RESUMO

The use of phosphate-solubilizing fungi in coffee cultivation is an alternative to the use of traditional fertilizers. The objective of this study was to analyze the mechanisms involved in the phosphorus solubilization of fungal strains and to evaluate the effect of a phosphate-solubilizing strain on coffee plants. For this, phosphorus-solubilizing fungal strains were selected for evaluation of their solubilization potential and phosphatase activity. Coffee plants were inoculated in the field with a phosphate-solubilizing strain, and the soil and foliar soluble phosphorus contents, as well as coffee bean yield, were quantified. Of the 151 strains analyzed, Sagenomella diversispora, Penicillium waksmanii, and Penicillium brevicompactum showed the highest solubilization. Aspergillus niger and P. waksmanii presented the highest soluble phosphorus values; however, P. brevicompactum showed the highest phosphatase activity. The P. brevicompactum strain inoculated on the coffee plants did not favor the foliar phosphorus content but increased the soil soluble phosphorus content in two of the coffee plantations. The plants inoculated with the phosphate-solubilizing strain showed an increase in coffee bean weight on all plantations, although this increase was only significant in two of the three selected coffee plantations.

RESUMO

This investigation was undertaken to determine the atrazine degradation by fungal enzyme extracts (FEEs) in a clay-loam soil microcosm contaminated at field application rate (5 µg g(-1)) and to study the influence of different soil microcosm conditions, including the effect of soil sterilization, water holding capacity, soil pH and type of FEEs used in atrazine degradation through a 2(4) factorial experimental design. The Trametes maxima-Paecilomyces carneus co-culture extract contained more laccase activity and hydrogen peroxide (H2O2) content (laccase = 18956.0 U mg protein(-1), H2O2 = 6.2 mg L(-1)) than the T. maxima monoculture extract (laccase = 12866.7 U mg protein(-1), H2O2 = 4.0 mg L(-1)). Both extracts were able to degrade atrazine at 100%; however, the T. maxima monoculture extract (0.32 h) achieved a lower half-degradation time than its co-culture with P. carneus (1.2 h). The FEE type (p = 0.03) and soil pH (p = 0.01) significantly affected atrazine degradation. The best degradation rate was achieved by the T. maxima monoculture extract in an acid soil (pH = 4.86). This study demonstrated that both the monoculture extracts of the native strain T. maxima and its co-culture with P. carneus can efficiently and quickly degrade atrazine in clay-loam soils.

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RESUMO

The effect of atrazine concentrations on mycelial growth and ligninolytic enzyme activities of eight native ligninolytic macrofungi isolated in Veracruz, México, were evaluated in a semi-solid culture medium. Inhibition of mycelial growth and growth rates were significantly affected (p = 0.05) by atrazine concentrations (468, 937, 1875, and 3750 mg/l). In accordance with the median effective concentration (EC50), Pleurotus sp. strain 1 proved to be the most tolerant isolate to atrazine (EC50 = 2281.0 mg/l), although its enzyme activity was not the highest. Pycnoporus sanguineus strain 2, Daedalea elegans and Trametes maxima showed high laccase activity (62.7, 31.9, 29.3 U mg/protein, respectively) without atrazine (control); however, this activity significantly increased (p < 0.05) (to 191.1, 83.5 and 120.6 U mg/protein, respectively) owing to the effect of atrazine (937 mg/l) in the culture medium. Pleurotus sp. strain 2 and Cymatoderma elegans significantly increased (p < 0.05) their manganese peroxidase (MnP) activities under atrazine stress at 468 mg/l. The isolates with high EC50 (Pleurotus sp. strain 1) and high enzymatic activity (P. sanguineus strain 2 and T. maxima) could be considered for future studies on atrazine mycodegradation. Furthermore, this study confirms that atrazine can increase laccase and MnP activities in ligninolytic macrofungi.

Se evaluó el efecto de diferentes concentraciones de atrazina sobre el crecimiento micelial y la actividad enzimática de ocho macrohongos ligninolíticos aislados en Veracruz, México. La inhibición del crecimiento micelial y la tasa de crecimiento diaria fueron significativamente (p < 0,05) afectadas por todas las dosis de atrazina (468, 937, 1875 y 3750 mg/l) adicionadas al medio de cultivo. De acuerdo con la concentración efectiva media (CE50), Pleurotus sp. cepa 1 fue el aislamiento más tolerante a la atrazina (CE50 = 2281 mg/l), aunque sus actividades enzimáticas no fueron altas. Pycnoporus sanguineus cepa 2, Daedalea elegans y Trametes maxima mostraron actividades altas de lacasa (62,7, 31,9 y 29,3 U mg/proteína, respectivamente) en ausencia de atrazina (control); estas actividades se incrementaron (p < 0,05) significativamente (191,1, 83,5 y 120,6 U mg/proteína, respectivamente) en presencia de atrazina (937 mg/l) en el medio de cultivo. Pleurotus sp. cepa 2 y Cymatoderma elegans incrementaron significativamente (p < 0,05) sus actividades de manganeso peroxidasa (MnP) bajo la concentración de 468 mg/l de atrazina. Los aislamientos con alta CE50 (Pleurotus sp. cepa 1) y alta actividad enzimática (P. sanguineus cepa 2 y T. maxima) podrían ser considerados para futuros estudios en la micodegradación de atrazina. Además, el presente estudio confirma que la atrazina puede incrementar las actividades lacasa y MnP en macrohongos ligninolíticos.

Assuntos

RESUMO

The effect of atrazine concentrations on mycelial growth and ligninolytic enzyme activities of eight native ligninolytic macrofungi isolated in Veracruz, México, were evaluated in a semi-solid culture medium. Inhibition of mycelial growth and growth rates were significantly affected (p = 0.05) by atrazine concentrations (468, 937, 1875, and 3750 mg/l). In accordance with the median effective concentration (EC50), Pleurotus sp. strain 1 proved to be the most tolerant isolate to atrazine (EC50 = 2281.0 mg/l), although its enzyme activity was not the highest. Pycnoporus sanguineus strain 2, Daedalea elegans and Trametes maxima showed high laccase activity (62.7, 31.9, 29.3 U mg/protein, respectively) without atrazine (control); however, this activity significantly increased (p < 0.05) (to 191.1, 83.5 and 120.6 U mg/protein, respectively) owing to the effect of atrazine (937 mg/l) in the culture medium. Pleurotus sp. strain 2 and Cymatoderma elegans significantly increased (p < 0.05) their manganese peroxidase (MnP) activities under atrazine stress at 468 mg/l. The isolates with high EC50 (Pleurotus sp. strain 1) and high enzymatic activity (P. sanguineus strain 2 and T. maxima) could be considered for future studies on atrazine mycodegradation. Furthermore, this study confirms that atrazine can increase laccase and MnP activities in ligninolytic macrofungi.(AU)

Se evaluó el efecto de diferentes concentraciones de atrazina sobre el crecimiento micelial y la actividad enzimática de ocho macrohongos ligninolíticos aislados en Veracruz, México. La inhibición del crecimiento micelial y la tasa de crecimiento diaria fueron significativamente (p < 0,05) afectadas por todas las dosis de atrazina (468, 937, 1875 y 3750 mg/l) adicionadas al medio de cultivo. De acuerdo con la concentración efectiva media (CE50), Pleurotus sp. cepa 1 fue el aislamiento más tolerante a la atrazina (CE50 = 2281 mg/l), aunque sus actividades enzimáticas no fueron altas. Pycnoporus sanguineus cepa 2, Daedalea elegans y Trametes maxima mostraron actividades altas de lacasa (62,7, 31,9 y 29,3 U mg/proteína, respectivamente) en ausencia de atrazina (control); estas actividades se incrementaron (p < 0,05) significativamente (191,1, 83,5 y 120,6 U mg/proteína, respectivamente) en presencia de atrazina (937 mg/l) en el medio de cultivo. Pleurotus sp. cepa 2 y Cymatoderma elegans incrementaron significativamente (p < 0,05) sus actividades de manganeso peroxidasa (MnP) bajo la concentración de 468 mg/l de atrazina. Los aislamientos con alta CE50 (Pleurotus sp. cepa 1) y alta actividad enzimática (P. sanguineus cepa 2 y T. maxima) podrían ser considerados para futuros estudios en la micodegradación de atrazina. Además, el presente estudio confirma que la atrazina puede incrementar las actividades lacasa y MnP en macrohongos ligninolíticos.(AU)

RESUMO

Background In the industrial biotechnology, ligninolytic enzymes are produced by single fungal strains. Experimental evidence suggests that co-culture of ligninolytic fungi and filamentous microfungi results in an increase laccase activity. In this topic, only the ascomycete Trichoderma spp. has been studied broadly. However, fungal ligninolytic-filamentous microfungi biodiversity interaction in nature is abundant and poorly studied. The enhancement of laccase and manganese peroxidase (MnP) activities of Trametes maxima as a function of time inoculation of Paecilomyces carneus and under several culture conditions using Plackett-Burman experimental design (PBED) were investigated. Results The highest increases of laccase (12,382.5 U/mg protein) and MnP (564.1 U/mg protein) activities were seen in co-cultures I3 and I5, respectively, both at 10 d after inoculation. This level of activity was significantly different from the enzyme activity in non-inoculated T. maxima (4881.0 U/mg protein and 291.8 U/mg protein for laccase and MnP, respectively). PBED results showed that laccase was increased (P < 0.05) by high levels of glucose, (NH4)2SO4 and MnSO4 and low levels of KH2PO4, FeSO4 and inoculum (P < 0.05). In addition, MnP activity was increased (P < 0.05) by high yeast extract, MgSO4, CaCl2 and MnSO4 concentrations. Conclusions Interaction between indigenous fungi: T. maxima-P. carneus improves laccase and MnP activities. The inoculation time of P. carneus on T. maxima plays an important role in the laccase and MnP enhancement. The nutritional requirements for enzyme improvement in a co-culture system are different from those required for a monoculture system.

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RESUMO

Soil properties and the environment have multiple outcomes on fungal communities. Although, the interaction effects between management intensity, pH, available phosphorus, organic carbon, soil texture and different fractions of water stable macro-aggregates on the communities of microscopic filamentous fungi (MFF), iron phosphate solubilizing fungi (PSF-Fe), and iron and calcium phosphate solubilizing fungi (PSF-(Fe+Ca)), have been previously evaluated in field conditions, this has never been performed in terms of their combined effects, neither with phosphate solubilizing fungi. To assess this, we collected 40 composite soil samples from eight Mexican and Colombian coffee plantations, with different management intensities and physico-chemical edaphic parameters, during 2008-2009. We isolated different communities of MFF, PSF-Fe and PSF-(Fe+Ca), by wet sieving and soil particles culture in Potato-Dextrose-Agar from soil samples, and we classified isolates in terms of their phosphate solubilizing ability. Following the principal component analysis results, we decided to analyze fungal communities and abiotic factors interactions for each country separately. Structural Equation Models revealed that organic carbon was positively associated to MFF richness and number of isolates (lambda>0.58), but its relationship with PSF-Fe and PSF-(Fe+Ca) were variable; while the available phosphorus, pH and water stable macro-aggregate fractions did not show a clear pattern. Management intensity was negatively related to PSF-Fe (lambda < or = -0.21) morphotype richness and the number of isolates in Colombian coffee plantations. We found that the relationships of clay and organic carbon content, and available phosphorus and soil pH, with the species richness and number of isolates of MFF, PSF-Fe and PSF-(Fe+Ca) were highly variable; this made impossible to generalize the responses between saprotrophic fungal groups and geographic zones. The management intensity was not related to species richness and number of isolates of MFF in any coffee areas, while for PSF the relationship could not be defined. The different water stable macro-aggregates fractions did not show a defined pattern in relation to the species richness and the number of isolates of saprophytic and phosphate solubilizing fungi (PSF). This study highlights the need to take into account edaphic and geographic context in order to reach a better understanding of the intensity management effects on MFF and PSF function in agroecosystems.

Assuntos

RESUMO

Soil properties and the environment have multiple outcomes on fungal communities. Although, the interaction effects between management intensity, pH, available phosphorus, organic carbon, soil texture and different fractions of water stable macro-aggregates on the communities of microscopic filamentous fungi (MFF), iron phosphate solubilizing fungi (PSF-Fe), and iron and calcium phosphate solubilizing fungi (PSF-(Fe+Ca)), have been previously evaluated in field conditions, this has never been performed in terms of their combined effects, neither with phosphate solubilizing fungi. To assess this, we collected 40 composite soil samples from eight Mexican and Colombian coffee plantations, with different management intensities and physico-chemical edaphic parameters, during 2008-2009. We isolated different communities of MFF, PSFFe and PSF-(Fe+Ca), by wet sieving and soil particles culture in Potato-Dextrose-Agar from soil samples, and we classified isolates in terms of their phosphate solubilizing ability. Following the principal component analysis results, we decided to analyze fungal communities and abiotic factors interactions for each country separately. Structural Equation Models revealed that organic carbon was positively associated to MFF richness and number of isolates (λ>0.58), but its relationship with PSF-Fe and PSF-(Fe+Ca) were variable; while the available phosphorus, pH and water stable macro-aggregate fractions did not show a clear pattern. Management intensity was negatively related to PSF-Fe (λ≤-0.21) morphotype richness and the number of isolates in Colombian coffee plantations. We found that the relationships of clay and organic carbon content, and available phosphorus and soil pH, with the species richness and number of isolates of MFF, PSF-Fe and PSF-(Fe+Ca) were highly variable; this made impossible to generalize the responses between saprotrophic fungal groups and geographic zones. The management intensity was not related to species richness and number of isolates of MFF in any coffee areas, while for PSF the relationship could not be defined. The different water stable macro-aggregates fractions did not show a defined pattern in relation to the species richness and the number of isolates of saprophytic and phosphate solubilizing fungi (PSF). This study highlights the need to take into account edaphic and geographic context in order to reach a better understanding of the intensity management effects on MFF and PSF function in agroecosystems.

El suelo y sus propiedades tienen múltiples relaciones con las comunidades fúngicas. El efecto conjunto de la intensidad de manejo y las variables edáficas, incluida la estabilidad de agregados sobre las comunidades de hongos microscópicos filamentosos (HMF), solubilizadores de fosfato de hierro (HSP-Fe) y solubilizadores tanto de fosfato de hierro como de calcio (HSP-(Fe+Ca)) no han sido evaluadas en campo. A partir de 40 muestras edáficas de ocho plantaciones de café de Colombia y México, con diferentes intensidades de manejo (IMPC) y con diferencias en sus variables edáficas, se aislaron y evaluaron las comunidades de HMF, HSP-Fe y HSP-(Fe+Ca) durante 2008-2009. Empleando modelos basados en ecuaciones estructurales se encontró que el carbono orgánico se relacionó positivamente con la riqueza y abundancia de HMF (λ>0.58) y fue variable en su relación con HSP-Fe y HSP-(Fe+Ca). Las relaciones del fósforo disponible, pH y las fracciones de macro-agregados fueron altamente variables. El IMPC se relacionó negativamente con HSP-Fe (λ≤-0.21) en cafetales colombianos. Se discuten las interacciones para cada conjunto de variables (químicas, estabilidad de macro-agregados y de manejo de plantación) y se explican las relaciones resultantes. Las relaciones de cada variable son inseparables del contexto edáfico y geográfico, los cuales imprimen marcadas diferencias.

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