Journal of BioScience and Biotechnology (JBB)

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https://doi.uni-plovdiv.bg/handle/store/2
p-ISSN: 1314-6238 / e-ISSN: 1314-6246

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Browsing Journal of BioScience and Biotechnology (JBB) by Author "Al-Quadan, Farouk"

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    A novel neutral protease from thermophilic Bacillus strain HUTBS62
    (Plovdiv University Press “Paisii Hilendarski”, 2012-10-15) Aqel, Hazem; Al-Quadan, Farouk; Yousef, Tahani K.
    A novel neutral highly thermostable protease was detected in the culture medium of thermophilic Bacillus strain HUTBS62 isolated from hot-spring located near to the Dead Sea, Jordan. The enzyme was purified by precipitation with 55-60% ammonium sulfate, gel filtration on Sephadex G-100 and DEAE ion exchange chromatography. The enzyme was purified 53-fold with 2% yield. The optimum pH and temperature for catalytic activity of protease was pH 6.8 and 80ºC, respectively, and 31% activity of protease remained even after heat treatment at 100ºC for 60 min. The relative activity of the enzyme was highly stable (90%) at 50ºC for 2 h. The half-life of the enzyme at 90ºC, 80ºC and 70ºC was estimated to be 3, 4 and 6 h, respectively. The activation energy of denaturation of purified enzyme was 21.7 kJmol-1. Iron, sodium, calcium, and manganese increased protease activity. On the other hand, magnesium, cobalt and zinc variably decreased the residual activity. But cadmium and copper drastically inhibited the enzyme activity. The enzymatic activity was highly stable in the presence of 1 and 2 mM EDTA at pH 6.8 and 80ºC. The neutral protease therefore could be defined as a highly thermostable with new properties make the present enzyme applicable for many biotechnological purposes.
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    Effects of temperature, pH-values and sodium chloride concentrations on the glucose-6-phosphate dehydrogenase activity by thermotolerant Bacillus strains
    (Plovdiv University Press "Paisii Hilendarski", 2012-05-20) Aqel, Hazem; Al-Quadan, Farouk; Boulenouar, Noureddin
    Thirteen new isolated thermotolerant Bacillus strains and four known Bacillus species were used to evaluate the effect of growth temperature, pH-values and NaCl concentrations on the intracellular glucose-6-phosphate dehydrogenase (G6PDH) activity. Results had shown a significant difference in G6PDH production among all species at all used temperatures (p<0.05). The response of individual new isolates and controls for production of G6PDH under growth conditions was variable. The optimal growth conditions did not correspond to the optimal cultivation conditions for maximum G6PDH production. The growth temperature showed the most significant effect on G6PDH activity. The combined effect of temperature and NaCl on the G6PDH activity was strongly pronounced in comparison with the combined effect of temperature and pH or pH and NaCl. Thermal stability at 53ºC and electrophoretic mobility were also investigated. G6PDH from HUTB41 was the most thermostable G6PDH enzyme with T50% of more than 360 minutes. Electrophoretic study demonstrated that G6PDH was composed of two isoenzymes for all strains except B. marinus and B. schlegelii that had three isoenzymes.