8/24/2016 Spiral Plater Analysis Analysis ·.Robotic arm spreads Membrane Filter Method bacteria on an agar plate Fluids with low microbial Volume of the inoculum is counts are often analyzed decreased as it moves to the with this technique outer edge Direct microscopic count 1:10,000 dilution is achieved may be used Counting grid needed to count colonies ·Use fewer plates But limited to liquid samples Analysis Analysis Hydrophobic grid membrane Fluorescent dyes stain filter method bacteria Fluorescent bacteria are ·1,600 grid filters counted Restrict microbial growth ·Restrict colony size a microsope factor ·1 ml filtered Used with meat,poultry. ·Count grids with DAPI stained bacterial colonies cells from drinking water Live dead cell stains Most probable number determined 2出 6 8/24/2016 6 Spiral Plater Analysis • Robotic arm spreads bacteria on an agar plate • Volume of the inoculum is decreased as it moves to the outer edge • 1:10,000 dilution is achieved • Counting grid needed to count colonies • Use fewer plates • But limited to liquid samples 21 Analysis Membrane Filter Method • Fluids with low microbial counts are often analyzed with this technique • Direct microscopic count may be used 22 Analysis Direct Epifluorescent Filter Technique • Fluorescent dyes stain bacteria • Fluorescent bacteria are counted • Calculate: average number of cells per field is multipled by a microsope factor • Used with meat, poultry, milk, and food contact surfaces • Live / dead cell stains DAPI stained bacterial cells from drinking water 23 Analysis Hydrophobic grid membrane filter method • 1,600 grid filters • Restrict microbial growth • Restrict colony size • 1 ml filtered • Count grids with colonies • Most probable number determined 24