ABSTRACT Application of filamentous fungi in biotechnological processes leads to the accumulation of biomass as waste. However, it is known that the fungal biomass contains various biopolymers among which is chitin -the precursor of chitosan. In the present work, fungal biomass was used as raw material for the extraction of a biopolymer containing chitosan by the acid/alkaline method. Different extraction conditions were assayed: the concentration of alkali, time, and temperature of treatments. The biopolymer was characterized and applied in the synthesis of nickel ferrite by the coprecipitation method demonstrating the possibility of obtaining a nanostructured magnetic system coated with fungal chitosan in a single step. The properties of the obtained nanostructured magnetic material were evaluated by X-ray diffraction, vibrating sample magnetometry, and Fourier-transform infrared spectroscopy. It was demonstrated that the nanostructured magnetic material coated with fungal chitosan removes 100 % of the arsenic present in a sample from a well of Comarca Lagunera (states of Durango and Coahuila, Mexico), as well as other ions that are not harmful to health. It was found that the capacity to remove arsenic is conserved in at least 15 tests of magnetic separation of this toxic pollutant. The results of the present work demonstrate the possibility of taking advantage of the fungal biomass residue, currently little used, for the design of magnetic nanomaterials with impact on the elimination of water from toxic pollutants by magnetic separation.

RESUMEN La aplicación de hongos filamentosos en procesos biotecnológicos conduce a la acumulación de biomasa como residuo. Sin embargo, la biomasa fúngica contiene diversos biopolímeros entre los cuales se encuentra la quitina -el precursor del quitosán. En el presente trabajo la biomasa fúngica se utilizó como materia prima para la extracción del biopolímero que contiene quitosán mediante el método ácido/alcalino. Se aplicaron diferentes condiciones de extracción: la concentración de álcali, el tiempo y la temperatura de los tratamientos. El biopolímero fue caracterizado y aplicado en la síntesis de ferrita de níquel por el método de coprecipitación, demostrando la posibilidad de obtener un sistema magnético nanoestructurado recubierto con quitosán fúngico en una sola etapa. Las propiedades del material magnético nanoestructurado obtenido se evaluaron por difracción de rayos-X, magnetometría de muestra vibrante y espectrometría infrarroja por transformada de Fourier. Se demostró que el material magnético nanoestructurado recubierto con quitosán fúngico remueve el 100 % del arsénico presente en muestras de agua proveniente de un pozo de la Comarca Lagunera (estados de Durango y Coahuila, México), así como otros iones no nocivos para la salud. Se comprobó que la capacidad para remover el arsénico se conserva en al menos 15 ensayos. Los resultados del presente trabajo demuestran la posibilidad de aprovechar el residuo de biomasa fúngica, actualmente poco utilizado, para el diseño de nanomateriales magnéticos con impacto en la eliminación de contaminantes tóxicos del agua mediante la remoción magnética.

Abstract Introduction: Melon is a fruit with a short storage period. An alternative to extend the shelf-life of this fruit is the application of an edible film. In present study was evaluated the effect of the application of an edible coating based on alginate-hydroxypropilmethyl-cellulose-parafine over the quality of Cantaloupe melon under two storage types. Method: Cantaloupe melon fruits were covered by an alginate-hydroxypropilmethyl-cellulose-parafine edible coating (ALG-HPMC-PAR), and uncovered (CONTROL). Experimental melons were stored for 21 days at 5 ºC and 95 % relative humidity. Every seven days, the fruits were subjected to analysis of chilling injury index, loss of weight, texture, and CO2 and ethylene concentration of internal atmosphere of the fruit. In addition, to simulate commercial management, at the end of each period of seven days in refrigeration, a sample of melons was extracted from the refrigerator and exposed to environmental conditions of temperature and relative humidity (25ºC and 21-25% respectively) during three days (combined storage), and measured the parameters mentioned above. Results: The application of the edible coating induced that melons had a higher CO2 and lower ethylene concentration in the fruit inner atmosphere, contributing to maintain their quality for a longer storage time than the control fruits, since the covered melons were firmer, had a lower weight loss, and suffered a lower chilling injury index. Discussion or Conclusion: The obtained results prove the feasibility of the application of edible coatings to maintain the Cantaloupe melon quality in cooling and combined storage.

Resumen Introducción: El melón es un fruto que tiene un corto periodo de almacenamiento. Una alternativa para extender este periodo es el uso de películas comestibles. En el presente estudio se evaluó el efecto de la aplicación de una película comestible de alginato de sodio-hidroxipropilmetilcelulosa-parafina (ALG-HPMC-PAR), sobre la calidad de melón Cantaloupe durante dos tipos de almacenamiento. Método: Frutos de melón Cantaloupe se cubrieron con una película comestible de alginato-hidroxipropilmetil celulosa-parafina (ALG-HPMC-PAR), y no cubiertos (CONTROL). Los melones se almacenaron por 21 días a 5ºC y 95% de humedad relativa (Hr). Cada siete días, los frutos se sometieron a análisis de índice de daños por frío, pérdida de peso, textura, y concentración de CO2 y etileno de la atmósfera interna del fruto. Además, para simular manejo comercial, al término de cada periodo de siete días en refrigeración, una muestra de melones era extraída del frigorífico y expuesta a condiciones ambientales de temperatura y humedad relativa (25ºC y 21-25% respectivamente) durante tres días (almacenamiento combinado), y medidos los parámetros anteriormente mencionados. Resultados: La aplicación de la película comestible provocó que los frutos cubiertos tuvieran una mayor concentración de CO2 y menor concentración de etileno en la atmósfera interna del fruto, contribuyendo a que los melones cubiertos mantuvieron su calidad por un mayor tiempo de almacenamiento, manteniéndose más firmes, con menor pérdida de peso y sufrir menor índice de daños por frío con respecto los frutos control. Discusión: Los resultados demuestran la factibilidad de la aplicación de películas comestibles para mantener la calidad del melón Cantaloupe almacenado en refrigeración y en almacenamiento combinado.

Due to the need for more efficient, economical and environmentally-friendly technological processes, the use of enzymes has increased. However, reuse of enzymatic hydrolytic complex is required. The immobilization of enzymes provides a basis for stability and allows their reuse reflected in aspects of economic feasibility. Magnetic nanoparticles are a promising supports since their magnetic character allows retrieval by applying an external magnetic field. This article presents an analysis and discussion of methods of biocatalyst immobilization, emphasizing lignocellulolytic enzymes immobilized in magnetic nanoparticles and their applications for the production of high-value compounds such as bioethanol.

Background: Inulinases have been extracted and characterized from inulin-storing tissues; however, production of microbial inulinases have recently draw much attention as they offer several industrial advantages. Many microorganisms, including filamentous fungi, yeast and bacteria have been claimed as inulinase producers. These hydrolases are usually inducible and their exo-acting forms may hydrolyze fructose polymers (inulin) and oligosaccharides such as sucrose and raffinose. Fungal inulinase extracts are often produced as stable mixture of highly active fructanhydrolases. From a practical prospective, the best known inulinases to date are those produced by species of Penicillium, Aspergillus and Kluyveromyces. Results: The production of extracellular inulinase by A. kawachii in liquid cultures, using either inulin or yacon derived materials as CES as well as inulinase inducers, is reported. In addition, a partial characterization of the enzyme activity is included. Conclusions: Yacon derived products, particularly yacon juice, added to the culture medium proved to be a good CES for fungal growth as well as an inducer of enzyme synthesis. Partial characterization of the enzyme revealed that it is quite stable in a wide range of pH and temperature. In addition, characterization of the reaction products revealed that this enzyme corresponds to an exo-type. These facts are promising considering its potential application in inulin hydrolysis for the production of high fructose syrups.

A pectinesterase foi extraída da batata (cultivar do alfa), purificada e parcialmente caracterizada. O protocolo usado levou a uma proteína purificada 58,8 vezes (51 850,2 units/mg da proteína) com uma recuperação de 15,5 % da atividade da proteína. A enzima purificada apresentou um peso molecular de 27 kDa e seu ponto isoelétrico foi ao redor 4,5. A pectinesterase exibiu pH e temperatura ótimos de respectivamente 8,0 e 60°C. A enzima purificada apresentou um único pico simétrico de atividade específica após as etapas de cromatografia. A homogeneidade da pectinesterase purificada foi confirmada por filtração em gel e por eletroforese em gel de poliacrilamida.

Pectinesterase was extracted from potato alpha cultivar, purified and partially characterized The used protocol resulted in a 58.8-fold purification (51 850.2 units/mg protein) with 15.5% recovery of pectinesterase activity. The purified enzyme had a molecular weight of 27 kDa and its isoelectric point was around 4.5 with pH and temperature optima of 8.0 and 60°C, respectively. The purified enzyme had a single symmetric peak of specific activity after chromatographic steps. The homogeneity of the purified pectinesterase was confirmed by gel filtration and polyacrylamide electrophoresis gel.