No significant differences in the generation times were observed between the 26 L.
monocytogenes and 8 L. innocua strains that were tested. The generation time of either of
the species that were enrichment cultured in combination did not determine whether there
was a negative result for L. monocytogenes isolation. These findings are consistent with a
recent description by Cornue et al. [7]. However, MacDonald et al. [9] reported the mean
generation time of 94.6 min for L. monocytogenes and 77.9 min for L. innocua cultured in
EB when analyzed by the plate-count method. Differences in sensitivity to the selective
agents, such as acriflavine, which are incorporated into the EB [6] may explain why
generation times vary among published studies. In support of this idea, the generation
times of both L. monocytogenes and L. innocua are similar in non-selective broth [8–10].
In some combinations of BLS producing L. innocua and BLS-sensitive L. monocytogenes
there was a decrease in recovery of L. monocytogenes with prolonged culture. The inhibition
was not restricted to a specific genotype, since all of the BLS-producing L. innocua, aswell as
the BLS-sensitive L. monocytogenes, showed distinct RAPD profiles.
Previously, we reported that many L. innocua strains isolated from various sources
produced BLS [14]. Furthermore, viable numbers of L. monocytogenes were generally low in
food samples [20]. IfBLS-producing L. innocua and low numbers of L. monocytogenes were
co-contaminants in food samples, the result may be inhibition of L. monocytogenes after
enrichment culture. The possibility of such false-negative results must be considered in an
investigation of food sampleswith a zero-tolerance for L. monocytogenes contamination [21].
Contrary to our findings, other reports show that L. innocua had no influence on the
isolation of L. monocytogenes from either meat [22] or dairy [23] samples artificially
contaminated with these Listeria species. However, only single strains of L. innocua and
L. monocytogenes were used and the BLS production and the sensitivity of
L. monocytogenes against the BLS were not investigated.
In conclusion, L. innocua strains often inhibit the isolation of L. monocytogenes after
enrichment culture. The inhibition is related to the BLS production by L. innocua and this
inhibition is unlikely to be dependent upon a particular genetic profile of L. innocua
producing the BLS and L. monocytogenes sensitive to the BLS. The generation times of
either of Listeria species do not govern the inhibitory effect.
No significant differences in the generation times were observed between the 26 L.
monocytogenes and 8 L. innocua strains that were tested. The generation time of either of
the species that were enrichment cultured in combination did not determine whether there
was a negative result for L. monocytogenes isolation. These findings are consistent with a
recent description by Cornue et al. [7]. However, MacDonald et al. [9] reported the mean
generation time of 94.6 min for L. monocytogenes and 77.9 min for L. innocua cultured in
EB when analyzed by the plate-count method. Differences in sensitivity to the selective
agents, such as acriflavine, which are incorporated into the EB [6] may explain why
generation times vary among published studies. In support of this idea, the generation
times of both L. monocytogenes and L. innocua are similar in non-selective broth [8–10].
In some combinations of BLS producing L. innocua and BLS-sensitive L. monocytogenes
there was a decrease in recovery of L. monocytogenes with prolonged culture. The inhibition
was not restricted to a specific genotype, since all of the BLS-producing L. innocua, aswell as
the BLS-sensitive L. monocytogenes, showed distinct RAPD profiles.
Previously, we reported that many L. innocua strains isolated from various sources
produced BLS [14]. Furthermore, viable numbers of L. monocytogenes were generally low in
food samples [20]. IfBLS-producing L. innocua and low numbers of L. monocytogenes were
co-contaminants in food samples, the result may be inhibition of L. monocytogenes after
enrichment culture. The possibility of such false-negative results must be considered in an
investigation of food sampleswith a zero-tolerance for L. monocytogenes contamination [21].
Contrary to our findings, other reports show that L. innocua had no influence on the
isolation of L. monocytogenes from either meat [22] or dairy [23] samples artificially
contaminated with these Listeria species. However, only single strains of L. innocua and
L. monocytogenes were used and the BLS production and the sensitivity of
L. monocytogenes against the BLS were not investigated.
In conclusion, L. innocua strains often inhibit the isolation of L. monocytogenes after
enrichment culture. The inhibition is related to the BLS production by L. innocua and this
inhibition is unlikely to be dependent upon a particular genetic profile of L. innocua
producing the BLS and L. monocytogenes sensitive to the BLS. The generation times of
either of Listeria species do not govern the inhibitory effect.
การแปล กรุณารอสักครู่..
No significant differences in the generation times were observed between the 26 L.
monocytogenes and 8 L. innocua strains that were tested. The generation time of either of
the species that were enrichment cultured in combination did not determine whether there
was a negative result for L. monocytogenes isolation. These findings are consistent with a
recent description by Cornue et al. [7]. However, MacDonald et al. [9] reported the mean
generation time of 94.6 min for L. monocytogenes and 77.9 min for L. innocua cultured in
EB when analyzed by the plate-count method. Differences in sensitivity to the selective
agents, such as acriflavine, which are incorporated into the EB [6] may explain why
generation times vary among published studies. In support of this idea, the generation
times of both L. monocytogenes and L. innocua are similar in non-selective broth [8–10].
In some combinations of BLS producing L. innocua and BLS-sensitive L. monocytogenes
there was a decrease in recovery of L. monocytogenes with prolonged culture. The inhibition
was not restricted to a specific genotype, since all of the BLS-producing L. innocua, aswell as
the BLS-sensitive L. monocytogenes, showed distinct RAPD profiles.
Previously, we reported that many L. innocua strains isolated from various sources
produced BLS [14]. Furthermore, viable numbers of L. monocytogenes were generally low in
food samples [20]. IfBLS-producing L. innocua and low numbers of L. monocytogenes were
co-contaminants in food samples, the result may be inhibition of L. monocytogenes after
enrichment culture. The possibility of such false-negative results must be considered in an
investigation of food sampleswith a zero-tolerance for L. monocytogenes contamination [21].
Contrary to our findings, other reports show that L. innocua had no influence on the
isolation of L. monocytogenes from either meat [22] or dairy [23] samples artificially
contaminated with these Listeria species. However, only single strains of L. innocua and
L. monocytogenes were used and the BLS production and the sensitivity of
L. monocytogenes against the BLS were not investigated.
In conclusion, L. innocua strains often inhibit the isolation of L. monocytogenes after
enrichment culture. The inhibition is related to the BLS production by L. innocua and this
inhibition is unlikely to be dependent upon a particular genetic profile of L. innocua
producing the BLS and L. monocytogenes sensitive to the BLS. The generation times of
either of Listeria species do not govern the inhibitory effect.
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