Characteristics of Staphylococcal Enterotoxin A Production and Growth of <i>Staphylococcus aureus</i> in Shaking and Stationary Cultures

Abstract

Staphylococcal food poisoning, which is still a serious health problem worldwide, is caused by staphylococcal enterotoxin SE. Among many types of SE, staphylococcal enterotoxin type A SEA is known to be the most responsible for staphylococcal food poisoning. Production by SEA-producing strains in shaking culture has been studied by many investigators, whereas the kinetical differences between shaking and stationary cultures have not been studied intensively. Therefore, this difference was studied at various temperatures from 14 to 46 in the present study. Consequently the maximum SEA concentration and populations of SEA producer in shaking culture was higher than those in stationary culture. Of interest, however, the productivity, which is the maximum SEA amount produced by one cell, in shaking cultures was lower than that in stationary culture. Kinetic analysis clarified that SEA gene expression in staphylococcal cells preceded toxin production at optimal temperature. Next, several SEA producers were studied for the maximum toxin production at various temperatures from 14 to 42 in shaking culture. Consequently all strains showed different patterns, suggesting that the characteristics of SEA production of these strains would be strain-specific. These results in this study would provide useful, basic information to prevent staphylococcal food poisoning outbreaks.

Effects of Lactic Acid and Salt on Enterotoxin A Production and Growth of Staphylococcus aureus

“…It is known that the toxin production varies among S. aureus strains and the toxin type (Czop & Bergdoll, ; Otero, Garcia, Garcia, Moreno, & Bergdoll, ). The varieties of SEA production and cell growth of the five strains in the present study were also observed in shaking culture (Elahi et al., ).…”

“…. varieties of SEA production and cell growth of the five strains in the present study were also observed in shaking culture (Elahi et al, 2018). When the maximum SEA and cell concentrations in the cocktail were compared to those of the individual strains, these values in the cocktail were higher than the averages of the five strains under the same conditions.…”

“…With the data shown in Figure and , the toxin productivities (the maximum SEA amounts produced by one cell) of staphylococcal cocktail at the two peaks of 30 °C and 10 °C were 0.136 × 10 −1 and 0.0627 × 10 −2 (fg/CFU), respectively. Here the toxin productivity was calculated by dividing the maximum SEA concentration by the population (Elahi et al., ). These results showed that the SEA productivity of the staphylococcal cocktail at 30 °C was 2.2 times higher than that at 10 °C.…”

“…Five S. aureus strains of 13008, 11658, 11727, f4, and St.1, which were the same strains studied in our previous studies, were used in the present study (Elahi & Fujikawa, ; Elahi et al., ). All the strains produced only SEA among classical SE types A to E; this was confirmed using a reversed passive latex agglutination test (Denka Seiken, Tokyo, Japan) (Fujikawa & Igarashi, ).…”

“…A cocktail of five S. aureus strains was used in this study (Elahi & Fujikawa, 2019;Stewart et al, 2002;Valero et al, 2009). The five strains were the same strains used in our previous studies for comparison (Elahi & Fujikawa, 2019;Elahi, Tsuchiaka, Mizutani, & Fujikawa, 2018). The growth of the strains was measured with colony counts on agar plates in the present study.…”