## 3 Results and Discussion
### Growth Curve Analysis  
Microbial population growth is usually graphically represented by a sigmoid growth curve that has three characteristic phases: the lag phase (\(\lambda\)) during which no growth occurs, the logarithmic (log) phase which is a phase of rapid growth in which the maximum growth rate (\(\mu_{\text{max}}\)) of the microorganism is observed, and the stationary phase that is reached when nutrients are exhausted [40,41]. During optimum microbial growth, a short lag phase and a high maximum growth rate are observed. However, any factor that may stress the microorganism and compromise its viability (e.g., temperature variation, osmotic pressure, reactive oxygen species (ROS), antimicrobial agents, etc.) creates a shift away from optimum growth conditions [40]. This is usually observed by a longer lag phase, a slower maximum growth rate, and a lower level of maximum population in the stationary phase. One common method to obtain the growth curve of a microorganism is by measuring optical density (OD at 600 nm) at regular time intervals (e.g., every 30 min) in an inoculated microbial broth at a specific temperature throughout the incubation of the microorganism (usually 24-48 h) and constructing a curve of optical density versus time [42]. The growth curves of the three yeasts were measured by automatic turbidometry using a Bioscreen C instrument (Figure 3). The lag phase is the time in which the yeast cells are biochemically active but still not dividing since they are trying to adjust to the new growth medium [36]. After the lag phase, the cells start dividing and enter the logarithmic phase in which the maximum growth rate is observed, and the slope of the curve grows sharply. Figure 3A-C shows the sigmoid curves of the yeasts when they are grown in nutrient broth at 37 \({}^{\circ}\)C in the absence of the natural extract (yeast only) and the growth curves of the yeasts in the presence of a natural extract. According to our results, the three different _S. cerevisiae_ strain-related models had different responses in growth rate in the presence of the three extracts. Moreover, the growth rate of the curves was calculated with the ComBase tool. At 37 \({}^{\circ}\)C, the rates of the yeasts grown in the presence of natural extracts were found to be significantly lower than that of the control (yeast only) (\(p<0.05\)), which is indicative of antimicrobial activity (Figure 3D). The same trend was observed at 30 \({}^{\circ}\)C (Supplementary Data Figure S3). Furthermore, in this method, the carrier oils of the natural extracts, caprylic triglyceride and sunflower oil did not exhibit statistically significant antifungal activity. This may be due to fact that the assessment of growth was performed in broth and not in static agar conditions [43]. According to previous reports, _H. perforatum_ extract may have antioxidant and antimicrobial activity toward microbial cells, which could be attributed to the presence of phytochemicals such as flavonoids and hypericin [44, 45, 46]. Moreover, _H. perforatum_ could protect food from diseases caused by spore-forming bacteria such as _B. mesentericus_ and _B. subtilis_ along with improved organoleptic and rheological properties [5]. In addition, mastic extract has strong antioxidant properties due to the presence of polyphenic compounds such as flavonoids and phenolic acids [47]. The essential oil of the resin of _P. lentiiscus var. Chia_ (mastic oil) was studied in vitro against a wide range of foodborne pathogenic and spoilage microorganisms; the results showed that Gram-positive were found to be more susceptible to the essential oil than Gram-negative microorganisms, and all fungi appeared very resistant to mastic oil [48]. In addition, several studies have suggested that mastic extract has antimicrobial activity against periodontal pathogens and the yeast _Candida albicans_[49]. Moreover, rosmary extracts showed biological bioactivities such as hepatoprotective, antifungal, insecticide, antioxidant, and antibacterial [13].