Browsing by Author "Alabdalall, Amira H."

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A survey of elastase-producing bacteria and characteristics of the most potent producer, Priestia megaterium gasm32
(2023) Ghadah A. AlShaikh-Mubarak; Essam Kotb; Alabdalall, Amira H.; Aldayel, Munirah F.
Ninety-one elastase-producing bacterial isolates were recovered from different localities of the Eastern Province of Saudi Arabia. Elastase from the best isolate Priestia megaterium gasm32, from luncheon samples was purified to electrophoretic homogeneity using DEAE-Sepharose CL-6B and Sephadex G-100 chromatographic techniques. The recovery was 17.7%, the purification fold was 11.7x, and the molecular mass was 30 kDa. Enzymatic activity was highly repressed by Ba2+ and almost completely lost by EDTA, but it was greatly stimulated by Cu2+ ions, suggesting a metalloprotease type. The enzyme was stable at 45°C and pH 6.0–10.0 for 2 hours. Ca2+ ions considerably enhanced the stability of the heat-treated enzyme. The Vmax and Km against the synthetic substrate elastin–Congo red were 6.03 mg/mL, and 8.82 U/mg, respectively. Interestingly, the enzyme showed potent antibacterial activity against many bacterial pathogens. Under SEM, most bacterial cells showed loss of integrity, damage, and perforation. SEM micrographs also showed a time-dependent gradual breakdown of elastin fibers exposed to elastase. After 3 hours, intact elastin fibers disappeared, leaving irregular pieces. Given these good features, this elastase may be a promising candidate for treating damaged skin fibers with the inhibition of contaminating bacteria.
Bioethanol Production from Lignocellulosic Biomass Using Aspergillus niger and Aspergillus flavus Hydrolysis Enzymes through Immobilized S. cerevisiae
(2023) Asma A. Almutari; Amira Alabdalall; Maryam H. Alsoufi; Lulwah Y. Alfuraih; Aldakheel, Lena A.; Alsoufi, Maryam H.; Alfuraih, Lulwah Y.; Elkomy, Hesham M.
fermentation culture, induces the production of cellulases. Cellulose accounts for 20% of the enzyme market worldwide, demonstrating benefits in diverse applications, especially bioethanol and biogas generation. The aim is to evaluate the optimal condition for bioethanol production by previously isolated fungal species from different soil types in the eastern region of the Kingdom of Saudi Arabia. This study attempts to evaluate and optimize the culture conditions of lignocellulosic biomass under SSF using the highest cellulases-producer strains in the region: Aspergillus niger and Aspergillus flavus (GenBank Accession No. MT328516 and MT328429, respectively) to produce raw sugar that consequently is used in the next step of bioethanol production. This process has two parts: (1) hydrolyze lignocellulosic biomass to obtain raw sugar using A. niger and A. flavus that produce cellulase, and (2) produce bioethanol through the conversion of the raw sugar produced from the cellulolysis into ethanol using Saccharomyces cerevisiae. The optimal conditions under SSF were seven days of incubation, 5% glucose as a carbon source, 1% ammonium sulfate as a nitrogen source, and 80% moisture for both isolates. Biochemical characterization showed stability for the immobilized enzyme in all temperature ranges (from 20 °C to 70 °C), while the free enzyme exhibited its maximum at 20 °C of 1.14 IU/mL. CMCase production was the highest at pH 4.0 (1.26 IU/mL) for free enzyme and at pH 5.0 (2.09 IU/mL) for the immobilized form. The CMCase activity increased steadily with an increase in water level and attained a maximum of 80% moisture content. The maximum enzyme activity was with coffee pulp as a substrate of 7.37 IU/mL and 6.38 IU/mL for A. niger and A. flavus after seven days of incubation, respectively. The Carboxymethyl Cellulase (CMCase) activity in immobilized enzymes showed good storage stability under SSF for six weeks, maintaining 90% of its initial activity, while the free enzyme retained only 59% of its original activity. As a carbon source, glucose was the best inducer of CMCase activity with coffee pulp substrate (7.41 IU/mL and 6.33 IU/mL for A. niger and A. flavus, respectively). In both fungal strains, ammonium sulfate caused maximum CMCase activities with coffee pulp as substrate (7.62 IU/mL and 6.47 IU/mL for A. niger and A. flavus, respectively). Immobilized S. cerevisiae showed an increase in ethanol production compared to free cells. In the case of immobilized S. cerevisiae cells, the concentration of ethanol was increased steadily with increasing fermentation time and attained a maximum of 71.39 mg/mL (A. niger) and 11.73 mg/mL (A. flavus) after 72 h of fermentation.
Isolation, Screening, and Identification of Alkaline Protease-Producing Bacteria and Application of the Most Potent Enzyme from Bacillus sp. Mar64
(2023) Kotb, Essam; Essam Kotb; Alsayed, Mariam A.; Azzah Ibrahim Alghamdi; Alkhaldi, Eida; AbdulAzeez, Sayed; Sayed Abdul Azeez
In this study, thirty-seven alkaline protease-producing bacteria were recovered from different regions of Saudi Arabia. The proteolytic strain with the highest productivity was identified as Bacillus sp. Mar64. Maximum productivity of Mar64P alkaline protease was reached at 60 h, pH 9.0, and 45 °C using 1% tyrosine and 0.5% maltose as nitrogen and carbon supplies, respectively. Specific activity was intensified to 8.5-fold with a recovery of 12.4% and SDS—PAGE revealed one band at 28 kDa after enzyme purification. Mar64P was maximally active at 55 °C and pH 11.0 with thermal stability up to 70 °C and pH stability at 7.0–12.0 for 1 h. It was inhibited by EDTA and unaffected by PMSF, therefore tentatively classified as metalloprotease-type. Storage efficacy was effective for up to eight weeks and it was durable in presence of organic solvents (20%, v/v) such as acetonitrile, acetone, and isopropanol upto to 15 days. The enzyme was compatible with dry detergents at both low and high temperature, in addition, was successful in removing various stains such as blood, egg yolk, chocolate, tea, coffee, and sweat. Furthermore, it was successful in removing skin hairs and hydrolyzing gelatin of waste X-ray films. Collectively, due to these unique properties, Mar64P could be considered an environmentally friendly candidate in both detergent and leather industries.
Screening for chitin degrading bacteria in the environment of Saudi Arabia and characterization of the most potent chitinase from Streptomyces variabilis Am1
(2023) Batool M. AlGarudi; Alabdalall, Amira H.; Safa K. AlZuwaid; Amira Alabdalall; Aldakeel, Sumayh A.; Essam Kotb; Ibtisam Mohammed Ababutain; Algarudi, Sakina M.; Ahmed, Asmaa A.; Albarrag, Ahmed M.
Forty-six promising chitinolytic isolates were recovered during a screening for chitinolytic bacteria in the environment of Saudi Arabia. The top three isolates belonged to the genus Streptomyces. Streptomyces variabilis Am1 was able to excrete the highest amount of chitinases, reaching the maximum at 84 h with 0.5% yeast extract and nitrogen source and 2% galactose as a carbon source. Purification of chitinase by DEAE-Cellulose and Sephadex G75 improved the specific activity to 18.6-fold and the recovery to 23.8% and showed a mass at 56 kDa. The optimal catalysis of the purified chitinase was at 40 °C and pH 8 with high thermostability and pH stability as reflected by a midpoint temperature value of 66.6 °C and stability at pH 4–9. The protein reagents SDS, EDTA, and EGTA significantly inhibited the enzyme and the EDTA-chelated chitinase restored its activity after the addition of Fe2+ ions suggesting a metallo-chitinase type with ferric ions as cofactors. Chitinase exerted high antifungal activity against some phytopathogenic fungi. Interestingly, the tested Streptomyces were able to produce chitosan nanocubes along with chitosan from chitin degradation which may be an additional power in their antifungal activity in nature. This work also reveals the importance of unexplored environments as a pool of promising microorganisms with biotechnological applications.