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G L Michaud

Publications and source records attributed to G L Michaud.

4 recordsLinked to original sources
PubMed1978

Automated food microbiology: potential for the hydrophobic grid-membrane filter.

Bacterial counts obtained on hydrophobic grid-membrane filters were comparable to conventional plate counts for Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus in homogenates from a range of foods. The wide numerical operating range of the hydrophobic grid-membrane filters allowed sequential diluting to be reduced or even eliminated, making them attractive as components in automated systems of analysis. Food debris could be rinsed completely from the unincubated hydrophobic grid-membrane filter surface without affecting the subsequent count, thus eliminating the possibility of counting food particles, a common source of error in electronic counting systems.

Bacteria↗
PubMed1975

Enumeration of high numbers of bacteria using hydrophobic grid-membrane filters.

Printing a wax grid on a conventional membrane filter yields a device functioning as a most probable number apparatus (MPN), used at a single dilution but with a very large number of growth compartments (e.g., 3,650). By restraining the lateral spread and confluence of colonies, the hydrophobic grid-membrane filter (HGMF) allows growth- or colony-forming units (GU) to be resolved at levels far above those which produce an uncountable lawn on a conventional membrane filter. It also eliminates the size variation of normal bacterial colonies. As a result, the HGMF can give more accurate estimates of the concentration of GU. The method by which grid-cell count observations can be used to obtain MPN estimates of the number of GUs is described, and estimates obtained using the MPN method on the HGMF are compared with those resulting from conventional colony count procedures on membrane filters. A linear relation was observed between MPNGU and the number of GUs, at levels up to 30,000 GUs, for pure cultures of bacteria and for samples of natural waters. The HGMF has great potential for reducing the labor required in quantitative microbiology, since it allows, with one filter, enumeration of microorganisms over a very large concentration range and therefore reduces the need to make dilutions.

Bacteria↗
PubMed1974

Hydrophobic grid-membrane filters: new approach to microbiological enumeration.

A square grid pattern, printed in hydrophobic material on conventional membrane filters, subdivided the surface into a plurality of areas. This separated colonies from one another and prevented lateral growth, spreading, and confluence. Very high colony-packing densities were achieved (2,500/in(2); ca. 1.61 x 10(5)/cm(2)) reducing the need to dilute samples. Recovery of organisms was better than on conventional filters, particularly at high inoculum levels. At the same time, visibility of normally pale or diffuse colonies was improved, since colonies grew upwards instead of sideways, and counting was facilitated because colonies grew in orderly arrays.

Bacteria↗