Papers by Qais Ali Al-Maqtari
A novel bacterial strain of acetic acid bacteria capable of producing riboflavin was isolated fro... more A novel bacterial strain of acetic acid bacteria capable of producing riboflavin was isolated from the soil sample collected in Wuhan, China. The isolated strain was identified as Gluconobacter oxydans FBFS97 based on several phenotype characteristics, biochemicals tests, and 16S rRNA gene sequence conducted. Furthermore, the complete genome sequencing of the isolated strain has showed that it contains a complete operon for the biosynthesis of riboflavin. In order to obtain the maximum concentration of riboflavin production, Gluconobacter oxydans FBFS97 was optimized in shake flask cultures through response surface methodology employing Plackett-Burman design (PBD), and Central composite design (CCD). The results of the pre-experiments displayed that fructose and tryptone were found to be the most suitable sources of carbon and nitrogen for riboflavin production. Then, PBD was conducted for initial screening of eleven minerals (FeSO 4 , FeCl 3 , KH 2 po 4 , K 2 HPO 4 , MgSO 4 , ZnSO 4 , NaCl, CaCl 2 , KCl, ZnCl 2 , and AlCl 3 .6H 2 O) for their significances on riboflavin production by Gluconobacter oxydans strain FBFS97. The most significant variables affecting on riboflavin production are K 2 HPO 4 and cacl 2 , the interaction affects and levels of these variables were optimized by CCD. After optimization of the medium compositions for riboflavin production were determined as follows: fructose 25 g/L, tryptone 12.5 g/L, K 2 HPO 4 9 g/L, and CaCl 2 0.06 g/L with maximum riboflavin production 23.24 mg/L. Riboflavin or the so-called vitamin B2 is a water-soluble vitamin that belongs to the B vitamins complex group, a vital component of the energy metabolism, and a bioactive molecule that has an important role in various cellular functions 1,2. In addition, to its role as the precursor of flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN), the major products of riboflavin that act a fundamental role in metabolism, acting as cofactors for a wide variety of enzymes intermediating many redox reactions in the cell 3,4. In contrast, to many microorganisms and plants, humans and animals cannot synthesize this vitamin, and thus need to supply their diet with external riboflavin to meet their nutritional requirements 5. Riboflavin is used on a large scale as food and feed additives, food colorant, and pharmaceutical preparations. The commercial production of this vitamin can be accomplished by chemical synthesis or biological synthesis, yet in recent times the chemical synthesis has totally replaced to the microbial fermentation because of its cost-effectiveness, reduction in waste and energy requirements, and the use of renewable resources 6. At present, several species of bacteria and fungi are harnessed open
This study aimed to analyze and compare volatile compounds in Foshou fruit peel and pulp by gas c... more This study aimed to analyze and compare volatile compounds in Foshou fruit peel and pulp by gas chromatography-mass spectrometry. Foshou fruit contains 56 Hydrocarbons Oxide compound, and 9 other compounds. The results of this study showed that the Foshou fruit was rich in volatile compounds,"But the comparison of the peel and the pulp demonstrated the peel to be more rich in most of the volatile compounds".
This study aimed to evaluate the extractability factor and bioavailability of phenolic compounds ... more This study aimed to evaluate the extractability factor and bioavailability of phenolic compounds and antioxidant activity of effervescent tablets of microencapsulated Foshou fruit extract by in vitro simulated gastrointestinal model. Total phenolic content and antioxidant capacity of the effervescent tablets were estimated in chemical extract (CE), buffer extract (BE), the extract after simulated digestion(GE), and the extract after simulated absorption(AE). The effervescent tablets of microencapsulated Foshou fruit extract by different carrier agents formulations were used in this study, the carrier agents formulations were Gum arabic/ Maltodextrin/ Modified starch/ Whey protein (GMSW); Gum arabic/ Maltodextrin/ Modified starch (GMS); Gum arabic/ Maltodextrin/ Whey protein (GMW); Gum arabic/ Modified starch/ Whey protein (GSW); Maltodextrin/ Modified starch/ Whey protein (MSW). The GE had the highest total phenolic content (15.43 mg GAE/g tablet) and antioxidant activity (IC50 7.40 mg tablet). The GMS tablets showed the highest total phenolic content and antioxidant activity among all extracts. GMS tablets showed the highest extractability factor for phenolic compounds in BE (1.81), GE (2.82), and AE (2.43), moreover in terms of extractability factor for antioxidant activity in BE (1.28), GE (2.44), and AE (1.69). The highest bioavailability index was in MSW tablets (0.90) for phenolic compounds, and in GSW tablets (0.73) for antioxidant activity. The results of this study indicate the possibility of using effervescent tablets as a method of improving the bioavailability of phenolic compounds and antioxidants in microencapsulated Foshou fruit extract.
The aim of this research was to study the effect of sonication at a different time on the propert... more The aim of this research was to study the effect of sonication at a different time on the properties of silver carp myofibrillar protein. The samples were treated by using the ultrasonic technique for 6, 8, 10, 12 and 14 min at 350W. Sonication at different times had a significant effect on antioxidant activity where the DPPH inhibition of samples ranged from 16.07% to 36.51%, and the ABTS inhibition of samples ranged from 14.17% to 22.58%. The treatments by sonication for 12 min showed the highest antioxidant activity, while sonication treatments at different times did not achieve a significant effect on the solubility of samples. The results showed a significant decrease in turbidity when treated with sonication. Water holding capacity significantly increased when the sonication time increased to 12 min. It is clear from the results of this study that the sonication time has an effect on the properties of silver carp myofibrillar protein. Moreover, can be used the sonication treatment to improve the properties of silver carp myofibrillar protein.
This study aimed to investigate the effect of pH-shifting combined with low-frequency ultrasound ... more This study aimed to investigate the effect of pH-shifting combined with low-frequency ultrasound on antioxidant and physicochemical properties of silver carp myofibrillar protein (MP). The antioxidant activity of the samples against DPPH ranged from 14.31% to 36.43%, and ABTS scavenging between 3.55 and to 22.56%. The ultrasonic treatment of the sample without changing the pH led to the best antioxidant activity against DPPH and ABTS. Protein solubility affected by treatments, which ranged from 30.11 to 88.26%, where the best solubility was at pH 8 with ultrasonic treatment which showed no significant difference to sample control. The turbidity increased in the treated samples at different pH levels without ultrasonic treatment, where the highest turbidity was 0.21 (A600) at pH 6 without ultrasound treatment, while the lowest turbidity was 0.03 (A600) at pH 12 with ultrasound. The highest water holding capacity of MP was achieved at pH 2 with ultrasonic treatment, which amounted to 7.83 g water/g MP. The results of this study indicate that the ultrasonic treatments of the samples at different pH significantly affected the antioxidant activities and physicochemical properties of MP obtained from silver carp.
The aim of present study was assessing of microbiological quality for commercial bottled water ma... more The aim of present study was assessing of microbiological quality for commercial bottled water marketed in Sana'a city, Yemen, through enumerate the Heterotrophic Bacteria count (HBC) and detect the presence or absence of Total Coliform (TC), Faecal Coliform (FC) and E. coli from Commercial Bottled water. Samples were collected from five different brands of bottled water (Al-Namudhajia, Qatr Al-Nudaa, Yanabie Azal, Al-Madinatayn and Al-Hikma), Four samples from each type were collected randomly from several shops and supermarkets located in Sana'a City, Yemen. All samples were examined by plate count technique and MPN methods. The result indicated that the HBC for all samples were in the range of 1.44-5.04 Log10/ ml at 22˚C, and 1.01-5.21 Log10/ml at 37 ˚C. Approximately 85% and 95% from samples at 22 and 37 ˚C respectively, did not comply with the safety regulation of Codex and UK for drinking water. About 60%, 50% and 25% of samples were contained Total Coliforms, Faecal Coliforms and E. coli respectively, higher than the permitted colony count regulated by YSMO, GSO, Codex, UK and WHO.
Microbial enzymes are widely used in different industries mainly because of vast availability of ... more Microbial enzymes are widely used in different industries mainly because of vast availability of sources. Microbial enzymes could be genetically modified and are considered as economical in comparison to plant and animal enzymes. Production of microbial enzymes by application of fermentation procedures involves microbial propagation like bacteria, mold and yeast to get desired product. The process of fermentation is classified based on specific parameters. There are different techniques employed to produce microbial enzymes using downstream processing methods that are aimed at enzyme purification and recovery. The improvement in concentration, purity and percentage of recovery of enzymes can be achieved based on standard principles which are microbial sources, improvement of strain and application of membrane augmented downstream processing method to improve specific activity of enzyme. There are two methods of fermentation used to produce enzymes. These are submerged fermentation and solid-state fermentation. Submerged fermentation involves the production of enzymes by microorganisms in a liquid nutrient media. Solid-state fermentation is the cultivation of microorganisms, and hence enzymes on a solid substrate. Carbon containing compounds in or on the substrate are broken down by the microorganisms, which produce the enzymes either intracellular or extracellular. Microbial enzymes exhibit wide variety of applications in different industries. Industries that use enzymes generated by fermentation are the brewing, wine making, baking, cheese making, dairy, milling, beverages, and cereals.
Cold-active enzymes are produced by organisms adapted to permanently cold habitats. Due to the de... more Cold-active enzymes are produced by organisms adapted to permanently cold habitats. Due to the depressive effect of low temperatures on reaction rates, these enzymes have to be adapted to secure appropriate reaction rates in those organisms that often thrive in environments characterized by temperatures close or below the freezing point of water. They are encountered in all prokaryotic or eukaryotic organisms adapted to cold such as microorganisms, invertebrates, insects and fish originating from the Arctic and Antarctic zones, as well as from alpine regions, glaciers or permafrost zones. They are characterized by a high specific activity at low temperatures, in any case higher than that of their mesophilic and thermophilic counterparts. This higher specific activity is generally accompanied by a decrease in thermal stability illustrated by a shift of the apparent optimum towards low temperatures, and by an important decrease in the thermodynamic stability characterized by a significantly lower stabilization enthalpy. The generally low stability induces an increase in the flexibility of the overall edifice or of crucial zones for activity of the molecular structure. There is apparently a continuum in the adaptation since some enzymes display extreme adaptation illustrated by a severe shift of the activity towards low temperatures whereas others are moderately adapted. This probably depends on their position in a metabolic pathway, on their intracellular or extracellular localization, on the environmental temperature and on the evolutionary history of the organisms.
The aim of this study was to evaluate antibacterial activity of the leaves of the Yemeni Lawsonia... more The aim of this study was to evaluate antibacterial activity of the leaves of the Yemeni Lawsoniainermis L. The aqueous, methanol, ethanol, and acetone extract of Lawsoniainermis Leaves were tested against standard bacterial cultures by agar well diffusion method on Mueller Hinton agar for bacterial cultures. Acetone extract showed significantly higher inhibitory effect compared to aqueous, methanol, and ethanol extracts on tested organisms, with no activity for aqueous extract. Results indicate the potential of these plants for further work on isolation and characterization of the active principle responsible for antibacterial activity and its exploitation astherapeutic agent.
This study was carried out to investigate the antioxidant and antimicrobial effects of 3 selected... more This study was carried out to investigate the antioxidant and antimicrobial effects of 3 selected plants collected from the area aroundSanàa University including Dodonaea viscose, Fragaria x ananassa Duch and Vernonia amygdalina. The leaves of three plants were dried, grinded and extracted with methanol. The obtained extracts were tested for their antioxidant activity using scavenging activity of DPPH radical method and for their antimicrobial activity using agar diffusion method. Result showed that three samples are effective antioxidant towards DPPH radical and the scavenging activity was approximately nearly from the pure antioxidant standard, ascorbic acid. The IC 50 values of Dodonaea viscose, Fragaria x ananassa Duch and Vernonia amygdalina leaf extracts were 150±1.5, 180±3.0 and 135±2.6µg/ml respectively, whereas for L-ascorbic acid was 120±2.0µg. All extract inhibited the growth of Micrococcus litius, Bacillus subtilis and Salmonella choleraesuis except for the Escherichia coli. The Dodonea viscose showed more potent against Micrococcus litius moderately inhibited the Bacillus subtilis and Salmonella choleraesuis, whereas, The Vernonia amygdalina moderately inhibited the Micrococcus litius, Bacillus subtilis and Salmonella choleraesuis when compared to the standard antibiotic Enrofloxacin. The Fragaria x ananassa Duch moderately inhibited the Bacillus subtilis and Salmonella choleraesui,. The selected extracts might be developed in order to establish new pharmacological possibilities for their applications.
The current study represents the investigation of four selected traditional plants used in Yemen,... more The current study represents the investigation of four selected traditional plants used in Yemen, Pulicaria jaubertii E, Rumex nervosus Vahl, Peganum harmala L, Caralluma wissmannii O. Schwartz which were collected from different localities of Yemen. The seeds of Peganum harmala , and the leafs of other plants were dried, grinded and extracted with methanol. The obtained extracts were tested for their antioxidant activity using scavenging activity of DPPH radical method and for their antimicrobial activity against two Gram-positive bacteria and two Gram-negative bacteria strains using agar diffusion method. In DPPH method, the four extracts showed antioxidant activity and the activity was concentration dependent. IC 50 values of Pulicaria jaubertii, Rumex nervosus, Caralluma wissmannii leaf extracts and Peganum harmala seeds were 350±23.0, 450±4.3, 550±5.7, 850±12.6µg/ml respectively, whereas for L-ascorbic acid was 320±2.0 µg/ml. The Pulicaria jaubertii leaf extract showed more potent against Micrococcus litius moderately inhibited the Bacillus subtilis and Salmonella choleraesuis and the effect was comparable with the standard antibiotics. Peganum harmala methanolic seed extract showed more potent against Micrococcus litius, at concentration of 100 and 200 mg/ ml only, low effect against Bacillus subtilis and Salmonella choleraesuis. Rumex nervosus Vahl showed low inhibition effect against Micrococcus litius, Bacillus subtilis and Salmonella choleraesuis at higher concentration 200 mg/ ml. Caralluma wissmannii showed low inhibition effect against Escherichia coli only. The results indicate that these plant are potential candidates to be used as antimicrobial and antioxidant. The selected extracts might be developed in order to establish new pharmacological possibilities for their applications.
Drafts by Qais Ali Al-Maqtari
The detection of SARS-Cov-2 in the sewage and water resources has increased the awareness among t... more The detection of SARS-Cov-2 in the sewage and water resources has increased the awareness among the people about the possibility survival of SARS-Cov-2 in the environment and the potential to transmit into the human through food chain or water resources. Moreover, the surface contaminated by the virus need to be disinfected frequently by using an effective disinfectant, the current chapter discussed the efficiency of the most traditional Preprints (www.preprints.org) | NOT PEER-REVIEWED | Posted: 21 June 2020 doi:10
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Papers by Qais Ali Al-Maqtari
Drafts by Qais Ali Al-Maqtari