BLOOMINGTON, Ind. -- An international team of microbiologists led by Indiana University researchers has identified a new bacterial growth process -- one that occurs at a single end or pole of the cell instead of uniform, dispersed growth along the long axis of the cell -- that could have implications in the development of new antibacterial strategies.
Based on past detailed studies of rod-shaped bacteria such as Escherichia coli and Bacillus subtilis, it has been assumed that most bacteria grow by binary fission, a dispersed mode of growth involving insertion of new cell wall material uniformly along the long axis of the cell. Growth requires breaking the cell wall at numerous places along the cylinder to allow insertion of new cell wall material, enabling uniform elongation of the cell, with the process culminated by cleavage at the mid-point of the cell to create two symmetric new cells.
The new research published today, Jan. 17, in Proceedings of the National Academy of Sciences reports on the surprising discovery that cell growth in a large group of rod-shaped bacteria occurs by insertion of new cell wall material only at a single end, or pole, of the cell rather than by the dispersed mode of growth. The cell wall of the progenitor cell remains largely intact, and all of the new cell wall material is partitioned into the new cell.
Polar growth of four bacterial species -- the plant symbiont Sinorhizobium meliloti, the plant pathogen Agrobacterium tumefaciens and the human pathogens Brucella abortus and Ochrobactrum anthropi -- was observed using time-lapse microscopy and transmission electron microscopy. The four related bacteria used in the study are all members of a large and diverse class of bacteria called the Alphaproteobacteria. The results reported suggest that polar growth is broadly distributed among many different bacterial taxa, including groups outside the Alphapr
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