Asymmetric Cell Division Of Rhodococcus Sp. R04 And Its Division Inhibition Under Biphenyl Stress

Cell growth and division are fundamental to all life processes and contribute to the morphological diversity of prokaryotes.To study the division of Rhodococcus sp.R04 cells and the effect of biphenyl on cellular morphology and division,we used fluorescence microscopy,scanning electron microscopy,and transmission electron microscopy to analyse the division of R.R04 cells cultured with different conditions.The results showed that R.R04 exhibits asymmetric(approximately 70%)and symmetric division(approximately 30%),and the culture conditions did not affect asymmetric division.The septum was located on the center to the poles,with some clustering at 30% and 50% of the cell length.R.R04 can degrade biphenyl,but its division would be inhibited by biphenyl.Microscopic observation showed that filaments were formed in mid-log phase R.R04 cells with biphenyl,and the cells exhibited abnormal division.As the culture time was prolonged,the cells finally restored normal division in the stationary phase.It revealed that Biphenyl/polychlorinated biphenyl(PCB)has a strong effect on the reproduction and growth of R.R04,but this effect can be antagonized by R.R04,which can self-repair and restore to normal division.Transcriptomics analysis indicated that the protein RHOGL008438 of Rhodococcus sp.R04 may be related to cell division.The heterologous expression of RHOGL008438 in Escherichia coli BL21 was performed to find out its physiological function on cellular morphology by fluorescence microscope.Results showed that the filamentous cells were formed.The results revealed that RHOGL008438 inhibited the formation of septum of E.coli,and confirmed it played a significant role in cell division.RHOGL008438 was then identified as cell-division-related protein FtsZ by sequence homology analysis.Live cell time-lapse imaging of R.R04 cells on the agarose pad showed asymmetric constriction and division to generate a short cell and a long cell.Fluorescence micrograph of R.R04 cells under FITC-Vanco showed that the poles of the cells were fluorescent,indicatingthat R.R04 cells were polar growth.The determination of FtsZ protein and polar growth of R.R04 cells were of great significance for the further study of its division mechanism.