We have previously examined the antimicrobial activity of sweet cherry (Prunus avium L.) extracts on a wide
spectrum of gram-positive and gram-negative bacteria in addition to the fungus, Candida albicans. To further understand
the effect of a variety of extracts of a related family of sour, tart cherries (Prunus cerasus L.) on bacterial and fungus
growth, the antimicrobial activities of black sour cherry extracts (SCE) were measured in culture. SCEs were subdivided
into variables: Whole juice extracts (WJE), methanol-extracted juice (MEJ), ddH2O-extracted pomace (dPOM), and
methanol-extracted pomace (mPOM). Bacteria and fungus were culturally grown on Mueller-Hinton agar suitable for
disk-diffusion method. WJE showed prominent inhibition of Enterococcus Group D (EGD), Staphylococcus aureus,
Citrobacter koseri, Enterobacter cloacae, and Klebsiella pneumoniae, with minor attenuation of Bacillus subtilis, Escherichia
coli ESBL, Proteus vulgaris, and C. albicans. By contrast, MEJ exhibited substantial inhibition of EGD, S.
aureus, Streptococcus Group A (GAS), Streptococcus Group B (GBS), E. cloacae, E. coli, E. coli ESBL, and K. pneumoniae,
with minor attenuation of B. subtilis, P. vulgaris, and C. albicans. Interestingly, prominent inhibitory/attenuation effect
was reported with dPOM on EGD, S. aureus, GAS, C. koseri, K. pneumoniae, and P. vulgaris, with minor effect on
E. cloacae, E. coli, E. coli ESBL, and C. albicans. Furthermore, mPOM exhibited substantial inhibition of EGD, S.
aureus, E. coli, K. pneumoniae, and P. vulgaris, with attenuation of GAS, and E. coli ESBL. Of note, whilst WJE, MEJ,
and dPOM had no tangible, measurable effect on P. aeruginosa, mPOM significantly inhibited this pathogen. These results
confirm the attenuating effect of black sour P. cerasus extracts on the differential growth of gram-positive and gramnegative
bacteria, and fungus. Since many of the aforementioned are pathogenic in their nature, sour cherry extracts are
interestingly of value in regulating and attenuating the growth of microorganisms of medical importance.