Characterization and antibacterial evaluation of Eco-friendly silver nanoparticles synthesized by halophilic Streptomyces rochei SSCM102 isolated from mangrove sediment.

BACKGROUND: Antimicrobial resistance has surged due to widespread antimicrobial drug use, prompting interest in biosynthesizing nanoparticles from marine-derived actinomycetes extracellular metabolites, valued for their diverse bioactive compounds. This approach holds promise for addressing the urgent need for novel antimicrobial agents. The current study aimed to characterize novel bioactive compounds from unexplored biodiversity hotspots, halophilic Streptomyces sp. isolated from mangrove sediment in the Pichavaram region, India. METHODS AND RESULTS: Streptomyces rochei SSCM102 was conclusively identified through morphological and molecular characterization. Synthesis of silver nanoparticles (AgNPs) from Streptomyces rochei SSCM102 was characterized using various techniques, including UV-Vis, XRD, SEM, EDX, and FT-IR. The UV-Vis spectrum of the reduced AgNPs exhibited a prominent peak at 380 nm, confirming the AgNPs. The UV-Vis spectrum confirmed the synthesis of AgNP, and SEM analysis revealed a cubic morphology with sizes ranging from 11 to 21 nm. The FTIR spectrum demonstrated a shift in frequency widths between 626 cm-1 and 3432 cm-1. The EDX analysis substantiated the presence of metallic silver, evident from a strong band at 1.44 keV. The synthesized AgNPs exhibited antibacterial efficacy against human pathogens Escherichia coli (64 ± 0.32 µg/ml), Klebsiella pneumoniae (32 ± 0.16 µg/ml), and Pseudomonas aeruginosa (16 ± 0.08 µg/ml) by MIC and MBC values of 128 ± 0.64 (µg/ml), 64 ± 0.32 (µg/ml) and 32 ± 0.16 (µg/ml), respectively. Additionally, at a concentration of 400 µg/ml, the AgNPs displayed a 72% inhibition of DPPH radicals, indicating notable antioxidant capacity. The LC50 value of 130 µg/mL indicates that the green-synthesized AgNPs have lower toxicity by Brine Shrimp Larvae assay. CONCLUSION: The study's novel approach to synthesizing eco-friendly silver nanoparticles using Halophilic Streptomyces rochei SSCM102 contributes significantly to the field of biomedical research and drug development. By demonstrating potent antibacterial properties and aligning with sustainability goals, these nanoparticles offer promising avenues for novel antibacterial therapies.

Polystyrene nanoplastics synergistically exacerbate diclofenac toxicity in embryonic development and the health of adult zebrafish.

In this study, we investigated the possible ecotoxicological effect of co-exposure to polystyrene nanoplastics (PS-NPs) and diclofenac (DCF) in zebrafish (Danio rerio). After six days of exposure, we noticed that the co-exposure to PS-NP (100 µg/L) and DCF (at 50 and 500 µg/L) decreased the hatching rate and increased the mortality rate compared to the control group. Furthermore, we noted that larvae exposed to combined pollutants showed a higher frequency of morphological abnormalities and increased oxidative stress, apoptosis, and lipid peroxidation. In adults, superoxide dismutase and catalase activities were also impaired in the intestine, and the co-exposure groups showed more histopathological alterations. Furthermore, the TNF-α, COX-2, and IL-1ß expressions were significantly upregulated in the adult zebrafish co-exposed to pollutants. Based on these findings, the co-exposure to PS-NPs and DCF has shown an adverse effect on the intestinal region, supporting the notion that PS-NPs synergistically exacerbate DCF toxicity in zebrafish.