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Chapter 1 : Geochemical Reactivity of Bacterial Surfaces: a Tribute to T. J. Beveridge
“Nature never jests,” this attitude is best reflected in Dr. Terry Beveridge’s pioneering studies on the molecular basis of bacterial cell wall reactivity, sorption of metals, as well as mineral precipitation and dissolution reactions. The essential link between these areas of research is the fundamental view that design and construction impart functionality. This chapter explores some of the early works on bacterial cell envelopes that paved the way for Terry and his studies on the geochemical reactivity of bacterial cell surfaces. Terry recognized that the enhanced electron contrast provided by heavy metals in thin sections and whole mounts of bacteria had something to do with how the metals interacted with the macromolecular constituents of the cells. Furthermore, it was clear from his Ph.D. work that certain metals like Ca2+ were important for the maintenance of bacterial cell envelope structure and integrity. The phosphate groups of lipopolysaccharide were identified as major sites for metal binding by using 31P-nuclear magnetic resonance and paramagnetic metal cation probes. The chapter highlights the importance of recognizing that all bacteria are obligated to grow from the inside out, and necessarily shed older cell wall fragments (and sometimes bacteriophage) into their surroundings. This means that new metal binding sites will be generated as bacterial cells grow, so absorbed as well as precipitated metals will slough off and be removed from the cell. In this sense, metal binding and precipitation by bacteria will be a continual source of particulate metals in natural systems.