title: The effect of temperature on antibacterial activity of biosynthesized silver nanoparticles.
abstract: The purpose of this study was the evaluation of two different temperatures on antibacterial activity of the biosynthesized silver nanoparticles. 38 silver nanoparticles-producing bacteria were isolated from soil and identified. Biosynthesis of silver nanoparticles by these bacteria was verified through visible light spectrophotometry. Two strains were relatively active for production of silver nanoparticles. These strains were subjected for molecular identification and recognized as Bacillus sp. and Acinetobacter schindleri. In the present study, the effect of temperatures was evaluated on structure and antimicrobial properties of the silver nanoparrticles by transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis and antimicrobial Agar well diffusion methods. The silver nanoparticles showed antibacterial activity against all the pathogenic bacteria; however, this property was lost after treatment of the silver nanoparticles by high temperatures (100 and 300 °C). TEM images showed that the average sizes of heated silver nanoparticles were >100 nm. However, these were <100 nm for non-heated silver nanoparticles. Although, XRD patterns showed the crystalline structure of heated silver nanoparticles, their antibacterial activities were less. This was possible because of the sizes and accordingly less penetration of the particles into the bacterial cells. In addition, elimination of the capping agents by heat might be considered another reason.
authors: Department of Microbiology, Science and Research Branch, Islamic Azad University, Fars, Iran. parastoo_pourali@yahoo.com
authors: Parastoo
authors: P
authors: Pourali
authors: Majid
authors: M
authors: Baserisalehi
authors: Sima
authors: S
authors: Afsharnezhad
authors: Javad
authors: J
authors: Behravan
authors: Rashin
authors: R
authors: Ganjali
authors: Nima
authors: N
authors: Bahador
authors: Sepideh
authors: S
authors: Arabzadeh
mesh_terms: D000150:Acinetobacter / Q000302:isolation & purification / Q000378:metabolism*; D000900:Anti-Bacterial Agents / Q000096:biosynthesis* / Q000737:chemistry / Q000494:pharmacology; D001407:Bacillus / Q000302:isolation & purification / Q000378:metabolism*; D052978:Disk Diffusion Antimicrobial Tests; D004355:Drug Stability; D006090:Gram-Negative Bacteria / Q000187:drug effects; D006094:Gram-Positive Bacteria / Q000187:drug effects; D006358:Hot Temperature; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D010316:Particle Size; D012834:Silver / Q000378:metabolism*; D012988:Soil Microbiology; D014961:X-Ray Diffraction
chemical_list: D000900:Anti-Bacterial Agents; D012834:Silver