Papers by mahmoud yassien
Scientific Reports, Jul 29, 2022
Strong biofilm-forming Enterococcus feacalis urinary tract pathogens (n = 35) were used to determ... more Strong biofilm-forming Enterococcus feacalis urinary tract pathogens (n = 35) were used to determine the lytic spectrum of six bacteriophages isolated from sewage samples. Only 17 Enterococcus feacalis isolates gave lytic zones with the tested bacteriophages from which five isolates were susceptible to all of them. The isolated enterococcal phages are characterized by wide range of thermal (30-90 °C) and pH (3-10) stability. They belong to order Caudovirales, from which four bacteriophages (EPA, EPB, EPD, EPF) belong to family Myoviridae and two (EPC, EPE) belong to family Siphoviridae. In addition, they have promising antibiofilm activity against the tested strong-forming biofilm E. faecalis isolates. The enterococcal phages reduced the formed and preformed biofilms to a range of 38.02-45.7% and 71.0-80.0%, respectively, as compared to the control. The same promising activities were obtained on studying the anti-adherent effect of the tested bacteriophages on the adherence of bacterial cells to the surface of urinary catheter segments. They reduced the number of adherent cells to a range of 30.8-43.8% and eradicated the pre-adherent cells to a range of 48.2-71.1%, as compared to the control. Overall, the obtained promising antibiofilm activity makes these phages good candidates for application in preventing and treating biofilm associated Enterococcus faecalis infections. Enterococcus species are commensals gram-positive bacteria which cause many infections in susceptible hosts, such as endocarditis, bacteremia, oral infections and urinary tract infections (UTI) especially device associated infections. In Egyptian UTI patients, Enterococcus faecalis (E. faecalis) is found to be the second highest prevalence after Escherichia coli. UTIs in hospitalized, catheterized and diabetic patients are higher than outpatients 1,2. One of the virulence factors of Enterococcus besides the enzymes and proteins secreted is its ability to form biofilm 3. The National Institutes of Health (NIH) revealed that among all microbial and chronic infections, 65% and 80%, respectively, are associated with biofilm formation. These include both, device and non-device-associated infections 4. Catheters associated urinary tract infections (CAUTI) account for 40% of all nosocomial infections, of which 15% to 30% are associated with E. faecalis and Enterococcus faecium (E. faecium) 5,6. E. faecalis lives as commensal organism in the gastrointestinal tract. Nonetheless, it may trigger life-threatening infections including endocarditis, bacteremia, UTI and meningitis, and it is particularly common in hospitals where antibiotic resistance has grown 7. The devices associated enterococcal infections, like CAUTI, are mainly due to biofilm associated bacteria 8. Biofilm forming bacteria show resistance to many antibiotics and immune response which results in treatment failure 9. Given the difficulty of treating and eradicating biofilm associated infections, there is an unmet need for therapeutic options other than antibiotics to prevent biofilm formation. New approaches were developed to overcome this problem, among which was bacteriophage therapy 10. Bacteriophages are the natural predators for bacteria, and are the most common biological entities on the planet; phage particles are usually five to ten times more abundant than bacterial cells. So, phage predation is thought to cut the global bacterial population in half every 48 h 11. Bacteriophages have many advantages over antibiotics therapy; they can affect all types of bacteria including multi drug resistant ones, they are promising in the economic aspect, and finally, being natural products, they are likely to be devoid of apparent toxicity 12 .
Molecular Biology Reports, Apr 17, 2019
About 24 h incubation of Azomonas (A.) macrocytogenes isolate KC685000 in 14L fermenter produced ... more About 24 h incubation of Azomonas (A.) macrocytogenes isolate KC685000 in 14L fermenter produced 22% poly (3-hydroxybutyrate) (PHB) per cell dry weight (CDW) biopolymer using 1 vvm aeration, 10% inoculum size, and initial pH of 7.2. To control the fermentation process, Logistic and Leudeking-Piret models were used to describe the cell growth and PHB production, respectively. These two models were in good agreement with the experimental data confirming the growth associated nature of PHB production. The best method for recovery of PHB was chemical digestion using sodium hypochlorite alone. The characterization of the produced polymer was carried out using FT-IR, 1 HNMR spectroscopy, gel permeation chromatography and transmission electron microscope. The analysis of the nucleotide sequences of PHA synthase enzyme revealed class III identity. The putative tertiary structure of PHA synthase enzyme was analyzed using Modular Approach to Structural class prediction software, Tied Mixture Hidden Markov Model server, and Swiss model software. It was deduced that PHA synthases' structural class was multidomain protein (α/β) containing a conserved cysteine residue and lipase box as characteristic features of α/β hydrolase super family. Taken together, all the results of molecular characterization and transmission electron microscope images supported that the PHB formation was attained by the micelle model. To the best of our knowledge, this is the first report on production of growth associated PHB polymer using A. macrocytogenes isolate KC685000, and its class III PHA synthase.
Research Square (Research Square), Nov 4, 2020
Background: Paromomycin is a 2 deoxystreptamine aminocyclitol aminoglycoside antibiotic with broa... more Background: Paromomycin is a 2 deoxystreptamine aminocyclitol aminoglycoside antibiotic with broad spectrum activity against Gram-negative, Gram-positive bacteria and many protozoa. This study introduces a strategy for paromomycin production through solid-state fermentation using Streptomyces rimosus subsp. paromomycinus NRRL 2455. Solid state fermentation has gained enormous attention in the development of several products because of their numerous advantages over submerged liquid fermentation. After selecting the best solid substrate, a time course study of paromomycin production was carried out followed by optimization of environmental conditions using response surface methodology. Paromomycin yields obtained using this technique were also compared to those obtained using submerged liquid fermentation. Results: Upon screening of 6 different substrates, maximum paromomycin concentration (0.51 mg/g initial dry solids) was obtained with the cost-effective agro-industrial byproduct, corn bran, impregnated with aminoglycoside production media. This value was higher than that obtained using submerged liquid fermentation using the same conditions. Optimization of environmental conditions using D optimal design yielded a 4.3-fold enhancement in paromomycin concentration reaching 2.21 mg/g initial dry solids at a pH of 8.5, inoculum size of 5% v/w and a temperature of 30 °C. Conclusion: Compared to submerged liquid fermentation, solid state fermentation resulted in higher paromomycin concentrations, cost reduction of raw materials, less energy consumption and waste water discharge, which have major implications in industrial fermentation. Therefore, SSF is a superior alternative to SLF for paromomycin production. To the best of our knowledge, this is the rst report on the optimized paromomycin production through solid state fermentation process.
Research Square (Research Square), Sep 2, 2019
Natural products particularly microbial metabolites have been the mainstay of cancer chemotherapy... more Natural products particularly microbial metabolites have been the mainstay of cancer chemotherapy and are likely to provide many of the lead structures and derivatives with new biological activities. In this research, the production of some potential cytotoxic metabolites from Streptomyces (S.) griseus isolate KJ623766 was carried out in 14 L laboratory fermenter under specified optimum conditions (28°C temperature, 200 RPM rotation speed, uncontrolled PH, 3 vvm aeration and 2 bar airflow pressure). After 72 hrs of incubation, the cell free culture supernatant (CFCS) was collected and extracted using ethyl acetate (1:1, v/v) at pH 7.0. Using 3-(4,5-dimethylthazol-2-yl)-2,5-diphenyl tetrazolium-bromide (MTT) assay, the cytotoxic activity of the ethyl acetate extract against Caco2 and Hela cancer cell lines was determined with CD50 of 14 µg/ml and 20 µg/ml, respectively. Bioassay guided fractionation of the ethyl acetate extract using different chromatographic techniques had led to the purification of the cytotoxic metabolites coded W1, R1 and R2 with reproducible amounts of 20, 5, and 1.5 mg/l, respectively. The structures of respective metabolites were determined based on the mass, 1D and 2D NMR spectroscopic analysis and were identified as genistein, β-rhodomycinone and γ-rhodomycinone, respectively. Accordingly, S. griseus isolate KJ623766 can be used as a potential industrial strain for the commercial production of the isoflavonoid genistein, as well as for the production of β-and γ-rhodomycinone to be used for the construction of new derivatives with more potent cytotoxic activities of the anthracycline family. To the best of our knowledge, this is the first report about the production of the isoflavonoid genistein by S. griseus KJ623766.
A Streptomyces strain MS-6-6 with promising anti-tuberculous activity was isolated from soil samp... more A Streptomyces strain MS-6-6 with promising anti-tuberculous activity was isolated from soil samples in Saudi Arabia. The nucleotide sequence of its 16S rRNA gene (1426 bp) evidenced a 100% similarity to Streptomyces mutabilis. Through an anti-tuberculous activity-guided approach, a polyketide macrolide was isolated and identified as treponemycin (TP). The structure of the isolated compound was determined by comprehensive analyses of its 1D and 2D NMR as well as HRESI-MS. In addition to the promising anti-tuberculous activity (MIC = 13.3 µg/mL), TP showed broad spectrum of activity against the Gram positive, Gram negative strains, and Candida albicans. Improvement of TP productivity (150%) was achieved through modification in liquid starch nitrate medium by replacing KNO3 with corn steep liquor and yeast extract or tryptone, and removing CaCO3 and K2HPO4. The follow up of TP percentage as well as its metabolites profile for each media was assessed by LC/DAD/MS.
Journal of Industrial Microbiology, 1995
The use of various medical devices including indwelling vascular catheters, cardiac pacemakers, p... more The use of various medical devices including indwelling vascular catheters, cardiac pacemakers, prosthetic heart valves, chronic ambulatory peritoneal dialysis catheters and prosthetic joints has greatly facilitated the management of serious medical and surgical illness. However, the successful development of synthetic materials and introduction of these artificial devices into various body systems has been accompanied by the ability of microorganisms to adhere to these devices in the environment of biofilms that protect them from the activity of antimicrobial agents and from host defense mechanisms. A number of host, biomaterial and microbial factors are unique to the initiation, persistence and treatment failures of device-related infections. Intravascular catheters are the most common devices used in clinical practice and interactions associated with these devices are the leading cause of nosocomial bacteremias. The infections associated with these devices include insertion site infection, septic thrombophlebitis, septicemia, endocarditis and metastatic abscesses. Other important device-related infections include infections of vascular prostheses, intracardiac prostheses, total artificial hearts, indwelling urinary catheters, orthopedic prostheses, endotracheal tubes and extended wear lenses. The diagnosis and management of biofilm-associated infections remain difficult but critical issues. Appropriate antimicrobial therapy is often not effective in eradicating these infections and the removal of the device becomes necessary. Several improved diagnostic and therapeutic modalities have been reported in recent experimental studies. The clinical usefulness of these strategies remains to be determined.
Enzyme and Microbial Technology, 2004
A keratinase enzyme was isolated and purified from a feather-degrading culture of Aspergillus ory... more A keratinase enzyme was isolated and purified from a feather-degrading culture of Aspergillus oryzae. Fractional precipitation of the crude enzyme with ethanol, acetone and ammonium sulfate yielded 21 fractions. The fraction obtained at 75–85% ammonium sulfate saturation showed the highest activity and about 3.3-fold purification. This fraction was further purified by gel filtration in Sephadex G-75 followed by ion exchange
AFRICAN JOURNAL OF BIOTECHNOLOGY, 2012
Improvement of the α-amylase productivity of Streptomyces clavifer was achieved through studying ... more Improvement of the α-amylase productivity of Streptomyces clavifer was achieved through studying the effect of some nutritional factors and ultra violet (UV) mutagenesis. Modification in the formula of liquid starch medium by decreasing the concentration of soluble starch to 1%, increasing the corn steep liquor to 2%, and adding 0.75% glucose and 0.01% L-valine caused significant increase in the enzyme productivity from 8640 to 23450 U/L. UV variants of high amylase productivity (54620 U/L) was isolated from the parent strain. A promising level of α-amylase production (50850 U/L) at large scale level was obtained by cultivating the tested strain in the optimum condition using laboratory fermentor of 14 L. Enzyme purification was achieved by ethanol precipitation, diethylaminoethyl cellulose (DEAE-C), and Sephadex G-100 gel filtration chromatography. The final preparation had 22.0% activity recovery and approximately 156.1 fold purification. The purified enzyme had molecular weight of approximately 50 kDa as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The purified enzyme exhibits maximum activity at pH 6 and 60°C and showed maximum stability at pH 6 and up to 40°C.
African Journal of Microbiology Research, 2012
The effect of environmental factors on glucose isomerase productivity of Saudi Arabia isolated St... more The effect of environmental factors on glucose isomerase productivity of Saudi Arabia isolated Streptomyces albaduncus was studied. During growth of the tested microorganism in the basal medium at 30°C, the glucose isomerase production reached the maximum level (6530 U/L) after 96 h incubation period. Irrespective of the carbon source, replacement of xylose with different carbohydrate did not increase the enzyme productivity. On the other hand, the highest enzyme productivity was obtained when corn steep liquor (2.0%, w/v) and yeast extract (1%) were used as nitrogen sources. Also, the optimum initial pH for maximum growth and enzyme productivity was 7. Further improvement in the glucose isomerase production was obtained after the addition of 0.01% (w/v) DL-isoleucine to the culture medium. Accordingly, optimization of the environmental condition associated with increase in the glucose isomerase enzyme productivity from S. albaduncus up to 15328 U/L which is approximately 2.3 more times as compared to that obtained under the initial condition. Finally, a promising production of glucose isomerase (14100 U/L) at large scale level was achieved by cultivation of the tested strain in the optimum environmental conditions using laboratory fermentor of 14 L.
World journal of pharmaceutical sciences, Sep 2, 2017
Recovery and molecular characterization of poly-β-hydoxybutyrate polymer by bacillus cereus isola... more Recovery and molecular characterization of poly-β-hydoxybutyrate polymer by bacillus cereus isolate P83. World J Pharm Sci 2017; 5(9): 237-249. This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, which allows adapt, share and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms. ABSTRACT Production of polyhydroxyalkanoates by Bacillus cereus isolate P83 was carried out in a 14L laboratory fermentor using mineral salt medium containing 0.7% corn oil and 0.1 g/L ammonium chloride as carbon and nitrogen sources, respectively at 28°C, 200 rpm, 2 vvm and 7.2 pH. The maximum level of polyhydroxyalkanoates (53% per dry weight) was achieved after 24 hours of incubation. Different methods (Digestion by sodium hypochlorite, dispersion of chloroform and hypochlorite, mechanical dispersion and chloroform extraction) were used for polymer recovery. According to the obtained results, the highest molecular weight of polymer (2.15*10 4 g/mole) and lowest polydispersity (1.15) were achieved using chloroform extraction method. The results of the characterization techniques, IR and 1H-NMR spectroscopy, showed polyhydroxybutyrate identity. Analysis of PHA synthase and PhaR subunit PCR products indicated class IV PHA synthase with enzymatic and specific activity (measured by DTNB assay) of 195U and 1500U/mg, respectively. In conclusion, Bacillus cereus isolate P83 is a candidate for commercial production of PHB polymer with high growth rate and promising polyhydroxybutyrate production level. The produced polymer is characterized by comparable molecular weight of polymer with low polydispersity value.
Molecules, Jun 30, 2021
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
Bioprocess and Biosystems Engineering, Sep 7, 2018
To control the poly-β-hydroxybutyrate (PHB) biopolymer production by Acinetobacter baumannii isol... more To control the poly-β-hydroxybutyrate (PHB) biopolymer production by Acinetobacter baumannii isolate P39 kinetic modeling of the fermentation process, polymer downstream processing, enzymological analysis, and molecular characterization of PHA synthase, key biosynthetic enzyme, should be addressed. A. baumannii isolate P39 produced 0.15 g/L PHB after 24 h of incubation with a polymer content of 28% per dry weight. Logistic and Leudeking-Piret models were used for describing cell growth and PHB production, respectively. They showed good agreement with the experimental data describing both cell growth and PHB production (average regression coefficient r 2 :0.999). The growth-associated production of PHB biopolymer as an electron acceptor was confirmed using Leudeking-Piret model and victim substrate experiment. The best method of recovery of PHB biopolymer was chemical digestion using sodium hypochlorite, since it produced the largest amount of polymer and highest molecular weight (16,000 g/mole) in comparison to other recovery methods. DTNB assay showed high activity of PHA synthase enzyme, 600 U activity, and 153.8 U/mg specific activity. Molecular analysis of PHA synthase enzyme confirmed class III identity. Taken together, micelle model was proposed for polyhydroxybutyrate formation in A. baumannii isolate P39.
BMC Microbiology, Jan 23, 2021
Background: Paromomycin is a 2-deoxystreptamine aminocyclitol aminoglycoside antibiotic with broa... more Background: Paromomycin is a 2-deoxystreptamine aminocyclitol aminoglycoside antibiotic with broad spectrum activity against Gram-negative, Gram-positive bacteria and many protozoa. This study introduces a strategy for paromomycin production through solid-state fermentation using Streptomyces rimosus subsp. paromomycinus NRRL 2455. Solid state fermentation has gained enormous attention in the development of several products because of their numerous advantages over submerged liquid fermentation. After selecting the best solid substrate, a time course study of paromomycin production was carried out followed by optimization of environmental conditions using response surface methodology. Paromomycin yields obtained using this technique were also compared to those obtained using submerged liquid fermentation. Results: Upon screening of 6 different substrates, maximum paromomycin concentration (0.51 mg/g initial dry solids) was obtained with the cost-effective agro-industrial byproduct, corn bran, impregnated with aminoglycoside production media. Optimization of environmental conditions using D-optimal design yielded a 4.3-fold enhancement in paromomycin concentration reaching 2.21 mg/g initial dry solids at a pH of 8.5, inoculum size of 5% v/w and a temperature of 30°C. Conclusion: Compared to submerged liquid fermentation, solid state fermentation resulted in comparable paromomycin concentrations, cost reduction of raw materials, less energy consumption and waste water discharge, which have major implications in industrial fermentation. Therefore, solid state fermentation is a promising alternative to submerged liquid fermentation for paromomycin production. To the best of our knowledge, this is the first report on the optimized paromomycin production through solid state fermentation process.
Archives of Pharmaceutical Sciences Ain Shams University
Polyhydroxyalkanoates (PHA) are environmentally friendly polymers produced by many bacteria under... more Polyhydroxyalkanoates (PHA) are environmentally friendly polymers produced by many bacteria under nutrientlimited conditions. However, their commercialization is hindered by production expenses. The present study aimed at cost-effective and efficient production of poly(3-hydroxybutyrate) (PHB) by Bacillus (B.) cereus isolate CCASU-P83. Through one factor at time optimization study on shake flask, B. cereus CCASU-P83 produced about 50 % polymer per dry weight after 48 hours incubation time. For better evaluation of the fermentation process, kinetic modeling using the Logistic and Leudking-piret models was applied. A preliminary economic analysis was carried out and leads to a 30.8 % reduction in the total cost. In comparison to the findings obtained on the level of shake flask, scaling up to the bioreactor resulted in producing about 53% PHB per dry weight after only 24 hours incubation. These models concluded that B. cereus produced PHB during the growth phase. Analysis of molecular weight of the produced polymer displayed a 26900 g/mole molecular weight with a polydispersity index (PDI) of 1.1. In conclusion, B. cereus CCASU-P83 is a potential candidate for industrial production of PHB polymer using corn oil in a short incubation period which highly reduced the cost of the production process.
Scientific Reports
Mushrooms are nutritious foods that are widely cultivated all over the world. They are rich in a ... more Mushrooms are nutritious foods that are widely cultivated all over the world. They are rich in a range of compounds linked to improving functions of the immune system including carotenoids, alkaloids, lectins, enzymes, folates, fats, organic acids, minerals, polysaccharides, phenolics, proteins, tocopherols, terpenoids, and volatile compounds. In this study we investigated, the immunomodulatory activity in rats of the aqueous extracts of five of the most common edible mushrooms belonging to Family Basidiomycota-white-rot fungi including, Lentinula edodes, Agaricus bisporus, Pleurotus ostreatus, Pleurotus columbinus, and Pleurotus sajor-caju. Male Wistar albino rats were assigned to thirteen groups and Immunosuppression was induced by oral administration of dexamethasone (0.1 mg/kg), followed by oral administration of the mushroom extracts at low (200 mg/kg) and high (400 mg/kg) doses. A positive control group received the immune stimulant Echinacea extract Immulant® at (30 mg/kg), w...
Infection and Drug Resistance
Background: Fungi are rich source of biologically active metabolites aimed for the improvement of... more Background: Fungi are rich source of biologically active metabolites aimed for the improvement of human health through the prevention of various diseases, including infections and inflammatory disorders. Aim: We aimed to in vitro examine the anti-SARS CoV-2 activity of the aqueous extract of each Pleurotus (P.) ostreatus, Lentinula (L.) edodes and Agaricus (A.) bisporus edible mushroom followed by docking analysis of certain metabolites against the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-main protease (protease M pro). Methods: Antiviral and cytotoxic effects were tested on hCoV-19/Egypt/NRC-3/2020/Vero-E6 cells and analyzed via (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide Assay (MTT) assay. Ligand-protein and protein-protein docking studies were performed to explore the interaction of different mushroom extracts at the binding site of protease M pro. Molecular dynamics (MD) simulations were performed on the most promising ligand-target complexes to investigate their dynamic properties and confirm docking results. Results: Substantial antiviral activities with an IC 50 of 39.19, 26.17, and 10.3.3 µg/mL and a selectivity index (SI) of 4.34, 3.44, and 1.5 for P. ostreatus, L. edodes and A. bisporus, were observed, respectively. Docking analysis revealed that, catechin from three mushroom isolates, chlorogenic acid from A. bisporus, kamperferol of P. ostreatus and quercetin from L. edodes, with a C-DOCKER interaction energy in the range of 22.8-37.61 (Kcal/mol) with protease compared to boceprevir ligand of 41.6 (Kcal/mol). Docking of superoxide dismutase, catalase from the three mushrooms, tyrosinase from A. bisporus showed ligand contact surface area with the protein as 252.74 Å 2 while receptor contact surface area was 267.23 Å 2. Conclusion: P. ostreatus, L. edodes and A. bisporus have potential and remarkable in vitro antiviral activities against SARS-CoV-2. Quercetin from L. edodes, Kaempferol from P. ostreatus, chlorogenic acid and ascorbic acid, catechin, superoxide dismutase and catalase of the three mushrooms extracts were effectively bounded to M pro of SARS-CoV-2 as conferred by docking analysis.
World journal of pharmaceutical sciences, Jun 1, 2018
This is an open access article distributed under the terms of the Creative Commons Attribution-No... more This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, which allows adapt, share and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.
World journal of pharmaceutical sciences, Sep 2, 2017
Recovery and molecular characterization of poly-β-hydoxybutyrate polymer by bacillus cereus isola... more Recovery and molecular characterization of poly-β-hydoxybutyrate polymer by bacillus cereus isolate P83. World J Pharm Sci 2017; 5(9): 237-249. This is an open access article distributed under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, which allows adapt, share and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms. ABSTRACT Production of polyhydroxyalkanoates by Bacillus cereus isolate P83 was carried out in a 14L laboratory fermentor using mineral salt medium containing 0.7% corn oil and 0.1 g/L ammonium chloride as carbon and nitrogen sources, respectively at 28°C, 200 rpm, 2 vvm and 7.2 pH. The maximum level of polyhydroxyalkanoates (53% per dry weight) was achieved after 24 hours of incubation. Different methods (Digestion by sodium hypochlorite, dispersion of chloroform and hypochlorite, mechanical dispersion and chloroform extraction) were used for polymer recovery. According to the obtained results, the highest molecular weight of polymer (2.15*10 4 g/mole) and lowest polydispersity (1.15) were achieved using chloroform extraction method. The results of the characterization techniques, IR and 1H-NMR spectroscopy, showed polyhydroxybutyrate identity. Analysis of PHA synthase and PhaR subunit PCR products indicated class IV PHA synthase with enzymatic and specific activity (measured by DTNB assay) of 195U and 1500U/mg, respectively. In conclusion, Bacillus cereus isolate P83 is a candidate for commercial production of PHB polymer with high growth rate and promising polyhydroxybutyrate production level. The produced polymer is characterized by comparable molecular weight of polymer with low polydispersity value.
Molecules, 2021
Background: This study aimed to produce, purify, structurally elucidate, and explore the biologic... more Background: This study aimed to produce, purify, structurally elucidate, and explore the biological activities of metabolites produced by Streptomyces (S.) griseus isolate KJ623766, a recovered soil bacterium previously screened in our lab that showed promising cytotoxic activities against various cancer cell lines. Methods: Production of cytotoxic metabolites from S. griseus isolate KJ623766 was carried out in a 14L laboratory fermenter under specified optimum conditions. Using a 3-(4,5-dimethylthazol-2-yl)-2,5-diphenyl tetrazolium-bromide assay, the cytotoxic activity of the ethyl acetate extract against Caco2 and Hela cancer cell lines was determined. Bioassay-guided fractionation of the ethyl acetate extract using different chromatographic techniques was used for cytotoxic metabolite purification. Chemical structures of the purified metabolites were identified using mass, 1D, and 2D NMR spectroscopic analysis. Results: Bioassay-guided fractionation of the ethyl acetate extract l...
Scientific Reports, 2022
Biofilm-formed enterococcal urinary tract clinical isolates (n = 92) were used for studying the a... more Biofilm-formed enterococcal urinary tract clinical isolates (n = 92) were used for studying the antibiofilm activity of cinnamon, ginger, and chemical AgNPs. The average particle sizes of cinnamon, ginger, and chemical AgNPs were 8.7, 41.98, and 55.7 nm, respectively. The results of Fourier transform infrared analysis revealed that phytocompounds, such as cinnamaldehyde and gingerol, were the main compounds incorporated in the synthesis of cinnamon and ginger AgNPs, respectively. The purity and crystalline nature of the AgNPs have been confirmed by energy dispersive X-ray and X-ray Diffraction analysis. The results of antimicrobial activity showed that MIC of ginger, cinnamon, and chemical AgNPs were 37.64, 725.7, and 61.08 μg/ml, respectively. On studying the antibiofilm activity of AgNPs at sub-MIC values (1/2, 1/4, and 1/8 MIC), the results revealed that it was concentration dependent. Therefore, further studies were carried out to evaluate the antibiofilm activity of AgNPs at a ...
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Papers by mahmoud yassien