TY - JOUR
T1 - Performance evaluation of a low conductive growth medium (LCGM) for growth of healthy and stressed Listeria monocytogenes and other common bacterial species
AU - Banada, Padmapriya P.
AU - Liu, Yi Shao
AU - Yang, Liju
AU - Bashir, Rashid
AU - Bhunia, Arun K.
N1 - Funding Information:
Sincere thanks to Prof. Mike Ladisch for helpful discussions. This research was supported through a cooperative agreement with the Agricultural Research Service of the US Department of Agriculture project number 1935-42000-035 and the Center for Food Safety and Engineering at Purdue University.
PY - 2006/8/15
Y1 - 2006/8/15
N2 - The performance of a low conductive growth medium (LCGM) (conductivity of < 1300 μS) was evaluated for its ability to support growth of food borne bacterial pathogens including Listeria monocytogenes and to determine the expression of the two key virulence proteins in L. monocytogenes for possible applications in an impedance-based microfluidic biochip detection platform. Growth of Listeria was monitored spectrophotometrically and the lag phase, generation time, growth rate and maximum population density were determined using the Gompertz equation. LCGM had a lag phase of 2.3 h and showed a higher cell density compared to Luria Bertini (LB) broth. Length of lag phase was highly dependent on initial inoculum concentrations. The changes in conductivity with respect to growth in the low conductive medium were monitored using a conductivity probe. L. monocytogenes growth could be detected within 2 h (0.1 mS) in LCGM and within 6 h in LB. The performance of the media was also evaluated for the recovery of Listeria cells exposed to various stresses as 42 °C for 1, 2 or 6 h, an osmotic stress in 10.5% NaCl, an acidic stress at pH 2, 3 or 5 and a combined stress of 10.5% NaCl, pH 5 and 1 h exposure at 42 °C. The recovery rate was comparable with that of Tryptic soy broth containing yeast extract (TSBYE). L. monocytogenes in LCGM supported the expression of two key virulence markers, actin polymerization protein (ActA) and internalin B (InlB), which could be detected using specific antibodies. In general LCGM also supported the growth of several other bacterial species suggesting its implication in microbial quality monitoring of products. In conclusion, LCGM is a sensitive low conductive medium that supports the growth as well as the expression of virulence markers for potential applications in sensitive detection of L. monocytogenes or other food borne pathogens in impedance-based sensor platform.
AB - The performance of a low conductive growth medium (LCGM) (conductivity of < 1300 μS) was evaluated for its ability to support growth of food borne bacterial pathogens including Listeria monocytogenes and to determine the expression of the two key virulence proteins in L. monocytogenes for possible applications in an impedance-based microfluidic biochip detection platform. Growth of Listeria was monitored spectrophotometrically and the lag phase, generation time, growth rate and maximum population density were determined using the Gompertz equation. LCGM had a lag phase of 2.3 h and showed a higher cell density compared to Luria Bertini (LB) broth. Length of lag phase was highly dependent on initial inoculum concentrations. The changes in conductivity with respect to growth in the low conductive medium were monitored using a conductivity probe. L. monocytogenes growth could be detected within 2 h (0.1 mS) in LCGM and within 6 h in LB. The performance of the media was also evaluated for the recovery of Listeria cells exposed to various stresses as 42 °C for 1, 2 or 6 h, an osmotic stress in 10.5% NaCl, an acidic stress at pH 2, 3 or 5 and a combined stress of 10.5% NaCl, pH 5 and 1 h exposure at 42 °C. The recovery rate was comparable with that of Tryptic soy broth containing yeast extract (TSBYE). L. monocytogenes in LCGM supported the expression of two key virulence markers, actin polymerization protein (ActA) and internalin B (InlB), which could be detected using specific antibodies. In general LCGM also supported the growth of several other bacterial species suggesting its implication in microbial quality monitoring of products. In conclusion, LCGM is a sensitive low conductive medium that supports the growth as well as the expression of virulence markers for potential applications in sensitive detection of L. monocytogenes or other food borne pathogens in impedance-based sensor platform.
KW - ActA
KW - Bacteria
KW - Conductivity
KW - Internalin B
KW - Listeria monocytogenes
KW - Low conductive growth medium
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U2 - 10.1016/j.ijfoodmicro.2006.04.040
DO - 10.1016/j.ijfoodmicro.2006.04.040
M3 - Article
C2 - 16790285
AN - SCOPUS:33747064625
SN - 0168-1605
VL - 111
SP - 12
EP - 20
JO - International Journal of Food Microbiology
JF - International Journal of Food Microbiology
IS - 1
ER -