The bacterial flora of surface-ripened cheeses with special regard to coryneforms

Abstract

Summary - Randomly-selected Austrian bacterial surface-ripened cheeses were examined for changes in the microbiological composition of the smear. The bacterial counts of the Tilsit cheeses from 14 cheese plants and of 3 types of soft cheeses selected varied fram 1()4 ta 109 cfu/cm2 smear 3 d after manufacture and fram 108 ta 109 cfu/cm2 smear after a ripening period of 3 weeks. The flora tolerated a NaCI content of at least 80 g/kg in the plate count agar. A total of 386 isolates of coryneform bacteria were identified. The bacterial flora proved ta be of mixed population. However, Brevibacterium linens accounted for a large share of the flora, comprising 30% of the total bacterial count, Besides Brevibacterium linens, the other main types found ta be present in the heterogeneous flora were creamcoloured and yellow-pigmented coryneforms, which were predominantly identified as Arthrobacter globiformis and Brevibacterium ammoniagenes. The coryneforms isolated fram the cheeses 3 d after manufacture were more prateoly1ic than those isolated at later stages of ripening.