Characterization of Stenotrophomonas acidaminiphila NCW-702 biofilm for implication in the degradation of polycyclic aromatic hydrocarbons.

AIMS: Biofilm formation and polycyclic aromatic hydrocarbons (PAHs) degradation by a marine bacterium Stenotrophomonas acidaminihila NCW-702 was investigated. METHODS AND RESULTS: The biofilm structure was studied by confocal laser scanning microscopy (CLSM). Both planktonic and biofilm cultures were used for PAHs (phenanthrene and pyrene) degradation. In 7 days, Sten. acidaminiphila biofilm culture efficiently degraded 71·1 ± 3·1% and 40·2 ± 2·4% of phenanthrene and pyrene, respectively, whereas 38·7 ± 2·5% of phenanthrene and 29·7 ± 1% of pyrene degradation was observed in planktonic culture. The presence of phenolic intermediates in the culture supernatant during degradation process was evaluated by Folin-Ciocalteu reagent. The average thickness and diffusion distance of Sten. acidaminiphila NCW-702 biofilm was found to be 23·94 ± 2·62 µm and 2·68 ± 0·7 µm, respectively. Bacterial biofilms have numerous metabolic features that aid in the degradation of hydrophobic organic pollutants. CONCLUSIONS: Biofilm of Sten. acidaminiphila NCW-702 was able to degrade PAHs more efficiently as compared to planktonic cells. The findings support the efficacy of biofilms over planktonic culture in bioremediation applications. SIGNIFICANCE AND IMPACT OF THE STUDY: The study provides a constructive application of bacterial biofilms for the bioremediation of hydrophobic organic contaminants. The biofilm mode remediation process has the advantage of reusability of bacterial biomass and is also a low cost process as compared to cell immobilization techniques.

Bacterial biofilm diversity in contact lens-related disease: emerging role of Achromobacter, Stenotrophomonas, and Delftia.

PURPOSE: Multi-species biofilms associated with contact lens cases and lenses can predispose individuals to contact lens-related inflammatory complications. Our study used culture-independent methods to assess the relationship between the severity of contact lens-related disease and bacteria residing in biofilms of contact lens cases and lenses. METHODS: Contact lens cases and lenses from 28 patients referred to the West Virginia University Eye Institute and diagnosed as having mild keratitis, keratitis with focal infiltrates, or corneal ulcers were processed and evaluated for bacterial composition based on 16S ribosomal RNA gene sequencing. Cases and lenses from nine asymptomatic contact lens wearers were processed in a manner similar to controls. Relationships between disease severity, bacterial types, and bacterial diversity were evaluated statistically. RESULTS: Disease severity and presenting visual acuity correlated with an increase in the diversity of bacterial types isolated from contact lens cases. A significant difference also was observed in the number of bacterial types associated with the three clinical groups. Achromobacter, Stenotrophomonas, and Delftia were prevalent in all disease groups, and Achromobacter and Stenotrophomonas were present in one asymptomatic control. Scanning electron microscopy revealed that Achromobacter and Stenotrophomonas formed a biofilm on the surface of contact lenses. CONCLUSIONS: Culture-independent methods identified an association between disease severity and bacterial diversity in biofilms isolated from cases and lenses of patients with contact lens-related corneal disease. Achromobacter, Stenotrophomonas, and Delftia were predominant bacteria identified in our study, drawing attention to their emerging role in contact lens-related disease.

[Isolation, identification and phylogenetic analysis of a pathogenic bacterium in channel catfish].

A pathogenic bacterium (CCF00024) was isolated from the kidney and liver of the diseased channel catfish with acute epidemic disease. Artificial infection proved that the bacterium was the pathogen of the disease. Its morphological, physiological, biochemical characteristics and 16S rDNA sequence analysis were studied. The isolated strain is an aerobic, non-fermentative bacterium. The bacteria are gram negative, rods, with polar multi-flagella; Oxidase-negative, methyl-red-negative, lysine decarboxylase-positive, DNAase-positive, urease-positive, lipase-positive and protease-positive. The bacteria can't utilize most of sugars with production of acid, except maltose and mannose. A phylogenetic tree was constructed by comparing the 16S rDNA sequence of the isolated strain (GenBank accession number AY970826) with other relative bacteria species in the RDP and GenBank databases. In the phylogenetic tree CCF00024, Stenotrophomonas maltophilia 13637T, Stenotrophomonas maltophilia MG958T, and Stenotrophomonas maltophilia M5-1 constitute a branch. The similarity value between strain CCF00024 and those 5 strains Stenotrophomonas maltophilia are 99.4%-99.6%. According to morphological, physiological, biochemical characteristics and phylogenetic analysis, the isolated strain (CCF00024) is identified as Stenotrophomonas maltophilia.

Weakening effect of cell permeabilizers on gram-negative bacteria causing biodeterioration.

Gram-negative bacteria play an important role in the formation and stabilization of biofilm structures on stone surfaces. Therefore, the control of growth of gram-negative bacteria offers a way to diminish biodeterioration of stone materials. The effect of potential permeabilizers on the outer membrane (OM) properties of gram-negative bacteria was investigated and further characterized. In addition, efficacy of the agents in enhancing the activity of a biocide (benzalkonium chloride) was assessed. EDTA, polyethylenimine (PEI), and succimer (meso-2,3-dimercaptosuccinic) were shown to be efficient permeabilizers of the members of Pseudomonas and Stenotrophomonas genera, as indicated by an increase in the uptake of a hydrophobic probe (1-N-phenylnaphthylamine) and sensitization to hydrophobic antibiotics. Visualization of Pseudomonas cells treated with EDTA or PEI by atomic force microscopy revealed damage in the outer membrane structure. PEI especially increased the surface area and bulges of the cells. Topographic images of EDTA-treated cells were compatible with events assigned for the effect of EDTA on outer membranes, i.e., release of lipopolysaccharide and disintegration of OM structure. In addition, the effect of EDTA treatment was visualized in phase-contrast images as large areas with varying hydrophilicity on cell surfaces. In liquid culture tests, EDTA and PEI supplementation enhanced the activity of benzalkonium chloride toward the target strains. Use of permeabilizers in biocide formulations would enable the use of decreased concentrations of the active biocide ingredient, thereby providing environmentally friendlier products.

Analysis of TNT (2,4,6-trinitrotoluene)-inducible cellular responses and stress shock proteome in Stenotrophomonas sp. OK-5.

In this study, the cellular responses of Stenotrophomonas sp. OK-5 to explosive 2,4,6-trinitrotoluene (TNT) have been extensively analyzed. The stress shock proteins, which might contribute to enhancing cellular resistance to TNT-mediated toxicity, were induced at different concentrations of TNT used as a substrate for cell culture of Stenotrophomonas sp. OK-5 capable of utilizing TNT. Proteomic analysis for 2-DE of soluble protein fractions from the culture of OK-5 exposed to TNT demonstrated approximately 300 spots on the silver-stained gel ranging from pH 3 to pH 10. Among them, 10 spots significantly induced and expressed in response to TNT were selected and analyzed. As the result of internal amino acid sequencing with ESI-Q TOF mass spectrometry, TNT-mediated stress shock proteins such as DnaK, OmpW, and OsmC were identified and characterized. Survival of strain OK-5 was periodically monitored in the presence of different concentrations of TNT along with the production of the stress shock proteins. Cells of strain OK-5 pre-exposed to TNT had in improved survival tolerance. Analysis of total cellular fatty acids in strain OK-5 suggested that several saturated or unsaturated fatty acids might increase or decrease under TNT-mediated stress condition. Scanning electron microscopy of cells treated with 0.8 mM TNT for 12 h revealed irregular rod shapes with wrinkled surfaces.