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The present article, based on reverse logistic, provides an environmentally beneficial and cost-effective method of producing calcium phosphate bioceramics (potassium calcium phosphates) aimed for soil conditioning, by a free-solvent mechanochemical process between eggshell waste and KH2PO4. The K3CaH(PO4)2 and possibly CaKPO4 phases formed provide better nutrient management of P, K and Ca, when applied in soil system the material first release K and form hydroxyapatite and important P and Ca bioavailable source at pH ~ 5, which comprises a large part of many countries soils.

Made available in DSpace on 2022-04-28T19:50:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-01-01 Organic acids produced by soil microorganisms can be useful to promote the release of potassium (K) from potassium mineral rocks (KR), but the complexity of low reactivity minerals limits K solubilization and their use as fertilizer. Here, we investigate the ways that different organic acids (gluconic, oxalic, and citric) can affect the solubilization of potassium minerals, in order to propose process strategies to improve their solubility. For this, evaluations were performed using the model minerals KRpolyhalite (sedimentary mineral), KRfeldspar (igneous mineral), and KCl (commercial fertilizer). For KCl and KRpolyhalite, complete solubilization was achieved using all the organic acids, while for KRfeldspar, the highest K+ solubilization (34.86 mg L−1) was achieved with oxalic acid. The solubility of KRfeldspar was further investigated under submerged cultivation with the filamentous fungus Aspergillus niger, as well as after a mechanochemical grinding treatment. The biotechnological route resulted in solubilized K up to 63.2 mg L−1. The mechanochemical route, on the other hand, increased the release of K by about 8.6 times (993 mg L−1) compared to the natural mineral, due to the greater fragmentation of the particles after the treatment (with a surface area about 2.5 times higher than for the in natura KRfeldspar). These findings demonstrated the potential of applying biotechnological and mechanochemical routes with organic acids to improve the solubilization of K present in low reactivity mineral rocks, indicating the possible use of these minerals in more sustainable agricultural practices. Laboratório Nacional de Nanotecnologia Para o Agronegócio (LNNA) Embrapa Instrumentação, Rua 15 de Novembro, 1452, Centro, SP Programa de Pós-Graduação Em Engenharia Química Universidade Federal de São Carlos (UFSCar), Rodovia Washington Luiz, km 235, SP Instituto de Química Universidade Estadual Paulista (UNESP), Avenida Professor Francisco Degni, 55, Jardim Quitandinha, SP Instituto de Química Universidade Estadual Paulista (UNESP), Avenida Professor Francisco Degni, 55, Jardim Quitandinha, SP

Fertilization is essential to provide suitable conditions for plant development and crop productivity, but the environmental cost of fertilizer production is a drawback for achieving a sustainable agriculture. Using unprocessed (raw) nutrient sources such as elemental sulfur (S0) and mineral oxides (ZnO, MnO, CuO) as fertilizers reduces the environmental impact, although they are not readily available to plants. Thus, we developed a polymeric coating material based on gelatinized starch loaded with S0 and oxides, and selected microorganisms – Aspergillus niger and Aciditiobacillus thiooxidans – aiming at a multi-nutrient fertilizer in which the biological components improve the solubility of the low reactive nutrient sources. The acidifying capacity of both microorganisms led to a synergic release and increased the availability of micronutrients and the elemental sulfur oxidation rate. For instance, the polymeric coating composition enabled a sulfate release of up to 76.4 and 71.3% for A. niger and A. thiooxidans, respectively. This innovative system can effectively supply nutrients to plants through the use of cheap and low reactivity nutrient sources with the advantage that it can be applied on currently used fertilizer granules, making easier the adoption by producers.

Intensive fertilization has been required to provide nutrients for plant growth under the current agricultural practices being applied to meet the global food demands. Micronutrients such as zinc, manganese, and copper are required in small quantities when compared to macronutrients (such as nitrogen, phosphorus and potassium), but they are essential for the plant growth cycle and consequently for increasing productivity. Mineral oxides such as ZnO, MnO, and CuO are used in agriculture as micronutrient sources, but their low solubility limits practical applications in plant nutrition. Similarly, elemental sulfur (S0) can provide a high-concentration source of sulfate, but its availability is limited by the ability of the soil to promote S0 oxidation. We propose here the integration of these nutrients in a composite based on a biodegradable starch matrix containing mineral oxides and S0 in a dispersion that allowed encapsulation of the acidifying agent Aspergillus niger, a native soil fungus. This strategy effectively improved the final nutrient solubility, with the composite starch/S0/oxidemixture multi-nutrient fertilizer showing remarkable results for solubilization of the oxides, hence confirming a synergic effect of S0 oxidation and microbial solubilization. This composite exhibited an extended shelf life and soil-plant experiments with Italian ryegrass (Lolium multiflorum Lam.) confirmed high efficiencies for dry matter production, nutrient uptake, and recovery. These findings can contribute to the development of environmentally friendly fertilizers towards a more sustainable agriculture and could open up new applications for formulations containing poorly soluble oxide sources.

The objective of this work was to evaluate the solubilization of phosphorus from a phosphate rock by Aspergillus niger, under solid-state cultivation (SSC) in sugarcane (Saccharum officinarum) bagasse, by maximizing the efficiency of citric acid production. The phosphate rock (IPR) chosen for the study is a type of igneous rock with a very low phosphorus solubility, obtained from the Itafós company, in Arraias, in the state of Tocantins, Brazil. The rotatable central composite design (RCCD) was used as a statistical tool to evaluate the effect of the concentrations of the carbon source (sucrose) and of the IPR on the SSC medium as a strategy to improve P solubilization. In the process without the IPR, there was a citric acid production of up to 300 g per kilogram of substrate. The experiments in the RCCD showed that the addition of the IPR affected citric acid production, with values of solubilized P ranging from 1.44 to 2.72 g per kilogram of substrate and of solubilized P yield from 12.96 to 48.94%. The analysis of the solubilized P/sucrose ratio showed favorable conditions for P solubilization and citric acid production. The obtained solubilized P values are promising considering that the IPR has a very low solubilization, with only 8.6% P2O5. Overall, these findings could contribute to the development of biotechnological processes for producing eco-friendly phosphate fertilizers, as an alternative for a more sustainable agriculture. Resumo: O objetivo deste trabalho foi avaliar a solubilização de fósforo de rocha fosfática por Aspergillus niger, em cultivo em estado sólido (CES) em bagaço de cana-de-açúcar (Saccharum officinarum), por meio da maximização da eficiência de produção de ácido cítrico. A rocha fosfática (IPR) escolhida para o estudo é um tipo de rocha ígnea com solubilização de fósforo muito baixa, obtida da empresa Itafós, em Arraias, no estado do Tocantins. Utilizou-se o delineamento composto central rotacional (DCCR) como ferramenta estatística para avaliar o efeito das concentrações da fonte de carbono (sacarose) e da IPR no meio para CES como estratégia para melhorar a solubilização de P. Para o processo sem a IPR, houve produção de ácido cítrico de até 300 g por quilograma de substrato. Os experimentos em DCCR mostraram que a adição da IPR afetou a produção de ácido cítrico, com valores de P solubilizado de 1,44 a 2,72 g por quilograma de substrato e rendimento de P solubilizado de 12,96 a 48,94%. Além disso, a análise da razão P solubilizado/sacarose mostrou condições favoráveis para solubilização de P e produção de ácido cítrico. Os valores de P solubilizado são promissores, ao se considerar que a IPR apresenta baixa solubilização, com apenas 8,6% de P2O5. No geral, esses resultados podem contribuir para o desenvolvimento de processos biotecnológicos, para a produção de fertilizantes fosfatados ambientalmente favoráveis, como alternativa para uma agricultura mais sustentável.

Phosphate chemical fertilizers are extensively used to improve agricultural productivity. However, the production of these fertilizers is expensive and can cause environmental damage. Alternatively, microbial solubilization of rock phosphate (RP) is a potential strategy for obtaining biofertilizers. This paper proposes the use of a novel combined mechanical-biological approach to produce soluble phosphate by cultivation of a selected strain of Aspergillus niger using RP with particle sizes in the nanometric range. The effect of Bayovar RP particle size on phosphate solubilization was analyzed for cultivations under submerged (SmF) and solid-state fermentation (SSF). The RP particle size played a key role in phosphate solubilization, with gains of up to 60% for SmF and 115% for SSF. The mechanical treatment of RP, combined with the biological cultivation process, resulted in an optimized solubilization of P, and it was shown that even short periods of milling could be highly effective. This proposed strategy could contribute to advances in the current bio-based economy and assist future developments in large-scale industrial production of biofertilizers.

The volatilization of nitrogen (N) in the form of greenhouse gases is the most significant environmental impact associated with fertilizer use. Losses of N may exceed 50 % of the quantity applied, especially when the nitrogen source is urea. This work describes an overcoating system for urea granules, based on starch (from maize or cassava crops) and elemental sulfur (S°) composites applied over a castor oil-based poly(urethane) coating, biologically activated by Aspergillus niger (A. niger). The results indicated that the system provided good control of urea dissolution and reduced NH3 volatilization after 28 days by 45.9 and 64.9 % for the U4%StA.niger and U4%CaA.niger treatments, compared to the control (uncoated urea). This effect occurs from the synergy between the starch and oil-based polyurethane coatings, improving the microorganism activity, due to increased acidity production. The findings support the use of A. niger in fertilizer management and evidence the suitability of natural-based polymer coatings for controlling N delivery and reducing environmental impacts.

In this work was optimized the composition of fermentation media for the growth of Phoma sp., which is a potential fungi to be used for the production of bioherbicide. For this purpose, the fungal growth was optimized, firstly, using synthetic media containing glucose, peptone and yeast extract. In a second moment, glucose was changed by sucrose food-grade and peptone and yeast extract by corn steep liquor and the growth optimized again. The optimized composition of synthetic media was glucose and peptone 20 g.L -1 , yeast extract 7.5 g.L -1 and initial pH of 6.0. For industrial media, the optimized composition was sucrose 20 g.L -1 , CSL 8% and initial pH of 6.0. At these conditions, maximum fungal biomass were 22 and 33 g.L -1 , respectively. This study shows that industrial medium was better than synthetic medium and provides cost savings for a possible increase in production scale.

In this work the bioherbicide production from Phoma sp. by solid-state fermentation was optimized. Agroindustrial residues such as bagasse, soybean bran and corn steep liquor were used as substrate. The bioherbicide was extracted from the fermented solid and the supernatant was applied for the control of the target plant. The evaluated responses in the bioassay were plant height, root length, fresh and dry weight, number of flowers and phytotoxicity. The results in the bioassays demonstrated that the bioherbicide presented activity towards the target plant and the intensity of the effect was influenced by the formulation of the fermentation medium. The optimized condition for bioherbicide production was (wt%): moisture content 70.0, soybean bran content 30.0 and corn steep liquor (CSL) 20.0, it being possible to obtain an injury phytotoxicity level of 40. The bioherbicide showed a mode of action based on the inhibition of carotenoid biosynthesis.