Silver resistance in Pseudomonas stutzeri

Abstract

Silver resistance was studied in a silver-resistant Pseudomonas stutzeri AG259 strain and compared to a silver-sensitive P. stutzeri JM303 strain. Silver resistance was not due to silver complexation to intracellular polyphosphate or the presence of low molecular weight metal-binding protein(s). Both the silver-resistant and silver-sensitive P. stutzeri strains produced H2S, with the silver-resistant AG259 strain producing lower amounts of H2S than the silver-sensitive JM303 strain. However, intracellular acid-labile sulfide levels were generally higher in the silver-resistant P. stutzeri AG259 strain. Silver resistance may be due to formation of silver-sulfide complexes in the silver-resistant P. stutzeri AG259 strain.

Formation of Nanoscale Elemental Silver Particles via Enzymatic Reduction by Geobacter sulfurreducens

“…Given the relatively high concentrations of chloride ions (15.5 mM) in the medium used in this study (11) and the very-lowsolubility product of AgCl (K sp ϭ 1.8 ϫ 10 Ϫ10 ), it is probable that the cells reduced insoluble AgCl in our initial experiments. Indeed this may explain why we were able to grow G. sulfurreducens in medium supplemented with up to 2 mM Ag(I) without a negative impact on growth of the organism; previous studies have also noted enhanced silver resistance in other organisms in the presence of chloride ions (5,19,20), presumably reflecting decreased bioavailability of the metal due to the formation of insoluble AgCl.…”

“…Despite the current interest in microbial interactions with silver (6,9,19,20), there has been little work on the microbial redox cycling of this metal. This is surprising given the obvious potential of metal-reducing microorganisms, such as Fe(III)-reducing bacteria of the genus Geobacter, to reduce Ag(I) to Ag(0), capturing the metal from solution.…”

Biogenic Synthesis of Nanoparticles and Potential Applications: An Eco- Friendly Approach

“…Bacillus species has depicted to synthesise metal nanoparticles, researchers showed the ability of bacteria to decrease silver and fabrication of extracellularly, consistently circulated nanoparticles, ranging from 10-20 nm size [58]. The Silver producing bacteria isolated from the silver mines exhibit the silver nanoparticles accumulated in the periplasmic space of Pseudomonas stutzeri AG259 [59]. Bacteria are also used to synthesize gold nanoparticles.…”

Biology of Pseudomonas stutzeri

“…Although plasmid pKK1 is still unsequenced, it has been demonstrated that the encoded silver resistance mechanism is energy dependent (329). This mechanism seems to produce intracellular silversulfide complexes (331). Interestingly, P. stutzeri AG259 is also able to accumulate large amounts of germanium, copper, lead, and zinc on the cells by energy-independent passive binding (215,330).…”