Ramlibacter ginsenosidimutans sp. nov., with ginsenoside-converting activity

Ramlibacter paludis sp. nov., isolated from wetland

A Gram-stain-negative, non-motile, rod-shaped, aerobic and white-coloured bacterium (designated XY19^T) was isolated from a soil sample of wetland from Godeok Ecological Park, Gangdong-gu, Seoul, Republic of Korea. On the basis of 16S rRNA gene sequencing, strain XY19^T clustered with species of the genus Ramlibacter and appeared closely related to R. ginsenosidimutans DSM 23480^T (98.42 %), R. alkalitolerans JCM 32081^T (97.68 %) and R. monticola JCM 31918^T (97.66 %). The average nucleotide identity between strain XY19^T and three strains (R. ginsenosidimutans DSM 23480^T, R. alkalitolerans JCM 32081^T and R. monticola JCM 31918^T) were 80.7, 81.1 and 81.4 %. And the digital DNA-DNA hybridization (dDDH) calculated between strain XY19^T and each of the three strains (R. ginsenosidimutans DSM 23480^T, R. alkalitolerans JCM 32081^T and R. monticola JCM 31918^T) were 24.1, 24.4 and 24.5 %. ANI value and dDDH results were a novel species of the genus Ramlibacter. Growth occurs at 10-37 °C on R2A medium in the pressence of 0-1 % NaCl (w/v) and at pH 6.0-8.5. The DNA G+C content of the genomic DNA was 68.7 mol%, and ubiquinone-8 (Q-8) was the major respiratory quinone. The major cellular fatty acids (>5 %) were C_16:1  ω7c and/or C_16:1 ω6c (summed feature 3), C_16 : 0, C_17 : 0 cyclo and C_18:1  ω7c and/or C_18:1  ω6c (summed feature 8). The polar lipids consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, three unidentified lipids and unidentified aminophospholipid. Physiological and biochemical characteristics indicated that strain XY19^T represents a novel species of the genus Ramlibacter, for which the name Ramlibacter paludis sp. nov. is proposed. The type strain is XY19^T (= KACC 22220^T = LMG 32190^T).

Comparative genomic analyses of four novel Ramlibacter species and the cellulose-degrading properties of Ramlibacter cellulosilyticus sp. nov

In this study, four novel bacterial strains, USB13^T, AW1^T, GTP1^T, and HM2^T, were isolated from various environments in Busan and Jeju Island, Republic of Korea. The 16S rRNA sequencing results indicated that the four novel strains belong to the genus Ramlibacter. All four strains were tested for their potential cellulolytic properties, where strain USB13^T was identified as the only novel bacterium and the first within its genus to show cellulolytic activity. When tested, the highest activities of endoglucanase, exoglucanase, β-glucosidase, and filter paper cellulase (FPCase) were 1.91 IU/mL, 1.77 IU/mL, 0.76 IU/mL, and 1.12 IU/mL, respectively at pH 6.0. Comparisons of draft whole genome sequences (WGS) were also made using average nucleotide identity, digital DNA-DNA hybridization values, and average amino acid identity values, while whole genome comparison was visualized using the BLAST Ring Image Generator. The G + C contents of the strains ranged from 67.9 to 69.9%, while genome sizes ranged from 4.31 to 6.15 Mbp. Based on polyphasic evidence, the novel strains represent four new species within the genus Ramlibacter, for which the names Ramlibacter cellulosilyticus sp. nov. (type strain, USB13^T = KACC 21656^T = NBRC 114839^T) Ramlibacter aurantiacus sp. nov. (type strain, AW1^T = KACC 21544^T = NBRC 114862^T), Ramlibacter albus sp. nov. (type strain, GTP1^T = KACC 21702^T = NBRC 114488^T), and Ramlibacter pallidus sp. nov. (type strain, HM2^T = KCTC 82557^T = NBRC 114489^T) are proposed.

Effect of Polyvinyl Chloride Microplastics on Bacterial Community and Nutrient Status in Two Agricultural Soils

Knowledge of the influence of microplastics on soil microbiome and nutrients is important for understanding the ecological consequences of microplastic pollution in terrestrial ecosystems. In this study, we investigated whether polyvinyl chloride (PVC) microplastic pollution at environmentally relevant concentrations would affect soil bacterial community and available nitrogen/phosphorus content. The results showed that although PVC microplastics at 0.1% and 1% levels did not have a significant effect on overall bacterial community diversity and composition in soil over the course of 35 days, a number of bacterial genera were significantly reduced or enriched by the presence of microplastics. Potentially due to their effect on certain functional groups, microplastics caused a significant change in soil available P content. It is noteworthy that, depending on soil type, pollution level and plasticizer presence, contrasting effects of microplastics may be observed. Further research is definitely warranted to gain a clearer picture of the threats posed by microplastic pollution in soil environments.

Ramlibacter terrae sp. nov. and Ramlibacter montanisoli sp. nov., Isolated from Soil

Two gram-negative, catalase-positive, strictly aerobic, and white colony-forming bacteria, strains H242^T and B156^T, were isolated from soil in South Korea. Cells of strain H242^T were oxidase-positive and non-motile short rods, while those of strain B156^T were oxidase-negative and long non-motile rods. Ubiquinone-8 was identified as the sole isoprenoid quinone in both strains. C_16:0, cyclo-C_17:0, and summed feature 3 (C_16:1 ω7c and/or C_16:1 ω6c) and phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol were identified in both strains as the major cellular fatty acids and polar lipids, respectively. The DNA G+C contents of strains H242^T and B156^T were 69.4 mol% and 69.3 mol%, respectively. Phylogenetic analyses based on 16S rRNA and 92 concatenated core gene sequences revealed that strains H242^T and B156^T formed distinct phylogenic lineages from other Ramlibacter type strains. The DNA-DNA hybridization (DDH) value between strains H242^T and B156^T was 24.6%. Strains H242^T and B156^T were most closely related to Ramlibacter ginsenosidimutans BXN5-27^T and Ramlibacter monticola G-3-2^T with 98.4% and 98.6% 16S rRNA gene sequence similarities, respectively. Digital DDH values between strain H242^T and R. ginsenosidimutans and between strain B156^T and R. monticola were 23.5% and 26.1%, respectively. Phenotypic, chemotaxonomic, and molecular analyses indicated that strains H242^T and B156^T represent two novel species of the genus Ramlibacter, for which the names Ramlibacter terrae sp. nov. and Ramlibacter montanisoli sp. nov., respectively, are proposed. The type strains of R. terrae and R. montanisoli are H242^T (=KACC 21667 ^T =JCM 33922^T) and B156^T (=KACC 21665 ^T =JCM 33920^T), respectively.

Ramlibacter algicola sp. nov., isolated from a freshwater alga Cryptomonas obovoidea

A Gram-stain-negative, strictly aerobic, catalase-negative, oxidase-positive and non-motile rod-shaped bacterium, designated strain CrO1^T, was isolated from a freshwater alga Cryptomonas obovoidea in the Nakdong river of South Korea. Colonies of CrO1^T were white, convex and circular and growth was observed at 25-40 °C (optimum, 37 °C) and pH 6.0-9.0 (optimum, pH 7) and in the presence of 0-0.5 % (w/v) NaCl (optimum, 0 %). CrO1^T contained C_16 : 0, summed feature 5 (comprising C_18 : 0ante and/or C_18 : 2ω6,9c), C_18 : 0, summed feature 3 (comprising C_16 : 1ω7c and/or C_16 : 1ω6c) and summed feature 8 (comprising C_18 : 1ω7c and/or C_18 : 1ω6c) as the major cellular fatty acids (>5 %) and ubiquinone-8 as the sole respiratory quinone. Phosphatidylethanolamine was detected as the major polar lipid. The DNA G+C content of CrO1^T, calculated from the whole genome sequence was 69.6 mol%. CrO1^T was most closely related to Ramlibacter humi 18x22-1^T with a 97.6 % 16S rRNA sequence similarity and shared less than 97.4 % 16S rRNA sequence similarities with other type strains. Phylogenetic analyses based on the 16S rRNA gene and whole genome sequences revealed that CrO1^T formed a distinct phyletic lineage within the genus Ramlibacter. On the basis of the results of phenotypic, chemotaxonomic and molecular analysis, CrO1^T clearly represents a novel species of the genus Ramlibacter, for which the name Ramlibacter algicola sp. nov. is proposed. The type strain is CrO1^T (=KACC 19926^T=JCM 33302^T).

Ramlibacter pinisoli sp. nov., a novel bacterial species isolated from pine garden soil

A Gram-stain-negative, aerobic, non-motile and rod- or coccoid-shaped novel bacterial strain, designated MAH-25^T, was isolated from soil sampled in a pine garden. The colonies were observed to be light pink-coloured, smooth, spherical and 1-2 mm in diameter when grown on nutrient agar for 2 days. Strain MAH-25^T was found to be able to grow at 15-35 °C, at pH 5.0-8.0 and at 0-2.0 % NaCl. Cell growth occurred on Reasoner's 2A agar and nutrient agar. The strain was found to be positive in both oxidase and catalase tests. According to 16S rRNA gene sequence comparisons, the isolate was identified as a member of the genus Ramlibacter and closely related to Ramlibacter solisilvae 5-10^T (98.0 % similarity), Ramlibacter henchirensis TMB834^T (97.7 %), Ramlibacter tataouinensis TTB310^T (97.6 %) and Ramlibacter rhizophilus YS3.2.7^T (97.3 %). The average nucleotide identity and digital DNA-DNA hybridization values between strain MAH-25^T and the four closely related type strains were in the range of 78.8-81.3 % and 22.3-24.1 %, respectively. The novel strain MAH-25^T has a draft genome size of 5 505 957 bp (11 contigs), annotated with 5210 protein-coding genes, 46 tRNA and three rRNA genes. The genomic DNA G+C content was determined to be 70.3 mol%. The predominant isoprenoid quinone was ubiquinone 8 (Q-8). The major fatty acids were identified as C_16 : 0, summed feature 3 (C_16 : 1  ω7c and/or C_16 : 1  ω6c) and summed feature 8 (C_18 : 1  ω7c and/or C_18 : 1  ω6c). The main polar lipids were phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol. On the basis of DNA-DNA hybridization, genotypic analysis, chemotaxonomic and physiological data, strain MAH-25^T represents a novel species within the genus Ramlibacter, for which the name Ramlibacter pinisoli sp. nov. is proposed, with MAH-25^T (=KACC 19839^T=CGMCC1.13660^T) as the type strain.

Culture-Independent Analysis of Linuron-Mineralizing Microbiota and Functions in on-Farm Biopurification Systems via DNA-Stable Isotope Probing: Comparison with Enrichment Culture

Our understanding of the microorganisms involved in in situ biodegradation of xenobiotics, like pesticides, in natural and engineered environments is poor. On-farm biopurification systems (BPSs) treat farm-produced pesticide-contaminated wastewater to reduce surface water pollution. BPSs are a labor and cost-efficient technology but are still mainly operated as black box systems. We used DNA-stable isotope probing (DNA-SIP) and classical enrichment to be informed about the organisms responsible for in situ degradation of the phenylurea herbicide linuron in a BPS matrix. DNA-SIP identified Ramlibacter, Variovorax, and an unknown Comamonadaceae genus as the dominant linuron assimilators. While linuron-degrading Variovorax strains have been isolated repeatedly, Ramlibacter has never been associated before with linuron degradation. Genes and mobile genetic elements (MGEs) previously linked to linuron catabolism were enriched in the heavy DNA-SIP fractions, suggesting their involvement in in situ linuron assimilation. BPS material free cultivation of linuron degraders from the same BPS matrix resulted in a community dominated by Variovorax, while Ramlibacter was not observed. Our study provides evidence for the role of Variovorax in in situ linuron biodegradation in a BPS, alongside other organisms like Ramlibacter, and further shows that cultivation results in a biased representation of the in situ linuron-assimilating bacterial populations.

Cassava/peanut intercropping improves soil quality via rhizospheric microbes increased available nitrogen contents

Background

Intercropping, an essential cultivation pattern in modern agricultural systems, increases crop yields and soil quality. Cassava and peanut intercropping systems exhibit advantages in solar utilization and cadmium absorption, etc. However, the inner mechanisms need to be elucidated. In this study, Illumina MiSeq platform was used to reveal the rhizospheric microbes and soil quality in cassava/peanut intercropping systems, and the results provided a reference for the application of this method in studying other intercropping systems.

Results

Both intercropping cassava/peanut (IP) and intercropping peanut/cassava (IC) systems significantly increased available N, available K, pH value, and urease activity, comparing with that in monocropping cassava (MC) and monocropping peanut (MP) system. However, there were few effects on the total N, total P, total K, available P, organic matter, protease activity, catalase activity, sucrase activity, and acid phosphatase activity. Both IP and MP soils contained more bacteria and fungi than those in the IC and MC soils, which were mainly made of Proteobacteria and Actinobacteria. Intercropping remarkably increased the number of Nitrospirae in IP and IC soils comparing those in MC and MP soils. Redundancy analysis (RDA) revealed that the abundances of DA101, Pilimelia, and Ramlibacter were positively correlated to the soil quality. These results suggest that intercropping enhances the available nitrogen content of soil through increasing the quantity of rhizospheric microbes, especially that of DA101 and Pilimelia.

Conclusions

The cassava/peanut intercropping system improves soil quality through increasing the available nitrogen content and abundance of DA101, Pilimelia, and Ramlibacter in the soil.

Microbial Enrichment Culture Responsible for the Complete Oxidative Biodegradation of 3-Amino-1,2,4-triazol-5-one (ATO), the Reduced Daughter Product of the Insensitive Munitions Compound 3-Nitro-1,2,4-triazol-5-one (NTO)

3-Nitro-1,2,4-triazol-5-one (NTO) is one of the main ingredients of many insensitive munitions, which are being used as replacements for conventional explosives. As its use becomes widespread, more research is needed to assess its environmental fate. Previous studies have shown that NTO is biologically reduced to 3-amino-1,2,4-triazol-5-one (ATO). However, the final degradation products of ATO are still unknown. We have studied the aerobic degradation of ATO by enrichment cultures derived from the soil. After multiple transfers, ATO degradation was monitored in closed bottles through measurements of inorganic carbon and nitrogen species. The results indicate that the members of the enrichment culture utilize ATO as the sole source of carbon and nitrogen. As ATO was mineralized to CO₂, N₂, and NH₄⁺, microbial growth was observed in the culture. Co-substrates addition did not increase the ATO degradation rate. Quantitative polymerase chain reaction analysis revealed that the organisms that enriched using ATO as carbon and nitrogen source were Terrimonas spp., Ramlibacter-related spp., Mesorhizobium spp., Hydrogenophaga spp., Ralstonia spp., Pseudomonas spp., Ectothiorhodospiraceae, and Sphingopyxis. This is the first study to report the complete mineralization of ATO by soil microorganisms, expanding our understanding of natural attenuation and bioremediation of the explosive NTO.

Ramlibacter humi sp. nov., isolated from tropical forest soil

A Gram-stain-negative, aerobic and non-motile strain, designated 18x22-1^T, was isolated from a forest soil sample collected from Limushan Nature Reserve in Hainan Province, PR China. Growth occurred at 15-37 °C and pH 6.0-8.0 without NaCl. The 16S rRNA gene sequence analyses showed that strain 18x22-1^T was closely related to Ramlibacter tataouinensis DSM 14655^T (98.5 %), followed by Ramlibacter henchirensis DSM 14656^T (97.9 %) and other Ramlibacter species and formed a stable cluster with R. tataouinensis DSM 14655^T, R. henchirensis DSM 14656^T, Ramlibacter solisilvae JCM 19319^T and Ramlibacter rhizophilus CCTCC AB 2015357^T. Results of chemotaxonomic analyses showed that ubiquinone-8 (Q-8) was the major respiratory quinone, and the major fatty acids (>10 % of the total amounts) were C_16 : 0 and C_17 : 0cyclo. The major polar lipids were phosphatidylglycerol, diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, two unidentified aminopholipids and four unidentified phospholipids. The draft genome sequence was 4.47 Mb long with a G+C content of 68.9 mol%. The average nucleotide identity and digital DNA-DNA hybridization values between strain 18x22-1^T and four closely related type strains were in the range of 79.3-82.3 % and 21.9-25.1 %, respectively. The results of phenotypic, phylogenetic and chemotaxonomic analyses supported that strain 18x22-1^T represents a novel species of the genus Ramlibacter, for which the name Ramlibacterhumi sp. nov. is proposed. The type strain is 18x22-1^T (=GDMCC 1.1584^T=KCTC 52922^T).

Ramlibacter rhizophilus sp. nov., isolated from rhizosphere soil of national flower Mugunghwa from South Korea

A Gram-negative, aerobic, non-motile, long rods or coccoid without flagellum strain, designated THG-YS3.2.7^T, was isolated from therhizosphere soil of a Mugunghwa flower collected from Kyung Hee University, Yongin, South Korea. Growth occurred at 10-40 °C (optimum 28-37 °C), at pH 6-8 (optimum 7) and at 0-5 % NaCl (optimum 1 %). The predominant ubiquinone was ubiquinone 8 (Q-8). The major cellular fatty acids were C10 : 0, C10 : 0 3OH, C16 : 0, C17 : 0, C17 : 0 cyclo, C18 : 0, C18 : 3ω6c (6,9,12), summed feature 3 (C16 : 1ω7c and/or C16 : 1ω6c) and summed feature 8 (C18 : 1 ω7c and/or C18 : 1ω6c). The major polar lipids were diphosphatidylglycerol (DPG), phosphatidylglycerol (PG), phosphatidylethanolamine (PE), phosphatidylcholine (PC). The DNA G+C content of strain THG-YS3.2.7^T was 69.4 mol%. Based on 16S rRNA gene sequence analysis, the nearest phylogenetic neighbours of strain THG-YS3.2.7^T were identified as Ramlibacter henchirensis DSM 14656^T (97.92 %), Ramlibacter tataouinensis DSM 14655^T (97.90 %), Ramlibacter solisilvae KACC 17567^T (97.04 %). DNA-DNA hybridization values between strain THG-YS3.2.7^T and R. henchirensis DSM 14656^T, R. tataouinensis DSM 14655^T, R. solisilvae KACC 17567^T were 32.5±1.5, 43.1±1.1, 42.8±1.1 %, respectively. On the basis of the phylogenetic analysis, chemotaxonomic data, physiological characteristics and DNA-DNA hybridization data, strain THG-YS3.2.7^T represent a novel species of the genus Ramlibacter, for which the name Ramlibacter rhizophilus sp. nov. is proposed. The type strain is THG-YS3.2.7^T (=KCTC 52083^T=CCTCC AB 2015357^T).

Notification of changes in taxonomic opinion previously published outside the IJSEM

The Bacteriological Code deals with the nomenclature of prokaryotes. This may include existing names (the Approved Lists of Bacterial Names) as well as new names and new combinations. In this sense the Code is also dealing indirectly with taxonomic opinions. However, as with most codes of nomenclature there are no mechanisms for formally recording taxonomic opinions that do not involve the creation of new names or new combinations. In particular, it would be desirable for taxonomic opinions resulting from the creation of synonyms or emended descriptions to be made widely available to the public. In 2004, the Editorial Board of the International Journal of Systematic and Evolutionary Microbiology (IJSEM) agreed unanimously that it was desirable to cover such changes in taxonomic opinions (i.e. the creation of synonyms or the emendation of circumscriptions) previously published outside the IJSEM, and to introduce a List of Changes in Taxonomic Opinion [Notification of changes in taxonomic opinion previously published outside the IJSEM; Euzéby et al. (2004). Int J Syst Evol Microbiol 54, 1429–1430]. Scientists wishing to have changes in taxonomic opinion included in future lists should send one copy of the pertinent reprint or a photocopy or a PDF file thereof to the IJSEM Editorial Office or to the Lists Editor. It must be stressed that the date of proposed taxonomic changes is the date of the original publication not the date of publication of the list. Taxonomic opinions included in the List of Changes in Taxonomic Opinion cannot be considered as validly published nor, in any other way, approved by the International Committee on Systematics of Prokaryotes and its Judicial Commission. The names that are to be used are those that are the ‘correct names’ (in the sense of Principle 6) in the opinion of the bacteriologist, with a given circumscription, position and rank. A particular name, circumscription, position and rank does not have to be adopted in all circumstances. Consequently, the List of Changes in Taxonomic Opinion must be considered as a service to bacteriology and it has no ‘official character’, other than providing a centralized point for registering/indexing such changes in a way that makes them easily accessible to the scientific community.

Identification and characterization of a ginsenoside-transforming β-glucosidase from Pseudonocardia sp. Gsoil 1536 and its application for enhanced production of minor ginsenoside Rg2(S)

The ginsenoside Rg₂(S), which is one of the pharmaceutical components of ginseng, is known to have neuroprotective, anti-inflammation, and anti-diabetic effects. However, the usage of ginsenoside Rg₂(S) is restricted owing to the small amounts found in white and red ginseng. To enhance the production of ginsenoside Rg₂(S) as a 100 gram unit with high specificity, yield, and purity, an enzymatic bioconversion method was developed to adopt the recombinant glycoside hydrolase (BglPC28), which is a ginsenoside-transforming recombinant β-glucosidase from Pseudonocardia sp. strain Gsoil 1536. The gene, termed bglPC28, encoding β-glucosidase (BglPC28) belonging to the glycoside hydrolase family 3 was cloned. bglPC28 consists of 2,232 bp (743 amino acid residues) with a predicted molecular mass of 78,975 Da. This enzyme was overexpressed in Escherichia coli BL21(DE3) using a GST-fused pGEX 4T-1 vector system. The optimum conditions of the recombinant BglPC28 were pH 7.0 and 37°C. BglPC28 can effectively transform the ginsenoside Re to Rg₂(S); the K_m values of PNPG and Re were 6.36±1.10 and 1.42±0.13 mM, respectively, and the V_max values were 40.0±2.55 and 5.62±0.21 µmol min⁻¹ mg⁻¹ of protein, respectively. A scaled-up biotransformation reaction was performed in a 10 L jar fermenter at pH 7.0 and 30°C for 12 hours with a concentration of 20 mg/ml of ginsenoside Re from American ginseng roots. Finally, 113 g of Rg₂(S) was produced from 150 g of Re with 84.0±1.1% chromatographic purity. These results suggest that this enzymatic method could be usefully exploited in the preparation of ginsenoside Rg₂(S) in the cosmetics, functional food, and pharmaceutical industries.

Immunostimulatory effect of fermented red ginseng in the mouse model

In this study, Woongjin fermented red ginseng extract (WFRG) was evaluated for its potential ability to act as an adjuvant for the immune response of mice. For the in vitro study, macrophages were treated with serial concentrations (1 μg/mL, 10 μg/mL, and 100 μg/mL) of WFRG. For in vivo studies, mice were administered different concentrations (10 mg/kg/day, 100 mg/kg/day, and 200 mg/kg/day) of WFRG orally for 21 days. In vitro, the production of nitric oxide and TNF-α by RAW 264.7 cells increased in a dose-dependent manner. In vivo, WFRG enhanced the proliferation of splenocytes induced by two mitogens (i.e., concanavalin A and lipopolysaccharide [LPS]) and increased LPS-induced production of TNF-α and IL-6, but not IL-1β. In conclusion, WFRG has the potential to modulate immune function and should be further investigated as an immunostimulatory agent.

List of new names and new combinations previously effectively, but not validly, published

The purpose of this announcement is to effect the valid publication of the following effectively published new names and new combinations under the procedure described in the Bacteriological Code (1990 Revision). Authors and other individuals wishing to have new names and/or combinations included in future lists should send a covering letter, a copy of, or a link to the published paper and electronic copies of certificates of deposit from at least two culture collections in different countries to the IJSEM Editorial Office (ijsem@sgm.ac.uk) for confirmation that all of the other requirements for valid publication have been met. It is also a requirement of IJSEM and the ICSP that authors of new species, new subspecies and new combinations provide evidence that types are deposited in two recognized culture collections in two different countries. It should be noted that the date of valid publication of these new names and combinations is the date of publication of this list, not the date of the original publication of the names and combinations. The authors of the new names and combinations are as given below. Inclusion of a name on these lists validates the publication of the name and thereby makes it available in the nomenclature of prokaryotes. The inclusion of a name on this list is not to be construed as taxonomic acceptance of the taxon to which the name is applied. Indeed, some of these names may, in time, be shown to be synonyms, or the organisms may be transferred to another genus, thus necessitating the creation of a new combination.

Characterization of a ginsenoside-transforming β-glucosidase from Paenibacillus mucilaginosus and its application for enhanced production of minor ginsenoside F₂

A novel β-glucosidase (BglPm) was identified from Paenibacillus mucilaginosus KCTC 3870(T) which has ginsenoside converting activity. The gene, termed bglPm, consists of 1,260 bp and belongs to glycoside hydrolase family 1 (GH1). After being overexpressed and purified from Escherichia coli, the enzymatic properties of BglPm were investigated. The enzyme exhibited an optimal activity at 45°C and pH 7.5 and showed high bioconversion ability for major ginsenoside Rb1 and Rd into ginsenoside F2. Thus, it was used for mass production of relatively high pure F2 from relatively abundant protopanaxadiol type ginsenosides mixture (PPDGM) with combined usage of ginsenoside Rc-hydrolyzing enzyme. Scale-up of production using 250 g of the PPDGM resulted in 152 g of F2 with 80.1% chromatography purity and 95.7% recovery. These results suggest that this enzyme would be useful in the preparation of pharmacologically active ginsenoside F2 in the functional food and pharmaceutical industries.

Identification and characterization of a Mucilaginibacter sp. strain QM49 β-glucosidase and its use in the production of the pharmaceutically active minor ginsenosides (S)-Rh1 and (S)-Rg2

Here, we isolated and characterized a new ginsenoside-transforming β-glucosidase (BglQM) from Mucilaginibacter sp. strain QM49 that shows biotransformation activity for various major ginsenosides. The gene responsible for this activity, bglQM, consists of 2,346 bp and is predicted to encode 781 amino acid residues. This enzyme has a molecular mass of 85.6 kDa. Sequence analysis of BglQM revealed that it could be classified into glycoside hydrolase family 3. The enzyme was overexpressed in Escherichia coli BL21(DE3) using a maltose binding protein (MBP)-fused pMAL-c2x vector system containing the tobacco etch virus (TEV) proteolytic cleavage site. Overexpressed recombinant BglQM could efficiently transform the protopanaxatriol-type ginsenosides Re and Rg1 into (S)-Rg2 and (S)-Rh1, respectively, by hydrolyzing one glucose moiety attached to the C-20 position at pH 8.0 and 30°C. The Km values for p-nitrophenyl-β-d-glucopyranoside, Re, and Rg1 were 37.0 ± 0.4 μM and 3.22 ± 0.15 and 1.48 ± 0.09 mM, respectively, and the Vmax values were 33.4 ± 0.6 μmol min(-1) mg(-1) of protein and 19.2 ± 0.2 and 28.8 ± 0.27 nmol min(-1) mg(-1) of protein, respectively. A crude protopanaxatriol-type ginsenoside mixture (PPTGM) was treated with BglQM, followed by silica column purification, to produce (S)-Rh1 and (S)-Rg2 at chromatographic purities of 98% ± 0.5% and 97% ± 1.2%, respectively. This is the first report of gram-scale production of (S)-Rh1 and (S)-Rg2 from PPTGM using a novel ginsenoside-transforming β-glucosidase of glycoside hydrolase family 3.

Mass production of the ginsenoside Rg3(S) through the combinative use of two glycoside hydrolases

The ginsenoside Rg3(S), which is one of the exceptional components of Korean red ginseng extract, has been known to have anti-cancer, anti-metastatic, and anti-obesity effects. An enzymatic bioconversion method was developed to obtain the ginsenoside Rg3(S) with a high specificity, yield, and purity. Two glycoside hydrolases (BglBX10 and Abf22-3) were employed to produce Rg3(S) as a 100g unit. The conversion reaction transformed ginsenoside Rc to Rd using Abf22-3, followed by Rb1 and Rd to Rg3(S), using BglBX10. It was performed in a 10L jar fermenter at pH 6.0 and 37°C for 24h, with a high concentration of 50mg/ml of purified ginsenoside mixture obtained from ginseng roots. Finally, 144g of Rg3(S) was produced from 250g of root extract with 78±1.2% chromatographic purity. These results suggest that this enzymatic method would be useful in the preparation of ginsenoside Rg3(S) for the functional food and pharmaceutical industries.