Ciprofloxacin For Thermophilic Streptococcus Grx02 Physiological Function And The Influence Of Protein Expression Research

Residue antibiotic was a common phenomenon in animal food materials (such as milk and meat), so when they were used for fermentation, the fermentation strains would be under the stress. At the same time, when human used antibiotics to cure diseases, Lactic acid bacteria would also be under the stress. Under the low concentration of antibiotics, probiotics would produce a series of physiological effects to prevent harmful substances into the cells, and this would affect physiological functions and metabolic pathways. Whether there was any harmful metabolism produced and what effects on fermentation products would produce haven’t been reported at present. Therefore, this paper studies the influence of trace ciprofloxacin on physiological function and protein expression of S.thermophilus grxO2, so as to provide references for further research on mechanisms and for reasonable use.(1) The minimum antibacterial concentration (MIC) of ciprofloxacin to S.thermophilus grx02was3.89μg/mL, it showed that S.thermophilus grx02was moderate sensitive to ciprofloxacin.(2) Microscopic morphological of S. thermophilus grx02in the stress treatment of different concentrations of trace ciprofloxacin was studied. The result showed that there was no obvious change between control group and the different sub-inhibitory concentration of ciprofloxacin, the colony morphology of S. thermophilus grx02was a long chain by optical microscope. It was confirm that trace ciprofloxacin had no impact on the colony morphology of S. thermophilus grxO2. Through transmission electron microscopy, it was found that the shape of S. thermophilus grx02was oval in control group, while shape in stress of ciprofloxacin was significantly shorter, and the higher the drug concentration was, the more obvious the semi-oval was. The capsule was thick and loose in control group, with the rise of the drug concentration, the capsule of S. thermophilus grx02was thinning and dense. It was confirm that trace ciprofloxacin had great impact on the cell morphology and capsule of S. thermophilus grx02.(3) By comparing the growth and fermentation properties of the strains at different concentration of trace ciprofloxacin stress treated. We found that:the logarithmic growth phase of strains of control group,1/10MIC group and1/50MIC group was6h,while the t logarithmic growth phase of strains of1/2MIC was8h. The bacterial growth rate and acid production rate were respectively decreased by24.89%and53.29%. It could be saw that trace amount of ciprofloxacin had significantly influenced the growth and acid production on S.thermophilus grx02.(4) Different concentrations of trace ciprofloxacin treatment of fermented milk and the control group were compared and found that the changes of pH value of the fermented milk, titratable acidity and hardness were not significant,it indicats that antibiotic residues has no significant impact on the pH value of fermented milk, titratable acidity and hardness. The viscosity of the fermented milk of the drug group (5037.3-5302.0) Pa·s with the control group (6032Pa·s) compared to the significantly reduced. The drug group syneresis39.40%-44.33%, significantly higher compared with the control group (22.46%). It indicats that antibiotic residues reduce the stability of fermented milk.(5) By comparing the fermented milk treated in different concentrations of ciprofloxacin and control groups, we found the group treated with1/10MIC ciprofloxacin which is not thick showed a small amount of syneresis, and score of organization was significantly lower than other groups. It’s sensory identification score was84.1±1.5that was significantly lower than other groups.The sensory identification score of the group treated with1/30MIC ciprofloxacin was88.5±1.7,which was significantly higher than1/10MIC group, but significantly lower than the control group (90.1±1.6) and1/50MIC group (90.2±1.2).Meanwhile, The sensory identification score of the group treated with1/50MIC ciprofloxacin showed little difference with the control group. The results show high concentrations of ciprofloxacin can effect on sensory quality of the fermented milk with S.thermophilusgrx02while when the concentration is low, the effect wasn’t significant.(6) Volatile flavor compounds in fermented milk under the stress of the different trace concentrations of ciprofloxacin were measured by GC-MS. It was founded that the total mass fraction of volatile flavor compounds in fermented milk significantly reduced, especially the total mass fraction of diacetyl flavor substances is significantly reduced, and the main flavor substances2,3-butanedione quality scores were significantly lower.(7) The preparation of bacterial protein of S.thermophihis grx02was extracted by grinded in liquid nitrogen-TCA/acetone-urea/thiourea/TBP pyrolysis,2-DE was used to separate the prepared protein, and we could get the maps of good effects, well repeatability and high resolution of S. thermophilus grx02, about298±7points of protein were detected, and this makes preparations for further study.(8) This study compares the proteins of S.thermophilus grxO2in the control group and the group with1/2MIC ciprofloxacin, more than300protein points were detected,27of them were more than two times in differently expression by T test,5were raised expression points,5were down-regulated expression points,12points didn’t appear in samples that were treated by ciprofloxacin, and5points were induced by ciprofloxacin.