Utilisation de la planification expérimentale pour l'optimisation de la production de l'α-amylase par Aspergillus oryzae Ahlburg (Cohen) 1042.72 cultivé sur milieu à base de déchets d'oranges

Production and Properties of a Thermostable, pH-Stable Exo-Polygalacturonase Using Aureobasidium pullulans Isolated from Saharan Soil of Algeria Grown on Tomato Pomace

Polygalacturonase is a valuable biocatalyst for several industrial applications. Production of polygalacturonase using the Aureobasidium pullulans stain isolated from Saharan soil of Algeria was investigated. Its capacity to produce polygalacturonase was assessed under submerged culture using tomato pomace as an abundant agro-industrial substrate. Optimization of the medium components, which enhance polygalacturonase activity of the strain Aureobasidium pullulans, was achieved with the aid of response surface methodology. The composition of the optimized medium was as follows: tomato pomace 40 g/L, lactose 1.84 g/L, CaCl₂0.09 g/L and pH 5.16. Practical validation of the optimum medium provided polygalacturonase activity of 22.05 U/mL, which was 5-fold higher than in unoptimized conditions. Batch cultivation in a 20 L bioreactor performed with the optimal nutrients and conditions resulted in a high polygalacturonase content (25.75 U/mL). The enzyme showed stability over a range of temperature (5–90 °C) with an optimum temperature of 60 °C with pH 5.0, exhibiting 100% residual activity after 1h at 60 °C. This enzyme was stable at a broad pH range (5.0–10). The enzyme proved to be an exo-polygalacturonase, releasing galacturonic acid by hydrolysis of polygalacturonic acid. Moreover, the exo-polygalacturonase was able to enhance the clarification of both apple and citrus juice. As a result, an economical polygalacturonase production process was defined and proposed using an industrial food by-product.

Optimization of submerged Aspergillus oryzae S2 α-amylase production

Use of 4 agro-industrial by products and organic materials as nitrogen sources for production of Aspergillus oryzae S2 α-amylase in liquid culture was investigated. The 2 agro-industrial byproducts maltose and saccharose, and also lactose and starch were individually evaluated for use as carbon sources. A Box-Behnken experimental design was used to determine optimal conditions for production of α-amylase. A maximum amylase activity of 750 U/mL was obtained at a temperature of 24°C, a urea concentration of 1 g/L, and a C/N ratio of 2. Laboratory scale application of optimal conditions in a 7 L fermentor produced a final α-amylase activity of 770 U/mL after 3 days of batch cultivation. Addition of 10% starch to the culture medium each 12 h immediately after the stationary phase of cell growth led to a production yield of 1,220 U/mL at the end of fed-batch cultivation.

Application of Asymetrical and Hoke Designs for Optimization of Laccase Production by the White-Rot Fungus Fomes fomentarius in Solid-State Fermentation

Statistical approaches were employed for the optimization of different cultural parameters for the production of laccase by the white rot fungus Fomes fomentarius MUCL 35117 in wheat bran-based solid medium. first, screening of production parameters was performed using an asymmetrical design 2(5)3(3)//16, and the variables with statistically significant effects on laccase production were identified. Second, inoculum size, CaCl(2) concentration, CuSO(4) concentration, and incubation time were selected for further optimization studies using a Hoke design. The application of the response surface methodology allows us to determine a set of optimal conditions (CaCl(2), 5.5 mg/gs, CuSO(4), 2.5 mg/gs, inoculum size, 3 fungal discs (6 mm Ø), and 13 days of static cultivation). Experiments carried out under these conditions led to a laccase production yield of 150 U/g dry substrate.

Application of a statistical design to the optimization of parameters and culture medium for alpha-amylase production by Aspergillus oryzae CBS 819.72 grown on gruel (wheat grinding by-product)

The production optimization of alpha-amylase (E.C.3.2.1.1) from Aspergillus oryzae CBS 819.72 fungus, using a by-product of wheat grinding (gruel) as sole carbon source, was performed with statistical methodology based on three experimental designs. The optimisation of temperature, agitation and inoculum size was attempted using a Box-Behnken design under the response surface methodology. The screening of nineteen nutrients for their influence on alpha-amylase production was achieved using a Plackett-Burman design. KH(2)PO(4), urea, glycerol, (NH(4))(2)SO(4), CoCl(2), casein hydrolysate, soybean meal hydrolysate, MgSO(4) were selected based on their positive influence on enzyme formation. The optimized nutrients concentration was obtained using a Taguchi experimental design and the analysis of the data predicts a theoretical increase in the alpha-amylase expression of 73.2% (from 40.1 to 151.1 U/ml). These conditions were validated experimentally and revealed an enhanced alpha-amylase yield of 72.7%.

Identification of two types of Iranian alfalfa gene pool-based on agro-morphological traits

There are two types of alfalfa landraces in Iran. The first is temperate landraces such as Hamedani, Gharah Younjeh and the second is sub-tropical landraces such as Bami, Nikshahri and Yazdi. Do they have different gene pools and could they be identified using agro-morphological traits. A total of 332 landraces which had been collected from different parts of Iran were planted in the experimental field. During 1998-2002, agro-morphological traits were evaluated according to IPGRI descriptors. One way ANOVA analysis showed that the variance among accessions within provinces is not significant for mostly of traits, whereas it was significant among provinces. Cluster analysis revealed that there are five clusters which are grouped in two main clusters. The first main cluster consisted of landraces of central to Northern provinces. The other main cluster consisted of landraces of central to Southern provinces. The results of t-test among quantitative traits in two main clusters and distribution of collected accessions of each province in the produced plot based on two first factor of factor analysis, confirmed the cluster analysis results. Therefore these results revealed that those accessions which were collected from Northern parts of the country were genetically different from Southern accessions. As a result, there are two types of gene pools for alfalfa landraces in Iran. Also this study showed that using agro-morphological traits could be used for distinguishing between two types of gene pools of alfalfa landraces in Iran.