminated soil samples, only boosted the accumulation of P in roots, with P content and biomass remaining unchanged in wheat shoots and grains. Our study highlights the role of the ERM in Pb transport its accumulation in wheat roots and how the protection effect exerted by AMF seemed to rely on MDOR application by increasing the P uptake rather than Pb.

El olivo es uno de los cultivos más extensos del mediterráneo que tiene un gran impacto social y económico. El método de obtención del aceite de oliva genera efluentes y mate-riales orgánicos que constituye un gran problema económico y ambiental en el sector olivarero y requieren de una gestión eficaz y comprometida, para garantizar la eficiencia del sector productor, la sostenibilidad medioambiental y mejorar la cadena de valor. La agricultura se enfrenta al enorme desafío de alimentar a una población mundial de más de 6 millones de personas. Para ello es necesario lograr cultivos resistentes de una manera sostenible para lo que es fundamental tener una fertilización adecuada y una bioestimulación con productos de base biológica. El propósito general de nuestra investigación ha sido la valorización del alperujo como residuo de la extracción del aceite de olive, en biofertilizante a traves de su transformación con hongos saprobios, para la mejora en los procesos de fertilización de ecosistemas degradados y la reducción del impacto ambiental del acumulo indiscriminado de alperujo.

Wastewaters polluted with hydrocarbons are an environmental problem that has a significant impact on the natural ecosystem and on human health. Thus, the aim of this research was to develop a bioreactor sorbent technology for treating these polluted waters. A lab-scale plant composed of three 1-L bioreactors with different sorbent materials inside (meltblown polypropylene and granulated cork) was built. Wastewater to be treated was recirculated through each bioreactor for 7 days. Results showed that hydrocarbon retention rates in the three bioreactors ranged between 92.6% and 94.5% of total petroleum hydrocarbons (TPHs) and that after one simple recirculation cycle, no hydrocarbon fractions were detected by gas chromatography/Mass Spectrometry (GC/MS) in the effluent wastewater. In addition, after the wastewater treatment, the sorbent materials were extracted from the bioreactors and deposited in vessels to study the biodegradation of the retained hydrocarbons by the wastewater indigenous microbiota adhered to sorbents during the wastewater treatment. A TPH removal of 41.2% was detected after one month of Pad Sentec carrier treatment. Further, the shifts detected in the percentages of some hydrocarbon fractions suggested that biodegradation is at least partially involved in the hydrocarbon removal process. These results proved the efficiency of this technology for the treatment of these hydrocarbon-polluted-waters.