Escherichia coligrowth and transport in the presence of nanosilver under variable growth conditions

Abstract

Nanosilver (silver nanoparticles) has the ability to anchor to the bacterial cell membrane and subsequently penetrate it, thereby causing structural changes (i.e., permeability) in the cell membrane and death of the cell. The bacterial responses to the presence of nanosilver usually vary depending on the concentration of nanosilver particles, exposure time and the bacterial physiological stage. Since bacterial anabolism dependents upon a stoichiometric ratio of carbon and inorganic elements (nutrients), the macronutrient ratio, i.e. carbon to nitrogen ratio (C/N) thus plays an important role of bacterial responses to the exposure of nanosilver. This study investigated the responses of Escherichia coli to the exposure of nanosilver under variable growth conditions. It was discovered that E. coli grown under different growth conditions had different responses to the presence of nanosilver. E. coli had least resistance to the toxicity of nanosilver when cultured under carbon-limited conditions. However, the presence of rhamnolipid, a commonly utilized biosurfactant for soil remediation increased the resistance of E. coli to nanosilver. The transport of E. coli cultured under carbon-limited conditions was further studied in silica sand columns. E. coli adsorption in silica sand increased when cultured in the presence of nanosilver. On the contrary, E. coli adsorption in silica sand was significantly reduced when cultured in the presence of rhamnolipid.

Biogenic Synthesis of Metal Nanoparticles Using a Biosurfactant Extracted from Corn and Their Antimicrobial Properties

“…Some authors have reported that the presence of biosurfactants can increase the resistance to some pathogenic microorganisms. For instance, Xie et al [58] have reported that the presence of rhamnolipid increased the resistance of E. coli to Ag NPs. Therefore, this fact can be related to the higher biocompatible character of these NPs in comparison with the NPs obtained in the absence of biosurfactants.…”

Electropolishing of surfaces: theory and applications

“…For example, it is known that the substrate roughness affects the adhesion of the bacteria. [86][87][88] With a careful electropolishing process, the stainless steel would have a microscopically smoother surface, leading to a decreasing bacterial attachment. 89 The selection of the electropolishing electrolyte of the stainless steel has some prerequisites: a.…”

Rhamnolipid biosurfactants: evolutionary implications, applications and future prospects from untapped marine resource

“…Production of nano-biosurfactants was achieved and it will help to replace synthetic nano-emulsions (Saeedi et al, 2014). A recent discovery showed that the presence of a rhamnolipid biosurfactant increased the resistance of E. coli to nanosilver (Xie et al, 2014). This study may facilitate a new line of research on enhanced nanosilver synthesis by engineered E. coli cells.…”