Molecular Identification and Phylogenetic Analysis of Multidrug-resistant Bacteria using 16S rDNA Sequencing

Bioconversion of Alpha-Cembratriene-4,6-diol into High-Value Compound Farnesal Through Employment of a Novel Stenotrophomonas maltophilia H3-1 Strain

Alpha-cembratriene-4,6-diol (α-CBT-diol) is a complex diterpenoid primarily found in Solanaceae (i.e., tobacco leaves), Pinaceae, and marine corals. Due to its intricate chemical structure, it serves as a precursor for several aroma compounds, including farnesal. Farnesal and its derivatives have applications across various fields, such as the fragrance and flavor industry, pharmaceuticals, agriculture, and cosmetics. In this study, Stenotrophomonas maltophilia H3-1, a strain capable of efficiently biodegrading α-CBT-diol into farnesal, was isolated from soil and identified through 16S rDNA sequence analysis. S. maltophilia H3-1 biodegraded 93.3% of α-CBT-diol (300 mg/L) within 36 h when grown under optimized culture conditions, including a temperature of 40 °C, pH of 8, 2 g/L maltose, and 2 g/L ammonium sulfate. Theoretically, this strain can produce 201 mg/L of farnesal during the biotransformation of α-CBT-diol. The putative α-CBT-diol bioconversion pathway expressed in S. maltophilia H3-1 is also proposed. This is the first study to report the bioconversion of α-CBT-diol into the high-value compound farnesal using a novel S. maltophilia H3-1 strain. It highlights that other compounds found in tobacco can also be bioconverted into valuable products.

The Antibacterial Activity of Rhazya stricta Extracts against Klebsiella pneumoniae Isolated from Some Soil Invertebrates at High Altitudes

Klebsiella is a common dangerous pathogen for humans and animals and is widely present in the digestive system. The genus Klebsiella is ubiquitous, as it is endemic to surface water, soil, and sewage. In this study, 70 samples were obtained from soil-dwelling invertebrates from September 2021 to March 2022 from Taif and Shafa in different altitudinal regions of Saudi Arabia. Fifteen of these samples were identified as Klebsiella spp. The Klebsiella isolates were genetically identified as Klebsiella pneumoniae using rDNA sequencing. The antimicrobial susceptibility of the Klebsiella isolates was determined. Amplification of virulence genes was performed using PCR. In this study, 16S rDNA sequencing showed a similarity from 98% to 100% with related K. pneumonia from the NCBI database, and the sequences were deposited in the NCBI GenBank under accession numbers ON077036 to ON077050. The growth inhibition properties of ethanolic and methanolic extracts of the medicinal plant Rhazya stricta's leaves against K. pneumoniae strains using the minimum inhibitory concentration (MIC) method and disc diffusion were evaluated. In addition, the biofilm inhibitory potential of these extracts was investigated using crystal violet. HPLC analysis identified 19 components divided into 6 flavonoids, 11 phenolic acids, stilbene (resveratrol), and quinol, and revealed variations in the number of components and their quantities between extracts. Both extracts demonstrated interesting antibacterial properties against K. pneumoniae isolates. The 2 extracts also showed strong biofilm inhibitory activities, with percentages of inhibition extending from 81.5% to 98.7% and from 35.1% to 85.8% for the ethanolic and methanolic extracts, respectively. Rhazya stricta leaf extract revealed powerful antibacterial and antibiofilm activities against K. pneumoniae isolates and could be a good candidate for the treatment or prevention of K. pneumonia-related infections.

Molecular diversity and profile analysis of virulence-associated genes in some Klebsiella pneumoniae isolates

The noticeable increase in the occurrence of multidrug-resistant Klebsiella pneumoniae strains separated from different hospitals in Taif city, (Saudi Arabia) demonstrates the limitation of antibiotics used for bacterial eradication. The aim of the present study is to detect the virulence genes in some K. pneumoniae isolates that collected from different hospitals in Taif governorate in Saudi Arabia. A total of 134 clinical samples were used to isolate about twenty three K. pneumoniae strains from various clinical specimens throw six months. They were identified by microbiological method as K. pneumoniae and confirmed with 16S rRNA sequencing analysis. The antimicrobial susceptibility of K. pneumoniae isolates was determined. The existence of virulence genes (AcrAB, tolC, arb, OmpK35, RmpA, fimH-1, entB, K2, irP-1 and Mdtk) were performed by PCR. The multidrug-resistant strains were detected in 16 (69.5%), that showed the presence of the most virulence genes. The multidrug-resistant isolates showed resistance against Ampicillin (96%), Amox-Clav (90%), Cephalothin (90%), Cefuroxime (90%), Ceftriaxone (85%), Aztreonam (87%), Cefepime (80%), Ceftazidime (80%), and Trim-Sulf (82%). Molecular diversity between K. pneumoniae isolates was determined using Rep-PCR markers technique. Thirty eight bands were resulted from the rep-PCR primers. Out of them, 31 bands were polymorphic with a polymorphism average of 81.6%. Total loci detected for each primer varied from 11 to 15 loci, and the loci size ranging from 200 to 2000 bp. These data may present novel epidemiological information regarding the clonal nature of K. pneumoniae separated from Taif governorate hospitals, Saudi Arabia.