Microbiological and Chemical Properties of Chokeberry Juice Fermented by Novel Lactic Acid Bacteria with Potential Probiotic Properties during Fermentation at 4 °C for 4 Weeks.

On the frame of this research survey, a novel potentially probiotic strain (Lactobacillus paracasei SP5) recently isolated from kefir grains was evaluated for chokeberry juice fermentation. Chokeberry juice was retrieved from the variety Aronia melanocarpa, a plant known to provide small, dark berries and to be one of the richest sources of antioxidants. The juice was subsequently fermented inoculating L. paracasei SP5 for 48 h at 30 °C. The fermented juices were left at 4 °C and tested regarding microbiological and physicochemical characteristics for 4 weeks. The potentially probiotic strain was proved capable of performing lactic acid fermentation at 30 °C. Cell viability of L. paracasei was detected in high levels during fermentation and the whole storage period, while the fermented juice showed higher levels of viability in juice with 40.3 g/L of initial sugar concentration. No ethanol was detected in the final fermented juice. Fermented chokeberry juice was characterized by aromatic desirable volatiles, which were retained in adequate levels for the whole storage period. Specifically, the occurrence of organic esters detected in fermented juices is considered as positive evidence of the provision of fruity and floral notes to the final product. During storage, total phenolics content and antioxidant activity were observed in higher levels in fermented chokeberry juice compared with non-fermented juice. Subsequently, fermentation of chokeberry juice by potentially probiotic lactic acid bacteria could provide high industrialization potential, providing the market with a nutritional beverage of good volatile quality with an enhanced shelf-life compared with an unfermented fresh juice.

Combined Action of Piperitenone Epoxide and Antibiotics Against Clinical Isolates of Staphylococcus aureus and Escherichia coli.

The aim of this study was to determine the antimicrobial efficiency of piperitenone epoxide (PEO) - a principal component of various aromatic plants' essential oil - in combination with various antibiotics against 28 strains of Staphylococcus aureus and 10 strains of Escherichia coli isolated from clinical samples. Mentha spicata's essential oil, initially collected by hydrodistillation, was then subjected to flush column chromatography affording PEO of high purity. Minimum inhibitory concentrations of PEO alone and in combination with various concentrations of antibiotics were assessed using the microdilution method. The combined action was estimated calculating the fractional inhibitory concentration (FIC) index from checkerboard assays. Our results showed that the average minimum inhibitory concentration (mg/l) of PEO alone against E. coli was 512 ± 364.7 µg/ml, which was significantly higher than 172.8 ± 180.7 µg/ml observed for S. aureus. From checkerboard assays, FIC values below the 0.5 index, indicating synergy, were observed for 59% of the drugs tested. Twelve percent of FIC index values were between 0.5 and 1, indicating additive effects, while 21% were indifferent. According to our results, PEO could be a promising antimicrobial compound when combined with specific antibiotics and deserves further study.

Comparative Susceptibility Study Against Pathogens Using Fermented Cranberry Juice and Antibiotics.

In the present study, unfermented and fermented cranberry juice in combination with the Antibiotics vancomycin and tigecycline were tested for their antimicrobial activity. Cranberry juice was fermented with a recently isolated potentially probiotic Lactobacillus paracasei K5. The tested strains selected for this purpose were Enterococcus faecalis, E. faecium, Enterobacter cloacae and Staphylococcus aureus. The methods followed were the determination of zones inhibition, Minimum Inhibitory Concentration (MIC) and Fractional Inhibitory Concentration Index (FICI). Tigecycline together with fermented juice exhibited larger Zones of Inhibition (ZOI) in strains of E. faecium (65 ± 4.8 mm) compared to the respective ZOI with tigecycline and unfermented juice (no zone). The same outcome was also obtained with E. cloacae. Vancomycin together with fermented juice exhibited larger ZOI in strains of E. faecium (28 ± 2.2 mm) compared to the respective ZOI with vancomycin and unfermented juice (24 ± 2.3 mm). The lowest MIC values were recorded when tigecycline was combined with fermented cranberry juice against S. aureus strains, followed by the same combination of juice and antibiotic against E. cloacae strains. FICI revealed synergistic effects between fermented juice and tigecycline against a strain of E. faecium (A2020) and a strain of E. faecalis (A1940). Such effects were also observed in the case of fermented juice in combination with vancomycin against a strain of S. aureus (S18), as well as between fermented juice and tigecycline against E. cloacae (E1005 and E1007) strains. The results indicate that the antibacterial activity of juice fermented with the potentially probiotic L. paracasei K5 may be due to synergistic effects between some end fermentation products and the antibiotic agents examined.