Jose A Rodriguez-Leon

Production, purification and properties of microbial phytases

Phytases (myo-inositol hexakisphosphate phosphohydrolase, EC 3.1.3.8) catalyse the release of phosphate from phytate (mycoinositol hexakiphosphate). Several cereal grains, legumes and oilseeds, etc., store phosphorus as phytate. Environmental pollution due to the high-phosphate manure, resulting in the accumulation of P at various locations has raised serious concerns. Phytases appear of significant value in effectively controlling P pollution. They can be produced from a host of sources including plants, animals and micro-organisms. Microbial sources, however, are promising for their commercial exploitations. Strains of Aspergillus sp., chiefly A. ficuum and A. niger have most commonly been employed for industrial purposes. Phytases are considered as a monomeric protein, generally possessing a molecular weight between 40 and 100 kDa. They show broad substrate specificity and have generally pH and temperature optima around 4.5-6.0 and 45-60 degrees C. The crystal structure of phytase has been determined at 2.5 A resolution. Immobilization of phytase has been found to enhance its thermostability. This article reviews recent trends on the production, purification and properties of microbial phytases.

Production of bio-ethanol from soybean molasses by Saccharomyces cerevisiae at laboratory, pilot and industrial scales.

The aim of this work was to develop an economical bioprocess to produce the bio-ethanol from soybean molasses at laboratory, pilot and industrial scales. A strain of Saccharomyces cerevisiae (LPB-SC) was selected and fermentation conditions were defined at the laboratory scale, which included the medium with soluble solids concentration of 30% (w/v), without pH adjustment or supplementation with the mineral sources. The kinetic parameters - ethanol productivity of 8.08g/Lh, YP/S 45.4%, YX/S 0.815%, m 0.27h(-1) and microX 0.0189h(-1) - were determined in a bench scale bioreactor. Ethanol production yields after the scale-up were satisfactory, with small decreases from 169.8L at the laboratory scale to 163.6 and 162.7L of absolute ethanol per ton of dry molasses, obtained at pilot and industrial scales, respectively.

Factors Affecting Solid-state Fermentation

To analyze the factors that may influence in solid-state fermentation, it is necessary to take into account a consideration which kind of factor we are considering. Generally, two types of factors exist: Biological factors: These factors are related with the biology, metabolic process and reproduction of a living species or organism. These determine the behaviour of the particular species in a specific way.

Influence of airflow intensity on phytase production by solid-state fermentation

Phytase production by Aspergillus niger F3 by solid state fermentation (SSF) on citrus peel was evaluated at pilot scale under different aeration conditions. The best airflow intensity was 1 VkgM (Lair kg medium(-1) min(-1)), which allowed to produce 65 units of phytases per gram in dry basis (65 Ug(-1) d.b.) as it removed the metabolic heat generated by the microorganism, Agitation did not improve heat removal. Airflow intensity was considered as scale-up criterion. When the airflow intensity was maintained at 1 VkgM for SSF with 2 and 20 kg of medium, the kinetics parameters for biomass and enzyme concentration at the end of fermentation differed by less than 2. The air flow intensity was required to maintain the temperature and cool the SSF and to provide oxygen for microbial growth. Air flow intensity is a key a factor that must be considered when scale-up of SSF is attempted.

INCREASE IN PHYTASE SYNTHESIS DURING CITRIC PULP FERMENTATION

Citric pulp bran was used for the first time as substrate for phytase synthesis under solid-state fermentation. An A. niger FS3 phytase strain was applied in optimization studies. A Plackett-Burman screening design identified significant physicochemical variables. These preselected variables were subsequently optimized using a central composite rotational design (CCRD). The maximum phytase production was achieved with the following optimum variables: 30°C temperature, 65% initial moisture content, 0.3 M Na-citrate buffer concentration, initial pH 5.0, and 1.5% urea concentration. An overall 4.3-fold improvement in phytase production was successfully achieved.

Xylanase production by Streptomyces viridosporus T7A in submerged and solid-state fermentation using agro-industrial residues

ABSTRACT The study of xylanase production was conducted by Streptomyces viridosporus T7A in submerged (SmF) and solid-state fermentation (SSF), using agro-industrial residues and sub-products. Napier grass, sugarcane bagasse and soybean bran were used as carbon source, substrate/support, and nitrogen source, respectively. In SmF, Napier grass (1% v/w) supplemented with soybean bran, hydroxyethylcellulose and B complex vitamins were used. Soybean bran (1.5 % w/v), B complex vitamins (0.1%), and hydroxyethilcellulose (0.15%) led to an increase in xylanase production (23.41 U/mL). In SSF, the effects of the following parameters were studied: substrate composition (sugarcane bagasse, Napier grass and soybean bran), initial moisture, and inoculum rate. In SSF, the highest xylanase activity (423.9 U/g) was reached with: 70 % sugarcane bagasse, 20% Napier grass and 10% soybean meal, 90% of moisture, and 10 7 /g substrate. Key words : Streptomyces ; xylanase, submerged fermentation, solid-state agro-industrial fermentation, residues

Monitoring fermentation parameters during phytase production in column-type bioreactor using a new data acquisition system

Fermentation parameters for phytase production in column-type bioreactor were monitored using a new data acquisition system. There are a number of studies reporting phytase production in flasks, but a lack of data about microorganism respiration behaviour during phytase production using column bioreactor. The objectives of this work were the monitoration of fermentation parameters during phytase production and its relation with fungal growth and forced air. Phytase production by A. niger FS3 increased with forced air. The O2 consumption and CO2 production during solid-state fermentation were monitored by sensors (in the bottom and top of the columns) linked to controllers, recorded by acquisition software and processed by Fersol2® software tool. Phytase synthesis was associated with fungal growth. Therefore, phytase could be used to estimate FS3 biomass formed in citric pulp degradation.

Recovery of phytase produced by solid-state fermentation on citrus peel

The extraction of phytase produced by solid-state fermentation of citrus peel was studied employing a multistage leaching process. It was observed that the extracts containing EDTA retained over 90% of phytase activity at room temperature after 24 h after the leaching. A fractional design 22 (with 4 replicates at the central point) was carried out for testing the pH and agitation as process independent factors. Only the interaction between the pH and agitation showed a significant influence. These factors were optimized with a central composite design. Agitation at 300 rpm and pH at 5.0 were the best conditions to extract the enzyme from solid matrix. The modeling of the process indicated that diffusivity of the enzyme in the solvent was the controlling mechanism. The corresponding kinetic constant and saturation concentration in this process were 0.89 min-1 and 4.0 IU/mL, respectively. The multistage process indicated that after two steps, it was possible to recover 85% of total enzyme produced.

Relationship between coffee husk caffeine degradation and respiration of Aspergillus sp. LPBx in solid-state fermentation

Studies were carried out in a packed-bed column fermentor using coffee husk as substrate in order to verify a relationship between caffeine degradation and the respiration of Aspergillus sp. LPBx. Fermentation conditions were optimized by using factorial design experiments. The kinetic study showed that the caffeine degradation was related to the development of mold and its respiration and also with the consumption of reducing sugars present in coffee husk. From the values obtained experimentally for oxygen uptake rate and CO2 evolved, we determined a biomass yield of 3.811 g of biomass/g of consumed O2 and a maintenance coefficient of 0.0031 g of consumed O2/(g of biomass·h). The maximum caffeine degradation achieved was 90%.

Production of spores of Trichoderma harzianum on sugar cane molasses and bagasse pith in solid state fermentation for biocontrol

Solid state fermentation was carried out for the production of spores from Trichoderma harzianum No 53 using sugar cane bagasse pith as solid matrix and sugar cane molasses as carbon and energy source. Different nitrogen sources such as urea, (NH4)2SO4 , NH4H2PO4 and (NH4)2HPO4 were added in the media to test their effect on spores production. Among these, urea was found most useful that resulted high no of spores (1x109/gDM). The influence of temperature and initial moisture of the substrate was studied through a 22 experimental plan design. No statistical differences were found within the range of 30-35oC and 60-70% for temperature and moisture respectively. The biotechnological parameters of the process were derived from the Oxygen Uptake Rate (OUR) pattern, which corresponded to the order of 109spores/g moist material. The specific growth rate, maintenance coefficient and the yield based on O2 consumption were 0.108 h-1, 0.001 g.O2/g.biomass.h and 2.7 g biomass/g O2 consumed, respectively.