Comparison of heat stress responses of immobilized and planktonic Salmonella enterica serovar Typhimurium

TY - JOUR

T1 - Comparison of heat stress responses of immobilized and planktonic Salmonella enterica serovar Typhimurium

AU - Nielsen, Maj-Britt

AU - Knudsen, Gitte M.

AU - Danino-Appleton, Vittoria

AU - Olsen, John Elmerdahl

AU - Thomsen, Line Elnif

PY - 2013/4

Y1 - 2013/4

N2 - Salmonellae are often present as immobilized cells in food products in the form of micro-colonies. Despite this, most research into Salmonella physiology has been performed with bacteria grown as planktonic cultures. In the current study, we compared the transcriptome of planktonic and immobilized Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) subjected to 30 min of heat stress at 45 °C. The expression of 538 genes was differently regulated between the two conditions after 30 min. Heat stress of an immobilized culture induced expression of flagella and virulence genes compared to the non-heat stressed immobilized bacteria. Immobilized heat stressed S. Typhimurium was more invasive in HeLa cells than the non-heat stressed controls, whereas the heat stress caused planktonic bacteria to be less invasive. The decrease in invasion of heat stressed planktonic cultures returned to non-heat stressed levels 30 min post treatment, whereas the increased invasion of HeLa cells of the heat stressed immobilized cultures still remained 30 min after the heat stress was terminated. This study shows that immobilized bacteria respond to heat stress differently than planktonic bacteria.

AB - Salmonellae are often present as immobilized cells in food products in the form of micro-colonies. Despite this, most research into Salmonella physiology has been performed with bacteria grown as planktonic cultures. In the current study, we compared the transcriptome of planktonic and immobilized Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) subjected to 30 min of heat stress at 45 °C. The expression of 538 genes was differently regulated between the two conditions after 30 min. Heat stress of an immobilized culture induced expression of flagella and virulence genes compared to the non-heat stressed immobilized bacteria. Immobilized heat stressed S. Typhimurium was more invasive in HeLa cells than the non-heat stressed controls, whereas the heat stress caused planktonic bacteria to be less invasive. The decrease in invasion of heat stressed planktonic cultures returned to non-heat stressed levels 30 min post treatment, whereas the increased invasion of HeLa cells of the heat stressed immobilized cultures still remained 30 min after the heat stress was terminated. This study shows that immobilized bacteria respond to heat stress differently than planktonic bacteria.

KW - Former LIFE faculty

KW - Salmonella Typhimurium

KW - immobilization½

KW - heat stress

KW - flagella

KW - SPI1

U2 - 10.1016/j.fm.2012.09.020

DO - 10.1016/j.fm.2012.09.020

M3 - Journal article

C2 - 23200655

SN - 0740-0020

VL - 33

SP - 221

EP - 227

JO - Food Microbiology

JF - Food Microbiology

IS - 2

ER -