Ralstonia pickettii Enhance the DDT Biodegradation by Pleurotus eryngii.

DDT is a hydrophobic organic pollutant, which can be bio-accumulated in nature and have adverse consequences on the physical condition of humans and animals. This study investigated the relationship between the white-rot fungus Pleurotus eryngii and biosurfactantproducing bacterium Ralstonia pickettii associated with the degradation of DDT. The effects of R. pickettii on fungal development were examined using in vitro confrontation assay on a potato dextrose agar (PDA) medium. R. pickettii culture was added to the P. eryngii culture at 1, 3, 5, 7, and 10 ml (1 ml ≈ 1.44 × 1013 CFU). After 7 d incubation, about 43% of the initial DDT (12.5 µM) was degraded by the P. eryngii culture only. The augmentation of 7 ml of R. pickettii culture revealed a more highly optimized synergism with DDT degradation being approximately 78% and the ratio of optimization 1.06. According to the confrontational assay, R. pickettii promoted the growth of P. eryngii towards the bacterial colony, with no direct contact between the bacterial cells and mycelium (0.71 cm/day). DDD (1,1-dichloro-2,2-bis(4- chlorophenyl) ethane), DDE (1,1-dichloro-2,2-bis(4-chlorophenyl) ethylene), and DDMU (1- chloro-2,2-bis(4-chlorophenyl) ethylene) were identified as metabolic products, indicating that the R. pickettii could enhance the DDT biodegradation by P. eryngii.

Bacterial Adhesion and Biofilm Formation on Textured Breast Implant Shell Materials.

BACKGROUND: Bacterial biofilms have been implicated with breast implant complications including capsular contracture and anaplastic large-cell lymphoma. The actual mechanisms for either are still under active investigation and are not clear. Due to their increased surface area, implants with textured surfaces may harbor greater biofilm loads than those with smooth surfaces. METHODS: Biofilm formation on the outer surface material was compared using implants with various surface areas and roughness, including Natrelle® (Smooth), SmoothSilk®/SilkSurface® (Silk), VelvetSurface ® (Velvet), Siltex®, and Biocell®. The roughness and surface area of each material were assessed using non-contact profilometry. Bacterial attachment (2 h) and biofilm formation (24 h) were evaluated for Staphylococcus epidermidis, Pseudomonas aeruginosa, and Ralstonia pickettii over nine independent experiments using a CDC biofilm reactor and viable plate counts (VPCs) as well as confocal scanning laser microscopy. VPCs of the textured implants were compared relative to the Smooth implant. RESULTS: Surface areas increased with roughness and were similar among the three least rough implants (Smooth, Silk, and Velvet) and among the roughest implants (Siltex and Biocell). Overall, VPC indicated there was significantly more bacterial attachment and biofilm formation on the Siltex and Biocell implants than the Silk or Velvet implants, although there were differences between species and time points. CSLM confirmed the formation of thicker biofilms on the implants with rougher surface textures. CONCLUSION: This in vitro study confirmed that implant surfaces with rougher texture, resulting in more surface area, harbored greater biofilm loads than those with smoother surfaces. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Association between gentamicin resistance and stress tolerance in water isolates of Ralstonia pickettii and R. mannitolilytica.

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.

Biosorption characteristics of a highly Mn(II)-resistant Ralstonia pickettii strain isolated from Mn ore.

Microorganisms play an important role in immobilizing and detoxifying excessive Mn; however, there is so far a lack of sufficient information concerning highly Mn(II)-tolerant bacteria. The present study was conducted to analyze the bio-sorption characteristics of a strain (HM8) isolated from manganese ore wastes. Analytical data from the 16S rDNA sequence determination showed that the species, HM8, had a 99% similarity to Ralstonia pickettii. Results from the designed physiological, biochemical and isothermal adsorption tests indicated that HM8 did not only grow well at a Mn(II) concentration level of 10,000 mg/L but also removed 1,002.83 mg/L of Mn(II) from the bulk solution of the culture, showing that the isolated strain possessed strong capabilities to tolerate and remove Mn(II). In the isothermal bio-sorption experiments performed to investigate the effects of relevant factors on Mn(II) sorption, the highest Mn(II) removal rate was obtained at the contact time 72 h, temperature 40°C, and pH 6.0, while the differences in both strain growth and Mn(II) removal rate between different inoculated HM8 doses were found to be insignificant within the tested range. Scanning electron microscopy showed that, under Mn(II) stress, HM8 cells appeared irregular and cracked, with apparent wrinkles on the surface. The peaks in the Fourier transform infrared spectra showed that hydroxyl and carboxyl groups were the main functional groups for Mn(II) adsorption. The experimental data supported the practical application of HM8 as a biological adsorbent for remediation of heavily Mn contaminated sites.

The Functional Influence of Breast Implant Outer Shell Morphology on Bacterial Attachment and Growth.

BACKGROUND: The introduction of texture to the outer shell of breast implants was aimed at increasing tissue incorporation and reducing capsular contracture. It has also been shown that textured surfaces promote a higher growth of bacteria and are linked to the development of breast implant-associated anaplastic large cell lymphoma. METHODS: The authors aimed to measure the surface area and surface roughness of 11 available implants. In addition, the authors aimed to subject these implant shells to an in vitro bacterial attachment assay with four bacterial pathogens (Staphylococcus epidermidis, S. aureus, Pseudomonas aeruginosa, and Ralstonia pickettii) and study the relationship among surface area, surface roughness, and bacterial growth. RESULTS: Surface area measurement showed grouping of implants into high, intermediate, low, and minimal. Surface roughness showed a correlation with surface area. The in vitro assay showed a significant linear relationship between surface area and bacterial attachment/growth. The high surface area/roughness implant texture grew significantly more bacteria at 24 hours, whereas the minimal surface area/roughness implant textures grew significantly fewer bacteria of all types at 24 hours. For implants with intermediate and low surface areas, some species differences were observed, indicating possible affinity of specific bacterial species to surface morphology. CONCLUSIONS: Implant shells should be reclassified using surface area/roughness into four categories (high, intermediate, low, and minimal). This classification is superior to the use of descriptive terms such as macrotexture, microtexture, and nanotexture, which are not well correlated with objective measurement and/or functional outcomes.

Preliminary Results of the Use of a Stabilized Hypochlorous Acid Solution in the Management of Ralstonia Pickettii Biofilm on Silicone Breast Implants.

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.

Intestinal Ralstonia pickettii augments glucose intolerance in obesity.

An altered intestinal microbiota composition has been implicated in the pathogenesis of metabolic disease including obesity and type 2 diabetes mellitus (T2DM). Low grade inflammation, potentially initiated by the intestinal microbiota, has been suggested to be a driving force in the development of insulin resistance in obesity. Here, we report that bacterial DNA is present in mesenteric adipose tissue of obese but otherwise healthy human subjects. Pyrosequencing of bacterial 16S rRNA genes revealed that DNA from the Gram-negative species Ralstonia was most prevalent. Interestingly, fecal abundance of Ralstonia pickettii was increased in obese subjects with pre-diabetes and T2DM. To assess if R. pickettii was causally involved in development of obesity and T2DM, we performed a proof-of-concept study in diet-induced obese (DIO) mice. Compared to vehicle-treated control mice, R. pickettii-treated DIO mice had reduced glucose tolerance. In addition, circulating levels of endotoxin were increased in R. pickettii-treated mice. In conclusion, this study suggests that intestinal Ralstonia is increased in obese human subjects with T2DM and reciprocally worsens glucose tolerance in DIO mice.

PVC-piping promotes growth of Ralstonia pickettii in dialysis water treatment facilities.

Biofilms forming inside dialysis water treatment systems are one of the main sources of microbiological contamination. Among the bacteria found in biofilms, Ralstonia pickettii is frequently encountered in dialysis water treatment systems and has been shown to develop extreme oligotrophic talents. In Austria, R. pickettii was exclusively detected in high numbers in dialysis water treatment facilities equipped with chlorinated polyvinyl chloride (PVC-C) piping. In this laboratory study it was shown that PVC-C effectively promotes growth of R. pickettii biofilms, while residual organic carbon in purified dialysis water is sufficient for promoting substantial growth of planktic R. pickettii. This provides evidence that PVC-C is an unsuitable material for piping in dialysis water treatment systems.

Ralstonia pickettii in environmental biotechnology: potential and applications.

Xenobiotic pollutants such as toluene and trichloroethylene are released into the environment by various industrial processes. Ralstonia pickettii possess significant biotechnological potential in the field of bioremediation and has demonstrated the ability to breakdown many of these toxic substances. Here, we provide a description of the major compounds that various strains of R. pickettii are capable of degrading and a brief review of their breakdown pathways and an argument for its use in bioremediation.