Search

Practically, AgNPs are converted to the positively charged Ag+ ions by dissolution process and will react with the negatively charged oxygen and nitrogen atoms in the vital organelles like DNA, mitochondrion, and the thiol group presented in protein structures and enzymes, which in terms interrupts the normal cell reproduction, and finally, the death of cell will occur according to the toxicity limit of (Ag+) silver ions level of each organ.

Background and Objectives: Methicillin-resistant Staphylococcus aureus (MRSA) is a major concern in Jordanian hospitals in terms of infection control. The purpose of this study was to identify the resistance patterns of Staphylococcus aureus strains isolated from surfaces of critical locations within the Al-Karak Governmental Hospital in 2019. Additionally, the study aimed to conduct whole-genome sequencing on the isolates. Materials and Methods: In February 2019, fourteen S. aureus strains were isolated from surfaces in critical sites in the Al-Karak Governmental Hospital. These isolates underwent antibiogram testing to determine their resistance profile. Genome sequencing using the Illumina MiSeq platform was applied to the extracted DNA from these isolates. The genomic data, including coding sequences, were analyzed to identify lineage, resistance genes, and plasmids. Results: The antibiogram results revealed that 11 of the 14 isolates were resistant to oxacillin, 6 to linezolid, and 1 to rifampicin, while none showed resistance to chloramphenicol. Eleven isolates were identified as MRSA, with a novel spa type (t4407) not previously reported in Jordan. High-quality sequencing data were obtained for only one isolate, i.e., A29, the genome showed 2,789,641 bp with a 32.7% GC content and contained 2650 coding sequences. Genomic analysis indicated the ST6 lineage, mecA gene (SCCmec type IVa(2B)), and a hybrid plasmid (pJOR_blaZ) carrying the blaZ gene for β-lactam resistance. Genomic data were deposited in NCBI (CP104989). The A29 genome closely resembled an MRSA genome isolated from a Danish hospital in 2011. The SNP analysis revealed identical antimicrobial resistance genes in these two genomes. Conclusions: This study unveils the first genomic sequence of an MRSA isolate from Jordan, marked by distinctive genotypic traits. The findings enhance our understanding of the MRSA types circulating in Jordan and the region and substantiate the phenomenon of intercontinental MRSA transmission. [ABSTRACT FROM AUTHOR]

Vitamin D3 is a fat-soluble prohormone that is activated inside the liver to produce 25-hydroxyvitamin D3 (calcidiol), and in the kidney to produce the fully active 1α, 25-dihydroxy vitamin D3 (calcitriol). A previous work piloted in our laboratory, resulted in a successful recovery of a local soil-promising Actinomyces hyovaginalis isolate CCASU-A11-2 capable of converting vitamin D3 into calcitriol. Despite the rising amount of research on vitamin D3 bioconversion into calcitriol, further deliberate studies on this topic can significantly contribute to the improvement of such a bioconversion process. Therefore, this work aimed to improve the bioconversion process, using the study isolate, in a 14 L laboratory fermenter (4 L fermentation medium composed of fructose (15 g/L), defatted soybean (15 g/L), NaCl (5 g/L), CaCO3 2 g/L); K2HPO4, (1 g/L) NaF (0.5 g/L) and initial of pH 7.8) where different experiments were undertaken to investigate the effect of different culture conditions on the bioconversion process. Using the 14 L laboratory fermenter, the calcitriol production was increased by about 2.5-fold (32.8 µg/100 mL) to that obtained in the shake flask (12.4 µg/100 mL). The optimal bioconversion conditions were inoculum size of 2% v/v, agitation rate of 200 rpm, aeration rate of 1 vvm, initial pH of 7.8 (uncontrolled); addition of vitamin D3 (substrate) 48 h after the start of the main culture. In conclusion, the bioconversion of vitamin D3 into calcitriol in a laboratory fermenter showed a 2.5-fold increase as compared to the shake flask level where, the important factors influencing the bioconversion process were the aeration rate, inoculum size, the timing of substrate addition, and the fixed pH of the fermentation medium. So, those factors should be critically considered for the scaling-up of the biotransformation process. Key points: Bioconversion of vitamin D into calcitriol has been performed in a 14 L laboratory fermenter using a local soil-promising Actinomyces hyovaginalis isolate CCASU-A11-2. The calcitriol production was increased by about 2.5-fold (32.8 µL/100 mL) to that obtained in the shake flask (12.4 µL/100 mL). Aeration rate, inoculum size, the timing of substrate addition, and the fixed pH were important factors influencing the bioconversion process. [ABSTRACT FROM AUTHOR]