A microscopic method to visualize Escherichia coli interaction with beef muscle.

The genetic determinant for enhanced green fluorescent protein (EGFP) was introduced into Escherichia coli JM109 (ATCC 53323) and E. coli O157:H7 (ATCC 43895) on plasmid EGFP. The expression of EGFP did not change the growth kinetics or surface properties tested (hydrophobicity and electrophoretic mobility). Microscope slides were modified to allow for optimal viewing of thick meat samples with an inverted microscope. Two fluorescent dyes, nile red and Cy3 were used to stain for lipid and protein portions of beef muscle, respectively. Laser scanning confocal microscopy was used to observe interaction of the EGFP-expressing E. coli strains and the fluorescently stained muscle components without changing the spatial and temporal environment of the organisms.