V L Santos

Publications (5)9.77 Total impact

• Source

  Available from: Patricia Moraes

  Article: Demulsifying properties of extracellular products and cells of Pseudomonas aeruginosa MSJ isolated from petroleum-contaminated soil.

  J O P A Coutinho, M P S Silva, P M Moraes, A S Monteiro, J C C Barcelos, E P Siqueira, V L Santos
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  ABSTRACT: A strain of Pseudomonas aeruginosa isolated from a site contaminated with refined oil products exhibited demulsification capabilities against Tween 80-Span 80 stabilized oil-in-water (O/W), Tween 80-stabilized water-in-oil (W/O) model emulsions (kerosene-water), and an industrial emulsion (Daido Dairoll PA-5A). GC-MS analysis confirmed the presence of fatty acids and carbohydrates in the extracellular biodemulsifier. The demulsifying activity of cells and culture supernatants was favored by growth in media containing 1% diesel oil. There was a correlation between culture age, de-emulsification and cellular hydrophobicity, and highest activities were observed for cells and supernatants from 96-h cultures. Activity increased with addition of up to 60mg cells or 300μL supernatant to emulsions. The activity was relatively stable at 20-40°C and to freezing, but was reduced by 69% by washing the cells with chloroform-methanol-water. This demulsifier has potential for application in biotreatment of emulsified oily wastewaters to promote recovery and/or degradation of oil.
  Bioresource technology 10/2012; 128C:646-654. · 4.25 Impact Factor
• Article: Identification and characterization of bioemulsifier-producing yeasts isolated from effluents of a dairy industry.

  A S Monteiro, M R Q Bonfim, V S Domingues, A Corrêa, E P Siqueira, C L Zani, V L Santos
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  ABSTRACT: New bioemulsifier-producing yeasts were isolated from the biological wastewater treatment plant of a dairy industry. Of the 31 bioemulsifier-producing strains, 12 showed emulsifying activity after 2months of incubation, with E(24) values ranging from 7% to 78%. However, only Trichosporon loubieri CLV20, Geotrichum sp. CLOA40, and T. montevideense CLOA70 exhibited high emulsion-stabilizing capacity, with E(24) values of 78%, 67%, and 66%, respectively. These isolates were shown to induce a strong emulsion stabilizing activity rather than the reduction of the interfacial tension. These strains exhibited similar growth rates in the exponential growth phase, with a clear acceleration after 24h and stabilization of the activity after 144h. Emulsification and stability properties of the bioemulsifiers were compared to those of commercial surfactants after the addition of NaCl and exposure to temperature of 100 degrees C. The compounds produced by the isolates appeared to be lipid-polysaccharide complexes. Gas chromatograph analysis of the lipidic fraction of the bioemulsifiers from CLV20, CLOA40, and CLOA70 shows the prevalence of (9Z,12Z)-octadeca-9,12-dienoic acid, in concentrations of 42.8%, 25.9%, and 49.8%, respectively. The carbohydrate composition, as determined by GC-MS of their alditol acetate derivatives, showed a predominance of mannose, galactose, xylose and arabinose.
  Bioresource technology 03/2010; 101(14):5186-93. · 4.25 Impact Factor
• Article: Degradation of phenol by Trichosporon sp. LE3 cells immobilized in alginate.

  V L Santos, N M Heilbuth, V R Linardi
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  ABSTRACT: The degradation of phenol by freely suspended cells of Trichosporon sp. LE3 and alginate-immobilized cells was studied in batch culture. The alginate concentration (2 or 4%) and the cross-linking salt used (BaCl2 or CaCl2) affected the rate and percentage of phenol degradation. The highest values were obtained for immobilized cells at 2% calcium alginate, although complete degradation of 15 and 18 mM phenol was not observed. When the cell concentrations in the assays were doubled, the 2% calcium alginate-immobilized cells were able to degrade up to 30 mM phenol in less than 120 hours, although the free cells did not completely degrade phenol at concentrations above 20 mM. The maximum phenol degradation rate was a strong function of initial phenol concentrations, being the highest values being observed for 20 mM phenol.
  Journal of Basic Microbiology 02/2001; 41(3-4):171-8. · 1.27 Impact Factor
• Article: Biodegradation of phenol by a filamentous fungi isolated from industrial effluents—identification and degradation potential

  V.L. Santos, Valter R. Linardi
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  ABSTRACT: Thirty filamentous fungal strains were isolated from effluents of a stainless steel industry (Minas Gerais, Brazil) and tested for phenol tolerance. Fifteen strains of the genera Fusarium sp., Aspergillus sp., Penicillium sp. and Graphium sp. tolerants up to 10 mM of phenol were selected and tested for their ability to degrade phenol. Phenol degradation was a function of strain, time of incubation and initial phenol concentration. FIB4, LEA5 and AE2 strains of Graphium sp. and FE11 of Fusarium sp. presented the highest percentage phenol degradation, with 75% degradation of 10 mM phenol in 168 h for FIB4. A higher starting cell density of Graphium sp. FIB4 lead to a decrease in the time needed for full phenol degradation and increased the phenol degradation rate. All strains exhibited activity of catechol 1,2-dioxygenase and phenol hydroxylase in free cell extracts obtained from cells grown on phenol, suggesting that catechol was oxidized by the ortho type of ring fission. These data reported demonstrate the prospect after the application of filamentous fungal strains in protecting the environment from phenol pollution.
  Process Biochemistry.
• Article: Identification and characterization of bioemulsifier-producing yeasts isolated from effluents of a dairy industry

  A.S. Monteiro, M.R.Q. Bonfim, V.S. Domingues, A. Corrêa, E.P. Siqueira, C.L. Zani, V.L. Santos
  [show abstract] [hide abstract]
  ABSTRACT: New bioemulsifier-producing yeasts were isolated from the biological wastewater treatment plant of a dairy industry. Of the 31 bioemulsifier-producing strains, 12 showed emulsifying activity after 2 months of incubation, with E24 values ranging from 7% to 78%. However, only Trichosporon loubieri CLV20, Geotrichum sp. CLOA40, and T. montevideense CLOA70 exhibited high emulsion-stabilizing capacity, with E24 values of 78%, 67%, and 66%, respectively. These isolates were shown to induce a strong emulsion stabilizing activity rather than the reduction of the interfacial tension. These strains exhibited similar growth rates in the exponential growth phase, with a clear acceleration after 24 h and stabilization of the activity after 144 h. Emulsification and stability properties of the bioemulsifiers were compared to those of commercial surfactants after the addition of NaCl and exposure to temperature of 100 °C. The compounds produced by the isolates appeared to be lipid–polysaccharide complexes. Gas chromatograph analysis of the lipidic fraction of the bioemulsifiers from CLV20, CLOA40, and CLOA70 shows the prevalence of (9Z,12Z)-octadeca-9,12-dienoic acid, in concentrations of 42.8%, 25.9%, and 49.8%, respectively. The carbohydrate composition, as determined by GC–MS of their alditol acetate derivatives, showed a predominance of mannose, galactose, xylose and arabinose.
  Bioresource Technology.