The effect of various amino acids as nitrogen source on biofilm formation of Aeromans spp.

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2012-12

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For generations, scientists have studied microorganisms in their planktonic form to discover basic information about microorganisms and to perform more detailed experiments, including testing the effectiveness of antimicrobial agents. The term biofilm was defined and the concept of the biofilm was formulated very recently. Therefore, relatively little is known about biofilm growth in otherwise well-characterized microbial species. This would be a minor issue if microbial growth within a biofilm was similar to planktonic growth, but this is not the case. The difference in microbial growth within a biofilm compared to that of planktonic bacteria is immense. The perspective on uses for and treatments of biofilms are changing as we learn more about microorganisms within biofilms. For this reason, it is important to further explore the bacterial biofilm.

A correlation between biofilm growth and nutrient environment has previously been observed but needs clarification. In this thesis project, I have isolated an Aeromonas environmental strain from the playa lake in Maxey Park in Lubbock, TX and analyzed the effect of varied nutrients, specifically nitrogen source, on biofilm formation of the environmental Aeromonas strain, comparing its biofilm formation capabilities to those of a reference Aeromonas hydrophila ATCC 7965 strain with the crystal violet assay. I have also assessed the accuracy of the crystal violet assay in quantifying cell concentrations by observing crystal violet absorbance of planktonic Aeromonas cells. Both the environmental Aeromonas isolate and the reference ATCC 7965 Aeromonas strain formed thicker biofilms in the presence of rich nutrient environments as compared to the more dilute nutrient environments. Our data suggests that Aeromonas ATCC 7965 is a more effective biofilm-former than the environmental isolate. It also reveals extreme variance in biofilm formation of both Aeromonas strains observed in the presence of different amino acids as nitrogen source. Finally, our assessment of the accuracy of the crystal violet assay and the calibration curve demonstrated the limitations of a common technique used in preliminary biofilm research.

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