Plant extract preparation and green synthesis of silver nanoparticles using Swertia chirata: Characterization and antimicrobial activity against selected human pathogens.

Herbal medicinal plants have been used for centuries in traditional medicine, and it is interesting to see how modern research has identified the active compounds responsible for their therapeutic effects. The green synthesis of silver nanoparticles using herbal medicinal plants, such as Swertia chirata, is particularly noteworthy due to its antimicrobial properties. In the current study, the Swertia chirata plant was collected for the first time from the region of Murree, Punjab, Pakistan. After collection, extracts were prepared in different solvents (ethanol, methanol, chloroform, and distilled water), and silver nanoparticles were synthesized by reducing silver nitrate (AgNO3). The UV-visible spectrophotometer, SEM, and EDX were used to characterize the synthesized nanoparticles in terms of their size and shape. The phytochemical analysis of crude extract was performed to determine the presence of different kinds of phytochemicals. The antibacterial activity of plant extracts and the silver nanoparticles were then assessed using the agar well diffusion method against various pathogenic bacteria. The results showed that the plant contains several phytochemicals with remarkable antioxidant potential. The antibacterial analysis revealed that silver nanoparticles and the plant extracts exhibited a significant zone of inhibition against human pathogenic bacteria (Escherichia coli, S. capitis, B. subtilis, and Pseudomonas aeruginosa) as compared to the cefixime and norfloxacin. This implies that the nanoparticles have the potential to be used in nano-medicine applications, such as drug delivery systems, as well as for their antibacterial, antifungal, and antiviral activities. Additionally, the development and application of materials and technologies at the nanometer scale opens possibilities for the creation of novel drugs and therapies. Overall, the study highlights the promising potential of herbal medicinal plants found in Murree, Punjab, Pakistan, and green-synthesized silver nanoparticles in various fields of medicine and nanotechnology.

Genome Annotation of Poly(lactic acid) Degrading Pseudomonas aeruginosa, Sphingobacterium sp. and Geobacillus sp.

Pseudomonas aeruginosa and Sphingobacterium sp. are well known for their ability to decontaminate many environmental pollutants while Geobacillus sp. have been exploited for their thermostable enzymes. This study reports the annotation of genomes of P. aeruginosa S3, Sphingobacterium S2 and Geobacillus EC-3 that were isolated from compost, based on their ability to degrade poly(lactic acid), PLA. Draft genomes of the strains were assembled from Illumina reads, annotated and viewed with the aim of gaining insight into the genetic elements involved in degradation of PLA. The draft genome of Sphinogobacterium strain S2 (435 contigs) was estimated at 5,604,691 bp and the draft genome of P. aeruginosa strain S3 (303 contigs) was estimated at 6,631,638 bp. The draft genome of the thermophile Geobacillus strain EC-3 (111 contigs) was estimated at 3,397,712 bp. A total of 5385 (60% with annotation), 6437 (80% with annotation) and 3790 (74% with annotation) protein-coding genes were predicted for strains S2, S3 and EC-3, respectively. Catabolic genes for the biodegradation of xenobiotics, aromatic compounds and lactic acid as well as the genes attributable to the establishment and regulation of biofilm were identified in all three draft genomes. Our results reveal essential genetic elements that facilitate PLA metabolism at mesophilic and thermophilic temperatures in these three isolates.

Biodegradation of Poly(3-hydroxybutyrate) and Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) by Newly Isolated Penicillium oxalicum SS2 in Soil Microcosms and Partial Characterization of Extracellular Depolymerase.

A fungus, designated as strain SS2 able to degrade aliphatic polyesters, poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV), was isolated from soil. Strain SS2 was identified through rDNA gene sequencing and showed maximum closeness to Penicillium oxalicum. The newly isolated P. oxalicum strain SS2 had completely degraded PHB and PHBV both in emulsion and films form within 36-48 h at 30 °C. Furthermore, P. oxalicum SS2 degraded PHB and PHBV films in soil environment in lab-built soil microcosms within 1 week. The polymer films were evaluated for changes after degradation through scanning electron microscopy (SEM), nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC) and Fourier Transform Infrared spectroscopy (FTIR). The PHBV depolymerase enzyme was purified to homogeneity through column chromatography and molecular mass was found approximately 36 kDa. The depolymerase was stable over a wide range of temperature (15-60 °C) and pH (3.0-8.0) with optimum 40 °C and pH 5.0. The enzyme activity was significantly affected by various metal ions and surfactants. The enzyme activity was strongly enhanced in the presence of divalent cationic metal Cu2+ while inhibited by Zn2+ and non-polar detergents Tween 20 and Tween 60. Finally, it is concluded that P. oxalicum strain SS2 has profound degradation capabilities, and can be applied for the treatment of plastic-contaminated environments.