In the emerging issue of increased multi-resistant properties in food borne pathogens, zinc oxide (ZnO) and nano-particle zinc oxide (nano-ZnO) are being used increasingly as antimicrobial agents. Thus, the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of nano-ZnO towards pathogens microbes Bacillus

Grafted alginate beads were prepared using the Encapsulator by two methods, the one-step and the two-step. The methods of grafting were characterized by thermal gravimetric analysis and infrared (IR). The glass transition (Tg) of both grafted gel beads showed gradual thermal improvement over the control gel. However, the one-step method showed higher Tg (231 °C) compared to the two-step method (220 °C). Both methods were also evaluated for immobilization of an important industrial enzyme, inulinase, to produce fructose, which is good for diet regimens and suitable for diabetics. The one-step method showed an enzyme loading capacity (ELC) of 530 U/g gel beads compared to 336 U/g gel beads for the two-step method. Accordingly, the one-step method has been chosen for further optimization. The ELC has been optimized to reach 1627 U/g gel using our locally prepared crude enzyme compared to 10.9 U/g by another author using purified inulinase. The immobilization process improved as did the enzyme’s thermal stability, from 50 to 60 °C, which is the most suitable temperature used in food industries to prevent microbial contamination. The enzyme’s thermal stability test at 60 °C and for an incubation time of 2 h, revealed a drastic decrease of the free enzyme activity to 21%, compared to 89% retention of activity for the immobilized enzyme. The immobilization process improved as well the enzyme’s shelf stability, where the free enzyme lost all of its activity at room temperature after 28 days, the immobilized enzyme retained over 77% of its initial activity. These results are encouraging to produce high fructose syrup on the industrial scale as the carrier is efficient and the method is simple and economic.

Phytase production by Penicillium purpurogenum GE1 isolated from soil around bean root nodules was investigated by solid state fermentation (SSF) using mixed substrates consisted of corn cob and corn bran. The SSF conditions were optimized by using one-variable-at-a-time strategy. The optimum conditions for phytase production were at 27 °C, pH 8 and 66% moisture content. The study of different carbon and nitrogen sources revealed that glucose and peptone registered the highest enzyme productivity (92 ± 5.6 U/g ds, 125 ± 4.9 U/g ds). Among different surfactants, maximum phytase productivity was observed with Tween 80 at 0.001 concentrations (170 ± 4.2 U/g ds). A Box-Behnken design was employed to investigate the optimization of the most significant variables affecting the enzyme production. Maximal phytase production was detected after the addition of (g/5 g ds): 0.75 glucose, 0.375 peptone and 0, 01 tween 80. This result represented an improvement in phytase production of 2.6 folds when compared to that previously obtained using the basal medium under the same cultivation conditions. The generated model was found to be very adequate for phytase production (90% accuracy) as the experimental value was 444 ± 3.5 U/g ds compared to 401 U/g ds for the predicted value. In brief, the production of phytase using corn cob and corn bran is a novel and cheap way for the production of this important enzyme and opens a new way for researchers to discover and explore this arena.

Inulinase has been extracted from Penicillium chrysogenum P36 and immobilized on a novel matrix of grafted biopolymer. The crude enzyme has been characterized in terms of specific activity, optimum temperature, and temperature stabilities. A novel matrix of alginate modified with polyimines and cross-linked with glutaraldehyde was prepared in beads shape using the Encapsulator to covalently immobilize crude inulinase. The modified beads were characterized using the FTIR and the DSC techniques. The FTIR showed the presence of the aldehydic’s carbonyl group at 1670 cm−1, which differs from that of the carboxylic group at 1620 cm−1. The DSC revealed a significant improvement of the gel’s thermal stability from 200 to 240 °C. The immobilization process improved the enzyme’s optimum temperature from 50 to 55 °C as well as the enzyme’s thermal stability for 2 h at 60 °C with 78% retention of activity as compared to only 7% for the free enzyme. The enzyme’s optimum pH slightly shifted from pH 4.8 for the free enzyme to pH 5 for the immobilized enzyme. However, at pH 5.2−5.5, the enzyme activity improved from 39% for the free enzyme to 75% for the immobilized enzyme. The novel matrix successfully immobilized the inulinase covalently with an enzyme loading capacity of 461 U/g gel. The reusability test proved the durability of the grafted alginate for 20 cycles with retention of 95% of the immobilized enzyme activity, whereas the untreated alginate gel completely dissolved by the eighth use. The results were promising; the grafting method is simple, and immobilization efficiency and enzyme loading capacity could be further improved by optimizing the gel beads’ formulations and the conditions of immobilization for the industrial applications.