Sprouts from nine producers were sampled from retail outlets and the microbial flora identified. Total aerobic plate counts were 108 cells/g; psychrotrophic counts were 107 cells/g; lactobacilli and fecal streptococci counts were low. Total coliforms and confirmed Klebsiella counts were each 106 cells/g. Fecal coliforms appeared to be part of the normal flora of sprouts (1,100 to 240,000 MPN per 100g). These were primarily K. pneumoniae. Sixty‐four percent of selected K. pneumoniae isolates were fecal coliform positive. The presence of K. pneumoniae in large numbers is a potential public health problem for people with decreased resistance.
From comparisons of 4% N-Z Amine NAK made with distilled water, naturally hard water, and synthetic salt solutions, it appeared that magnesium and, to a lesser extent, iron were limiting factors in the production of staphylococcal enterotoxins B and C but not A. Maximum enterotoxin production with NAK medium was achieved by the addition of 5 mg of Mg2" per liter (for a total of 9 mg of Mg2e per liter) and 0.5 mg of Fe2" per liter. Higher levels of magnesium were not inhibitory. Supplementing NAK with commonly used complex components, which added Mg2e above the 9-mg/liter level, did not result in maximum yields of enterotoxin. Variability in the ability of different lots of NAK to support enterotoxin production may be minimized by supplementing NAK medium with magnesium and iron.
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