The growth interactions between Geotrichum candidum and Lactobacillus rhamnosus GG were studied in milk. The effect of temperature on the growth rate of the fungus was modelled using the cardinal temperature model with inflection. The secondary modelling was applied also on the other data set containing the growth rates of G. candidum in co-culture with a commercial starter culture. The low temperature in combination with L. rhamnosus GG in co-culture showed the most negative effect on the growth rate of G. candidum. On the other hand, neither L. rhamnosus GG nor the starter culture had significant effect on the optimum and maximum temperature parameters calculated for growth of G. candidum. Their values ranged from 28.9 °C to 31.3°C  and 35.3°C  to 37.3°C, respectively. The quantitative data presented in the study showed a non-specific effect of lactic acid bacteria on the growth rate of G. candidum observed mainly around the optimal temperature.

Geotrichum candidum species exhibits properties of both moulds and yeasts and its affiliation to one of the groups has been intensively discussed. It is because this filamentous microscopic fungus is displaying substantial morphological variability and wide phenotypic diversity. The present study assesses the variability of arthrosporic nucleus number of twelve isolates of G. candidum originating from artisanal manufacturing and ripened traditional Slovak cheeses. Results showed that arthrospores of the studied isolates contained on average 1.5 ± 0.7 (on the Gorodkova medium) and 1.5 ± 0.6 (on the McClary medium) Hoechst 33258-stained nuclei (range 1–4 nuclei on both agars) after a 7-day cultivation at 25°C. Majority of arthrospores comprised one nucleus, irrespective to the used nutrient-limited medium. Generally, a higher relative nucleus number per arthrospore was exhibited in yeast-like isolates with microscopic structure composed predominantly of spores, while it was lower in vegetative hyphae. These isolates originated from ewe’s lump cheese. Our study reveals that the arthrosporic nucleus number of the G. candidum strains is closely related to morphotype and origin of this yeast.