Nuttapon Songnaka

The widespread prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in community and healthcare settings has driven the urgent search for novel antibacterial agents. Mangrove sediments are an underexplored source of antimicrobial-producing bacteria. This study characterized an antimicrobial fraction and the genome of the mangrove-derived isolate Brevibacillus sp. A34. The active fraction was purified via ammonium sulfate precipitation, cation-exchange chromatography, and reversed-phase chromatography. De novo MS/MS analysis assigned the octapeptide LLLLLLAH (905.19 Da), designated as A34 AMP, which was further confirmed by chemical synthesis. This active peptide inhibited all four tested S. aureus strains, including three MRSA strains, with a minimum inhibitory concentration (MIC) of 62 µg/mL. At 2× and 4× MIC, A34 AMP exhibited a concentration-dependent bactericidal effect within 20 h. Increased SYTOX Green uptake and morphological alterations supported a membrane permeabilization mechanism, and antimicrobial activity was retained following thermal, pH, protease, and surfactant treatments. Genome mining identified 23 putative biosynthetic gene clusters, including an 11-module nonribosomal peptide synthetase (NRPS) cluster linked to A34 AMP through three-dimensional adenylation-domain modeling. Collectively, these findings highlight A34 AMP from Brevibacillus sp. A34 as a promising bioactive anti-staphylococcal peptide scaffold.

The escalating methicillin-resistant Staphylococcus aureus (MRSA) crisis necessitates urgent therapeutic innovations. C-serum from Hevea brasiliensis is a protein-rich waste byproduct generated during rubber latex production. The primary objective of this research was to discover and evaluate a new antimicrobial peptide generated through the enzymatic digestion of C-serum protein waste. Enzymatic digestion liberated a novel cryptic hexapeptide, LLKKKY (CSPH-AMP). This peptide exhibited potent efficacy against planktonic and biofilm-associated S. aureus TISTR 517 and MRSA strains (142, 1096, and 2468). It demonstrated minimum inhibitory (MIC) and bactericidal (MBC) concentrations of 4 and 16 μg/mL, alongside minimum biofilm inhibitory (MBIC) and eradication (MBEC) concentrations of 16 and 128 μg/mL, respectively. SYTOX Green assays confirmed that the peptide induces rapid membrane permeabilization. Coarse-grained molecular dynamics simulations demonstrated that initial electrostatic peptide adsorption transitions into a bent transmembrane conformation, inducing localized lipid deformation and aqueous channel formation. Complementary proteomic analysis revealed that CSPH-AMP triggers targeted metabolic and structural cellular repair networks to counter membrane depolarization. Furthermore, CSPH-AMP demonstrated excellent thermal and proteolytic stability. By combining rapid membrane-lytic bactericidal action with robust physical stability, CSPH-AMP emerges as a promising, sustainably sourced candidate for future therapeutic development against drug-resistant MRSA.

Marine-derived Streptomyces are among the most prolific producers of structurally diverse and biologically active natural products. Adaptation to unique marine environments, including deep-sea sediments, hydrothermal vents, mangrove ecosystems, marine invertebrates, and hypersaline habitats, has promoted the evolution of specialized biosynthetic systems capable of generating a broad spectrum of secondary metabolites. These metabolites include polyketides, non-ribosomal peptides (NRPs), ribosomally synthesized and post-translationally modified peptides (RiPPs), terpenoids, alkaloids, and hybrid compounds with significant antibacterial, antifungal, antiviral, antiparasitic, anti-inflammatory, and anticancer activities. Recent advances in genome sequencing, bioinformatics, genome mining, metabolomics, synthetic biology, and artificial intelligence (AI)-assisted discovery have substantially expanded marine natural product research by enabling the identification and prioritization of previously inaccessible biosynthetic gene clusters (BGCs). However, major challenges remain, including silent biosynthetic pathways, low cultivation efficiency, rediscovery of known compounds, metabolite yield instability, dereplication bottlenecks, and limited ecological interpretation. These constraints continue to impede the translation of biosynthetic potential into pharmaceutical applications. This review summarizes current strategies for marine natural product discovery and highlights emerging translational approaches integrating multi-omics technologies, pathway engineering, and AI-guided prioritization. Collectively, these advances provide a roadmap for advancing marine Streptomyces research from descriptive omics-based exploration toward experimentally validated and clinically relevant drug discovery.

This study characterizes the genomic identity, functional efficacy, and computational biophysics of FNL62-AMP, a novel antimicrobial peptide isolated from a phylogenomically distinct, newly identified Brevibacillus species. Production kinetics revealed a late-exponential phase onset of antibacterial activity with sustained potency against methicillin-resistant Staphylococcus aureus (MRSA). LC-MS/MS analysis identified the peptide sequence as NH₂-LLLLFR-COOH. FNL62-AMP demonstrated excellent formulation resilience, retaining full anti-MRSA activity under high thermal stress (80 °C for 6 h) and showing robust resistance to generic trypsin and proteinase K proteolysis. Formulative co-incubation assays demonstrated charge-dependent compatibility, where nonionic Triton X-100 preserved baseline efficacy while ionic surfactants induced antagonism. In vitro time-kill kinetics, scanning electron microscopy, and SYTOX Green assays confirmed rapid, concentration-dependent bactericidal action driven by immediate membrane permeabilization. Molecular dynamics simulations successfully captured the spontaneous self-assembly of 64 FNL62-AMP monomers into a stable macro-aggregate. This consolidation process was quantitatively characterized by a simultaneous contraction in the radius of gyration (R_g), a sharp drop in solvent-accessible surface area (SASA), and a transitional plateau in mean squared displacement (MSD). Ultimately, the high thermal stability, structural resilience, and predictable surfactant compatibility of FNL62-AMP propose ways to be developed for lead optimization and druggability.

Microbial genomes represent a vast and still underexplored reservoir of biosynthetic diversity with significant pharmaceutical and biotechnological potential. Advances in whole-genome sequencing and computational genome mining have enabled the systematic identification of biosynthetic gene clusters (BGCs), providing insights into microbial secondary metabolic capabilities that may not be apparent under standard laboratory conditions.In this study, we performed genome mining of Brevibacillus laterosporus SA14 (TISTR 2453) using antiSMASH 8.0 to investigate its biosynthetic potential. The analysis identified a diverse repertoire of biosynthetic gene clusters, including non-ribosomal peptide synthetase (NRPS), type I polyketide synthase (T1PKS), terpene-associated, and multiple hybrid biosynthetic architectures.Notably, a large 133.5 kb hybrid biosynthetic gene cluster (Region 8) containing NRPS, T1PKS, and terpene-associated biosynthetic features was identified within a single contiguous genomic locus. The genomic organization of this region suggests a complex hybrid biosynthetic architecture with the potential to encode structurally diverse secondary metabolites. Comparative analysis indicated limited similarity to currently characterized biosynthetic gene clusters, highlighting Region 8 as a candidate source of previously uncharacterized biosynthetic diversity.The coexistence of peptide-, polyketide-, and terpene-associated biosynthetic features within a single genomic region highlights the evolutionary plasticity of microbial secondary metabolism and the potential for generating chemically diverse metabolites through hybrid biosynthetic systems. Such architectures are increasingly recognized as important contributors to microbial biosynthetic diversity and natural product innovation.Overall, the genome of B. laterosporus SA14 (TISTR 2453) contains a rich repertoire of biosynthetic gene clusters and represents a promising resource for future functional characterization, metabolomic investigation, and synthetic biology-based exploration of microbial secondary metabolism.

Marine-derived Streptomyces have emerged as one of the most prolific microbial resources for structurally diverse and pharmacologically significant natural products. Adaptation to highly competitive marine ecological niches, including deep-sea sediments, hydrothermal vents, mangrove ecosystems, marine invertebrates, and saline habitats, has driven the evolution of specialized biosynthetic systems capable of generating chemically complex secondary metabolites. Recent advances in genome sequencing, bioinformatics, metabolomics, synthetic biology, and artificial intelligence-assisted discovery pipelines have significantly expanded understanding of cryptic biosynthetic gene clusters (BGCs) encoded within marine actinomycete genomes. These BGCs produce structurally diverse metabolites including polyketides, non-ribosomal peptides, ribosomally synthesized and post-translationally modified peptides (RiPPs), terpenoids, alkaloids, and hybrid metabolites with potent antibacterial, antifungal, antiviral, antiparasitic, anti-inflammatory, and anticancer activities. Nevertheless, despite rapid technological progress, major translational limitations remain, including low cultivation efficiency, silent pathway expression, rediscovery of known compounds, metabolite yield instability, dereplication bottlenecks, and insufficient ecological interpretation. This critical review comprehensively discusses the biosynthetic diversity of marine Streptomyces-derived metabolites with emphasis on biosynthetic pathways, enzymatic tailoring reactions, genome mining strategies, metabolomics-guided discovery, synthetic biology approaches, and pharmaceutical applications. In addition, current limitations and future perspectives in marine natural product research are critically evaluated to highlight the transition from descriptive omics-driven exploration toward functionally validated and translationally relevant drug discovery.

Bacterial infection is a cause of life-threatening diseases. The emergence of antimicrobial-resistant bacteria exacerbates this situation, highlighting the need for the discovery of new antimicrobial agents. Our previous study identified a novel antimicrobial peptide, BrSPR20-P1 (P1), which showed potential activity against MRSA. Additionally, silver nanoparticles (AgNPs) exhibit broad-spectrum antibacterial activity, capable of killing multidrug-resistant bacteria. The combination of antimicrobial agents presents a novel strategy for combating these pathogens. This study aimed to evaluate the antibacterial activity of the combination of P1 and AgNPs. It revealed that the combinations showed synergy. The P1 and AgNP mixture at a concentration of 1 and 8 µg/mL (1:8) doubled the activity against S. aureus and MRSA, while that combination of 64 and 64 µg/mL (64:64) exhibited broad-spectrum activity, expanding to E. coli with a 32-fold increase. These combinations exhibited a bactericidal effect, showing the rapid killing of tested bacteria at 10× MIC, with killing rates during the first 3 h ranging from 4.04 ± 0.01 to 4.31 ± 0.03 h⁻¹. The P1 and AgNP mixtures caused a low risk of antibacterial resistance up to 30 passages. It was demonstrated that the synergistic activity of P1 and AgNPs occurred through the disruption of cell walls and membranes, leakage of intracellular materials, and cell lysis. Additionally, the mixtures appeared to interact with bacterial genomic DNA, as indicated by a gel retardation assay. These activities of the combinations were concentration-dependent. The 1:8 µg/mL mixture caused low hemolysis and cytotoxicity and did not impede the wound healing process. In contrast, although the 64:64 µg/mL mixture showed excellent antibacterial efficacy, it was toxic to erythrocytes and mammalian cells. It implies that dose optimization is required to balance its efficacy and toxicity. Therefore, the P1 and AgNP combinations exhibit synergistic antimicrobial activity and have the potential to resolve bacterial infections.

Background/Objectives: Antimicrobial resistance (AMR) contributes to millions of deaths globally each year, creating an urgent need for new therapeutic agents. Antimicrobial peptides (AMPs) have emerged as promising candidates due to their potential to combat AMR pathogens. This study aimed to evaluate the antimicrobial activity of an AMP from a soil-derived bacterial isolate against Gram-negative bacteria. Method: Soil bacteria were isolated and screened for antimicrobial activity. The bioactive peptide was purified and determined its structure and antimicrobial efficacy. Genomic analysis was conducted to predict the biosynthetic gene clusters (BGCs) responsible for AMP production. Results: Genomic analysis identified the isolate as Paenibacillus sp. Na14, which exhibited low genomic similarity (61.0%) to other known Paenibacillus species, suggesting it may represent a novel species. The AMP from the Na14 strain exhibited heat stability up to 90 °C for 3 h and retained its activity across a broad pH range from 3 to 11. Structural analysis revealed that the Na14 peptide consisted of 14 amino acid residues, adopting an α-helical structure. This peptide exhibited bactericidal activity at concentrations of 2–4 µg/mL within 6–12 h, and its killing rate was concentration-dependent. The peptide was found to disrupt the bacterial membranes. The Na14 peptide shared 64.29% sequence similarity with brevibacillin 2V, an AMP from Brevibacillus sp., which also belongs to the Paenibacillaceae family. Genomic annotation identified BGCs associated with secondary metabolism, with a particular focus on non-ribosomal peptide synthetase (NRPS) gene clusters. Structural modeling of the predicted NRPS enzymes showed high similarity to known NRPS modules in Brevibacillus species. These genomic findings provide evidence supporting the similarity between the Na14 peptide and brevibacillin 2V. Conclusions: This study highlights the discovery of a novel AMP with potent activity against Gram-negative pathogens and provides new insight into conserved AMP biosynthetic enzymes within the Paenibacillaceae family.

Antimicrobial resistance (AMR) is a global health threat, with methicillin-resistant Staphylococcus aureus (MRSA) being one of the major resistant pathogens. This study reports the isolation of a novel mangrove-derived bacterium, Virgibacillus chiguensis FN33, as identified through genome analysis and the discovery of a new anionic antimicrobial peptide (AMP) exhibiting anti-MRSA activity. The AMP was composed of 23 amino acids, which were elucidated as NH₃-Glu-Gly-Gly-Cys-Gly-Val-Asp-Thr-Trp-Gly-Cys-Leu-Thr-Pro-Cys-His-Cys-Asp-Leu-Phe-Cys-Thr-Thr-COOH. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for MRSA were 8 µg/mL and 16 µg/mL, respectively. FN33 AMP induced cell membrane permeabilization, suggesting a membrane-disrupting mechanism. The AMP remained stable at 30–40 °C but lost activity at higher temperatures and following exposure to proteases, surfactants, and extreme pH. All-atom molecular dynamics simulations showed that the AMP adopts a β-sheet structure upon membrane interaction. These findings suggest that Virgibacillus chiguensis FN33 is a promising source of novel antibacterial agents against MRSA, supporting alternative strategies for drug-resistant infections.