Phenotypic Characterization and Comparative Genomic Analysis of Novel Salmonella Bacteriophages Isolated from a Tropical Rainforest.

Salmonella infections across the globe are becoming more challenging to control due to the emergence of multidrug-resistant (MDR) strains. Lytic phages may be suitable alternatives for treating these multidrug-resistant Salmonella infections. Most Salmonella phages to date were collected from human-impacted environments. To further explore the Salmonella phage space, and to potentially identify phages with novel characteristics, we characterized Salmonella-specific phages isolated from the Penang National Park, a conserved rainforest. Four phages with a broad lytic spectrum (kills >5 Salmonella serovars) were further characterized; they have isometric heads and cone-shaped tails, and genomes of ~39,900 bp, encoding 49 CDSs. As the genomes share a <95% sequence similarity to known genomes, the phages were classified as a new species within the genus Kayfunavirus. Interestingly, the phages displayed obvious differences in their lytic spectrum and pH stability, despite having a high sequence similarity (~99% ANI). Subsequent analysis revealed that the phages differed in the nucleotide sequence in the tail spike proteins, tail tubular proteins, and portal proteins, suggesting that the SNPs were responsible for their differing phenotypes. Our findings highlight the diversity of novel Salmonella bacteriophages from rainforest regions, which can be explored as an antimicrobial agent against MDR-Salmonella strains.

Green Synthesis and Characterization of Silver Nanoparticles Using Spondias mombin Extract and Their Antimicrobial Activity against Biofilm-Producing Bacteria.

Multidrug resistant bacteria create a challenging situation for society to treat infections. Multidrug resistance (MDR) is the reason for biofilm bacteria to cause chronic infection. Plant-based nanoparticles could be an alternative solution as potential drug candidates against these MDR bacteria, as many plants are well known for their antimicrobial activity against pathogenic microorganisms. Spondias mombin is a traditional plant which has already been used for medicinal purposes as every part of this plant has been proven to have its own medicinal values. In this research, the S. mombin extract was used to synthesise AgNPs. The synthesized AgNPs were characterized and further tested for their antibacterial, reactive oxygen species and cytotoxicity properties. The characterization results showed the synthesized AgNPs to be between 8 to 50 nm with -11.52 of zeta potential value. The existence of the silver element in the AgNPs was confirmed with the peaks obtained in the EDX spectrometry. Significant antibacterial activity was observed against selected biofilm-forming pathogenic bacteria. The cytotoxicity study with A. salina revealed the LC50 of synthesized AgNPs was at 0.81 mg/mL. Based on the ROS quantification, it was suggested that the ROS production, due to the interaction of AgNP with different bacterial cells, causes structural changes of the cell. This proves that the synthesized AgNPs could be an effective drug against multidrug resistant bacteria.

Genome Characterization of Enterococcus faecalis Bacteriophage EFKL.

We characterized the complete genome of the lytic Enterococcus faecalis phage EFKL, which was isolated from a sewage treatment plant in Kuala Lumpur, Malaysia. The phage, which was classified in the genus Saphexavirus, has a 58,343-bp double-stranded DNA genome containing 97 protein-encoding genes and shares 80.60% nucleotide similarity with Enterococcus phage EF653P5 and Enterococcus phage EF653P3.

Complete genome sequences of Lactococcus lactis D1_2, a bacterium with antimicrobial properties isolated from peat soil.

Lactococcus lactis is a beneficial lactic acid bacterium commonly studied for its probiotic properties and role in dairy production. Here, we present a complete genome of Lactococcus lactis D1_2, isolated from peat swamp forests. To discover the potential antimicrobial properties, the complete genome of the strain was sequenced and analyzed.

Genome characterization of Dickeya solani bacteriophage W2B.

We have successfully characterized the complete genome sequence of the lytic Dickeya solani bacteriophage W2B, isolated from the Bunus Sewage Treatment Plant. The lytic phage from the Ningirsuvirus family has a 40,385-bp linear double-stranded DNA genome containing 51 coding sequences (CDSs).

Complete Genome Sequence of Dickeya chrysanthemi Bacteriophage DchS19.

We characterized the complete genome of a lytic Dickeya chrysanthemi bacteriophage, DchS19, which was isolated from a soil sample in Sungai Petani, Kedah, Malaysia. The phage, from the Autographviridae family, has a 39,149-bp double-stranded DNA genome containing 49 protein-coding genes and shares 94.65% average nucleotide identity with Erwinia phage pEp_SNUABM_12.

Complete Genome Sequence of Salmonella enterica Bacteriophage PRF-SP1.

We characterized the complete genome sequence of the lytic Salmonella enterica bacteriophage PRF-SP1, isolated from Penang National Park, a conserved rainforest in northern Malaysia. The novel phage species from the Autographiviridae family has a 39,966-bp double-stranded DNA (dsDNA) genome containing 49 protein-encoding genes and shares 90.96% similarity with Escherichia phage DY1.