Characterization of an Antibacterial Compound from the Mangrove Bacterium Bacillus velezensis ES8024 and the Impacts of Anthropogenic and Climatic Factors on Its Production

Bioactive potential of endophytic Bacillus pumilus BPSL8 isolated from the medicinal plant Dillenia pentagyna Roxb.

Aim: The study aimed at studying, identifying, and evaluating the bioactive properties of endophytic bacteria isolated from the medicinal plant Dillenia pentagyna Roxb. Methods: An agar well diffusion assay was employed for antimicrobial screening. 16S rRNA gene sequencing was done to identify selected bacteria. Antioxidant assays using DPPH and ABTS radical scavenging assays were performed. Cytotoxicity was tested using the MTT assay, and detection of secondary metabolites was done using HPTLC. Results: Among the 96 isolates, one endophytic bacterium, BPSL8, identified as Bacillus pumilus, had the most significant activity. The crude methanol extract of BPSL8 exhibited antibacterial activity against Micrococcus luteus, Bacillus subtilis, and Klebsiella pneumoniae. BPSL8 has a potent antioxidant capacity of DPPH and ABTS free radicals with an IC₅₀ of 6.29 and 4.25 µg/mL, respectively. BPSL8 was found to have cytotoxicity against HT29 (IC50 55.2 µg/mL) and HeLa (IC50 51.9 µg/mL). HPTLC analysis done for three fractions (DCM, EA, and MeOH) of BPSL8 detected the presence of phytochemicals. Conclusion: This study demonstrates the potential of the identified endophytic bacterium B. pumilus as a source of as a potent antibacterial, antioxidant, and anticancer agent with a key role in providing insights into their impact on the host as well as their applications in the field of pharmaceuticals.

Discovery of penicillic acid from mangrove endophytic fungi: anti-Vibrio screening and cell envelope disruption in V. parahaemolyticus

Mangrove endophytic fungi are recognized as prolific sources of structurally diverse and bioactive natural products. In this study, 19 cultivable endophytic fungal strains were isolated and taxonomically characterized from mangrove plant tissues collected at the Shankou Mangrove Nature Reserve (Guangxi, China). One isolate, Aspergillus sclerotiorum BM19, exhibited broad-spectrum inhibitory activity against multiple aquatic pathogenic Vibrio strains. Bioactivity-guided fractionation of its ethyl acetate crude extract led to the isolation of penicillic acid (1), whose structure was fully elucidated by 1D/2D NMR and HRESIMS. Penicillic acid showed potent anti Vibrio parahaemolyticus activity with a minimum inhibitory concentration (MIC) of 6.25 μg/mL and displayed no obvious cytotoxicity toward human HaCaT keratinocytes. Growth curve assays revealed a concentration-dependent antibacterial effect: 0.5 × MIC delayed logarithmic growth, whereas 1 × and 2 × MIC completely suppressed bacterial proliferation. Transmission electron microscopy (TEM) visualized cellular distortion, compromised cell envelopes, and cytoplasmic leakage at MIC, with severe envelope disruption at 2 × MIC. Confocal laser scanning microscopy (CLSM) combined with SYTO 9/PI double staining further confirmed the concentration-dependent impairment of cell envelope integrity, as evidenced by reduced green fluorescence (intact cells) and increased red fluorescence (damaged cells). Collectively, these findings indicate that penicillic acid inhibits V. parahaemolyticus and is associated with concentration-dependent impairment of cell-envelope integrity. Although penicillic acid is a known mycotoxin, its selective activity against pathogenic vibrios and low toxicity to human keratinocytes highlight its potential as a lead compound for aquaculture applications. Nevertheless, further systematic evaluation of in vivo efficacy and biosafety is required prior to translational development.

Antibacterial, antioxidant, and cytotoxic potential of an endophytic Fusarium verticillioides from yacon (Smallanthus sonchifolius) leaves

Endophytic fungi, residing within plant tissues without causing disease, serve as an important reservoir of bioactive compounds with pharmaceutical potential. This research focuses on isolating and identifying endophytic fungi from the leaves of Smallanthus sonchifolius and evaluating their antioxidant, antibacterial, and cytotoxic activities. A total of five fungal isolates (DY1–DY5) were obtained and subjected to in vitro bioassays and molecular identification. Internal transcribed spacer (ITS) sequencing revealed that isolate DY5 corresponded to Fusarium verticillioides, which consistently demonstrated notable bioactivities. Antioxidant activity was confirmed through the DPPH radical scavenging assay, where DY5 exhibited an IC₅₀ value of 241.23 μg/mL. Antibacterial evaluation against Escherichia coli ATCC 25922 revealed an inhibition zone of 12.22 ± 0.98 mm and a minimum inhibitory concentration (MIC) of 500 μg/mL. Cytotoxic screening using the Artemia salina lethality assay indicated moderate toxicity, with LC₅₀ values of 197.54 μg/mL for DY1 and 386.32 μg/mL for DY5, thereby meeting the threshold of bioactive extracts. This study provides evidence that endophytic fungi from S. sonchifolius, notably F. verticillioides (DY5), can serve as potential sources of bioactive compounds with pharmaceutical relevance. Further research focusing on metabolite profiling, compound isolation, and mechanistic evaluation is warranted to elucidate their chemical diversity and therapeutic significance in drug discovery efforts

Assessment of physicochemical factors and partial screening of the biosurfactant producing bacteria in marine water of Kerala

This research examined the physico-chemical characteristics and cultivable bacterial diversity of a marine water samples collected from Chombala of kerala and also assessing the potential for biosurfactant production. The physical parameters indicated (Alkalinity (total), NH₃/NH₄⁺, Ca²⁺, Cl⁻, Dissolved oxygen, Electrical conductivity, Mg²⁺, NO₃⁻, NO₂⁻, pH, PO₄³⁻, Salinity, SiO2, Temperature, TDS, Total hardness & Turbidity. A total of fifteen bacterial strains were isolated, characterized morphologically, biochemically and identified as Bacillus sp. (40%), along with Vibrio sp., Pseudomonas aeruginosa, Halomonas sp., Serratia marcescens, among others. The biosurfactant screening methods employed (Including Drop Collapse, Oil Spread, Atomized Oil Spray, Microplate Assay, Tilting Slide & Emulsification (24h), Hemolytic Assay, CTAB-MB Plate, Hydrocarbon Overlay and Aggregation) revealed that 10 strains (67%) tested positive, predominantly consisting of Bacillus and Pseudomonas species. The oligotrophic and saline environment supported a diverse community of halotolerant bacteria with significant biosurfactant production potential, underscoring implications for bioremediation and aquaculture.

Morpho-molecular approach reveals a myco-endophyte, Aspergillus novoparasiticus CBS126849 (MTCC-13997) from the roots of Capparis decidua with therapeutic and enzymatic potential

Isolation and characterization of an algicolous endophytic Mucor circinelloides from macroalga Colpomenia sinuosa as a promising source of bioactive metabolites for dermocosmetic applications

Overall, this study reports the first isolation of M. circinelloides from Egyptian C. sinuosa and highlights its potential as a promising source of bioactive metabolites with enhanced antibacterial activity and multifunctional properties suitable for pharmaceutical and dermocosmetic applications.