A flow cytometric technique for quantification and differentiation of bacteria in bulk tank milk
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A flow cytometric technique for quantification and differentiation of bacteria in bulk tank milk. / Holm, C.; Mathiasen, T.; Jespersen, Lene.
In: Journal of Applied Microbiology, Vol. 97, No. 5, 2004, p. 935-941.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - A flow cytometric technique for quantification and differentiation of bacteria in bulk tank milk
AU - Holm, C.
AU - Mathiasen, T.
AU - Jespersen, Lene
PY - 2004
Y1 - 2004
N2 - AIMS: The present study describes a flow cytometric technique for quantification and differentiation of bacteria in bulk tank milk according to the main cause of elevated counts.METHODS AND RESULTS: A total of 75 Danish bulk tank milk samples exceeding the grading level of 3.0 x 10(4) CFU ml(-1) were examined by both flow cytometry and traditional microbiological analyses. The correlation coefficient (r) between the two methods was 0.71. For the differential analyses of the dominant bacterial populations four different parameters were used to give a species-characteristic pattern. The four parameters were as follows: staining with Oregon Green conjugated wheat germ agglutinin that binds to the cell wall of bacteria, staining with hexidium iodide that binds to all bacterial DNA, the flow cytometric forward scatter and the flow cytometric side scatter. Three regions in the flow cytometric plot were defined: region 1 includes bacteria mainly associated with poor hygiene, region 2 includes psychrotrophic hygiene bacteria and region 3 includes bacteria mainly related to mastitis. The ability of the flow cytometric technique to predict the main cause of elevated bacterial counts on routine samples was examined. Comparing these results with results obtained by traditional microbiological analyses for identification showed that for 81% of the samples the two techniques agreed on the main cause of an elevated bacterial count.CONCLUSIONS: The ability of the presented flow cytometric technique to enumerate and differentiate bacteria in bulk tank milk according to the main cause of elevated counts was demonstrated.SIGNIFICANCE AND IMPACT OF THE STUDY: This study described the first step in development of a technique suitable for routine analyses of bulk tank milk samples. A technique indicating the main cause of an elevated count will enable the farmer to eliminate the contamination source within a short time limit.
AB - AIMS: The present study describes a flow cytometric technique for quantification and differentiation of bacteria in bulk tank milk according to the main cause of elevated counts.METHODS AND RESULTS: A total of 75 Danish bulk tank milk samples exceeding the grading level of 3.0 x 10(4) CFU ml(-1) were examined by both flow cytometry and traditional microbiological analyses. The correlation coefficient (r) between the two methods was 0.71. For the differential analyses of the dominant bacterial populations four different parameters were used to give a species-characteristic pattern. The four parameters were as follows: staining with Oregon Green conjugated wheat germ agglutinin that binds to the cell wall of bacteria, staining with hexidium iodide that binds to all bacterial DNA, the flow cytometric forward scatter and the flow cytometric side scatter. Three regions in the flow cytometric plot were defined: region 1 includes bacteria mainly associated with poor hygiene, region 2 includes psychrotrophic hygiene bacteria and region 3 includes bacteria mainly related to mastitis. The ability of the flow cytometric technique to predict the main cause of elevated bacterial counts on routine samples was examined. Comparing these results with results obtained by traditional microbiological analyses for identification showed that for 81% of the samples the two techniques agreed on the main cause of an elevated bacterial count.CONCLUSIONS: The ability of the presented flow cytometric technique to enumerate and differentiate bacteria in bulk tank milk according to the main cause of elevated counts was demonstrated.SIGNIFICANCE AND IMPACT OF THE STUDY: This study described the first step in development of a technique suitable for routine analyses of bulk tank milk samples. A technique indicating the main cause of an elevated count will enable the farmer to eliminate the contamination source within a short time limit.
KW - Animals
KW - Bacteria
KW - Bacterial Typing Techniques
KW - Cattle
KW - Colony Count, Microbial
KW - Flow Cytometry
KW - Food Microbiology
KW - Hygiene
KW - Industrial Microbiology
KW - Mastitis, Bovine
KW - Milk
U2 - 10.1111/j.1365-2672.2004.02346.x
DO - 10.1111/j.1365-2672.2004.02346.x
M3 - Journal article
C2 - 15479408
VL - 97
SP - 935
EP - 941
JO - Proceedings of the Society for Applied Bacteriology
JF - Proceedings of the Society for Applied Bacteriology
SN - 0370-1778
IS - 5
ER -
ID: 131497230