Mathematical Modeling And Numerical Simulation Of Quorum Sensing For Bacterial Biofilm

An extremely complex,highly organized and systematized microbial communities,which is attached to the carrier surface,is called a biofilm.Existing extensively in the natural and industrial environment,biofilms have affected the life and health of human beings.Quorum sensing is a peculiar information exchange system of bacterial biofilms,which participates in regulating various habits and physiological processes of bacteria.It is benefit for bacteria to adapt to the external surroundings.For quite a long time,the information exchange among bacterial biofilms have been neglected.Therefore,it is vital for the study of bacterial biofilms to explore the quorum sensing process of biofilms.This paper mainly focuses on the following points:First,the biofilm model is established,and is simulated by Fluent and MATLAB software to investigate the influence of the external fluid velocity on quorum sensing.It can be found that high biofilm fluid velocity greatly prevents the bacterial growth and has adverse effects on the quorum sensing process,while low flow velocity has little effect on quorum sensing and the error is big.Therefore,a medium flow velocity is selected as the biofilm fluid velocity.Second,the mathematical model of quorum sensing process based on ordinary differential equations is established,and the model is simulated by MATLAB software.The results indicate that before the initiation of quorum sensing process,the bacterial biomass is mainly constituted by down-regulated bacteria biomass,and the up-regulated bacteria biomass and signal molecules are almost zero.As the down-regulated bacteria translate to up-regulated bacteria,the concentration of signal molecules increases gradually and the quorum sensing is induced.Last,the mathematical model based on partial differential equations is established to research the quorum sensing process of complicated conditions.The model is simulated by MATLAB software.The results show that before quorum sensing initiation,the nutrient consumption rate of bacterial biofilms is slow.Down-regulated bacteria account for the majority of bacteria biomass,and the concentration of up-regulated bacteria and signal molecules are extremely low.With the transformation of the bacteria biomass,the nutrient consumption rate and the concentration of up-regulated bacteria increases dramatically.In addition,the secretion volume of quorum sensing signal molecules increases gradually,and the concentration of signal molecules increases.When the concentration reaches the threshold,biofilms steps into the quorum sensing process.