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Chelating agents used in agriculture and land reclamation practices must exhibit the capacity to firmly bind metal ions while also rapidly decomposing into non-toxic compounds due to their introduction into the environment in substantial quantities. It is therefore crucial to identify an alternative to EDTA, a prevalent chelating agent known for its low biodegradability and relatively high toxicity. This study focuses on assessing the degree of biodegradation of iminoglutamic succinic acid (IGSA) and the toxicity of its half-decomposition products. For this purpose, two bacterial and fungal isolates capable of decomposing IGSA were isolated and characterized, identified as Ralstonia pickettii and Fusarium foetens, respectively. The results of a 28-day experiment demonstrated that Ralstonia pickettii was capable of decomposing IGSA by 18.0% according to the manometric test and by 24.5% based on the analysis of decomposition products via HPLC. In comparison, Fusarium foetens exhibited a more effective biodegradation capacity, with rates of 20.3% and 32.5%, respectively. The half-decomposition products of IGSA were characterized by low ecotoxicity levels (LID10) concerning Paramecium caudatum (11.2-13.2 g/l) and Ceriodaphnia affinis (3.6-8.9 g/l). However, a stimulating effect was observed on microalgae, with growth stimulation ranging from 63.65-96.60%., Competing Interests: Declarations. Conflict of interest: The authors declare no competing interests., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Ralstonia pickettii are ubiquitous in water environments. Members of this species are frequently, but not always, resistant to both gentamicin and arsenite. Gentamicin and arsenite co-resistance and the putative molecular mechanisms were investigated. A group of 37 R. pickettii strains isolated from drinking water and hospital wastewater were characterized for gentamicin and arsenite resistance phenotypes, the number and size of plasmids, and screened for genetic elements associated with arsenite tolerance, Integrative and Conjugative Elements (ICEs), among other. The genomes of three representative strains were compared. Most gentamicin resistant (GR) isolates (32/33) were resistant to arsenite, and harbored ICE- and ars operon-related genes. These genetic elements were not detected in any of the five arsenite susceptible strains, regardless of the GR (n = 1) or gentamicin susceptibility (GS) (n = 4) phenotype. The comparison of the genomes of two GR (one resistant and one susceptible to arsenite) and one GS strains suggested that these phenotypes correspond to three phylogroups, distinguished by presence of some genes only in GR isolates, in addition to point mutations in functional genes. The presence of ICEs and ars operon-related genes suggest that arsenite resistance might have been acquired by GR lineages., Competing Interests: Declaration of competing interest The authors declare no conflict of interests., (Copyright © 2020 Institut Pasteur. Published by Elsevier Masson SAS. All rights reserved.)

Members of the species Ralstonia pickettii and R. mannitolilytica, although ubiquitous and lacking major virulence factors, have been associated with nosocomial outbreaks. Tolerance to metals, antibiotics, and disinfectants may represent an advantage for their ubiquity and opportunistic pathogenic potential. In this study, we compared five strains that differed on the origin (hospital effluent, tap water, mineral water) and in the susceptibility to aminoglycosides, regarding their tolerance to metals and disinfection. The growth kinetics and biofilm formation capacity were tested in four R. pickettii strains and one R. mannitolilytica at sub-inhibitory concentrations of aminoglycosides or arsenite. The survival to UV radiation, chlorine, or hydrogen peroxide was also compared in aminoglycoside resistant and susceptible strains. Aminoglycoside-resistant strains presented a higher tolerance to arsenite than the susceptible ones and either aminoglycosides or arsenite was observed to stimulate the biofilm formation. Sub-inhibitory concentrations of the aminoglycoside gentamicin or arsenite significantly decreased the growth rate and yield, but only arsenite caused a significant increase of the lag phase. Hydrogen peroxide presented higher disinfection effectiveness against aminoglycoside susceptible than against resistant strains, an effect that was not observed for UV or chlorine. Although this conclusion needs validation based on a larger number of isolates, including clinical, the results suggest that aminoglycoside resistance may be associated with traits that influence Ralstonia spp. fitness in the environment.

Background: Ralstonia Pickettii biofilms are associated with pocket infections following breast implant surgeries. Biofilm protects bacteria most topically applied antimicrobial irrigations., Objectives: To evaluate the effectiveness of four antimicrobial solutions on the planktonic form and established biofilm of Ralstonia Pickettii grown on 3 different types of silicone breast implants., Methods: Time kill assays at clinical concentrations of chlorhexidine gluconate, povidone iodine, triple-antibiotic solution, and a 0.025% hypochlorous acid solution stabilized in amber glass were evaluated. Normal saline was the control. Three types of silicone implants, two with a textured surface and one smooth surface, were selected. Planktonic assays were performed after implants were soaked for one, five, 30, and 120 minute time points. Biofilm assays were performed after 5 and 120 minutes of implant soak time. Both tests evaluated cell-forming units (CFU/mL)., Results: Triple antibiotic solution had no effect on R. pickettii and was dropped from the study. Remaining solutions showed total kill of planktonic bacteria at one minute. Saline control showed no significant effect on biofilm as anticipated. Stabilized hypochlorous acid was the only solution tested capable of eradicating R. pickettii biofilm on all implant surfaces tested within the first five minute soak time., Conclusions: Noncytotoxic, 0.025% hypochlorous acid in normal saline, stabilized in amber glass, successfully eradicated Ralstonia pickettii in planktonic and mature biofilm on three types of silicone implants during initial five minute soak time and may be the preferred antimicrobial solution for pocket lavage. This preliminary study requires further investigation. Leaching and implant compatibility testing is currently in progress.