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Microscopy Enumeration of Bacteria

IP.com Disclosure Number: IPCOM000081992D
Original Publication Date: 1974-Sep-01
Included in the Prior Art Database: 2005-Feb-28
Document File: 3 page(s) / 26K

Publishing Venue

IBM

Related People

Stone, JF: AUTHOR

Abstract

Microorganisms are enumerated by direct observation with reflected light microscopy of the population as it exists in a sample of aqueous ink. This technique relates to jet printer inks and its contaminants, but can be applied to other areas in microbiological testing.

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Microscopy Enumeration of Bacteria

Microorganisms are enumerated by direct observation with reflected light microscopy of the population as it exists in a sample of aqueous ink. This technique relates to jet printer inks and its contaminants, but can be applied to other areas in microbiological testing.

Given the nature of the sample to be tested for bacterial contamination--an opaque solution of dye--and the need to characterize the specific cause of system failure when circulating such a solution through micron-size filter media, this methodology has been established to count and characterize types of bacterial contamination. The technique simplifies the counting of bacteria with immediate results and little investment of materials. The low incident of operator handling and time is conducive to proper, repeatable results.

Enumeration of bacteria as a means of monitoring and evaluation of additives to inks has to be reapplied to those conditions, where failure of a system has occurred due to bacterial growth. This procedure allows the bacterial population to be viewed on a flat substrate in the manner they exist in the sample. This is valuable in interpretation of enumeration data - growth and subsequent particle size of chains and agglomerates considered. The bacteria used in development of this procedure were Pseudomonas aeruginosa. The procedure involves an aqueous sample whose saline content is usually 1-2% with a pH of 10.0.

Enumeration Procedure.

Sampling: The product to be sampled is shaken per A.P.H.A. Standard Method for milk population counts.

The sample is collected in a sterile syringe for in

situ staining. Usually 1.0 ml

sample is sufficient for enumeration for the quantities

stated below.

Staining: All staining solutions and rinses are ultrafiltered to 0.22 mu before use.

Staining the sample in situ enhances the reflected light

technique by minimizing residue, and increasing contrast

between the stained bacteria and nonstained polymer filter

substrate. The stain solution is similar to Truant's

fluorescent slide technique preparation,

but is modified for further cytoplasmic staining

with diethylene glycol monobutyl

ether (butyl CARBITOL*).

The stain formula is: 0.3 gm rhodamine B dye

10.0 gm ethanol

100.0 gm distilled water

3.0 gm butyl CARBITOL....