ABSTRACT
Objective To investigate the periodic variety at the germ form, quantity, flagellar expression and activity of breath enzyme etc during the swarming motility of Proteus mirabilis (PM). Methods The 2, 3, 5-tetraphenyltetrazolium chloride (TTC), as indictor of breath enzyme, was added to the culture medium. Electronic microscope was adopted to observe the germ form and flagellar. Quantity of PM was measured by turbidimetry. Results During the PM growth and migration at LB medium, the germ quantity reduced and form changed from short and small to long and thin, flagellar got more and breath enzyme turned into inactive. Conclusion At the LB medium, PM in growth process appeared varieties in length of germ body, flagellar quantity and germs density, etc. PM in solid medium appeared wave motility, resulting from many factors including the environment, the signal transduction in cells and the density of germ.
ABSTRACT
Objective To study the technique of transposon mutagenesis involving the use of Mini-Tn5 on a suicide plasmid for Citrobacter freundii (C. freundii). Methods A conjugation method was used in transposon mutagenesis. The stability of exconjugants was confirmed by series passages under nonselective condition. Detection of anti-ampicillin resistance and purification of the plasmid were conducted for excluding the possibility of plasmid-encoded antibiotic resistance. All exconjugants were screened for auxotrophic mutants and swarming motility mutants. Results Analysis of the generated exconjugants indicated that Mini-Tn5 Km was transposed in C. freundii at a high frequency (ca. 9.2?10 -6). The mutants were stable and retained the transposon-encoded antibiotic resistance after incubation for three passages under nonselective condition. The frequency of auxotrophic mutants in the population confirmed that the insertion of the transposon was random and the C. freundii chromosome did not contain significant insertional hot spots of transposition. No extrachromosomal plasmid DNA was found. Conclusion Transposon mutagenesis of Mini-Tn5 is a suitable technique for the study of differentiation in C. freundii.
ABSTRACT
A strain of P. Aeruginosa,which was seperated from clinical environment ,shows a special characteristic . It keeps normal short rod shape when cultured at 37℃,however,it forms filament without pyocyanin producing when cultured at 25℃ overnight. The filaments will divide and form short rods,simultaneously,produce pyocyanin when culture time is prolonged to over 72h or culture temperature is raised to 37℃. The preliminary study indicates that this phenomenin has nothing to do with nutritive conditions and could the inbluenced by inoculating density and irradiating with ultraviolet rays The absence of pyocyanin was not the cause of filamentous formation by the test results.
ABSTRACT
Objective To investigate the correlation between bacterial cryptic growth cell(CGC)and irritable bowel syndrome(IBS).Methods The techniques of micro-culture and morphological observation were employed in examination of the CGC in feces specimens of patients suffering from IBS.Furthermore,the animal monitoring tests was applied in the aspects of CGC formation under inducing factors and colonization at local intestinal mucus.Results A great deal of CGC could be observed in the feces of IBS patients and exhibited continuous proliferation characteristics regardless of using or not using antibiotics.And the CGC in feces showed auto-lysis features when the patients suffered from the disease.The monitoring tests demonstrated that the antibiotics often used presently to IBS patients could induce the formation and colonization of intestinal bacterial CGC.Conclusion Based on the experimental and clinical data,we presume that there is a correlation between intestinal bacterial CGC and IBS.