| Summary: | Abstract In this work antimicrobial activity of eight Finnish berries and their phenolic extracts were measured against selected Gram-positive and Gram-negative human pathogens. The results showed that berry compounds selectively inhibit the growth of pathogenic bacterial species, specially Salmonella and Staphylococcus strains, and cloudberry and raspberry were the best inhibitors. In general, berry compounds did not affect the growth of probiotic Lactobacillus rhamnosus strain and of Listeria strains. The only exception was cranberry, which inhibited the growth of Listeria bacteria. Introduction Berries are good sources of plant phenolics which besides their other health-inducing effects have been found to possess antimicrobial activities. Our previous studies showed that phenolic berry extracts especially inhibited the growth of Gram-negative but not Gram-positive bacteria such as Lactobacillus. Especially cloudberry, raspberry and strawberry extracts proved to be strong inhibitors of the avirulent Salmonella (I ). Materials and methods Bilberry (Vaccinium myrtillus), lingonberry (Vaccinium vitis-idaea), cranberry (Vaccinium oxycoccus), raspberry (Rubus idaeus, var. Ottawa), cloudberry (Rubus chamaemorus), strawberry (Fragaria ananassa Seaga Sengana), blackcurrant (Rites nigrum, var. Ojeby) and sea buckthorn berry (Hippophae rhamnoides), were used in the study. For antimicrobial studies berries were freeze-dried and ground to fine powder. Phenolics were extracted from the berries by aqueous 70% acetone (2). Antimicrobial activity of freeze-dried grounded berries (2 or 10 mg/ml) and phenolic berry extracts (1 or 5 mg/ml) was analysed by determining the bacterial growth curves in liquid cultures (I). The bacterial strains used were Listeria monocytogenes VTT E-991205, L. innocua VTT E-981011, Salmonella enterica ser. Typhimurium VTT E-981151, S. enterica ser. Infantis VTT E-97738, Staphylococcus aureus VTT E-70045 and Lactobacillus rhamnosus VTT E-96666 (ATCC 53103). Results discussion Salmonella strains were ...
|
|---|