Synthesis of M-Ag3PO4, (M = Se, Ag, Ta) Nanoparticles and Their Antibacterial and Cytotoxicity Study.

Silver Phosphate, Ag3PO4, being a highly capable clinical molecule, an ultrasonic method was employed to synthesize the M-Ag3PO4, (M = Se, Ag, Ta) nanoparticles which were evaluated for antibacterial and cytotoxicity activities post-characterization. Escherichia coli and Staphylococcus aureus were used for antibacterial testing and the effects of sonication on bacterial growth with sub-MIC values of M-Ag3PO4 nanoparticles were examined. The effect of M-Ag3PO4 nanoparticles on human colorectal carcinoma cells (HCT-116) and human cervical carcinoma cells (HeLa cells) was examined by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) assay and DAPI (4',6-diamidino-2-phenylindole) staining. Additionally, we analyzed the effect of nanoparticles on normal and non-cancerous human embryonic kidney cells (HEK-293). Ag-Ag3PO4 exhibited enhanced antibacterial activity followed by Ta-Ag3PO4, Ag3PO4, and Se-Ag3PO4 nanoparticles against E. coli. Whereas the order of antibacterial activity against Staphylococcus aureus was Ag3PO4 > Ag-Ag3PO4 > Ta-Ag3PO4 > Se-Ag3PO4, respectively. Percentage inhibition of E. coli was 98.27, 74.38, 100, and 94.2%, while percentage inhibition of S. aureus was 25.53, 80.28, 99.36, and 20.22% after treatment with Ag3PO4, Se-Ag3PO4, Ag-Ag3PO4, and Ta-Ag3PO4, respectively. The MTT assay shows a significant decline in the cell viability after treating with M-Ag3PO4 nanoparticles. The IC50 values for Ag3PO4, Se-Ag3PO4, Ag-Ag3PO4, and Ta-Ag3PO4 on HCT-116 were 39.44, 28.33, 60.24, 58.34 µg/mL; whereas for HeLa cells, they were 65.25, 61.27, 75.52, 72.82 µg/mL, respectively. M-Ag3PO4 nanoparticles did not inhibit HEK-293 cells. Apoptotic assay revealed that the numbers of DAPI stained cells were significantly lower in the M-Ag3PO4-treated cells versus control.

Handwashing Knowledge, Attitudes, and Practices among Students in Eastern Province Schools, Saudi Arabia.

Background. Lack of knowledge about appropriate handwashing practices has caused great concerns for human health, especially in the risk of many communicable diseases. The objective of the current study is to determine the level of handwashing knowledge, attitudes, and practices among school students in Eastern Province Schools, Saudi Arabia. A cross-sectional survey was recruited from November 2019 to March 2020 to assess the level of the students' handwashing knowledge. A reliable questionnaire was prepared (Cronbach's alpha = 0.608) and conducted using a two-stage sampling technique. A total of 271 students participated in the study from primary, middle, and high schools; 80% were boys, most of whom displayed an acceptable level of knowledge on hand hygiene. Nearly 75% and 74% of boys and girls, respectively, gained knowledge about hand hygiene practices from their parents. Only 46% of the students thought that handwashing is a potential protective measure against diseases, whereas 34% thought it only removes dirt. Prevalence of handwashing with soap after using the toilet was recognized among 52% of the students. Additionally, 93% of the students used water and soap to wash their hands (p value < 0.001) and 97% suggested that soap and water are the best methods to wash their hands (p value < 0.001). There was a positive correlation between the mother's education and hand hygiene practices (p value = 0.044). Results collectively indicated that handwashing knowledge and practices among school students in the Eastern Province are acceptable interventions in preventing the transmission of infectious diseases such as COVID-19. Indeed, further improvement conducted through specific health education programs to emphasize the role of handwashing in health hygiene is highly recommended.

Insights into the COVID-19 pandemic: Origin, pathogenesis, diagnosis, and therapeutic interventions.

Coronavirus disease (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a member of the human coronavirus (HCoV) family that targets the lower part of the respiratory tract and causes severe acute respiratory syndrome (SARS). In a short span of time, this infection has led to a global pandemic and has become a significant threat to the existence of present human society. Currently, there are no treatments for this infection and the measures established across various countries such as social distancing, usage of mask to prevent entry of the virus into the respiratory tract, quarantine, and containment together have reduced the prevalence of this disease and mortality in highly susceptible individuals. Here, we examine the structure, replication cycle, phylogeny and genomic organization of this virus and discuss the role of spike (S) protein of the virus, an important structure that interacts with the host ACE2 receptor facilitating viral entry. Further, we explore the epidemiology, symptoms of the disease, describe the reverse transcriptase-polymerase chain reaction (RT-PCR) that establishes the diagnosis of the disease and also review its unique diagnostic features in the chest CT-Scan. Finally, we review the current approaches to develop therapies and vaccines as a measure for disease prevention and control.

Bacterial biopolymer (polyhydroxyalkanoate) production from low-cost sustainable sources.

Twenty-six different bacterial strains were isolated from samples taken from different locations Dammam, Saudi Arabia, for screening of their polyhydroxyalkanoate (PHA) production capability. The initial screening was conducted by staining with Sudan Black B and Nile Red, followed by examination under fluorescence and electron microscopes to characterize PHA granule formation. The PHA-producing bacterial isolates were identified using 16S rRNA gene analyses; the most potent bacterial strain was identified as Pseudomonas sp. strain-P(16). The PHA production capability of this strain in the presence of different low-cost carbon sources, such as rice bran, dates, and soy molasses, was analyzed. PHA production in the presence of rice bran, dates, and soy molasses was 90.9%, 82.6%, and 91.6%, respectively.

Enhanced production of lipase by the thermophilic Geobacillus stearothermophilus strain-5 using statistical experimental designs.

Statistically based experimental designs were applied to optimize the cultural conditions for the production of a glycerol-inducible lipase from the thermophilic Geobacillus stearothermophilus strain-5. The effect of nineteen culture conditions on enzyme production was evaluated using Plackett-Burman factorial design. Tween 80, K(2)HPO(4), glycerol and glucose were the most significant factors in improving enzyme production. The selected parameters were then further investigated using central composite design to define the optimal process conditions. Maximal enzyme activity (578 U/ml) was reached under the following conditions: glycerol, 2.24% (v/v); Tween 80, 0.76% (v/v); glucose, 0.76% (w/v) and K(2)HPO(4), 0.38% (w/v) which is about five folds the activity in basal medium. A verification experiment was carried out to examine model validation and revealed more than 98% validity.

Production of poly-gama-glutamate (PGA) biopolymer by batch and semicontinuous cultures of immobilized Bacilluslicheniformis strain-R

Production of Polyglutamate (PGA) biopolymer by immobilized Bacilluslicheniformis strain-R was intensively investigated. Preliminary experiments were carried out to address the most suitable immobilization methodology. Entrapment of Bacillus cells in alginate-agar led optimal PGA production (36.75 g/l), with 1.32- and 2.18-fold increase in comparison with alginate- or K-carrageenan-immobilized cells, respectively. During semicontinuous cultivation of agar-alginate gel-cell mixture, production of PGA by 10 ml mixture was increased from 2nd to 3rd run whereas, increased till the 4th run using 15ml mixture. Adsorption was the most suitable immobilization technique for production of PGA and the sponge cubes was the preferred matrix recording 43.2 g/l of PGA with the highest cell adsorption. Furthermore, no PGA was detected when B. licheniformis cells were adsorbed on wood and pumice. Although luffa pulp-adsorbed cells recorded the highest PGA production (50.4 g/l), cell adsorption was the lowest. Semicontinuous cultivation of B. licheniformis cells adsorbed on sponge led to increase of PGA production till the 3rd run and reached 55.5 g/l then slightly decreased in the 4th run. The successful use of fixed-bed bioreactor for semicontinuous cultivation of B. licheniformis cells held on sponge cubes (3 runs, 96 hours/run) provides insight for the potential biotechnological production of PGA by immobilized cells.

Production of Poly-γ-Glutamate (PGA) Biopolymer by Batch and Semicontinuous Cultures of Immobilized Bacilluslicheniformis strain-R.

Production of Polyglutamate (PGA) biopolymer by immobilized Bacillus licheniformis strain-R was intensively investigated. Preliminary experiments were carried out to address the most suitable immobilization methodology. Entrapment of Bacillus cells in alginate-agar led optimal PGA production (36.75 g/l), with 1.32-and 2.18-fold increase in comparison with alginate-or K-carrageenan-immobilized cells, respectively. During semicontinuous cultivation of agar-alginate gel-cell mixture, production of PGA by 10 ml mixture was increased from 2(nd) to 3(rd) run whereas, increased till the 4(th) run using 15ml mixture. Adsorption was the most suitable immobilization technique for production of PGA and the sponge cubes was the preferred matrix recording 43.2 g/l of PGA with the highest cell adsorption. Furthermore, no PGA was detected when B. licheniformis cells were adsorbed on wood and pumice. Although luffa pulp-adsorbed cells recorded the highest PGA production (50.4 g/l), cell adsorption was the lowest. Semicontinuous cultivation of B. licheniformis cells adsorbed on sponge led to increase of PGA production till the 3(rd) run and reached 55.5 g/l then slightly decreased in the 4(th) run. The successful use of fixed-bed bioreactor for semicontinuous cultivation of B. licheniformis cells held on sponge cubes (3 runs, 96 hours/run) provides insight for the potential biotechnological production of PGA by immobilized cells.

Possible involvement of an extracellular superoxide dismutase (SodA) as a radical scavenger in poly(cis-1,4-isoprene) degradation.

Gordonia westfalica Kb1 and Gordonia polyisoprenivorans VH2 induce the formation of an extracellular superoxide dismutase (SOD) during poly(cis-1,4-isoprene) degradation. To investigate the function of this enzyme in G. polyisoprenivorans VH2, the sodA gene was disrupted. The mutants exhibited reduced growth in liquid mineral salt media containing poly(cis-1,4-isoprene) as the sole carbon and energy source, and no SOD activity was detectable in the supernatants of the cultures. Growth experiments revealed that SodA activity is required for optimal growth on poly(cis-1,4-isoprene), whereas this enzyme has no effect on aerobic growth in the presence of water-soluble substrates like succinate, acetate, and propionate. This was detected by activity staining, and proof of expression was by antibody detection of SOD. When SodA from G. westfalica Kb1 was heterologously expressed in the sodA sodB double mutant Escherichia coli QC779, the recombinant mutant exhibited increased resistance to paraquat, thereby indicating the functionality of the G. westfalica Kb1 SodA and indirectly protection of G. westfalica cells by SodA from oxidative damage. Both sodA from G. polyisoprenivorans VH2 and sodA from G. westfalica Kb1 coded for polypeptides comprising 209 amino acids and having approximately 90% and 70% identical amino acids, respectively, to the SodA from Mycobacterium smegmatis strain MC(2) 155 and Micrococcus luteus NCTC 2665. As revealed by activity staining experiments with the wild type and the disruption mutant of G. polyisoprenivorans, this bacterium harbors only one active SOD belonging to the manganese family. The N-terminal sequences of the extracellular SodA proteins of both Gordonia species showed no evidence of leader peptides for the mature proteins, like the intracellular SodA protein of G. polyisoprenivorans VH2, which was purified under native conditions from the cells. In G. westfalica Kb1 and G. polyisoprenivorans VH2, SodA probably provides protection against reactive oxygen intermediates which occur during degradation of poly(cis-1,4-isoprene).

Degradation of natural rubber by Achromobacter sp. NRB and evaluation of culture conditions.

A natural rubber degrading candidate was isolated from a soil sample from Aswan, Egypt. The strain was able to grow on natural rubber as a sole source for carbon and energy. According to its degradation behavior, it grew adhesively and in direct contact with the rubber substrate and led to disintegration of the material during cultivation. Furthermore, this strain was not able to form a clear zone (translucent halos) around bacterial colonies after cultivation on NR latex plates. Taxonomic analysis of the strain based on partial 16S rRNA similarity examinations indicated that bacterial candidate belongs to genus Achromobacter sp. Schiff's reagent staining tests performed during cultivation of the strain on NR latex gloves of different sizes, treated or nontreated, revealed that the strain was able to colonize the rubber surface. Formation of bacterial films and occurrence of compounds containing aldehyde groups during cultivation was observed. The tested strain showed a higher colonization efficiency on small or treated pieces of NR latex gloves, while a lower colonization efficiency was recognized when grown on large or nontreated NR latex gloves. Plackett-Burman experimental design, based on numerical modeling, was applied to evaluate the significance of culture conditions affecting natural rubber degradation by the bacterial candidate. Eleven variables through fourteen trials were studied simultaneously. Based on rubber mineralization data, the highest positive variables affecting rubber degradation were NR granules, K2HPO4, Na-succinate and NH4Cl, while MgSO4 x 7H2O and KH2PO4 were the lowest significant variables.

Polyglutamic acid (PGA) production by Bacillus sp. SAB-26: application of Plackett-Burman experimental design to evaluate culture requirements.

A locally isolated thermostable Bacillus strain producing polyglutamic acid (PGA) was characterized and identified based on 16S rRNA sequencing. Phylogenetic analysis revealed its closeness to Bacillus licheniformis. To evaluate the effect of different culture conditions on the production of PGA, Plackett-Burman factorial design was carried out. Fifteen variables were examined for their significance on PGA production. Among those variables, K(2)HPO(4), KH(2)PO(4), (NH(4))(2)SO(4) and casein hydrolysate were found to be the most significant variables that encourage PGA production. A correlation between cellular growth, PGA and the produced traces of polysaccharides was illustrated. An inverse relationship practice between cell dry weights and the produced PGA was demonstrated. On the other hand, a direct proportional relation was shown between polysaccharides on one side and cell dry weight and produced PGA on the other. The pre-optimized medium, based on statistical analysis, showed a production of 33.5 g/l PGA, which is more than three times the basal medium.

Identification, cloning and expression of Pseudomonas aeruginosa Ps-x putative urate oxidase gene in Escherichia coli.

In a previous study we reported for the first time the isolation and characterization ofurate oxidase enzyme from Pseudomonas aeruginosa. In this work we isolated and cloned a 1.350 kilobase DNA fragment that encode a putative urate oxidase gene from the genomic library of P. aeruginosa Ps-x. The nucleotide sequence of the cloned DNA insert revealed an open reading frame that encodes a protein of a molecular weight of 54.0 kDa. The cloned DNA fragment showed an uricolytic activity when expressed in E. coli DH5alpha. Surprisingly, the nucleotide sequence of the cloned gene showed more than 99% identity to the gene encoding hypothetical protein of P. aeruginosa PAO1. Moreover, the sequence of the cloned gene was closely similar to the corresponding uricase gene of Cellulomonas flavigena (44% similarity), but showed lower similarity values to that of Bacillus sp. BT-90 (24% similarity), Candida utilis (24% similarity). Interestingly, the isolated uricase gene showed closer similarity to uricase from yeast-like symbiotic fungi Beauveria bassiana (35%), Tolypocladium inflatum (29%), Paecilomyces tenuipes (27%) and Cerataphis fransseni (24%).

Gordonia westfalica sp. nov., a novel rubber-degrading actinomycete.

A cis-1,4-polyisoprene-degrading bacterium (strain Kb2T) was isolated from foul water taken from the inside of a deteriorated automobile tyre found on a farmer's field in Westfalia, Germany. The strain was aerobic, Gram-positive, exhibited orange smooth and rough colonies on complex nutrient agar, produced elementary branching hyphae that fragmented into rod/coccus-like elements and showed chemotaxonomic markers which were consistent with its classification within the genus Gordonia, i.e. the presence of mesodiaminopimelic acid, arabinose and galactose in whole-cell hydrolysates (cell-wall chemotype IV), N-glycolylmuramic acid in the peptidoglycan wall, a fatty-acid pattern composed of unbranched saturated and monounsaturated fatty acids plus tuberculostearic acid, mycolic acids comprising 56-60 carbon atoms and MK-9(H2) as the only menaquinone. The 16S rDNA sequence of strain Kb2T was found to be most similar to the 16S rDNA sequences of the type strains of Gordonia alkanivorans (DSM 44369T) and Gordonia nitida (KCTC 0605BPT). However, DNA-DNA relatedness data showed that strain Kb2T ( =DSM 44215T NRRL B-24152T) could be distinguished from these two species and represented a new species within the genus Gordonia, for which the name Gordonia westfalica is proposed.