Characterization of xylanase produced by aspergillus niger fermented on corn cob

The use of waste as raw material is important for government economy and natural balance. This article investigates a strain of Aspergillus niger for xylanase production in solid state fermentation [SSF] using different agricultural residues without pretreatment. The organism produced 164.4 [micro mol/ ml/min] of xylanase in static flask on corn cob, an inexpensive lignocellulosic biomass, without enrichment of medium [only distilled water]. Using surfactant solution [Tween 80, 1%] for enzyme extraction from solid substrate increased the yield by 515%. Maximum xyianase activity was recorded at 55°C, with high activity at wide range of temperature [50-60°C]. The enzyme produced on corn cob showed good thermal stability with residual activity of 62.1 and 54.3% after 2 hr incubation at 50 and 60°C, respectively, Addition of glycerol [50%] improved stability against temperature by 19.9% after incubation at 60°C for 1hr, and 17.8% after incubation at 60°C for 2 hr. The optimum pH for the enzyme activity was 4.5, increasing pH causing decreasing in activity. Xylanase enzyme was stable at different pH's after 1 hr with remaining activity of 89.6% and 55.0%, respectively at pH 4.0 and 9.0. The enzyme possessed 70.6 and 37.6% of its activity by storage at room temperature after 10 and 30 days. In presence of metal ions such as Na[2+], Ca[2+] and protein disulphide reducing agents such as dithiothreitol [DTT], the activity of enzyme was increased by 34.9, 10.7 and 32.8%, respectively. Sodium dodecyl sulphate [SDS] and Cu[2+] ion strongly inhibited the enzyme by 56,8 and 23.7%, respectively. Saccarification of different wastes by the enzyme was studied. The highest yield of reducing sugars [20.3 mg/ 200 mg dry weight substrate] was obtained from corn cob with maximum saccharification after 72 hr [71.8%] as compared to other wastes

Functional change of dextran-modified alpha-amylase from bacillus acidocaldarius

ALPHA-AMYLASE from Bacillus acidocaldarius was modified by covalent coupling to activated dextran with retained activity of 77.7%. After conjugation, the enzyme was stable within a broader pH range than the native enzyme and its optimum temperature increased by 10°C compared to the native enzyme. The conjugated a amylase exhibited a higher K[m] [Michaelis constant], lower V[max] [maximal reaction rate] and lower E[A] [activation energy] than the native enzyme. Covalent attachment of alpha- amylase to activated dextran protected the enzyme against heat inactivation. In the presence of the substrate, the conjugated enzyme retained 68.2% of its original activity after incubation at 70°C for 30 min which was more than that retained by the native enzyme [50.3%] under the same conditions. The calculated t[1/2] [half-life time] values of heat inactivation energy at 50, 60°C were 89 and 56 mm, respectively for the conjugated enzyme, whereas at these temperatures the native enzyme was less stable [t[1/2] 60 and 47 min, respectively]. The deactivation rate constant at 80°C for the conjugated a-amylase is about 11.9x10[-3]/ min, which is lower than that of the native enzyme [14.8x10[-3]/ min]. Conjugated a-amylase was more stable against chemical denaturation than the native enzyme, and retained 70.6% of its activity in presence of CuSO[4] [10 mM] while the native form of retained only 34.1%

Production of Bacillus licheniformis ATCC 21415 alkaline protease in batch, repeated batch and continuous culture

Bacillus licheniformis ATCC 21415 cells were immobilized on different carriers using different methods of immobilization including physical adsorption, covalent binding, ionic binding and entrapment. The immobilized cells were prepared by covalent binding on wool (as a new carrier) through 1% glutaraldehyde had the highest enzyme activity (9.0 U/mL) with the highest specific productivity (6.17 U/g wet cells/h). Alkaline protease production and the stability of biocatalyst were investigated in both free and immobilized cells. The results showed that the immobilized cells were more efficient for enzyme production by repeated batch fermentation (5 cycles, 480 h) with 57% residual activity whereas the free cells retained 35% after 2 cycles. In continuous production the highest enzyme activity (9.9 U/mL) was obtained at a dilution rate of 0.1/h while the highest enzyme yield (763.6 U/h) and the highest reactor productivity (3.32 U/mL/h) were attained at a dilution rate of 0.4/h. Packed-bed bioreactor was a successful method for continuous production of alkaline protease for a long time (168 h) with 53% relative activity. The bioreactor affected the highest specific productivity (118.2 U/g wet cells/h) which was 12-24 times higher than other systems of enzyme production.

parasitological study on the use of biotherapeutic yeast in the treatment of Schistosoma mansoni infected mice

Infection with Schistosoma mansoni induces humoral and T cell mediated responses and leads to a delayed hypersensitivity that result in granulomatous inflammatory disease around the parasite eggs. The nonpathogenic Saccharomyces species have potential as an exogenously administered agent for maintaining colonization resistance during antibiotic therapy, preventing diarrhea and other gastrointestinal diseases as well as its antagonistic activity [in vitro and in vivo] against various bacterial pathogens. Saccharomyces boulardii exerts its immunoprotective effect through the secretion of immunoglobulins. In this work the antibilharzial effect of S. boulardii and Saccharomyces cerevisiae was studied. Both yeast products were given orally to mice for 21 days before infection. Their effects on worm burden, egg count, fecundity and granuloma diameter were elucidated. Both were effective in reducing worm burden and egg count resulting in a significant decrease in granuloma diameter. The obtained data show that S. cerevisiae gave more potent effects on S. mansoni parasitism than S. boulardii

Effect of growth hormone administration of serum somatomedin-C levels in bilharzial and liver disorders patients

This work was designed in an attempt to clarify the effect of the growth hormone injection on the serum somatomedin-C [SM-C] levels in Egyptian children with urinary bilharziasis, advanced bilharzial hepatic fibrosis and children suffering from chronic hepatitis compared with 11 healthy age and sex matched children served as controls. SM-C levels were studied prior and after the injection of human growth hormone [hGH]. The basal and hGH-stimulated SM-C levels were significantly reduced in bilharzial patients compared with controls. Patients with hepatitis had significantly lower serum SM-C values prior or post hGH administration. Liver tests carried out for bilharzial patients showed impaired function both on admission and after treatment. It can be concluded that shortness in children with bilharzial hepatic fibrosis may results from hepatic and endocrinal and nutritional factors. Also, the results suggested that the delayed skeletal maturation in chronic hepatitis cases is probably secondary to liver dysfunction, malnutrition and associated endocrinopathies

Comparative study on the levels of alpha-fetoprotein [AFP] in different pathological cases

This research represented a trial to demonstrate the changes which may take place in AFP levels as a tumor marker among pregnant Egyptian women suffering from bilharzial and cancerous infestations. It was found that combination of schistosomal infection with pregnancy leads to obvious high significant increase in AFP in late pregnancy [6 - 8 months] compared with unpregnant patients. Although the combination between bilharzial infestation and early pregnancy leads to increase in AFP level, the differences were nonsignificant compared with unpregnant ones. There is an extremely significant increase in AFP levels among urinary and intestinal schistosomal pregnant patients compared with healthy pregnant women which was higher in intestinal infection and more pronounced in early pregnancy than late ones. Malignancy in combination with pregnancy caused remarkable significant increase compared with unpregnant patients, and the increase was slightly higher in bladder than colonic cancerous cases and their AFP levels were gradually increased with progress of both pregnancy and malignancy