The ability of nine commercial broths to enrich healthy and 90% sanitizer-injured Salmonella Typhimurium
and Salmonella cocktail on mung bean sprouts was evaluated to select an optimum broth for
detection. Results showed that S. Typhimurium multiplied faster and reached a higher population in
buffered peptone water (BPW), Salmonella AD media (AD) and ONE broth-Salmonella (OB), compared
with other broths. Healthy and 90% sanitizer-injured Salmonella at low concentrations increased by 4.0
log CFU/ml in these three broths. However, no Salmonella growth was observed in lactose broth (LB).
Further investigation showed that during incubation, pH of LB dropped from 6.7 to 4.2, due to production
of lactic (66 mM) and acetic acids (62 mM) by lactic acid bacteria that were identified as dominant
microbiota in bean sprouts. Though no cell membrane damage was detected by propidium monoazide
combined with real-time PCR, it was found that LB inhibited Salmonella growth, especially from low
inoculum levels. This study suggests that in consideration of effectiveness and cost, BPW would be a
suitable enrichment broth to use for isolating and detecting Salmonella on mung bean sprouts, while
using LB might cause false negative results in Salmonella detection by either PCR or standard cultural
method.
The ability of nine commercial broths to enrich healthy and 90% sanitizer-injured Salmonella Typhimuriumand Salmonella cocktail on mung bean sprouts was evaluated to select an optimum broth fordetection. Results showed that S. Typhimurium multiplied faster and reached a higher population inbuffered peptone water (BPW), Salmonella AD media (AD) and ONE broth-Salmonella (OB), comparedwith other broths. Healthy and 90% sanitizer-injured Salmonella at low concentrations increased by 4.0log CFU/ml in these three broths. However, no Salmonella growth was observed in lactose broth (LB).Further investigation showed that during incubation, pH of LB dropped from 6.7 to 4.2, due to productionof lactic (66 mM) and acetic acids (62 mM) by lactic acid bacteria that were identified as dominantmicrobiota in bean sprouts. Though no cell membrane damage was detected by propidium monoazidecombined with real-time PCR, it was found that LB inhibited Salmonella growth, especially from lowinoculum levels. This study suggests that in consideration of effectiveness and cost, BPW would be asuitable enrichment broth to use for isolating and detecting Salmonella on mung bean sprouts, whileusing LB might cause false negative results in Salmonella detection by either PCR or standard culturalmethod.
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