Study On Quorum Sensing In Acidithiobacillus Thiooxidans

Many species of bacteria apply a manner of intercellular communication known as quorum sensing(QS).QS is a population-dependent adaptive behavior of bacteria in the process of growing,which coordinates gene expression based on the density of cells.QS is regulated by small molecules termed autoinducers which are synthesized intracellularly and released into the surrounding environment.With the number of cells in a bacterial colony increase,so do the extracellular concentration of the autoinducers.The QS system of bacteria plays an important role in regulating gene expression and functional activity.The study show that quorum sensing signal system has been detected in Acidithiobacillus thiooxidans(A.thiooxidans)which can can produce AHL signal molecules.QS system of A.thiooxidans may be involved in attachment and biofilm formation on pentlandite.However,little is known on QS function in A.thiooxidans.In this study,a strain of A.thiooxidans was isolated and identified in morphological.The results showed that the A.thiooxidans was the gram-negative chemolithotrophic obligate bacterium,which obtained energy by oxidizing the sulfur and released H+.The pH of medium did not decrease anymore,indicating that A.thiooxidans had completely oxidized the sulfur.Acylated homoserine lactone(AHL)is the most common class of autoinducer used by Gram-negative bacteria,which can be detected simply by bioassay.In this study,wu used Agrobacterium tumefaciens NTL4(pZLR4)as the indicator bacterium to detect the extract of A.thiooxidans medium,showing that A.thiooxidans produced AHL signal molecules.It is proved that there is LuxR / I signal system in A.thiooxidans.Based on the research of laboratory,three QS signal molecule analogues and furanone C-30 were synthesized,which structures were characterized by 1H NMR ?13CNMR ?ESI-MS.After treatment with biofilm inhibitors,the results showed that the biofilm formation of A.thiooxidans was inhibited.It is feasible to control acid mine drainage through the inhibition of bioleaching bacteria biofilm formation by 4 biofilm inhibitors.This study provides a promising strategy to control AMD.