4. Microbial interference
General microbial interference is an effective nonspecific control mechanism common to all populations and environments including foods. It represents the inhibition of the growth of certain microorga nisms by other members of a habitat and was first used to describe the suppression of virulent staphylococci by avirulent strains (Shinefield et al., 1971). In order to operate efficiently the interfering flora, generally the normal background flora of the habitat, needs to outnumber the target host many times. The mechanisms involved include nutrient competition, generation of an unfavourable environment, competiption for attachment /adhesion sites and are common to all genera.