RT - Journal Article T1 - Impact of silver nanoparticles on bacterial flora of the cotton rhizosphere and bulk soil JF - MGJ YR - 2019 JO - MGJ VO - 14 IS - 1 UR - http://mg.genetics.ir/article-1-36-en.html SP - 63 EP - 72 K1 - Bactreial flora K1 - Cotton K1 - DGGE K1 - Nanosilver particles. AB - In this study, the effect of two types of colloidal nanosilver formulations, LS2000 and L2000 on cotton bulk and rhizosphere soil bacterial communities was investigated. Soil was treated with 0, 5, 10, 25 and 50 ppm of each formulation before seed planting. Soil samples were collected from rhizosphere and bulk soil of cotton at seedling, squaring and bolling stages. Enumeration of bacteria was carried out on Tryptic Soy Agar (TSA). PCR–DGGE (Denaturing Gradient Gel Electrophoresis) was performed to show bacterial diversity in soil samples treated with different concentrations of nanosilver formulations. Total numbers of culturable bacteria in the soil samples were approximately 104 to 107 CFU/g of dried soil for balk and rhizosphere respectively. The average numbers of culturable soil bacteria were decreased following soil treatment with 5, 10, 25 and 50 ppm of both nanosilver formulations compared to the control. The inhibitory effect of LS2000 was more than L2000 at all concentration especially in rhizosphere soil samples. Total numbers of rhizosphere bacteria significantly (P≤ 0.01) increased with development stage of cotton. At the seedling stage, sensitivity of bacterial flora to nanosilver formulations was higher and LS2000 and L2000 completely inhibited growth of soil bacteria at 5 and 25 ppm concentrations respectively. Based on the molecular data, the diversity of 16S rDNA gene in cotton bulk and rhizosphere soil changed when LS2000 or L2000 was added to soil. Data revealed that the effect of LS2000 on the PCR-DGGE profile of 16S rDNA gene was more than L2000. LA eng UL http://mg.genetics.ir/article-1-36-en.html M3 ER -