EFFECTS OF PH AND SODIUM-CHLORIDE ON THE INTERACTIONS BETWEEN GEOTRICHUM-CANDIDUM AND BREVIBACTERIUM LINENS

The interactions between 14 isolates of Geotrichum candidum and 14 iso lates of Brevibacterium linens were analyzed to understand their behav ior in cheese making. Mixed cultures were grown in a peptone broth con taining various NaCl concentrations and various pH. The pH and the con centration of NaCl affected the interactions. According to the pH, in many strain pairs, B. linens strongly stimulated the growth of G. cand idum, and this interaction varied depending on the pH. Inhibition occu rred only at pH 5.0. In fewer pairs, G. candidum moderately stimulated the growth of B. linens, and the optimal pH for this stimulation and the inhibition were 7.0 and 5.0, respectively. The number of pairs in which the growth of G. candidum was increased by the presence of B. li nens was highest with 1.5% added NaCl. With increasing NaCl concentrat ion, stimulation of the growth of B. linens by G. candidum decreased b ecause of the sensitivity of G. candidum and resistance of B. linens t o NaCl. Brevibacterium linens isolates were similarly grown in the pre sence of filtrates of stationary phase cultures of G. candidum. The fi ltrates exhibited effects analogous to, but larger than, those of the strains from which the filtrates were prepared.