Isolation and characterization of a haloalkaliphilic protease producer bacterium from Wadi Natrun in Egypt

Lotfy, Walid A.; Abd-El-Karim, Neveen Mohamed; El-Sharouny, Ebaa Ebrahim; El‐Helow, Ehab R.

doi:10.5897/ajb2017.15984

Cited by 8 publications

(2 citation statements)

References 43 publications

(44 reference statements)

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“…DOE are more effective, reliable and consume less materials, time, and effort to determine the near optimum settings for each variable. Recently, these designs have been successfully employed in many bioprocess optimizations (Lotfy et al, 2017(Lotfy et al, , 2018aGhanem et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

Biosynthesis of Silver Nanoparticles by Aspergillus terreus: Characterization, Optimization, and Biological Activities

Lotfy

Alkersh

Sabry

et al. 2021

Front. Bioeng. Biotechnol.

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In this study, mycelial filtrate of Aspergillus terreus BA6 was used to reduce AgNO3 to form silver nanoparticles (AgNPs). The effect of seven independent variables on the diameter of AgNPs was studied by applying design of experiments (DOE). At optimal conditions, the diameter of AgNPs was reduced by approximately 26.7% compared to the basal culture condition and AgNO3 concentration was found to be the most significant factor affecting the diameter of AgNPs. A. terreus nano-Ag was characterized using UV-visible spectroscopy, transmission electron microscopy, energy dispersive X-ray (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Zeta potential. The maximum UV absorption was obtained at 420 nm and the microscopic results showed particles with narrow size distribution ranging from 7 to 23 nm. XRD pattern of AgNPs revealed four diffraction peaks of metallic silver and the EDX spectrum showed a strong signal attributed to Ag nano-crystals. AgNPs mycofabricated by A. terreus showed potent minimum inhibitory concentration (MIC) and broad minimum bactericidal/fungicidal concentration (MBC/MFC) against 12 reference microorganisms. The MIC and MBC/MFC values of AgNPs were 0.312 to 1.25 μg/ml and 0.625 to 10 μg/ml, respectively. Nevertheless, AgNPs did not demonstrate any antagonistic activity against Coxsackie B virus. The in vitro cytotoxicity of the mycosynthesized AgNPs showed significant antitumor activity against adenocarcinoma epithelial cells from human breast cancer (Mcf-7) cell line with an inhibitory concentration (IC50) of 87.5 μg/ml.

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Section: Introductionmentioning

confidence: 99%

Biosynthesis of Silver Nanoparticles by Aspergillus terreus: Characterization, Optimization, and Biological Activities

Lotfy

Alkersh

Sabry

et al. 2021

Front. Bioeng. Biotechnol.

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“…To maximize the production of aflatoxins by A. flavus, a fraction factorial design, the Plackett-Burman design (Plackett and Burman, 1946;Lotfy et al, 2017), and Box-Behnken design, a response surface methodology, were applied (Box and Behnken, 1960;Lotfy et al, 2018). The purpose of first statistical design was to identify which variable has a significant effect on aflatoxin production by A. flavus.…”

Section: Elucidation Of the Factors Affecting Aflatoxin Production Bymentioning

confidence: 99%

The Inhibitory Effect of Wheat Husks Addition on Aflatoxins Production by Aspergillus flavus in Liquid Culture With Various Wheat Compositions as Carbon Sources

et al. 2020

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Wheat may be infected by the aflatoxigenic mold Aspergillus flavus during pre-and post-harvest activities. Control strategies reported to manage aflatoxin contamination of wheat are expensive and require extensive testing to verify the absence of toxic secondary metabolites or newly formed compounds. The objective of this study was to develop an in vitro new control strategy based on assessing the influence of wheat husks on aflatoxin production by A. flavus in liquid culture. The results showed that aflatoxin production is significantly influenced by the existence of husks in the wheat forms used as carbon substrates according to the following order: full wheat grains < halfcrushed wheat grains < wheat flour 82% < wheat flour 72%. By applying a fractional factorial design and a response surface methodology, maximum aflatoxin production (2.567 ng/mg) was predicted when wheat flour 72% (39 g/l) as a carbon source, yeast extract (5 g/l), and a 75-ml medium volume/250 ml flask were utilized. At this optimized condition, after addition of wheat husk extract, the growth and synthesis of aflatoxins of A. flavus were repressed by 74.85 and 98.72%, respectively. This finding paves the way to examine the antifungal potential of wheat husk constituents and to compare their efficacy with thyme, cinnamon, sweet basil, and coriander essential oils, which possess antimycotic activities. Accordingly, the wheat husk component SiO 2 showed the highest growth inhibition (67.04%) and reduction of A. flavus aflatoxins (82.67%). These results are comparable to those obtained from various examined antimycotic essential oils.

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Diversity of esterase and lipase producing haloalkaliphilic bacteria from Lake Magadi in Kenya

et al. 2019

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Lipids are hydrocarbons comprised of long‐chain fatty acids and are found in all living things. In the environment, microorganisms degrade them to obtain energy using esterases and lipases. These enzymes are nowadays used in different industrial applications. We report isolation of 24 bacteria with esteresic and lipolytic activity from Lake Magadi, Kenya. The isolates were characterised using morphological, biochemical, and molecular methods. Isolates grew at an optimum salt concentration of 5–8% (w/v), pH range of 8.0–9.0, and temperature range of 35–40°C. The isolates were positive for esterase and lipase assay as well as other extracellular enzymes. Phylogenetic analysis of the 16S ribosomal RNA gene showed that the isolates were affiliated to the genus Bacillus, Alkalibacterium, Staphylococcus, Micrococcus, Halomonas, and Alkalilimnicola. None of the bacterial isolates produced antimicrobial agents, and all of them were resistant to trimethoprim and nalidixic acid but susceptible to streptomycin, amoxillin, chloramphenicol, and cefotaxime. Growth at elevated pH, salt, and temperature is an indicator that the enzymes from these organisms could function well under haloalkaline conditions. Therefore, Lake Magadi could be a good source of isolates with the potential to produce unique biocatalysts for the biotechnology industry.

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Isolation and characterization of a haloalkaliphilic protease producer bacterium from Wadi Natrun in Egypt

Cited by 8 publications

References 43 publications

Biosynthesis of Silver Nanoparticles by Aspergillus terreus: Characterization, Optimization, and Biological Activities

Biosynthesis of Silver Nanoparticles by Aspergillus terreus: Characterization, Optimization, and Biological Activities

The Inhibitory Effect of Wheat Husks Addition on Aflatoxins Production by Aspergillus flavus in Liquid Culture With Various Wheat Compositions as Carbon Sources

Diversity of esterase and lipase producing haloalkaliphilic bacteria from Lake Magadi in Kenya

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