Effect Of Candida Albicans On The Growth And Drug Resistance Of Enterococcus Faecalis

Objectives:The study aims to investigate the interaction between Enterococcus faecalis and Candida albicans and their impact on strain resistance at the single-cell scale.Then build a universal research system for the growth interaction and drug resistance research of complex structures such as multibacteria,in situ flora and even biofilms.Last but not least,lay the foundation for the personalized medicine and precise medicine.Methods:（1）After different concentrations of heavy water acted on Enterococcus faecalis ATCC29212,the growth changes of Enterococcus faecalis cells were measured(value of OD₆₀₀),while the metabolic activity of Enterococcus faecalis was measured at the same time（the C-D ratio was obtained by collecting single-cell Raman spectra）.By comparing the two evaluation systems based on growth and metabolism,the sensitivity and universality of Raman technology for evaluating bacterial metabolic activity were determined.（2）After different concentrations of Candida albicans ATCC10231 acted on Enterococcus faecalis ATCC29212,the changes of the growth state of Enterococcus faecalis cells(value of OD₆₀₀)were measured,while the metabolic activity of Enterococcus faecalis was measured at the same time（C-D ratio was obtained by collecting single-cell Raman spectra）.On this basis,the effects of Candida albicans on the Enterococcus faecalis’growth and metabolic activity were investigated.（3）Using heavy-water Raman technology,with the minimum inhibitory concentration of metabolic activity（MIC-MA）as the reference index,we explored the effect of commonly used oral root canal irrigation solution on the metabolic activity of Enterococcus faecalis.Comparing the MIC-MA of root canal irrigation solution on Enterococcus faecalis after different concentrations of Candida albicans,we explore the effect of Candida albicans on the drug resistance of Enterococcus faecalis.（4）To explore the effects of Candida albicans on the gene function and metabolic pathways of Enterococcus faecalis,we expounded the differences in gene expression and function of Enterococcus faecalis and the changes in metabolic responses at the single-cell level after exposure to Candida albicans.Results:（1）The growth of Enterococcus faecalis was not inhibited in 30%heavy water environment（p>0.05）,but was significantly inhibited in 40%heavy water environment（p<0.05）;Enterococcus faecalis actively metabolized heavy water in physiological state,this is manifested in the form of a heavy water peak in a specific region in the Raman spectrum,and the heavy water peak area is positively correlated with the heavy water concentration（R²=0.96,p<0.01）.Therefore,the heavy water peak can be used to characterize the metabolic activity of cells.To sum up,in this experiment,the heavy water concentration that does not affect the growth of the strain and can produce an obvious heavy water peak.Therefore,30%heavy water was selected as the default heavy water concentration for subsequent studies.（2）The study found that Candida albicans not only inhibited the growth of Enterococcus faecalis,but with the increase of Candida albicans concentration,the inhibitory effect became more obvious（p<0.05）.Candida albicans also inhibited the metabolic activity of Enterococcus faecalis,with the increase of the concentration,the inhibitory effect became more obvious（p<0.05）.Through the observation of"fingerprints"of nucleic acids,proteins and lipids by Raman spectroscopy,it was found that the biological activity of Enterococcus faecalis was significantly reduced after the action of Candida albicans.The interacted E.faecalis was significantly different from the wild strain.（3）After the interaction of Candida albicans,the drug concentration that required to inhibit the metabolic activity of Enterococcus faecalis decreased,which was manifested as the decrease of the MIC-MA of root canal irrigation on Enterococcus faecalis（p<0.05）.It is suggested that the drug resistance of Enterococcus faecalis is reduced after the interaction with C.albicans.Moreover,with the increased concentration of Candida albicans,the MIC-MA of root canal irrigation acting on E.faecalis showed a decreasing trend（p<0.05）.（4）By analyzing the research data of transcriptomics,it was found that the effect of Candida albicans inhibited the arginine metabolism,quorum sensing and intercellular communication of Enterococcus faecalis,which is provided a reasonable explanation of the situation that the growth and metabolism of Enterococcus faecalis were inhibited after the interaction of Candida albicans.Conclusions:（1）The subject established a universal research system for evaluating the metabolic activity of pathogenic bacteria based on heavy water Raman technology.（2）By measuring the changes of pathogen growth(value of OD₆₀₀)and metabolism（C-D ratio value）,it was confirmed that after the interaction between Candida albicans and Enterococcus faecalis,the growth and metabolic activity of Enterococcus faecalis were inhibited.The higher the concentration of C.albicans,the higher the degree of inhibition.（3）Furtherly,the study evaluated the effect of Candida albicans on the drug resistance of Enterococcus faecalis,and confirmed that the drug resistance of Enterococcus faecalis decreased after the effect of Candida albicans.（4）Finally,the analysis explains how the interaction regulates the changes of E.faecallis,and illustrates the negative effects of C.albicans on the gene expression function and metabolic response of E.faecalis.