| Yhteenveto: | The global rise in antibiotic-resistant bacterial pathogens underscores the need for alternative antimicrobial agents, particularly natural sources like berries known for their high phenolic content. This study aimed to evaluate the antimicrobial properties of eight Finnish berry extracts (rowanberry, lingonberry, cloudberry, bilberry, raspberry, blackcurrant, raspberry, and chokeberry) against Streptococcus mutans, Staphylococcus aureus, Salmonella enterica serovar Typhimurium, Pseudomonas aeruginosa, and Escherichia coli. Extracts obtained from the Department of Chemistry were tested for antimicrobial activity using CFU/ml counts. Positive (ampicillin) and negative phosphate buffer saline, brain heart infusion and Luria-Bertani media (PBS, BHI and L-media) controls were used to assess bacterial viability, providing insights into the potential of these extracts as natural antibacterial agents. Minimum inhibitory concentrations were evaluated using a 96-well plate, with optical density recorded after 24 hours. Biofilm formation was analyzed with crystal violet staining and absorbance at 595 nm. Colony-forming unit measurements yielded inconsistent results across different conditions, leading the study to focus on analyses conducted in liquid media to better evaluate the antimicrobial effects of berry extracts. Berry extracts inhibited E. coli growth, with higher concentrations (0.1 mg/ml, 0.01 mg/ml) showing significant OD reductions; rowanberry, lingonberry, cloudberry, and raspberry were most effective. Bilberry strongly inhibited E. coli and S. Typhimurium. Streptococcus mutans were inhibited by cloudberry and raspberry, while minimal effects were seen on S. mutans. Pseudomonas aeruginosa showed resistance. Staphylococcus aureus had moderate susceptibility, with rowanberry and cloudberry reducing growth at 0.1 mg/ml. Ampicillin consistently showed superior efficacy over berry extracts. This study concludes that Finnish berry extracts, especially at higher concentrations, show promise as natural antibacterial agents against E. coli and S. mutans, supporting their further exploration as complementary treatments for resistant pathogens.
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