Comparative Study Of The Growth Curves Of B. subtilis, K. pneumoniae, C. xerosis And E. coli Bacteria In Medium Containi
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Comparative Study Of The Growth Curves Of B. subtilis, K. pneumoniae, C. xerosis And E. coli Bacteria In Medium Containing Nanometric Silicon Particles Lilyanna Péreza, Marjorie Floresa, J. Avalosa, L. San Miguelb, O. Restob, L. Fonsecab; School of Science, Technology, and Health, Universidad Metropolitana, San Juan, PR; b Department of Physics, Universidad de Puerto Rico, San Juan, PR a
ABSTRACT
In this research nanometric particles from luminescent (625nm) porous silicon film were synthesized. This particles were later inoculated in bacterial strains of B. subtilis (BSi) and K. pneumoniae (KSi). A comparison of the behavior of their growth curve and the ones reported for C. xerosis (XSi) and E. coli (ESi) in presence of silicon nanoparticles is presented. The growth curve of BSi, as well as the KSi, present changes compared to their standard curves. The BSi growth curve grows below the standard curve after the fifth hour, while in the KSi this happens after the eighth hour. Based on our preliminary findings we can speculate that at this point in time a critical population is present, and this may give rise to the possible incorporation of the silicon particles by the bacteria, or a possible pleomorphism inhibits reproduction.The stationary region, in both cases, takes place sooner than in the standard curve. No significant oscillations are observed in any case, which differs form the XSi curve, were oscillations of intervals of almost 1 hour were reported. In addition, these curves have a different behavior when compared to the ESi growth curve, in which no significant differences between the standard and the particle containing sample were reported.
INTRODUCTION
Biosensors have been developed to detect a variety of biomolecular complexes, including oligonucleotides [1-4], antibody-antigen interactions [5, 6], hormone-receptor interactions [7], enzyme-substrate interactions [8, 9] and lectin-glycoprotein interactions [10]. Since the discovery of light emission, porous silicon (PSi) has been shown to serve as the platform for a broad range of applications, such as sensing and bioanalysis, utilizing a number of different signal transduction schemes. For instance, Sailor and Harper demonstrated the sensitivity of the photoluminescence (PL) efficiency with respect to NO concentration in Ar, rendering a PSi useful as a chemo sensor for this compound and other gases [11]. By functionalizing oxidized porous silicon surfaces with biological molecules such as biotin and single-stranded DNA, porous silicon can act as an effective optical interferometric biosensor for quantifying streptavidin and complementary strand of DNA, respectively, as shown by Sailor and Ghadiri [12]. Also Buriak and Siuzdak discovered that PSi can replace the organic matrix in MALDI (matrix-assisted laser desorption ionization) mass spectrometry, which allows for high sensitivity and a remarkable salt tolerance, with the added advantage of integration of porous Silicon (PSi) silicon wafer-based micro fluidic devices for on-chip analysis [
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