Characterization and Genome Analysis of Arthrobacter bangladeshi sp. nov., Applied for the Green Synthesis of Silver Nanoparticles and Their Antibacterial Efficacy against Drug-Resistant Human Pathogens.

Abstract

The present study describes the isolation and characterization of novel bacterial species Arthrobacter bangladeshi sp. nov., applied for the green synthesis of AgNPs, and investigates its antibacterial efficacy against drug-resistant pathogenic Salmonella Typhimurium and Yersinia enterocolitica. Novel strain MAHUQ-56T is Gram-positive, aerobic, non-motile, and rod-shaped. Colonies were spherical and milky white. The strain showed positive activity for catalase and nitrate reductase, and the hydrolysis of starch, L-tyrosine, casein, and Tween 20. On the basis of the 16S rRNA gene sequence, strain MAHUQ-56T belongs to the Arthrobacter genus and is most closely related to Arthrobacter pokkalii P3B162T (98.6%). Arthrobacter bangladeshi MAHUQ-56T has a genome 4,566,112 bp long (26 contigs) with 4125 protein-coding genes, 51 tRNA and 6 rRNA genes. The culture supernatant of Arthrobacter bangladeshi MAHUQ-56T was used for the easy and green synthesis of AgNPs. Synthesized AgNPs were characterized by UV–vis spectroscopy, FE-TEM, XRD, DLS, and FT-IR. Synthesized AgNPs were spherical and 12–50 nm in size. FT-IR analysis revealed various biomolecules that may be involved in the synthesis process. Synthesized AgNPs showed strong antibacterial activity against multidrug-resistant pathogenic S. typhimurium and Y. enterocolitica. MIC values of the synthesized AgNPs against S. typhimurium and Y. enterocolitica were 6.2 and 3.1 ug/mL, respectively. The MBC of synthesized AgNPs for both pathogens was 12.5 ug/mL. FE-SEM analysis revealed the morphological and structural alterations, and damage of pathogens treated by AgNPs. These changes might disturb normal cellular functions, which ultimately leads to the death of cells.