The amylolytic enzymes are the most important group of commercially produced enzymes such as α-amylase (EC 3.2.1.1) and debranching pullulanase (pullulan 6-glucanohydrolase; EC 3.2.1.41). In the present study, optimization of physical and nutritional parameters influencing pullulanase and α-amylase production attempted using the response surface methodology (RSM) from a strain of Clavispora lusitaniae ABS7 isolated from arid zone wheat seeds (Algerian Sahara). A Plackett-Burman design was used for screening of critical components, while the optimum selected factors are determined by the Wilson-Box design. Eight variables (agitation, pH, temperature, starch, yeast extract, (NH4)2SO4, salts and trace-elements) were studied with the screening test. The results revealed that six factors had greater influence on the amylopullulanase production. The CCD was then used to determine the maximum amylopullulanase concentration. The optimum conditions for the highest α-amylase production (13456,36 ± 300 U) and pullulanase production (12611,6±154 were as follows: agitation 136,56 rpm, temperature 54,14°C, starch 2,66 g/l, yeast extract 0,365 g/l, salts solution 8,75 ml/l and trace-elements solution 4,3 ml/l. Also the strain grows at the optimum condition, in fermenter and produces maximally amylopullulanase on an alkaline medium.

In this study, the growth kinetics of Bacillus subtilis in M9 minimal medium containing lignocellulosic components such as cellulose, lignin and D-xylose as a sole carbon source were determined. Cell growth in glucose, sucrose and starch were also studied. Studies were conducted in a 2.0 liter fermenter. The specific growth rates and maximum specific growth rates of B. subtilis in 0.1 % of the carbon sources mentioned were determined. The substrate utilization constant of B. subtilis was determined using a wide range of concentrations. The change in pO2, acid and alkali additions during the growth in the fermenter was recorded. The study revealed that B. subtilis was grown in all of the carbon sources tested. The specific growth rate (h-1), maximum specific growth rate (h-1) and substrate utilization constant (mg/L) of B. subtilis in minimal medium containing glucose, sucrose, starch, cellulose, xylose and lignin were (0.481, 0.2, 1.3), (0.334, 0.1, 39.58), (0.074, 0.094, 67.32), (0.046, 0.049, 500), (0.077, 0.136, 132.2) and (0.034, 0.07,660) respectively. In all the carbon sources except cellulose, a decrease in pH was observed. The study concludes that B. subtilis can be efficiently grown using minimal medium containing lignocellulosic substrates as a sole carbon source.

Mosaic, yellowing and malformation symptoms were detected on leaves of mulberry plants (Morus spp. L.), grown in the Experimental Farm of Faculty of Agriculture, Ain Shams University, Cairo, Egypt, during the spring of 2012. Viral assay experiment which carried out on sensitive host (Phaseolus vulgaris), resulted in appearance of virus-like symptom. The detected virus was found to have a narrow host range. Electron microscopy studies of ultrathin sections of healthy and infected mulberry leaves revealed that the detected virus affected the plant cell structure of the diseased plants. The viral particles were icosahedral in symmetry and double capsid of 57 nm in diameter and the diameter of the inner core was found to be 42 nm. The isolated mulberry mosaic virus is a tentative member of the Genus Begomovirus in the Family Geminiviridae. Isozyme polymorphism in the healthy and infected plants was studied. Differences were detected in the ideogram of peroxidase, α-esterase and β-esterase isozymes of the infected plants relative to that of the healthy plants. According to the available literature, this may be the first report of mulberry mosaic virus in Egypt.