Bioactive compounds obtained from Coriolus versicolor (Trametes versicolor (L.: Fr) Lloyd, 1920.) mushrooms cultivated
in a stirred-tank bioreactor were tested to determine their antimicrobial potential. Extracellular polysaccharides
were isolated from the fermentation broth by ethanol precipitation. A methanol extract was prepared
from mycelium. The cultivation conditions applied during the fermentation process provided for significant
biomass 6.63 ± 0.31 g dry weight L−1 and yield of extracellular polysaccharides (EPS) (0.74 ± 0.12 g L−1
).
Microscopic analyses revealed that the mycelium grew predominately in the form of fluffy pellets. The methanol
extract demonstrated very good activity against all the tested Gram-positive bacteria. Bacillus spizizeni
and Staphylococcus epidermidis were the most sensitive strains (minimum inhibitory concentration
(MIC) b0.3125 mg mL−1
). Among the Gram-negative bacteria, Yersinia enterocolitica had the lowest
MIC value, 5 mg mL−1
. Microbicidal activity of mycelia methanol extract was established in seven out of
ten tested Gram-negative bacteria strains with minimum bactericidal concentration (MBC) values ranged
from 20 to 40 mg mL−1
. Enterococcus faecalis and Staphylococcus aureus showed higher sensitivity to the
extracellular polysaccharides (MIC values 2.5 mg mL−1
). FTIR analysis revealed a more complex chemical
composition of the methanol extract compared to EPS, which might explain the better antibacterial activity
of the methanol extract.
Our results suggested that the submerged cultivation of Coriolus versicolor followed by ethanol precipitation
of EPS and the methanol extraction of mycelia can be a promising process to obtain biological active
compounds with significant antimicrobial activity.
Industrial Relevance: Mushrooms contain a large number of chemicals with potential use as antimicrobial
compounds.
One of the biggest challenges for providing biologically active compounds from mushrooms is short-term process
standardization with a low risk for contamination. Submerged culture cultivation is the best choice for providing
antimicrobial compounds from mushrooms. The submerged culture method represents an effective and energyefficient
means to produce novel antibacterial compound from mushrooms. Antibacterial activity testing
revealed that methanol extract and isolated exopolysaccharides exhibited strong antibacterial activity, especially
against Gram-positive bacteria.