Chryseobacterium panacisoli sp. nov., isolated from ginseng-cultivation soil with ginsenoside-converting activity

A Gram-stain-negative, non-motile, non-spore-forming, aerobic, rod-shaped and yellow-pigmented bacterium, designated strain Gsoil 183T, was isolated from ginseng-cultivation soil sampled in Pocheon Province, Republic of Korea. This bacterium was characterized to determine its taxonomic position by using a polyphasic approach. Strain Gsoil 183T grew at 10–37 °C and at pH 5.0–9.0 on tryptic soy agar. Strain Gsoil 183T had β-glucosidase activity, which was responsible for its ability to convert ginsenoside Rb1 (one of the dominant active components of ginseng) to F2. Based on 16S rRNA gene sequencing, strain Gsoil 183T clustered with species of the genus Chryseobacterium and appeared to be closely related to Chryseobacterium sediminis LMG 28695T (99.1 % sequence similarity), Chryseobacterium lactis NCTC 11390T (98.6%), Chryseobacterium rhizoplanae LMG 28481T (98.6%), Chryseobacterium oncorhynchi CCUG 60105T (98.5%), Chryseobacterium viscerum CCUG 60103T (98.4%) and Chryseobacterium joostei DSM 16927T (98.3%). Menaquinone MK-6 was the predominant respiratory quinone and the major fatty acids were iso-C15 : 0, iso-C17 : 0-3OH and summed feature 3 (C16 : 1 ω6c and/or C16 : 1 ω7c). The polar lipids were phosphatidylethanolamine, six unidentified glycolipids, five unidentified aminolipids and three unidentified lipids. The G+C content of the genomic DNA was 36.6 mol%. Digital DNA–DNA hybridization between strain Gsoil 183T and the type strains of C. sediminis , C. lactis , C. rhizoplanae , C. oncorhynchi , C. viscerum and C. joostei resulted in values below 70 %. Strain Gsoil 183T could be differentiated genotypically and phenotypically from the recognized species of the genus Chryseobacterium . The isolate therefore represents a novel species, for which the name Chryseobacterium panacisoli sp. nov. is proposed, with the type strain Gsoil 183T (=KACC 15033T=LMG 23397T)

Allelopathic effects of ginsenoside on soil sickness, soil enzymes, soil disease index and plant growth of Ginseng

Soil sickness of ginseng (Panax ginseng C. A. Mey.) has become a major limiting factor in ginseng cultivation. We found that Total Ginsenoside in Ginseng Root (TSPG) significantly decreased the activities of soil urease, acid phosphatase and laccase. Its high concentration of TSPG (10.00 mg L-1) significantly reduced the activity of soil sucrose. Besides, the TSPG can inhibited the growth of ginseng and increased the incidence of disease. Therefore, allelopathic effects of TSPG may be one of the main causes of Soil Sickness in ginseng.

Multi-Locus Phylogeny and Taxonomy of the Fungal Complex Associated With Rusty Root Rot of Panax ginseng in China

Panax ginseng rusty root rot caused by the Ilyonectria species complex is a devastating disease, and it is one of the main factors contributing to the difficulty in continual cropping. Rusty root rot occurs in all ginseng fields, but little is known about the taxonomy of the fungal pathogen complex, especially Ilyonectria and Ilyonectria-like species. Rusty root rot samples were collected from commercial ginseng cultivation areas of China, and the pathogens were isolated and purified as single spores. Based on the combination analysis of multiple loci (rDNA-ITS, TUB, HIS3, TEF, ACT, LSU, RPB1, RPB2, and SSU) and morphological characteristics, the pathogens causing ginseng rusty root rot were determined. Fungal isolates were obtained from infected roots in 56 locations within main cultivation areas in China. A total of 766 strains were identified as Ilyonectria, Ilyonectria-like and Rhexocercosporidium species, including I. robusta (55.0%), I. communis (21.7%), I. mors-panacis (10.9%), I. pseudodestructans (2.0%), I. changbaiensis (1.3%), I. qitaiheensis (1.3%), Neonectria obtusispora (2.0%), Dactylonectria torresensis (0.5%), D. sp. (0.5%), and R. panacis (1.5%), and four novel species, Thelonectria ginsengicola (1.0%), T. jixiensis (1.0%), T. mulanensis (0.8%) and T. fusongensis (0.5%), with a total of 14 species. As the pathogen present in the highest proportion, I. robusta was the most prevalent and damaging species, unlike the pathogens reported previously. All of the examined strains were proven to cause ginseng rusty root rot. Our results indicate that the taxonomy of the fungal complex associated with ginseng rusty root rot includes Ilyonectria, Ilyonectria-like genera (Dactylonectria, Neonectria, and Thelonectria) and Rhexocercosporidium.

The fungal community in non-rhizosphere soil of Panax ginseng are driven by different cultivation modes and increased cultivation periods

Continuous cropping obstacles severely hindered the sustained development of the ginseng industry. Among the obstacles, an imbalance of soil microbiome community was considered one of the major culprits. The fungal community is an essential part of the soil microbiome community. Extensive characterization of the fungal community composition and variation during ginseng cultivation will help us understand the mechanism underlying continuous cropping obstacles. By using a high-throughput amplicon sequencing method, the non-rhizospheric fungal community of farmland cultivated ginseng of 2 years old (C2) and 5 years old (C5), understory wild ginseng of 15 years old (W15) and 35 years old (W35), fallow fields which have been abandoned for 10 (F10) years were characterized. Farmland cultivated ginseng and understory wild ginseng harbored distinct non-rhizospheric fungal communities, and extension of cultivation periods enlarged the fungal community difference between two cultivation modes. Extended cultivation periods significantly decreased the OTU richness and PD whole tree indices, and OTU number and cultivation periods were negatively correlated. Extension of cultivation periods led to an increased abundance of pathotrophs. Still, the increased abundance of pathotrophs may not be the leading cause of severe continuous cropping obstacles in farmland cultivated ginseng. Compared with understory wild ginseng, farmland cultivated ginseng had a lower abundance of symbiotrophs and a higher abundance of saprotrophs. This changed symbiotrophs/saprotrophs ratio may have some correlation with the severe continuous cropping obstacles that occurred in farmland cultivated ginseng. Fallowing on the fungal community of the non-rhizosphere soil was generally opposite of that of extension of ginseng cultivation periods. The impacts of farmland cultivation on the fungal community of the non-rhizosphere soil can last for decades, even if the following is practiced.

Machine learning for a rapid discrimination of ginseng cultivation age using 1H-NMR spectra

The scientific and systematic classification of cultivation age is important for preventing age falsification and ensuring the quality of ginseng. Therefore, we applied deep learning to classify the cultivation age of ginseng. Deep learning, which is based on an artificial neural network, is one of the new class of models for machine learning, and is state-of-the-art. It is a powerful tool and has been used to solve complex problems in many fields. In the present study, powdered samples of 4-, 5-, and 6-year-old ginseng were measured using high-resolution magic angle spinning nuclear magnetic resonance (HR-MAS NMR) spectroscopy. NMR data were analyzed with deep learning and partial least-squares discriminant analysis (PLS-DA) to improve accuracy. The accuracy of the PLS-DA was 87.1% and the accuracy of the deep learning model was 93.9%. NMR spectroscopy with deep learning can be a useful tool for discrimination of ginseng cultivation age.