## 3 Results and Discussion
### The Effect of Essential oils on the Viability of Bifidobacterium in In Vitro Conditions
They identified 30 compounds but the GC-MS analysis showed that the main component of the juniper berry essential oil was \(\alpha\)-piper (45.63%), which is in line with the research of other authors [52]. The results reported by [PERSON] et al. [10] also confirmed the results obtained in our work. In the study by [PERSON] et al. [51], the juniper berry essential oil showed an antibacterial effect on all three tested bacteria, with _P. aeruginosa_ found to be the most resistant. A growth inhibition zone of 4.5 mm was observed only with the use of a 100% concentration of essential oil. The most sensitive among the tested bacteria was _E. coli_ and its growth inhibition zones that were observed for concentrations of essential oils of 0%, 10%, 20%, 50%, and 100% were measured at 0, 6.1, 7.2, 8.3, and 2.2 mm, respectively. The inhibition zones of the Gram-positive _S. aureus_, similar to the _Bifidobacterium_ strains tested in this work, that were observed with 0%, 10%, 20%, 50%, and 100% concentrations of essential oils were measured at 0, 2.1, 4.8, 5.0, and 3.5 mm, respectively. These results on _S. aureus_ are very similar to those found in our work for _B. animalis_ subsp. _lactis_ Bb-12, which turned out to be the most sensitive. Some researchers have shown that essential oils obtained from juniper berries did not show any antibacterial action and only exhibited an antifungal effect [11], or weak antibacterial and antifungal activities [53]. [PERSON] et al. [54] examined the antibacterial activity of the juniper berry essential oil, with different fractions, in their study. These authors reported that the native juniper berry essential oil did not show a strong antibacterial effect compared to fractions containing a high amount of \(\alpha\)-pinene and a mixture of sabinene and \(\alpha\)-pinene, which showed the highest antimicrobial activity on almost all tested microorganisms (_B. cereus_, _E. coli_, _Listeria monocytogenes_, _Corynebacterium_ sp., _P. aeruginosa_, _S. aureus_, _C. albicans_, _Alternaria_ sp., _Aspergillus nidulans_, and _Aspergillus niger_). The MIC values estimated by [PERSON] et al. [42] for 21 different essential oils and four species of Gram-negative bacteria (_E. coli_, _K. pneumoniae_, _P. aeruginosa_, and _P. vulgaris_) and two species of Gram-positive bacteria (_B. subtilis_ and _S. aureus_) indicated that these results are similar to those obtained in our work. For Gram-positive bacteria, the MIC value of the lemon essential oil (12.8 and 12.8 mg/mL, respectively) was higher than that of the clove essential oil (6.4 and 3.2 mg/mL, respectively) which confirms that the clove essential oil has a stronger antibacterial effect than the lemon essential oil. The results obtained in our work, to some extent, coincide with those of [PERSON] et al. [43], who studied the antimicrobial activity of a eugenol extract (the main component of the clove essential oil, limonene),the main component of the lemon essential oil, and a citrus extract (a mixture of different components such as citric acid, sodium acid, citrusic polyphenols, biofilms, citrus sugars, and citric acid) on three bacterial species, including two lactic acid bacteria (LAB), and three yeast species. The MIC values determined by [PERSON] et al. [43] indicated that limonene showed less antimicrobial activity than eugenol on the tested bacteria (>1000 and >600 ppm, respectively). It should be noted that several compounds that were identified as strong antioxidants belong to the group of flavonoids found in the citrus extract, as well as the groups of other phenolic compounds. [PERSON] et al. [43] showed that these substances acted synergistically. It can be argued that limonene, as a single compound, did not exhibit as strong a antimicrobial effect as the citrus extract that contained many additional compounds that synergistically increased its antimicrobial effect.