Effects of heterologous genome microinjection on the enlargement of Enterococcus faecalis protoplasts

The lactic acid bacterium Enterococcus faecalis genomic DNA and seven phylogenetically distant bacterial genomic DNAs were microinjected into 126 enlarged protoplasts of E. faecalis. After the microinjection, a time-lapse observation was performed on how the cells enlarged. Most cells did not stop enlarging. The enlargement patterns were compared with the enlargement of E. faecalis protoplasts not treated by microinjection (control). They were clustered into three groups, with different levels and speeds of protoplast enlargement. The statistical analyses showed that the protoplasts injected by E. faecalis and four of the seven phylogenetically different bacterial genomic DNAs had enlargement patterns significantly different from those of the control. Thus, injected genomic DNAs affected the protoplast enlargement. Most of the affected cells, including the E. faecalis genome, had weakened enlargement.