الفهرس 
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Abstract
Composting biodegrades organic waste i.e. food waste, manure, leaves,, paper, wood, feathers, crop residue etc., and turns it into a valuable organic fertilizer or other useful compounds.
Microbial Enzymes they can be classified into:
(1) Amylases that break down starch into glucose molecules.
(2) Proteases, (or proteinase ), which split up proteins into their
component amino acid building blocks.
(3) Lipase, which split up animal and vegetable fats and oils into their component part: glycerol and fatty acids.
(4) Cellulase (of various types) which breaks down the complex molecule of cellulose into more digestible components of single and multiple ugars.
(5) Beta-glucanase, (or gumase) which digest one type of vegetable gum into sugars and / or dextrins .
Homogalacturonan (HG)
HG is a linear polymer formed by D-galacturonic acid which can be acetylated and/or methyl esterified.
Rhamnogalacturonan I (RGI)
RG I is composed of the repeating disaccharide rhamnose- galacturonic acid.
Rhamnogalacturonan II (RGII)
Despite its name, RGII is a homogalacturonan chain with complex side chains attached to the galacturonic residues. Both RG chains are also called hairy regions of pectin molecule.
Application of Pectinases the major industrial applications of pectinases include:
1. Fruit Juice Extraction
2. Maceration of Plant Tissue
3 Liquefaction and Saccharification of Biomass
4. Retting and Degumming of Fiber Crops
5. Textile Processing and Bioscouring of Cotton Fibers
6. Treatment of Pectic Wastewater
7. Paper Making
8. Oil extraction
9. Coffee and Tea fermentation
Environmental Factors environmental factors such as: temperature, pH, water activity, oxygen levels and concentrations of nutrients and products significantly affect microbial growth and product formation.
In submerged stirred cultures, environmental control is elatively simple because of the homogeneity of the suspension of microbial cells and of the solution of nutrients and products in the liquid phase.
Pectinase production was studied in a submerged culture of Aspergillus flavus isolated from rotten oranges and apples fruits. Effects of the different growth factors on the enzyme production were studied using response surface methodology (RSM).
A two levels ―Plackett-Burman‖ design was used firstly for screening the effect of seven factors; ammonium sulfate concentration, orange pomace concentration, pH, temperature, inoculums size, aeration rate and incubation time on the pectinase production. Based on the obtained results; orange pomace concentration, pH and incubation time were selected for further studies due to their significant positive effect on the exo- polygalactouronase production.
the optimal fermentation conditions for pectinase as; medium pH of 8.0, orange pomace concentration of 30g/l and incubation time of 48 hr.
The enzyme was purified to homogeneity using Sephadex G-100. The optimal pectinase activity was detected in assays conducted at pH 7.0. The enzyme revealed a good thermal stability, as it lost 50% of its
activity when it was incubated at 500C for 50 minutes. The enzyme activity was enhanced in the presence of Cu+2 and Ca+2 .and it gave a Vmax value of 2000 U/ml and Km value of 0.8mg/ml.
Maximum enzyme activity was achieved, when both incubation time and pomace concentration set at their optimum levels of 48hr and 40g/l, respectively. These results are in contrast to that obtained by khalaf (2000)who reported that the exopectinase activity was reached to the maximum value after 4 days.