The effect of Chinese wild blueberry fractions on the growth and membrane integrity of various foodborne pathogens

Abstract

The objective of this study was to evaluate the antibacterial effect of Chinese wild blueberry extract and its fractions against Listeria monocytogenes, Staphylococcus aureus, Salmonella Enteritidis, and Vibrio parahaemolyticus. Chinese wild blueberry (Vaccinium uliginosum) crude extract (BBE) was obtained using methanol extraction, and sugars plus organic acids (F1), phenolics fraction (F2), and anthocyanins plus proanthocyanidins (F3) fractions were separated using C‐18 Sep‐Pak columns. The minimal inhibitory concentration and minimal bactericidal concentration of each fractional component were determined using a two‐fold‐serial dilution method. Nucleic acid leakage (OD260 nm) and protein release (Bradford protein assay) were determined by spectrophotometry, to evaluate the permeability of the cell membrane. F3 was found to exhibit the greatest antimicrobial activity against the four tested strains, followed by F2, F1, and BBE. V. parahaemolyticus was the most sensitive to the all fractions, followed by S. Enteritidis, L. monocytogenes, and S. aureus. Survival curve analysis showed that the number of bacteria decreased from six log colony‐forming units (CFU) to less than 10 CFU after bacteria were treated with fractions for 12 hr, which demonstrated the bactericidal effect of blueberry fractions. Furthermore, when the pathogens were treated with fractions for 2 hr, the OD260 nm and OD595 nm values increased significantly (P < 0.01), which indicated the significant release of nucleic acid and protein. The results from this study indicated that blueberry fractions, especially F3, inhibited the growth of foodborne pathogens by damaging their cell membrane, and may be developed as a natural preservative to prevent and control foodborne pathogens.Practical ApplicationA blueberry crude extract and its sugars plus organic acids, phenolics, and anthocyanins plus proanthocyanidins fractions, inhibited the growth of foodborne pathogens by destroying their cell membrane. Therefore, Chinese wild blueberries have potential as a natural preservative to prevent and control foodborne pathogens.

Anthocyanins in Blueberries Grown in Hot Climate Exert Strong Antioxidant Activity and May Be Effective against Urinary Tract Bacteria

“…Similarly, compounds in purified proanthocyanins from cranberry extracts inhibited the agglutination of E. coli and K. pneumoniae [ 88 ]. However, this effect was strain- specific and dose-dependent [ 53 , 88 ]. Blueberry extracts affected the growth of E. coli and P. aeruginosa , and they were able to significantly inhibit their biofilm formation and bacterial adhesion [ 50 ]—both important factors in their surface colonisation and infection [ 54 ].…”

“…Additionally, Sun et al [ 52 ] obtained lower MICs and MBCs of L. monocytogenes and S. Enteritidis (MIC=0.27 mg/mL; MBC = 0.53) for blueberry anthocyanins. Other studies dealing with blueberry extracts presented MIC of L. monocytogenes ranging from 100 to 300 mg/mL and an MBC of 100 to 450 mg/mL, while for S. Enteritidis, a MIC of 100 to 450 mg/mL and an MBC of 100 to 600 mg/mL [ 49 , 53 ]. However, Zhou et al [ 53 ] also suggested that L. monocytogenes might be more resistant than S. Enteritidis.…”

“…Many studies have reported the antibacterial activity of anthocyanins extracted from blueberries against various Gram-positive ( Listeria monocytogenes , Staphylococcus aureus and Clostridium perfringens ) and Gram-negative ( Salmonella enterica , E. coli and Campylobacter spp.) foodborne pathogens [ 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 ]. However, many of these studies were performed with complex extracts, obtained using different methods.…”

Whole Blueberry and Isolated Polyphenol-Rich Fractions Modulate Specific Gut Microbes in an In Vitro Colon Model and in a Pilot Study in Human Consumers

“…Four major ingredient fractions of BB were prepared essentially as previously described in several previous publications [32][33][34][35][36][37]. In detail, whole frozen BB, cv.…”

“…To further elucidate the interactions between BB ingredients and the human gut microbiome, we profiled the compositional changes that occurred in batch fermentations inoculated with the fecal microbiota of healthy young adults and supplemented with isolated BB polyphenol-rich fractions. These fractions are individually enriched for different major classes of presumptive bioactive BB ingredients, and have been tested for their activity in multiple previous publications [33][34][35][36][37]. To detect microbiota taxa that are responsive to human BB consumption, 17 healthy female volunteers in two age groups consumed freeze-dried BB for 6 weeks, and their gut microbiota composition was analyzed before and after the dietary intervention.…”