Medium pH, carbon and nitrogen concentrations modulate the phosphate solubilization efficiency of Penicillium purpurogenum through organic acid production.

AIMS: To study phosphate solubilization in Penicillium purpurogenum as function of medium pH, and carbon and nitrogen concentrations. METHODS AND RESULTS: Tricalcium phosphate (CP) solubilization efficiency of P. purpurogenum was evaluated at acid or alkaline pH using different C and N sources. Glucose- and (NH(4) )(2) SO(4) -based media showed the highest P solubilization values followed by fructose. P. purpurogenum solubilizing ability was higher in cultures grown at pH 6·5 than cultures at pH 8·5. Organic acids were detected in both alkaline and neutral media, but the relative percentages of each organic acid differed. Highest P release coincided with the highest organic acids production peak, especially gluconic acid. When P. purpurogenum grew in alkaline media, the nature and concentration of organic acids changed at different N and C concentrations. A factorial categorical experimental design showed that the highest P-solubilizing activity, coinciding with the highest organic acid production, corresponded to the highest C concentration and lowest N concentration. CONCLUSIONS: The results described in the present study show that medium pH and carbon and nitrogen concentrations modulate the P solubilization efficiency of P. purpurogenum through the production of organic acids and particularly that of gluconic acid. In the P solubilization optimization studies, glucose and (NH(4) )(2) SO(4) as C and N sources allowed a higher solubilization efficiency at high pH. SIGNIFICANCE AND IMPACT OF THE STUDY: This organism is a potentially proficient soil inoculant, especially in P-poor alkaline soils where other P solubilizers fail to release soluble P. Further work is necessary to elucidate whether these results can be extrapolated to natural soil ecosystems, where different pH values are present. Penicillium purpurogenum could be used to develop a bioprocess for the manufacture of phosphatic fertilizer with phosphate calcium minerals.

Production of laccase and manganese peroxidase by Fomes sclerodermeus grown on wheat bran.

The aim of this work was to study the growth and production of ligninolytic enzymes by Fomes sclerodermeus using a natural medium based on wheat bran as the principal substrate in a solid-state fermentation. Growth was monitored by measuring the chitin content in the substrate. The maximum rate of growth was observed between days 7 and 18. A 38% total dry-weight loss of the substrate was measured after 28 days of cultivation. Differential hydrolysis of the substrate revealed that cellulose was more extensively degraded than lignin. In the 28-day incubation period, the losses of cellulose and lignin were 38 and 15%, respectively. No lignin peroxidase activity was found in any of the media tested. The maximum manganese-dependent peroxidase activity recorded was 6.3 U g(-1) at 14 days, while the maximum laccase activity was 270 U g(-1) at 28 days post-inoculation. Addition of commonly used inducers such as copper or manganese did not produce a further increase in the enzyme activities, nor did addition of glucose, asparagine, or malt extract.

[Enzymes of white rot fungi involved in lignin degradation]. / Enzimas de hongos de pudrición blanca involucradas en la degradación de lignina.

The presence of oxidases and peroxidases was tested qualitatively in 12 strains of white rot Basidiomycetes. Plate tests with gallic acid, tannic acid, guayacol, Poly R-478 and Azure B were used. Fomes sclerodermeus, Phlebia sp. and Pycnoporus sanguineus were selected for further studies because they produced the largest areas of degradation in all media tested. Poly R-478 degradation and manganese peroxidase, lignin peroxidase and laccase activities were measured in glucose-asparagine (N-sufficient) and Kirk (N-limited) media. The highest activities were produced by F. sclerodermeus cultured in glucose asparagine medium.

Enzimas de hongos de pudrición blanca involucradas en la degradación de lignina / Enzymes of white rot fungi involved in lignin degradation

The presence of oxidases and peroxidases was tested qualitatively in 12 strains of white rot Basidiomycetes. Plate tests with gallic acid, tannic acid, guayacol, Poly R-478 and Azure B were used. Fomes sclerodermeus, Phlebia sp. and Pycnoporus sanguineus were selected for further studies because they produced the largest areas of degradation in all media tested. Poly R-478 degradation and manganese peroxidase, lignin peroxidase and laccase activities were measured in glucose-asparagine (N-sufficient) and Kirk (N-limited) media. The highest activities were produced by F. sclerodermeus cultured in glucose asparagine medium.

Enzimas de hongos de pudrición blanca involucradas en la degradación de lignina / Enzymes of white rot fungi involved in lignin degradation

The presence of oxidases and peroxidases was tested qualitatively in 12 strains of white rot Basidiomycetes. Plate tests with gallic acid, tannic acid, guayacol, Poly R-478 and Azure B were used. Fomes sclerodermeus, Phlebia sp. and Pycnoporus sanguineus were selected for further studies because they produced the largest areas of degradation in all media tested. Poly R-478 degradation and manganese peroxidase, lignin peroxidase and laccase activities were measured in glucose-asparagine (N-sufficient) and Kirk (N-limited) media. The highest activities were produced by F. sclerodermeus cultured in glucose asparagine medium.(AU)

Enzimas de hongos de pudrición blanca involucradas en la degradación de lignina. / [Enzymes of white rot fungi involved in lignin degradation]

The presence of oxidases and peroxidases was tested qualitatively in 12 strains of white rot Basidiomycetes. Plate tests with gallic acid, tannic acid, guayacol, Poly R-478 and Azure B were used. Fomes sclerodermeus, Phlebia sp. and Pycnoporus sanguineus were selected for further studies because they produced the largest areas of degradation in all media tested. Poly R-478 degradation and manganese peroxidase, lignin peroxidase and laccase activities were measured in glucose-asparagine (N-sufficient) and Kirk (N-limited) media. The highest activities were produced by F. sclerodermeus cultured in glucose asparagine medium.

Interacción entre hongos coprófilos y su efecto en la degradación de su sustrato natural / Interaction between coprophilous fungi and its impact on its natural substrate degradation

Six species of coprophilous fungi were isolated from cow dung. Each species, or a combination of two or more, were inoculated on dung and their capacity of degradation of the substrate was measured as dry weight loss, endoglucanase activity and loss of cellulose. Degradation of CMC agar medium was also established. As a result of their interespecific relationship, a minor degradative capacity was observed when more than one species were cultured except for one combination.

Interacción entre hongos coprófilos y su efecto en la degradación de su sustrato natural / Interaction between coprophilous fungi and its impact on its natural substrate degradation

Six species of coprophilous fungi were isolated from cow dung. Each species, or a combination of two or more, were inoculated on dung and their capacity of degradation of the substrate was measured as dry weight loss, endoglucanase activity and loss of cellulose. Degradation of CMC agar medium was also established. As a result of their interespecific relationship, a minor degradative capacity was observed when more than one species were cultured except for one combination.(AU)

[Interaction between coprophilous fungi and its impact on its natural substrate degradation]. / Interacción entre hongos coprófilos y su efecto en la degradación de su sustrato natural.

Six species of coprophilous fungi were isolated from cow dung. Each species, or a combination of two or more, were inoculated on dung and their capacity of degradation of the substrate was measured as dry weight loss, endoglucanase activity and loss of cellulose. Degradation of CMC agar medium was also established. As a result of their interespecific relationship, a minor degradative capacity was observed when more than one species were cultured except for one combination.