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A consortium of fungal isolates may improve phytoremediation by stimulating root growth whereas biochar reduces metal leaching in contaminated soils. We combined these treatments to evaluate to what extent Jacaranda mimosifolia D. Don seedlings extract metals (Cu, Mn, and Zn) and reduce leaching in soil columns. Contamination treatments were established by combining Cu (200 mg dm−3), Mn (450 mg dm−3), and Zn (450 mg dm−3). A spore suspension of five fungal isolates (Beauveria bassiana, Metarhizium anisopliae, Pochonia chlamydosporia, Purpureocillium lilacinum, and Trichoderma asperella) was sprayed on plant shoots and the soil surface. Biochar (1% m/v) was produced by the pyrolysis of wood sawdust and applied to the soil surface. Finally, control treatments were established in a completely randomized block design. The consortium of fungal isolates increased shoot and root mass, improved the translocation potential of Cu (translocation factor (TF) of 0.25), Mn (TF of 2.93), and Zn (TF of 1.79) from roots to shoots, and increased the total accumulated mass of Mn and Zn in shoots and roots. Biochar applications improved Cu, Mn, and Zn translocation and increased the total accumulated mass of shoot Mn. Moreover, a combination of fungal isolates and biochar increased the translocation factor to 0.44 for Cu, 1.70 for Mn, and 1.34 for Zn relative to the treatment with J. mimosifolia in contaminated soil (CJ); increased shoot Cu concentration; and reduced total leached Cu by a factor of 22.9, Mn by 5.5, and Zn by 22.9 relative to the CJ treatment. A photochemical profile, based on chlorophyll a fluorescence, showed that Jacaranda mimosifolia was tolerant to contaminated soil and is a potential phytoremediator of Cu, Mn, and Zn. Overall, the consortium of fungal isolates and biochar improved the efficiency of phytoremediation by concentrating metals in plant tissue and reducing the risks of leaching.

Soil phosphatase is a biochemical indicator of soil quality, and its activity plays a key role in the productivity of terrestrial ecosystems. Modeling the kinetic parameters of soil phosphatase is central to integrate ecological processes in tropical soils under different land use ecosystems. The goal of this study was to determine the kinetic parameters of soil acid phosphatase (APsoil) and assess the relationship between its kinetic parameters and soil quality indicators in two topsoil layers (at the 0–5 and 5–10 cm depths) from an Oxisol under the native Cerrado, pine, soya and sugarcane ecosystems. APsoil activity was assessed with different substrate concentrations (0, 0.75, 1.5, 3, 4.5, 6, 12 and 18 mmol L−1 of p-nitrophenol phosphate in buffer) at 37 °C, pH 6.5 and acetate buffer. The kinetic parameters (Km and Vmax) were estimated using the Michaelis-Menten (M-M) and Eadie-Hofstee (E-H) equations. Soil organic carbon (SOC), total nitrogen (TN), soil microbial respiration (SMR), microbial biomass carbon (MBC) and nitrogen (MBN), and dehydrogenase activity (DHA) were also measured. In both models, the highest Vmax and Km values were found in native Cerrado soil, followed by pine soil in two surface layers. Soya and sugarcane soils presented low Km values, showing a great substrate affinity of soil phosphatase in these ecosystems. The M-M model estimated higher Vmax and Km values than the E-H model. The M-M model did not show any difference in Km between the two layers of ecosystems, but the E-H model revealed significant differences between the layers with the lowest Km values at the 5–10 cm depth. The results revealed that Km has a significant correlation with SOC (r = 0.71), TN (r = 0.72), MBC (r = 0.75) and MBN (r = 0.75). The results also showed a greater correlation between the Km of the E-H model and soil quality indicators than the M-M model. Our study shows the importance of modeling the APsoil in the Brazilian Cerrado in relation to land use ecosystems, depths and the model applied.

Some fungal isolates affect soil by solubilizing nutrients and promoting plant growth; however, little is known about the effects of applications of these isolates on soil biology and fertility. Thus, the aim of the present study was to identify the effect of five well-known fungal endophytes, namely, Beauveria bassiana, Trichoderma asperellum, Metarhizium anisopliae, Purpureocillium lilacinum and Pochonia chlamydosporia on plant growth and the biological and chemical properties of the rhizosphere soil under Phaseolus vulgaris L. Spore suspensions from each of the five fungal isolates and three consortia (T. asperellum/P. lilacinum; B. bassiana/M. anisopliae; and a consortium of all five species) were applied to seeds, soil and shoots of common bean plants in a greenhouse assay. All fungal treatments resulted in greater root colonization by arbuscular mycorrhizal fungi (53.6% of root length in control and 66.6%–77.0% in the remaining treatments), concentration of rhizosphere soil magnesium (10%–33% higher than the control) and base saturation of cation exchange capacity (48.5% in control and 50.7%–55.1% in all other treatments). Applications of B. bassiana/M. anisopliae and of the consortium of five fungal isolates increased fluorescein diacetate hydrolysis (FDA) by 63% and 72% respectively, relative to the control. β-Glucosidase activity was lower in the applications of T. asperellum (20% lower), P. chlamydosporia (15% lower) and B. bassiana/M. anisopliae (18% lower) than in the control. Acid phosphatase was lower in the M. anisopliae (29%), P. chlamydosporia (22%) and T. asperellum/P. lilacinum (21%) and B. bassiana/M. anisopliae consortia (27%) treatments. Some fungal isolate applications stimulated shoot accumulations of N, P, B, Cu, Fe, Mn and Zn (mass). Applications of B. bassiana, T. asperellum, M. anisopliae, P. chlamydosporia and the consortium of five fungal isolates resulted in higher root dry mass relative to the control, while treatments of P. lilacinum, the B. bassiana/M. anisopliae consortium and the five fungal isolates resulted in higher dry shoot weight. Arylsulfatase activity and phosphate solubilizing fungi were not affected by the treatments. The values of the rhizosphere soil chemical and biological, accumulated nutrient mass and plant growth variables were highest in the (A) five fungi consortium, followed, in descending order, by (B) the B. bassiana/M. anisopliae consortium; (C) T. asperellum, B. bassiana and M. anisopliae; and (D) the T. asperellum/P. lilacinum consortium, P. lilacinum and P. chlamydosporia. These findings may benefit sustainable agricultural management systems that use fungal isolate treatments to eliminate or reduce the environmental impacts of mineral fertilizers and pesticides.

The Araucaria forest is a sub-type of Atlantic Forest and it is critically endangered because of deforestation. Despite significant researchers’ attention, little is known about the microbial and functional soil diversity of this ecosystem. Our aim was to assess structural diversity (phospholipid fatty acid; PLFA), functional diversity (Biolog ecoplates) and physicochemical soil properties to identify which indicators are the most sensitive to alterations in the Araucaria ecosystems. Soils of three different areas (disturbed, reforested, and native Araucaria forest soils), in two parks of Southeast Brazil, were collected in contrasting seasons (dry and rainy). Principal components analysis (PCA) showed that fatty acid profiles, Biolog and physicochemical properties in Araucaria forest soils were more dissimilar between the different park geographic locations than by forest disturbance levels. However, discriminant analysis identified several variables with greater power to discriminate among forest disturbance levels (native, disturbed, and reforested) within each season. Reforested soils were lower in pH, Al+3, and base cation content compared to disturbed and native soils. Soils disturbed by recreational and understory deforestation were sandier in texture and elevated in P compared to native and deforested soils. Native soil microbial communities utilized certain Biolog substrates to a greater extent, depending on season, compared to communities of disturbed and reforested soils. The best discriminating variable among native, disturbed, and reforested soils for both seasons was γ-hydroxybutyric acid consumption, which was positively related to native, and negatively correlated to disturbed and reforested soils. Thus, γ-hydroxybutyric acid consumption may be a useful indicator to monitor the recovery of reforested and disturbed Araucaria soils in reference to its native state.

Processed organic agricultural byproducts such as liquid organic fertilizer (LOF) are promising alternatives that can improve crop productivity while reducing mineral fertilizer use and improving sustainability. The effects on beneficial soil organisms, such as arbuscular mycorrhizal (AM) fungi and phosphate solubilizing microorganisms (PSM), caused by LOF spraying on shoots is poorly understood. Therefore, we evaluated how AM colonization and soil PSM are affected by LOF spraying on common beans (Phaseolus vulgaris L.) grown in a greenhouse. The LOF was obtained by anaerobically fermenting a mixture of fresh water, cattle manure, bovine milk, sugarcane molasses and mineral salts. LOF was applied twice on the plant shoots. Fresh and dry mass of root and shoot, P content, P accumulation in the shoots and AMF spore counts in the soil were not LOF dose dependent. However, we found that a 5% LOF application stimulated AM colonization and led to dose-dependence for calcium and aluminium phosphate solub...

Plant growth and arbuscular mycorrhizal colonization were studied in sugarcane, corn and soybean by applying five plant growth promoting fungi: Beauveria bassiana, Metarhizium anisopliae, Pochonia chlamydosporia, Purpureocillium lilacinum, and Trichoderma asperella. Sugarcane, corn and soybean were grown in pots under two treatments: (1) inoculation with the fungal consortium and (2) control without inoculation. In the inoculated treatment, fungal spore suspension were applied to the seeds and shoots were sprayed every 28 days. Means were analyzed by analysis of variance and Tukey’s test at 5% probability level. The experiment was arranged in a completely randomized design, with six replications. Fungi consortium mediate root growth in soybean and corn, and arbuscular mycorrhizal colonization in soybean and sugarcane. These findings are probably caused by the fungi producing phytohormones and inducing the plants to synthesize phytohormones: auxins for root growth; and jasmonic, abscisic, and salicylic acids with a role in the regulation of mycorrhizal colonization. These effects are important when seeking conservation strategies in agriculture and livestock production, since Fungi consortium can better mediate soil resource acquisition, promoting greater absorption of nutrients and water.