Food Microorganisms Influencing the Growth of Staphylococcus aureus

Abstract

Some 870 cultures of predominating micro-organisms were isolated from market samples of hamburger, fresh pork sausage, fresh fish fillets, stewing beef, frozen chicken pot pie, frozen corn, frozen peas, and pasteurized and raw milk, before and after storage at different temperatures. The isolates were screened for their ability to influence the growth of Staphylococcus aureus strain 196E by means of spot-plate tests on APT and nutrient agars at 25 C. The 438 cultures that influenced the growth of S. aureus were retested on spot plates at 15, 30, and 42 C. After elimination of replicates, the 143 remaining cultures were classified into species, genera, or groups, and 14 different cultures were tested for their influence on the growth of S. aureus in APT broth at 25 C. Over half of the effective cultures inhibited S. aureus and less than half were stimulatory. Pork sausage had the highest proportion of inhibitory cultures, and stewing beef had the lowest. APT agar was better than nutrient agar for screening, and incubation at 15 C gave more effector organisms than at 30 and 42 C. Most of the lactic acid bacteria were inhibitory, but other groups of bacteria contained more stimulatory cultures than inhibitory ones. The three Escherichia coli cultures were stimulatory, but most other Escherichia cultures were inhibitory. Aerobacter and Paracolobactrum isolates were mostly stimulatory. Cultures of other kinds of bacteria were more or less evenly distributed between inhibitory ones and stimulatory ones. Genera containing mostly inhibitory bacteria were Streptococcus, Leuconostoc , and Lactobacillus . Inhibitory species were E. freundii and E. intermedia . Tests with S. aureus in broth indicated that all cultures inhibitory according to spot plates were inhibitory in broth, but stimulation on spot plates did not always indicate the same phenomenon in broth.

Bayesian modeling of two- and three-species bacterial competition in milk

“…P. fluorescens produces extracellular materials resulting in a competitive advantage over other species (Nadell & Bassler, 2011) such that the competitor is physically displaced (Schluter, Nadell, Bassler, & Foster, 2015) or the nutrients access impeded (Kim, Racimo, Schluter, Levy, & Foster, 2014). In early research on the topic, Graves & Frazier (1963) and Seminiano & Frazier (1966) reported the enhancement of Staphylococcus aureus's growth in the presence of Pseudomonas spp. Marshall & Schmidt (1991;1988) and (Farrag & Marth (1989a) found similar results when Listeria monocytogenes was co-cultured in the presence of P. fluorescens.…”

ESKAPEE Pathogen Biofilm Control on Surfaces with Probiotic Lactobacillaceae and Bacillus species

“…Among cases where information on the origin of the isolates was provided, probiotic bacteria were most frequently isolated from more and less fermented food (22 times) [20,22,26,41,[43][44][45]48,49,74,95,102,107,109,110,128,[134][135][136][137][138][139] and dairy products (11 times) [24,31,40,57,58,69,79,86,90,97,108,117]. Some were of human origin; these included bacteria of vaginal origin (six times) [64,65,72,93,119,140], such isolated from infant GI-tracts (six times) [24,42,62,77,94], and bacteria from the oral cavity (three times) [56,58,…”