A biotechnological strategy for the production of an alternative P fertilizer is described in this work. The fertilizer was produced through rock phosphate (RP) solubilization by Aspergillus niger in a solid-state fermentation (SSF) with sugarcane bagasse as substrate. SSF conditions were optimized by the surface response methodology after an initial screening of factors with significant effect on RP solubilization. The optimized levels of the factors were 865 mg of biochar, 250 mg of RP, 270 mg of sucrose and 6.2 ml of water per gram of bagasse. At this optimal setting, 8.6 mg of water-soluble P per gram of bagasse was achieved, representing an increase of 2.4 times over the non-optimized condition. The optimized SSF product was partially incinerated at 350°C (SB-350) and 500°C (SB-500) to reduce its volume and, consequently, increase P concentration. The post-processed formulations of the SSF product were evaluated in a soil–plant experiment. The formulations SB-350 and SB-500 increased the growth and P uptake of common bean plants (Phaseolus vulgaris L.) when compared with the non-treated RP. Furthermore, these two formulations had a yield relative to triple superphosphate of 60% (on a dry mass basis). Besides increasing P concentration, incineration improved the SSF product performance probably by decreasing microbial immobilization of nutrients during the decomposition of the remaining SSF substrate. The process proposed is a promising alternative for the management of P fertilization since it enables the utilization of low-solubility RPs and relies on the use of inexpensive materials.

Background Pisolithus microcarpus (Cooke & Massee) G. Cunn is a gasteromycete that produces closed basidiocarps in symbiosis with eucalypts and acacias. The fungus produces a complex basidiocarp composed of peridioles at different developmental stages and an upper layer of basidiospores free of the hyphae and ready for wind dispersal upon the rupture of the basidiocarp pellis. During basidiosporogenesis, a process that takes place inside the basidiocarp peridioles, a conspicuous reserve of fatty acids is present throughout development. While several previous studies have described basidiosporogenesis inside peridioles, very little is known about gene expression changes that may occur during this part of the fungal life cycle. The objective of this work was to analyze gene transcription during peridiole and basidiospore development, while focusing specifically on cell cycle progression and lipid metabolism.ResultsThroughout different developmental stages of the peridioles we analyzed, 737 genes were regulated between adjacent compartments (>5 fold, FDR-corrected p-value < 0.05) corresponding to 3.49% of the genes present in the P. microcarpus genome. We identified three clusters among the regulated genes which showed differential expression between the peridiole developmental stages and the basidiospores. During peridiole development, transcripts for proteins involved in cellular processes, signaling, and information storage were detected, notably those for coding transcription factors, DNA polymerase subunits, DNA repair proteins, and genes involved in chromatin structure. For both internal embedded basidiospores (hereto referred to as “Internal spores”, IS) and external free basidiospores (hereto referred to as “Free spores”, FS), upregulated transcripts were found to involve primary metabolism, particularly fatty acid metabolism (FA). High expression of transcripts related to β-oxidation and the glyoxylate shunt indicated that fatty acids served as a major carbon source for basidiosporogenesis.ConclusionOur results show that basidiocarp formation in P. microcarpus involves a complex array of genes that are regulated throughout peridiole development. We identified waves of transcripts with coordinated regulation and identified transcription factors which may play a role in this regulation. This is the first work to describe gene expression patterns during basidiocarp formation in an ectomycorrhizal gasteromycete fungus and sheds light on genes that may play important roles in the developmental process.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-017-3545-5) contains supplementary material, which is available to authorized users.

Agradeço ao meu anjo da guarda que sempre rege pelo meu bem-estar. Aos meus pais, Ana Dalva e Anastácio, por ter me criado no melhor que puderam e sempre serem meu apoio. Às minhas irmãs, Letícia, por fazer com que meus dias terem mais risadas, e Aline, por ser uma segunda mãe da qual sempre me apoiou e me direcionou. Ao Cristiano, por ter feito meus dias em Piracicaba melhores e pela ajuda imensurável na dissertação. Ao Guilherme Furlan, pela amizade, confiança e ter ajudado durante a chegada na Esalq. Ao meu amigo Josimar, que vem ajudando a tantos anos, da caneta a enxada. As companheiras de apartamento Daiana, Thays, Jéssica e Líllian pelo ótimo convívio. Os amigos do departamento de solos, principalmente ao Aijanio e Arnaldo, pela ajuda no sol quente com o solo. Aos amigos do laboratório Multiusuário, Bruno, Walquiria, Renan, Aline, Ana, Felipe Brendler, Laís, Victor, André, Danyllo, em especial para a Jackellyne e Thais pelos cafezinhos da tarde. Aos muito trabalhadores e companheiros de sala, Guilherme, Felipe Sartori e Thaise, pela convivência inacreditavelmente descontraída e por serem tão solícitos. A todos estagiários do Gfasp. Ao meu orientador Durval Dourado Neto, por sua bondade, prestatividade, por me mostrar que existe um outro nível de inteligência e conhecimento. Ao coorientador Gilberto, por ser uma inspiração na minha vida acadêmica e um exemplo de pesquisador. A professora Tsai, e seus alunos, por disponibilizarem a área experimental e equipamentos. Os professores que estiveram na minha banca de defesa. A todos funcionários da produção vegetal, principalmente ao Neto e Wilson, por dar uma mãozinha nos momentos de aperto e peso. As secretárias Luciane, Fabiana e Eveline. À Esalq pela oportunidade, CNPq e Fapesp pelo apoio. A todos meus professores que fizeram parte da minha formação acadêmica desde infância até chegar onde cheguei. Enfim, a todos que em algum momento, direta ou indiretamente, contribuíram na minha caminhada e que estarão ainda por perto me ajudando a traçar o futuro. Meu muito obrigada.

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