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  • Thumbnail for Investigation of Cellular Morphology During the Absence of Min System Proteins in Acinetobacter baylyi Imaged Under Atomic Force Microscopy
    Investigation of Cellular Morphology During the Absence of Min System Proteins in Acinetobacter baylyi Imaged Under Atomic Force Microscopy by Worsham, Sara Liang

    Cell morphology in bacteria is a crucial factor for survival in that it affects evading predators and acquiring nutrition leading to growth and development. In order to grow, bacteria divide through binary fission to create two daughter cells identical in size, shape, and genome. One of the main contributors to accurate and efficient cell division is the Min system. Composed of proteins, MinC, MinD, and MinE, the following work together to place the FtsZ ring in the middle of the cell for septum formation. While the Min system and its effects have been heavily studied in other model organisms, little is known about its function and mechanism in the Gram-negative soil bacteria, Acinetobacter baylyi (ADP1). Bioinformatics tools such as sequence alignments, protein and operon predictions demonstrated evolutionary similarities between ADP1 and other rod-shaped organisms such as Bacillus subtilis, Escherichia coli, and Pseudomonas aeruginosa. In this study, we utilized ADP1’s high transforming capabilities to create individual knockout mutants of minC, minD, and minE. Based on bioinformatics, it is predicted that the min mutants would exert similar compromised growth and division morphologies of filamentation and minicell production as seen in other organisms. To test this hypothesis, cells were imaged under atomic force microscopy (AFM), and we acquired detailed nanoscopic data that showcased many filamented cells with few minicells. Features such as indents, side, and through bites also appeared on the surface of the mutant cells. Indents are shallow dips that appear on the cell surface, while bites are deeper features that either depress through the width of the cell (through bite) or asymmetrically along the side of the cell (side bite). Due to the mutation in division, bites and indent distribution were random as expected in the min mutants. This preliminary finding into the morphology effects of the Min system provides further insight into the complex mechanism of bacterial cell division.