ABSTRACT
In this study, a series of secondary metabolites from Ganoderma sp. were screened against Staphylococcus aureus protein targets, including as phosphotransacetylase, clumping factor A, and dihydrofolate reductase, using molecular docking simulations. The chemicals that showed the strongest binding energy with the targeted proteins were ganodermanontriol, lucidumol B, ganoderic acid J, ergosterol, ergosterol peroxide, 7-oxoganoderic acid Z, ganoderic acid AM1, ganosinoside A, ganoderic acid D, and 24R-ergosta-7,2E-diene-3ß,5α,6ß-triol. Interestingly, ganosinoside A showed the greatest affinity for the protein clumping factor A, a result validated by molecular dynamic simulation. Additionally, three natural Ganoderma sp. Strains as Ganoderma lingzhi VNKKK1903, Ganoderma lingzhi VNKK1905A2, and Amauroderma subresinosum VNKKK1904 were collected from Kon Ka Kinh National Park in central land of Vietnam and evaluated for their antibacterial activity against Staphylococcus aureus using an agar well diffusion technique. These results suggest that the fungal extracts and secondary metabolites may serve as valuable sources of antibiotics against Staphylococcus aureus. These findings provided an important scientific groundwork for further exploration of the antibacterial mechanisms of compounds derived from Ganoderma sp. in future research.
ABSTRACT
Aeromonas spp. are commonly found in the aquatic environment and have been responsible for motile Aeromonas septicemia (MAS) in striped catfish, resulting in significant economic loss. These organisms also cause a range of opportunistic infections in humans with compromised immune systems. Here, we conducted a genomic investigation of 87 Aeromonas isolates derived from diseased catfish, healthy catfish and environmental water in catfish farms affected by MAS outbreaks in eight provinces in Mekong Delta (years: 2012-2022), together with 25 isolates from humans with bloodstream infections (years: 2010-2020). Genomics-based typing method precisely delineated Aeromonas species while traditional methods such as aerA PCR and MALDI-TOF were unable identify A. dhakensis. A. dhakensis was found to be more prevalent than A. hydrophila in both diseased catfish and human infections. A. dhakensis sequence type (ST) 656 followed by A. hydrophila ST251 were the predominant virulent species-lineages in diseased catfish (43.7 and 20.7â%, respectively), while diverse STs were found in humans with bloodstream infections. There was evidence of widespread transmission of ST656 and ST251 on striped catfish in the Mekong Delta region. ST656 and ST251 isolates carried a significantly higher number of acquired antimicrobial resistance (AMR) genes and virulence factors in comparison to other STs. They, however, exhibited several distinctions in key virulence factors (i.e. lack of type IV pili and enterotoxin ast in A. dhakensis), AMR genes (i.e. presence of imiH carbapenemase in A. dhakensis), and accessory gene content. To uncover potential conserved proteins of Aeromonas spp. for vaccine development, pangenome analysis has unveiled 2202 core genes between ST656 and ST251, of which 78 proteins were in either outer membrane or extracellular proteins. Our study represents one of the first genomic investigations of the species distribution, genetic landscape, and epidemiology of Aeromonas in diseased catfish and human infections in Vietnam. The emergence of antimicrobial resistant and virulent A. dhakensis strains underscores the needs of enhanced genomic surveillance and strengthening vaccine research and development in preventing Aeromonas diseases in catfish and humans, and the search for potential vaccine candidates could focus on Aeromonas core genes encoded for membrane and secreted proteins.