Wild-simulated ginseng (WSG, Panax ginseng C.A. Meyer) must be cultivated in mountainous forests without installation of artificial facilities or treatment of chemicals. Because cultivation of these medicinal plants requires a long-term period, soil properties and rhizobacteria are known as major factors affecting their growth. This study was aimed to investigate correlations of soil bacterial community with soil chemical properties and growth of 10-year-old WSG. Most of the growth characteristics of WSG were higher in southern region than in northern regions, while leaflet length and leaflet width of WSG were higher in northern regions. In all WSG cultivation sites, the most dominant phyla were Proteobacteria and Acidobacteria in the bacterial community. In Principal component analysis (PCA), soil bacterial community was affected by exchangeable cations (calcium, magnesium), soil pH, total nitrogen, cation exchange capacity, and organic matter. Soil pH was the most effective factor in this study because all studied sites were acidic soils. In spearman’s coefficient analysis, 9 of 13 growth characteristics of WSG showed significantly positive correlation with the relative abundance of Actinobacteria, while rhizome length and number of rootlets showed significant negative correlations with population of Acidobacteria. Therefore, growth characteristics of WSG in different cultivation sites can be affected by various soil environmental factors. These results can help foresters find suitable cultivation sites for WSG.

Tolaasin, a pore-forming bacterial peptide toxin secreted by Pseudomonas tolaasii, causes brown blotch disease in cultivated mushrooms by forming membrane pores and collapsing the membrane structures. Tolaasin is a lipodepsipeptide, MW 1985, and pore formation by tolaasin molecules is accomplished by hydrophobic interactions and multimerizations. Compounds that inhibit tolaasin toxicity have been isolated from various food additives. Food detergents, sucrose esters of fatty acids, and polyglycerol esters of fatty acids can effectively inhibit tolaasin cytotoxicity. These chemicals, named tolaasin-inhibitory factors (TIF), were effective at concentrations ranging from 10⁻⁴ to 10⁻⁵ M. The most effective compound, TIF 16, inhibited tolaasin-induced hemolysis independent of temperature and pH, while tolaasin toxicity increased at higher temperatures. When TIF 16 was added to tolaasin-pretreated erythrocytes, the cytotoxic activity of tolaasin immediately stopped, and no further hemolysis was observed. In the artificial lipid bilayer, the single-channel activity of the tolaasin channel was completely and irreversibly blocked by TIF 16. When TIF 16 was sprayed onto pathogen-treated oyster mushrooms growing on the shelves of cultivation houses, the development of disease was completely suppressed, and normal growth of oyster mushrooms was observed. Furthermore, the treatment with TIF 16 did not show any adverse effect on the growth of oyster mushrooms. These results indicate that TIF 16 is a good candidate for the biochemical control of brown blotch disease.

Wild-simulated ginseng (WSG, Panax ginseng C.A. Meyer) is one of the most valuable medicinal plants in the world. This study aimed to investigate the correlation between growth and ginsenoside content of WSG in two different cultivation environments: coniferous and mixed forests. The results showed that air temperature, soil moisture content, and solar radiation were higher in mixed forest than in coniferous forest. Regarding soil properties, electrical conductivity, organic matter, total nitrogen, exchangeable potassium, and magnesium were higher in mixed forest than in coniferous forest. However, exchangeable sodium was lower in mixed forest than in coniferous forest. The analysis of growth characteristics revealed that the number of leaflets was significantly higher in WSG cultivated in mixed forest than in WSG cultivated in coniferous forest, whereas rhizome length, root diameter, root weight, and dry weight were significantly higher in coniferous forest. In contrast, total ginsenoside content and the content of each ginsenoside were much higher in WSG cultivated in mixed forest than in WSG cultivated in coniferous forest. The growth of WSG showed significantly positive correlations with electrical conductivity, organic matter, total nitrogen, exchangeable cations (K⁺, Mg²⁺, Na⁺), and cation exchange capacity. The number of leaflets per stem showed significantly positive correlations with six ginsenosides, whereas petiole length showed significantly negative correlations with mRb1, mRc, and Rb1. In conclusion, growth characteristics of WSG were higher in coniferous forest, but ginsenoside contents were higher in mixed forest. These results might be helpful for establishing the most optimal growth model of WSG, which is affected by various environmental factors.

Yeong-Bae Yun, Min-Hee Kim, Ji-Hye Han, and Young-Kee Kim. JABC 2017;60:179-84. https://doi.org/10.3839/jabc.2017.029