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1.  Disruption of Microbial Biofilms by an Extracellular Protein Isolated from Epibiotic Tropical Marine Strain of Bacillus licheniformis 
PLoS ONE  2013;8(5):e64501.
Marine epibiotic bacteria produce bioactive compounds effective against microbial biofilms. The study examines antibiofilm ability of a protein obtained from a tropical marine strain of Bacillus licheniformis D1.
Methodology/Principal Findings
B. licheniformis strain D1 isolated from the surface of green mussel, Perna viridis showed antimicrobial activity against pathogenic Candida albicans BH, Pseudomonas aeruginosa PAO1 and biofouling Bacillus pumilus TiO1 cultures. The antimicrobial activity was lost after treatment with trypsin and proteinase K. The protein was purified by ultrafiltration and size-exclusion chromatography. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and matrix assisted laser desorption/ionization-time of flight (MALDI-TOF) analysis revealed the antimicrobial agent to be a 14 kDa protein designated as BL-DZ1. The protein was stable at 75°C for 30 min and over a pH range of 3.0 to 11.0. The sequence alignment of the MALDI-fingerprint showed homology with the NCBI entry for a hypothetical protein (BL00275) derived from B. licheniformis ATCC 14580 with the accession number gi52082584. The protein showed minimum inhibitory concentration (MIC) value of 1.6 µg/ml against C. albicans. Against both P. aeruginosa and B. pumilus the MIC was 3.12 µg/ml. The protein inhibited microbial growth, decreased biofilm formation and dispersed pre-formed biofilms of the representative cultures in polystyrene microtiter plates and on glass surfaces.
We isolated a protein from a tropical marine strain of B. licheniformis, assigned a function to the hypothetical protein entry in the NCBI database and described its application as a potential antibiofilm agent.
PMCID: PMC3655075  PMID: 23691235
2.  Disruption of Yarrowia lipolytica biofilms by rhamnolipid biosurfactant 
Aquatic Biosystems  2012;8:17.
Yarrowia lipolytica is an ascomycetous dimorphic fungus that exhibits biofilm mode of growth. Earlier work has shown that biosurfactants such as rhamnolipids are efficient dispersants of bacterial biofilms. However, their effectiveness against fungal biofilms (particularly Y. lipolytica) has not been investigated. The aim of this study was to determine the effect of rhamnolipid on a biofilm forming strain of Y. lipolytica. Two chemical surfactants, cetyl-trimethyl ammonium bromide (CTAB) and sodium dodecyl sulphate (SDS) were used as controls for comparison.
The methylene blue dye exclusion assay indicated an increase in fungal cell permeability after rhamnolipid treatment. Microtiter plate assay showed that the surfactant coating decreased Y. lipolytica biofilm formation by 50%. Rhamnolipid treatment disrupted pre-formed biofilms in a more effective manner than the other two surfactants. Confocal laser scanning microscopic studies showed that biofilm formation onto glass surfaces was decreased by 67% after sub-minimum inhibitory concentration (sub-MIC) treatment with rhamnolipids. The disruption of biofilms after rhamnolipid treatment was significant (P<0.05) when compared to SDS and CTAB.
The results indicate a potential application of the biological surfactant to disrupt Y. lipolytica biofilms.
PMCID: PMC3445841  PMID: 22839701
Biofilm; Biosurfactant; CTAB; Rhamnolipid; SDS; Yarrowia lipolytica

Results 1-2 (2)