title: Effect of pH and oxygen tension on staphylococcal growth and enterotoxin formation in fermented sausage.
abstract: Commercial fermented 0sausages that contained significant numbers of viable coagulase-positive staphylococci were found to have the growth localized in the outermost areas of the sausage where oxygen tension was highest. Staphylococci were found to be more acid-tolerant aerobically than anaerobically. With chemical acidulation of sausage, growth could be controlled both aerobically and anaerobically with approximately 1.5% glucono delta lactone. Biological acidulation with a high inoculum of Pediococcus cerevisiae inhibited anaerobic staphylococcal growth but failed to suppress aerobic growth completely. A staphylococcal count of approximately 4 x 10(7) cells/g of sausage appeared to be necessary to produce detectable enterotoxin A within 24 hr in sausage. A minor difference existed in the relative rates of production of the different types of enterotoxin. Detectable enterotoxin A was produced in 24 hr in sausage held in atmospheres containing 10, 15, and 20% oxygen. In an atmosphere containing 5% oxygen, toxin was detected after 48 hr of incubation. No toxin was detected after 120 hr under anaerobic conditions. Most staphylococcal strains tested initiated growth and produced detectable enterotoxin aerobically at a pH of 5.1 in broth media. Anaerobically, however, most strains failed to produce detectable enterotoxin below pH 5.7.
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D003030:Coagulase / Q000096:biosynthesis; D004768:Enterotoxins / Q000032:analysis / Q000096:biosynthesis* / Q000145:classification / Q000302:isolation & purification; D005516:Food Microbiology; D006863:Hydrogen-Ion Concentration; D005779:Immunodiffusion; D007783:Lactones; D008460:Meat; D010100:Oxygen; D010313:Partial Pressure; D010376:Pediococcus / Q000254:growth & development; D013210:Staphylococcus / Q000201:enzymology / Q000254:growth & development* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D003030:Coagulase; D004768:Enterotoxins; D007783:Lactones; D010100:Oxygen