ABSTRACT
RESUMEN A partir de un Typic Melanudands cultivado con café (Coffea arabica variedad Caturra), proveniente del Departamento del Cauca (Colombia), se aislaron hongos con capacidad solubilizadora de fosfato de aluminio (Al-P), de los cuales se seleccionaron dos microorganismos que presentaron la mayor actividad, identificados como cepa UNHI (Mycelia sterilia), y UNH2 (Penicillium sp). Los hongos seleccionados fueron evaluados por quince días en medio líquido Pikovskaya (PVK) con Al-P bajo dos condiciones, con agitación (método A) y en reposo con aireación (método B). Al comparar los resultados se encontraron diferencias estadísticas significativas en el porcentaje de fósforo soluble, el método A presentó mejores resultados con un porcentaje de 73,8% frente a 62% con la cepa UNH1 y en menor proporción con la cepa UNH2 49% y 44%. El incremento de biomasa fue mayor con el método B y el pH de los medios de cultivo no mostraron diferencias significativas, con un pH promedio de 2,7.
ABSTRACT Based on Typic Melanudands grow with coffea (Coffea Arabica Caturra variety) resulting from the Cauca department, fungi with solubilization capacity of aluminum phosphate were isolated (Al-P), from which two microorganisms with greater solubilization activity were selected, identified as strain UNH!: Mycelia sterilia y UNH2: Penicillium sp. Selected fungi were evaluated through the Pikovskaya liquid (PVK) with (Al-P), under two conditions, with stirring (A method) and repose with aireation ( B method), for fifteen days. When comparing the results, significant statistical differences were found in the percentage of soluble phosphorus, method A presented better results with a percentage of 73.8% compared to 62% with the strain UNH1 and in smaller proportion with the strain UNH2 49% and 44 %. The increase in biomass was greater with method B and the pH of the culture media did not show significant differences, with an average pH of 2.7.
RESUMO De PVAc Melanudands cultivadas com café (Coffea arabica variedade caturra), a partir do Departamento (Colômbia), fungos foram isoladas com fosfato de alumínio capacidade de solubilização (Al-P), de que introduziu foram seleccionados dois microrganismos a atividade mais alta, identificada como cepa UNH1 (Mycelia sterilia) e UNH2 (Penicillium sp). fungos seleccionados foram avaliadas durante duas semanas em meio líquido Pikovskaya (PVK) com Al-P sob duas condições, com agitação (método A) e que descansa com arejamento (método B). Ao comparar os resultados estatisticamente diferenças significativas na percentagem de fósforo solúvel encontrada, método A proporcionou melhores resultados com uma percentagem de 73,8% versus 62% com a estirpe UNH1 e em menor grau com a estirpe UNH2 49% e 44 %. O aumento da biomassa foi maior com o método B e o pH do meio de cultura não mostrou diferenças significativas, com um pH médio de 2,7.
ABSTRACT
The aims of this work were to evaluate the phosphate-solubilization and hydrogen peroxide (H2O2) production by the soil-borne micromycetes, Aspergillus japonicus, Penicillium italicum and Penicillium dipodomyicola, isolated from Phragmites australis rhizosphere and to study the effect of several concentrations of Cadmium (Cd(2+)) on both variables. Our results showed that P. italicum achieved a higher P-solubilization and H2O2 production than A. japonicus and P. dipodomyicola, as only P. italicum showed a positive correlation (R(2) = 0.71) between P-solubilization and H2O2 production. In dose-response assays, P. italicum was also more tolerant to Cd(2+) (0.31 mM) in comparison to A. japonicus (0.26 mM). Analysis of the 2(4) factorial experimental design showed that P-solubilization by P. italicum was negatively affected by increases in Cd(2+) (p = 0.04) and yeast extract (p = 0.02) in the culture medium. The production of H2O2 was positively affected only by glucose (p = 0.002). Fungal biomass production was reduced significantly (p = 0.0009) by Cd(2+) and increased (p = 0.0003) by high glucose concentration in the culture medium. The tolerance and correlation between P-solubilization and H2O2 production in the presence of Cd(2+) was strain and species dependent. The effects of Cd(2+), glucose, ammonium sulfate and yeast extract on those variables were evaluated through a two-level factorial design. P. italicum is promising for P-solubilization in soils contaminated with Cd(2+) and may be an alternative for manufacture of biofertilizers to replace chemical fertilizers.