The Application Of Light Signals In The Differentiation Of Microorganisms And The Study Of Antimicrobial Activity Of Medicine

It is known that light signals through light absorption,light scattering,fluorescence and phosphorescence,could be qualitatively and quantitatively applied.In this contribution,light scattering signals obtained from fluorescence spectrophotometer were applied to differentiate microorganisms,and use the fluorescent signals from flow cytometer to study the antimicrobial activity of modified cefotaxime sodium and cellular prion protein(PrP~c).The specific content studied show as follows:1,Light scattering signals for differentiating microorganismsLight scattering signals occurred in the interaction process of light photon and particles which are related to the size,the shape and the refraction index of the particles.With a common fluorescence spectrophotometer that equipped polarizer by keeping excitation and emission wavelengths equal,to scan the excitation and emission monochromator,we obtained the light scattering spectra to study the two different strain of Escherichia coli(E.coli):E.coli(DH5α)and E.coli(BL-21).The results showed that polarized synchronous light scattering can differentiate this two microorganisms,with high simplicity,sensitivity and speediness.2,The fluorescent signals from flow cytometer to study the antimicrobial activity of antimicrobial medicine Flow cytometer can not only detect the light scattering signals,but also can detect the fluorescent signals of a sample,Thus,we use flow cytometer to study the antimicrobial activity of the antimicrobial medicine.(1)Modified the amino at 7-side chain of cefotaxime sodium with chitosan through glutaric dialdehyde,By incubating S.aureus with cefotaxime sodium or with the cefotaxime sodium which modified with chitosan through glutaric dialdehyde respectively,Dyeing with propidium iodide and detecting the change of fluorescent intensity of the sample,We found that the antimicrobial activity of cefotaxime sodium to S.aureus is enhanced after modification.Further investigation on the influence of temperature on the antimicrobial activity of the modified cefotaxime sodium showed that cefotaxime sodium modified at 60℃has the strongest antimicrobial activity.Investigation on the action of the modified cefotaxime sodium by incubating with S.aureus at different concentration and different incubation time cound provide some basis for clinical drug administration.(2)Investigation on the antimicrobial function of PrP~c to five randomly choosed bacteria, including Staphylococcus aureus(S.aureus),Bacillus subtilis(B.subtilis),Bacillus megaterium(B. megaterium),Bacillus thuringiensis(B.thuringiensis)and Escherichia coli(BL-21)[E.coli(BL-21)] showed that PrP~c has visible antimicrobial effect on S.aureus and B.subtilis,but no effect on the other three bacteria,B.megaterium,B.thuringiensis and E.coli(BL-21).The results will provide some experimental data for the exploring of aitimicrobial peptide and for the clarifying the physiological function of PrP~c.