Ink-Jet Printing of Encapsulated Bacteria
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0921-T05-26
Ink-Jet Printing of Encapsulated Bacteria Faith M. Coldren1, John B. McGuirt1, Nicole Levi1, Elizabeth Palavecino2, and David L. Carroll1 1 Physics, Center for Nanotechnology and Molecular Materials, Wake Forest University, Winston-Salem, NC, 27109-7507 2 Pathology, Wake Forest University School of Medicine, Winston-Salem, NC, 27157
ABSTRACT Even though viability for printed bacteria has been demonstrated, the effect of thermal inkjet printing on cellular ultrastructures is unknown. Retention of viability is useful when colony growth is desired. However, when bacteria are isolated from a human infection they often exhibit characteristics that can be lost when grown in standard laboratory cultures. Ideally, individual bacteria from an infection could be printed and studied without extensive culturing or processing. We have investigated the gram-positive organism Staphylococcus aureus and the extracellular polymeric ultrastructure that encapsulates the bacterial cell. The capsule is composed of cell-wall associated polysaccharides. Our goal was to use ink-jet printing to spatially control the placement of S. aureus, without affecting the extracellular ultrastructure. Observation by scanning electron microscopy comparing the integrity and uniformity of encapsulated S. aureus before and after thermal ink-jet printing suggests that the capsule is disrupted, possibly completely removed, during printing. INTRODUCTION The printing of bacteria is of interest in clinical bacteriology because it could allow for rapid placement of uncultured isolates onto substrates for observation. The gram-negative bacterium Escherichia coli remains viable after thermal printing, presenting a quick method for fabricating bacterial arrays, and suggesting minimal damage to the cells [1]. However, the bacteria may be altered from their naturally occurring state, which might limit the relevance of studies done on these arrays. In our studies, we have applied a modified ink-jet system to the printing of bacterial-inks, specifically Staphylococcus aureus, for the purpose of examining damage to the extracellular ultrastructures typically associated with these bacteria. The species S. aureus produces eleven different types of cell-wall associated polysaccharide capsules. Thus, bacterial-inks provide a simple, inexpensive system for investigating the effects of thermal printing on polymeric ultrastructures. S. aureus is a common bacterium, and when isolated from infections it can lose its capsule through culturing under standard laboratory conditions [2]. In order to microscopically study individual bacteria from infections without culturing first, a precise positioning method needs to be developed. This method must also not disturb the polymeric ultrastructures commonly expressed in clinically isolated S. aureus [3]. We used optical microscopy and scanning electron microscopy to compare printed S. aureus with the traditional microscopy preparation method of pipette dispensing suspensions. There are two commonly available types of printe
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