The use of chitosan in protecting wooden artifacts from damage by mold fungi

Background: Many buildings in Egypt e.g. museums, mosques and churches, do not possess controlled environments for minimizing the risks of damage of wooden artifacts due to the growth of fungi. Fungal damage usually appears as change in wood color, appearance of stains, and sometimes deformation of wooden surfaces. In this study we focused on the effect that some fungi exert on the properties of wooden artifacts and evaluated the effectiveness of different concentrations of chitosan on their protection against damage by mold fungi. Results: Samples were collected from different monuments and environments, and fungi growing on them were isolated and identified. The isolated Penicillium chrysogenum, Aspergillus flavus and /Aspergillus niger strains were used for the infestation of new pitch pine samples. The results revealed that the lightness of samples infected with any of the tested fungi decreased with increasing incubation times. XRD analysis showed that the crystallinity of incubated samples treated individually with the different concentrations of chitosan was lower than the crystallinity of infected samples. The crystallinity index measured by the first and the second method decreased after the first and second months but increased after the third and fourth months. This may due to the reducing of amorphous part by enzymes or acids produced by fungi in wooden samples. Conclusions: The growth of fungi on the treated wood samples decreased with increasing the concentration of chitosan. Hence, it was demonstrated that chitosan prevented fungal growth, and its use could be recommended for the protection of archeological wooden artifacts.

Study on Thermodynamics and Adsorption kinetics of Purified endoglucanase (CMCase) from Penicillium notatum NCIM NO-923 produced under mixed solid-state fermentation of waste cabbage and Bagasse

In the current study, one thermostable endoglucanase was purified from Penicillium notatum NCIM NO-923 through mixed solid state fermentation of waste cabbage and bagasse. The molecular weight of the purified enzyme was 55kDa as determined by SDS polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme had low activation energy (Ea) of 36.39KJ mol-1 for carboxymethyl cellulose hydrolysis and the enthalpy and entropy for irreversible inactivation was 87 kJ mol −1 and 59.3 J mol −1 K−1 respectively. The enzyme was quite thermostable with a Tm value of 62.2˚C. The pKa1 and pKa2 of ionizable groups of the active sites were 2.5 and 5.3 respectively. Apparent Km, Vmax and Kcat of the enzyme were found to be 5.2 mg mL-1, 80 U/gds and 322.4 sec-1 respectively. The enzyme showed about 1.4 fold increased activity in presence of 10mM MgSO4. Adsorption of endoglucanase on Avicel at wide pH range was studied at different temperatures. Langmuir type adsorption isotherm at 10˚C showed maximum adsorption strength of enzyme at pH 3.0, which was in a range of optimum pH of the enzyme.

Biodegradation of phenol in static cultures by Penicillium chrysogenum ERK1: catalytic abilities and residual phototoxicity / Biodegradación de fenol en cultivos estáticos por Penicillium chrysogenum ERK1: habilidades catalíticas y fitotoxicidad residual

A phenol-degrading fungus was isolated from crop soils. Molecular characterization (using internal transcribed spacer, translation elongation factor and beta-tubulin gene sequences) and biochemical characterization allowed to identify the fungal strain as Penicillium chrysogenum Thorn ERK1. Phenol degradation was tested at 25 °C under resting mycelium conditions at 6, 30, 60, 200, 350 and 400 mg/l of phenol as the only source of carbon and energy. The time required for complete phenol degradation increased at different initial phenol concentrations. Maximum specific degradation rate (0.89978 mg of phenol/day/mg of dry weight) was obtained at 200 mg/l. Biomass yield decreased at initial phenol concentrations above 60 mg/l. Catechol was identified as an intermediate metabolite by HPLC analysis and catechol dioxygenase activity was detected in plate assays, suggesting that phenol metabolism could occur via ortho fission of catechol. Wheat seeds were used as phototoxicity indicators of phenol degradation products. It was found that these products were not phytotoxic for wheat but highly phytotoxic for phenol. The high specific degradation rates obtained under resting mycelium conditions are considered relevant for practical applications of this fungus in soil decontamination processes.

Un aislamiento fúngico capaz de degradar fenol como única fuente de carbono y energía fue aislado de suelos agrícolas. La caracterización molecular (basada en el empleo de secuencias de espaciadores de transcriptos internos, de factores de la elongación de la traducción y del gen de la beta-tubulina) y la caracterización bioquímica permitieron identificar a esta cepa como Penicillium chrysogenum Thom ERK1. Se estudió la degradación de fenol a 25 °C en cultivos estáticos con 6, 30, 60, 200, 350 y 400 mg/l de fenol inicial. El tiempo requerido para completar la degradación de fenol aumentó al elevarse las concentraciones iniciales de dicho compuesto. La máxima tasa de degradación específica (0,89978 mg de fenol/día/mg de peso seco) se obtuvo con 200 mg/l. El rendimiento en biomasa disminuyó con concentraciones Iniciales de fenol mayores de 60 mg/l. Se identificó al catecol como intermediarlo metabolico por HPLC y se observó actividad de catecol dioxigenasa en placa, lo que sugiere que el metabolismo de degradación del fenol ocurre vía orto fisión del catecol. Se utilizaron semillas de trigo como indicadores de fitotoxicidad de los productos de degradación. Estos productos no fueron fitotóxicos para trigo, mientras que el fenol mostró una alta fitotoxicidad. La alta tasa de degradación específica obtenida en condiciones estáticas resulta de gran interés para la aplicación de este hongo en procesos de descontaminación de suelos.

Penicillin production by wild isolates of Penicillium chrysogenum in Pakistan

The present study was aimed at exploring the native wild isolates of Penicillium chrysogenum series in terms of their penicillin production potential. Apart from the standard medium, the efforts were made to utilize suitable agro-industrial wastes for the maximum yield of penicillin. Two series of P. chrysogenum were isolated from local sources and named as P. chrysogenum series UAF R1 and P. chrysogenum series UAF R2. The native series were found to possess better penicillin production potential than the already reported series of P. chrysogenum. However, P. chrysogenum series UAF R1 was found to be the best candidate for high yield of penicillin starting at 100 hour as compared to P. chrysogenum series UAF R2 which produced the highest yield of penicillin at 150 hours for a shorter period of time. Addition of Corn Steep Liquor (CSL) to the fermentation medium resulted in the production of 1.20g/L penicillin by P. chrysogenum series UAF R1 and P. chrysogenum series UAF R2. The fermentation medium in which Sugar Cane Bagasse (SCB) was replaced with CSL resulted in the highest yield of penicillin (1.92g/L) by both native series of P. chrysogenum. The penicillin production was increased by 62.5% in medium with SCB as compared to that with CSL. The penicillin yield of medium containing lactose and phenyl acetate was higher than that of control medium. Overall results revealed that P. chrysogenum series UAF R1 and P. chrysogenum series UAF R2 may be recommended for better yield of natural penicillin and this efficiency may be further enhanced by utilizing SCB as substrate in the growth medium.

Determinación de fosfatasas en hongos de praderas / Phosphatases determination in praire fungi

Se realizó un estudio para determinar la actividad de la fosfatasa ácida y alcalina en 180 cepas fúngicas aisladas desde suelo rizósferico y la rizósfera de tres plantas forrajeras (Dactilys glomerata, Lolium perenne y Trifollium repens) cultivadas en una pradera en rotación y una pradera permanente. Las fosfatasas fueron determinadas por el método desarrollado por Tabatabai & Bremner (1969) y se leyeron en un espectrofotómetro a 400 nm. Los resultados obtenidos se sometieron a un análisis de varianza (ANDEVA). En las cepas fúngicas ensayadas se determinó actividad para fosfatasa ácida y alcalina. Los mayores valores tanto para fosfatasa ácida (139.68 mg/mL*g micelio) y alcalina (127.12 mg/mL*g micelio) los registró la cepa 14-2R de Penicillium chrysogenum aislada de la rizófera de L. perenne cultivado en pradera permanente. Entre las mejores cepas evaluadas de la pradera permanente existió una mejor concordancia entre los valores determinados para fosfatasa ácida y alcalina.

Ocorrência de ácido oxálico na biossíntese de penicilina / Oxalis acid in periillin industrial fermentation

Foi observado, em processo industrial de produçäo de penicilina, que aproximadamente 20 (por cento) dos tanques havia a formaçäo de cristais de oxalato de cálcio. Nestes tanques a produtividade era pouco superior a 80 (por cento) de tanques normais. O teor de oxalato nos tanques com baixa produtividade atingiu 10 a 20 vezes o encontrado em tanques normais. Dos tanques com prblemas foi isolada uma variante apigmentada de Penicillium chrysogenum que produzia 1,27g/1 de oxalato e apresentava uma produtividade de penicilina igual a 18,5 (por cento) da normal (au)