Conversion of major ginsenoside Rb1 to 20(S)-ginsenoside Rg3 by Microbacterium sp. GS514

Ginseng saponin, the most important secondary metabolite in ginseng, has various pharmacological activities. Many studies have been directed towards converting major ginsenosides to the more active minor ginsenoside, Rg3. Due to the difficulty in preparing ginsenoside Rg3 enzymatically, the compound has been mainly produced by either acid treatment or heating. A microbial strain GS514 was isolated from soil around ginseng roots in a field and used for enzymatic preparation of the ginsenoside Rg3. Blast results of the 16S rRNA gene sequence of the strain GS514 established that the strain GS514 belonged to the genus Microbacterium. Its 16S rRNA gene sequence showed 98.7%, 98.4% and 96.1% identity with those of M. esteraromaticum, M. arabinogalactanolyticum and M. lacticum. Strain GS514 showed a strong ability to convert ginsenoside Rb1 or Rd into Rg3. Enzymatic production of Rg3 occurred by consecutive hydrolyses of the terminal and inner glucopyranosyl moieties at the C-20 carbon of ginsenoside Rb1 showing the biotransformation pathway: Rb1-->Rd-->Rg3.     

Microbial conversion of ginsenoside Rb1 to minor ginsenoside F2 and gypenoside XVII by Intrasporangium sp. GS603 isolated from soil

A new strain, GS603, having beta-glucosidase activity was isolated from soil of a ginseng field, and its ability to convert major ginsenoside Rb(1) to minor ginsenoside or gypenoside was studied. Strain GS603 was identified as an Intrasporangium species by phylogenetic analysis and showed high ginsenoside-converting activity in LB and TSA broth but not in nutrient broth. The culture broth of the strain GS603 could convert ginsenoside Rb(1 )into two metabolites, which were analyzed by TLC and HPLC and shown to be the minor ginsenoside F(2) and gypenoside XVII by NMR.     

Extraction of ginsenosides from fresh ginseng roots (Panax ginseng C.A. Meyer) using commercial enzymes and high hydrostatic pressure

A combination of high hydrostatic pressure (HHP) and enzymatic hydrolysis (HHP-EH) was applied for the extraction of ginsenosides from fresh ginseng roots (Panax ginseng C.A. Myer). The highest yield of ginsenosides was obtained by using a mixture of three enzymes (Celluclast + Termamyl + Viscozyme) along with HHP (100 MPa, at 50 °C for 12 h) in comparison to control samples (no enzymes, atmosphere pressure, P < 0.05). Total ginsenosides increased by 184 % while Rg1 + Rb1 increased by 273 %. Application of these conditions significantly increased total ginsenosides by 49 % and Rg1 + Rb1 by 103 % compared to HHP treatment alone (P < 0.05). The effect of HHP on increased yield of ginsenosides is likely due in part, to acceleration of enzyme activity. Thus HHP-EH significantly improves the extraction of ginsenosides from fresh ginseng roots.     

Flavobacterium kyungheensis sp. nov., isolated from soil of a ginseng field

A Gram-staining negative, strictly aerobic, motile by gliding, non-spore-forming, pale yellow pigmented and rod-shaped bacterium designated strain THG-107^T was isolated from soil of a ginseng field on Ganghwa Island in the Republic of Korea and its taxonomic position was investigated by using a polyphasic study. Growth of strain THG-107^T was found to occur at 4–37 °C (optimum, 20–30 °C), at pH 5.5–10 (optimum, pH 7.0) and in the presence of 0–1 % (w/v) NaCl (optimum, absence) on R2A agar. On the basis of 16S rRNA gene sequence similarity, strain THG-107^T was shown to belong to the family Flavobacteriaceae and was related to Flavobacterium denitrificans ED5^T (99.1 % similarity). The G+C content of the genomic DNA was determined to be 34.2 mol%. These results are consistent with characteristics of members of the genus Flavobacterium. The only isoprenoid quinone detected in strain THG-107^T was menaquinone-6 (MK-6) and the major polyamine was identified as homospermidine (82.9 %). The major polar lipid detected was phosphatidylethanolamine and the major cellular fatty acids were identified as iso-C_15:0 (26.3 %), iso-C_17:0 3OH (12.6 %) and summed feature 3 (comprising C_16:1 ω7c and/or C_16:1 ω6c; 11.6 %). Flexirubin-type pigments were found to be present. Strain THG-107^T has β-glucosidase activity to convert ginsenosides Rb₁ and Rd into Gyp17 and F₂. DNA-DNA hybridization with F. denitrificans ED5^T was 52 %. Strain THG-107^T could be distinguished from F. denitrificans ED5^T and the other species of the genus Flavobacterium by its phylogenetic and genetic distinctiveness and by several phenotypic properties. Therefore, strain THG-107^T is considered to represent a novel species in the genus Flavobacterium, for which the name Flavobacterium kyungheensis sp. nov. is proposed (type strain THG-107^T = KACC 16219^T = LMG 26575^T).     

Growth kinetics and ginsenosides production in transformed hairy roots of American ginseng—Panax quinquefolium L

A thin, profusely branched, fast growing hairy root line of Panax quinquefolium (American ginseng) was established by co-culturing epicotyl explants with a wild type strain of Agrobacterium rhizogenes. The transformed roots grew by over 10-fold from the initial inoculum within 8 weeks. The crude ginsenosides content in the roots was about 0.2 g/g dry wt level up to the 10th week of culture. Ginsenosides Rb2, Rd, Re, Rf and Rg1 constituted 47–49% of the crude saponin fraction between 6 and 8 weeks of growth whereas, Rc ginsenoside was accumulated only after 9th weeks when the biomass started receding. PCR amplification analysis of the hairy roots confirmed their transgenic nature by showing the presence of Ri-TL DNA with rolA, rolB and rolC genes in their genome.     

Chryseobacterium yeoncheonense sp. nov., with ginsenoside converting activity isolated from soil of a ginseng field

A Gram-staining negative, aerobic, non-motile, non-flagellate, yellow-pigmented, rod-shaped bacterial strain, designated strain DCY67^T, was isolated from ginseng field in Republic of Korea. Strain DCY67^T contained β-glucosidase activity which converts ginsenoside Rb1 to compound K. Optimum growth of DCY67^T occurred at 30 °C and pH 6.0–6.5. Analysis of the 16S rRNA gene sequences revealed that strain DCY67^T belonged to the family Flavobacteriaceae and was most closely related to Chryseobacterium ginsenosidimutans THG 15^T (97.5 %). The genomic DNA G+C content was 36.1 mol%. The predominant quinones were MK-6 (90.9 %) and MK-7 (9.15 %). The major fatty acids were iso-C_15:0, summed feature 3 (containing C_16:1 ω7c and/or C_16:1 ω6c) and iso-C_17:0 3-OH. On the basis of these phenotypic, genotypic and chemotaxonomic studies, strain DCY67^T represents a novel species of the genus Chryseobacterium, for which, name Chryseobacterium yeoncheonense sp. nov. proposed the type strain is DCY67^T (=KCTC 32090^T = JCM 18516^T).     

Comparison of ginsenoside composition in native roots and cultured callus cells of Panax quinquefolium L.

In order to compare the ginsenoside composition in native Panax quinquefolium and in suspension cultured cells derived from root callus, HPLC–ESI-MSⁿ analysis was performed. Under the present HPLC–ESI-MSⁿ conditions, ten ginsenosides from native root were acquired in the positive and negative ion modes, namely Rg₁, Re, Ro, malonyl-Rb₁, Rf, Rb₁, Rc, Rb₂, Rb₃ and Rd. Only four ginsenosides (Rg1, Re, Rf and Rb1) were identified from callus cells. Radical scavenging activity of P. quinquefolium callus cells with 250 mg l^?1 methanolic extract on 1,1-diphenyl-2-picrylhydrazyl (DPPH) was 55.72 %, while only 6.31 % DPPH inhibition was obtained in native root.     

Efficient biotransformation for preparation of pharmaceutically active ginsenoside Compound K by Penicillium oxalicum sp. 68

Pathogenic fungus Penicillium oxalicum sp. 68 was screened from soil and identified by ITS sequencing. The strain was found to be able to transform protopanaxadiol-type ginsenosides to produce a series of bioactive metabolites. Glycosidase from the culture of P. oxalicum sp. 68 was partially purified with a simple two-step procedure consisting of DEAE-cellulose chromatography and ammonium sulfate precipitation. Bioactive ginsenoside Compound K was prepared selectively and efficiently by biotransformation of ginsenosides Rb1, Rb2, Rc and Rd using the partially purified glycosidase. The optimal conditions for transforming Rb1 into Compound K were pH 4.0, 55 °C and 0.5 mg mL^?1 Rb1. The sole product is Compound K and the maximum yield reached 87.7 % (molar ratio). The transformation pathways of Rb1, Rb2, Rc and Rd are Rb1→Rd→F2→Compound K, Rb2→CO→CY→Compound K, Rc→Mb→Mc→Compound K and Rd→F2→Compound K, respectively. This biotransformation method showed great potential for preparing minor bioactive ginsenosides, especially Compound K, in the pharmaceutical industry because of its high specificity and favorable environmental compatibility.     

Ginsenosidases and the pathogenicity of Pythium irregulare

American ginseng (Panax quinquefolius L.) produces triterpenoid saponins, ginsenosides, that possess mild fungitoxic activity toward some common ginseng leaf pathogens. However, numerous oomycete root pathogens of ginseng, most notably Pythium irregulare Buisman, are able to partially deglycosylate 20 (S)-protopanaxadiol ginsenosides Rb1, Rd and gypenoside XVII via extracellular glycosidases, leading to a common product, ginsenoside F2. Conversion of the common 20 (S)-protopanaxadiols into F2 requires both β (1 → 6) and β (1 → 2) glucosidase activity. In the present study, the ability of nine distinct isolates of P. irregulare, as well as a P. ultimum Trow isolate and two isolates of Trichoderma hamatum (Bonord.) Bainier, to deglycosylate 20 (S)-protopanaxadiols, in vitro was examined. The pathogenicity of each isolate was also examined by scoring the severity of disease symptoms caused by each in separate inoculations of one- and two-year old ginseng seedlings. Disease severity was scored using a disease severity index, as well as by taking F_v/F_m measurements of leaves during a 14-day infection period. Based on these measurements, it was concluded that (1) the use of direct F_v/F_m measurements correlates strongly with observations of disease severity (R² = 0.79), and that (2) the pathogenicity of P. irregulare isolates correlates with their ability to deglycosylate ginsenosides (R² = 0.57). These results further support the hypothesis that the pathogenicity of P. irregulare on ginseng roots is dependent, in part, on the ability of this organism to deglycosylate ginsenosides.     

Nocardioides panaciterrulae sp. nov., isolated from soil of a ginseng field, with ginsenoside converting activity

A Gram-positive, coccoid to rod-shaped, non-spore-forming bacterium, designated Gsoil 958^T, was isolated from soil of a ginseng field located in Pocheon province in South Korea. This bacterium was characterized in order to determine its taxonomic position by using a polyphasic approach. Strain Gsoil 958^T was observed to grow well at 25–30 °C and at pH 7.0 on R2A and nutrient agar without NaCl supplementation. Strain Gsoil 958^T was determined to have β-glucosidase activity and the ability to transform ginsenoside Rb₁ (one of the dominant active components of ginseng) to F₂ via gypenoside XVII and Rd. On the basis of 16S rRNA gene sequence similarity, strain Gsoil 958^T was shown to belong to the family Nocardioidaceae and related most closely to Nocardioides koreensis MSL-09^T (97.6 % 16S rRNA gene sequence similarity), Nocardioides aquiterrae GW-9^T (97.0 %), and Nocardioides sediminis MSL-01^T (97.0 %). The sequence similarities with other validly named species within the genus Nocardioides were less than 96.8 %. Strain Gsoil 958^T was characterized chemotaxonomically as having LL-2,6-diaminopimelic acid in the cell-wall peptidoglycan, MK-8(H₄) as the predominant menaquinone, and iso-C_16:0, iso-C_16:1 H, iso-C_14:0, iso-C_15:0 were identified as the major fatty acids. The G + C content of genomic DNA was determined to be 70.8 mol %. The chemotaxonomic properties and phenotypic characteristics supported the affiliation of strain Gsoil 958^T to the genus Nocardioides. The results of both physiological and biochemical tests allowed for differentiation of strain Gsoil 958^T from the recognized Nocardioides species. Therefore, strain Gsoil 958^T is considered to represent a novel species of the genus Nocardioides, for which the name Nocardioides panaciterrulae sp. nov. is proposed, with the type strain Gsoil 958^T (KACC 14271^T = KCTC 19471^T = DSM 21350^T).     

Microbial transformation of ginsenoside Rb1 to compound K by Lactobacillus paralimentarius

In this study, the major ginsenoside Rb1 was transformed into the more pharmacologically active minor compound K by food grade Lactobacillus paralimentarius LH4, which was isolated from kimchi, a traditional Korean fermented food. The enzymatic reaction was analyzed by TLC, HPLC, and NMR. Using the cell-free enzyme of Lactobacillus paralimentarius LH4 at optimal conditions for 30 °C at pH 6.0, 1.0 mg ml^?1 ginsenoside Rb1 was transformed into 0.52 mg ml^?1 compound K within 72 h, with a corresponding molar conversion yield of 88 %. The cell-free enzyme hydrolyzed the two glucose moieties attached to the C-3 position and the outer glucose moiety attached to the C-20 position of the ginsenoside Rb1. The cell-free enzyme hydrolyzed the ginsenoside Rb1 along the following pathway: ginsenoside Rb1 → gypenoside XVII and ginsenoside Rd → ginsenoside F2 → compound K. Our results indicate that Lactobacillus paralimentarius LH4 has the potential to be applied for the preparation of compound K in the food industry.     

Deinococcus radiotolerans sp. nov., a gamma-radiation-resistant bacterium isolated from gamma ray-irradiated soil

Two gamma-radiation-resistant bacterial strains, designated C1^T and C2, were isolated from a soil sample collected at Jeongeup-Si, South Korea. These strains were observed to be Gram-negative, non-motile, rod-shaped, and to form pink colonies. Phylogenetic analysis based on 16S rRNA gene sequences revealed that these strains belong to the genus Deinococcus in the family Deinococcaceae. Strains C1^T and C2 have the highest sequence similarities with Deinococcus daejeonensis MJ27^T (97.56 %) and Deinococcus grandis DSM 39663^T (97.50 %). Like other members of the genus Deinococcus, the novel isolates showed resistance to gamma-radiation with a D₁₀ value in excess of 8 kGy. The isolates were found to have menaquinone MK-8 as the predominant respiratory quinone and an unidentified phosphoglycolipid as major polar lipid. In addition, the most abundant fatty acids of strain C1^T were identified as C_15:1 ω6c (25.5 %), C_16:1 ω7c (18.7 %) and C_15:0 (9.7 %). Genomic analysis results showed that the DNA G+C contents of strain C1^T and C2 are 68.59 and 68.57 %, respectively. Taken together, the polyphasic taxonomic data support the proposal that the isolates C1^T and C2 represent a novel species of the genus Deinococcus, for which the name Deinococcus radiotolerans sp. nov. is proposed. The type strain is a strain C1^T (=KCTC 33150^T = JCM 19173^T).     

Ginsenoside Rg1 Decreases Oxidative Stress and Down-Regulates Akt/mTOR Signalling to Attenuate Cognitive Impairment in Mice and Senescence of Neural Stem Cells Induced by <Emphasis Type="SmallCaps">d</Emphasis>-Galactose

Adult hippocampal neurogenesis plays a pivotal role in learning and memory. The suppression of hippocampal neurogenesis induced by an increase of oxidative stress is closely related to cognitive impairment. Neural stem cells which persist in the adult vertebrate brain keep up the production of neurons over the lifespan. The balance between pro-oxidants and anti-oxidants is important for function and surviving of neural stem cells. Ginsenoside Rg1 is one of the most active components of Panax ginseng, and many studies suggest that ginsenosides have antioxidant properties. This research explored the effects and underlying mechanisms of ginsenoside Rg1 on protecting neural stem cells (NSCs) from oxidative stress. The sub-acute ageing of C57BL/6 mice was induced by subcutaneous injection of d-gal (120 mg kg^?1 day^?1) for 42 day. On the 14th day of d-gal injection, the mice were treated with ginsenoside Rg1 (20 mg kg^?1 day^?1, intraperitoneally) or normal saline for 28 days. The study monitored the effects of Rg1 on proliferation, senescence-associated and oxidative stress biomarkers, and Akt/mTOR signalling pathway in NSCs. Compared with the d-gal group, Rg1 improved cognitive impairment induced by d-galactose in mice by attenuating senescence of neural stem cells. Rg1 also decreased the level of oxidative stress, with increased the activity of superoxide dismutase and glutathione peroxidase in vivo and in vitro. Rg1 furthermore reduced the phosphorylation levels of protein kinase B (Akt) and the mechanistic target of rapamycin (mTOR) and down-regulated the levels of downstream p53, p16, p21 and Rb in d-gal treated NSCs. The results suggested that the protective effect of ginsenoside Rg1 on attenuating cognitive impairment in mice and senescence of NSCs induced by d-gal might be related to the reduction of oxidative stress and the down-regulation of Akt/mTOR signaling pathway.     

Lactobacillus ginsenosidimutans sp. nov., isolated from kimchi with the ability to transform ginsenosides

Biotransformation of ginsenosides was examined using lactic acid bacteria isolated from several kinds of kimchi. A Gram-positive, facultatively anaerobic, non-motile, non-spore-forming, and rod-shaped lactic acid bacterial strain, designated EMML 3041^T, was determined to have ginsenoside-converting activity and its taxonomic position was investigated using a polyphasic approach. Strain EMML 3041^T displayed β-glucosidase activity that was responsible for its ability to transform ginsenoside Rb₁ (one of the dominant active components of ginseng) to F₂ via gypenoside XVII, ginsenoside Rb₂ to compound Y via compound O, ginsenoside Rc to compound Mc via compound Mc₁, and ginsenoside Rd to ginsenoside F₂. On the basis of the 16S rRNA gene sequence similarity, strain EMML 3041^T was shown to belong to the genus Lactobacillus and is closely related to Lactobacillus versmoldensis KU-3^T (98.3 % sequence similarity). Polyphasic taxonomy study confirmed that the strain EMML 3041^T represents a novel species, for which the name Lactobacillus ginsenosidimutans sp. nov. is proposed, with EMML 3041^T (=KACC 14527^T = JCM 16719^T) as the type strain.     

Production of ginsenoside aglycons and Rb1 deglycosylation pathway profiling by HPLC and ESI-MS/MS using Sphingobacterium multivorum GIN723

Using enrichment culture, Sphingobacterium multivorum GIN723 (KCCM80060) was isolated as having activity for deglycosylation of compound K and ginsenoside F1 to produce ginsenoside aglycons such as S-protopanaxadiol (PPD(S)) and S-protopanaxatriol (PPT(S)). Through BLAST search, purified enzyme from S. multivorum GIN723 was revealed to be the outer membrane protein. The purified enzyme from S. multivorum GIN723 has unique specificity for the glucose moiety. However, it has activity with PPD and PPT group ginsenosides such as ginsenosides Rb1, Rb2, Rb3, Rc, F2, CK, Rh2, Re, and F1. From these results, it was predicted that the enzyme has activity on several ginsenosides. Therefore, the biotransformation pathway from Rb1, which is a major, highly glycosylated compound of ginseng, was analyzed using high-performance liquid chromatography and electrospray ionization mass spectrometry/mass spectrometry. The dominant biotransformation pathway from Rb1 to PPD(S) was determined to be Rb1 → Gp-XVII → Gp-LXXV → CK → PPD(S). S. multivorum GIN723 can be used as a whole cell biocatalyst because its activity as whole cells is nine times higher than its activity as cell extracts. The specific activity of whole cells is 2.89 nmol/mg/min in the production of PPD(S). On the other hand, the specific activity of cell extracts is 0.32 nmol/mg/min. The productivity of this enzyme in whole cell form is 500 mg/1 l of cultured cell. Its optimum reaction condition is 10 mM of calcium ions added to a phosphate buffer with a pH of 8.5.     

Expression,purification, and characterization of recombinant mangrove glutamine synthetase

To expand our knowledge about the relationship of nitrogen use efficiency and glutamine synthetase (GS) activity in the mangrove plant, a cytosolic GS gene from Avicennia marina has been heterologously expressed in and purified from Escherichia coli. Synthesis of the mangrove GS enzyme in E. coli was demonstrated by functional genetic complementation of a GS deficient mutant. The subunit molecular mass of GSI was ~40 kDa. Optimal conditions for biosynthetic activity were found to be 35 °C at pH 7.5. The Mg²⁺-dependent biosynthetic activity was strongly inhibited by Ni²⁺, Zn²⁺, and Al³⁺, whereas was enhanced by Co²⁺. The apparent K _m values of AmGLN1 for the substrates in the biosynthetic assay were 3.15 mM for glutamate, and 2.54 mM for ATP, 2.80 mM for NH₄ ⁺ respectively. The low affinity kinetics of AmGLN1 apparently participates in glutamine synthesis under the ammonium excess conditions.     

Paracoccus pacificus sp. nov., isolated from the Western Pacific Ocean

A Gram-stain negative, short rod-shaped, non-motile, catalase- and oxidase-positive, aerobic bacterium, designated F14^T, was isolated from the Western Pacific Ocean. Phylogenetic and phenotypic properties of the organism supported that it belongs to the genus Paracoccus. The levels of 16S rRNA gene sequences similarity between strain F14^T and other type strains of recognized members of the genus Paracoccus were 93.6–96.5 %. Growth of strain F14^T was observed at 4–40 °C (optimum, 28–30 °C), pH 6.0–10.0 (optimum, pH 7.0–8.0) and in the presence of 0–7 % (w/v) NaCl (optimum, 1–2 %). The major cellular fatty acid was summed feature 8 (C_18:1 ω6c and/or C_18:1 ω7c). The major respiratory quinone was ubiquinone-10. The polar lipid pattern indicated the presence of diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, phosphatidylcholine and three unknown lipids. The DNA G+C content was 61.4 mol%. On the basis of polyphasic characterization, strain F14^T represents a novel species, for which the name Paracoccus pacificus sp. nov. is proposed. The type strain is F14^T (=CGMCC 1.12755^T=LMG 28106^T=MCCC 1A09947^T).     

Mycotoxigenic fungi and mycotoxins associated with stored maize from different regions of Lesotho

Samples of stored maize from villages located in five different agroecological zones (southern lowlands, northern lowlands, Senqu river valley, foothills and mountains) of Lesotho were collected in 2009/10 and 2010/11 and assessed for contamination with toxigenic fungi. The water activity of all samples collected during the two seasons was <0.70. The total fungal populations of the maize from different regions in the two seasons was not significantly different (p?>?0.05). Fusarium verticillioides, F. proliferatum and F. subglutinans predominated in different regions in both seasons based on molecular analyses. In the 2009/10 season, the isolates of these species all produced FB₁, while in the 2010/11 season, very few produced FB₁. A. flavus isolates (2009/10) were recovered from mountains and Senqu river valley samples while the 2010/11 isolates were predominantly from the foothills and northern lowlands. The mountain isolates of Aspergillus section Flavi produced the highest levels of AFB₁ (20 mg kg^?1). Aspergillus parasiticus was only isolated from the foothills, Senqu river valley and southern lowlands samples, and the AFB₁ levels produced ranged from ‘none detected’ to 3.5 mg kg^?1. The Aspergillus ochraceous isolates were least frequently encountered in both seasons. In the 2009/10 season, the isolates from the northern lowlands produced ochratoxin A (OTA) in culture. No isolates of A. niger from different regions in both seasons produced any OTA. Multi-mycotoxin analyses of the maize samples were done for a range of mycotoxins. At least one sample from each region in both seasons was FB₁-positive. FB₁ levels for 2010/11 samples (7–936 μg kg^?1) were higher than in the 2009/10 season (2–3 μg kg^?1). In both seasons, the mountains registered the highest levels of FB₁. Deoxynivalenol (DON) was recovered from all the samples analysed, with the highest mean contamination of 1,469 μg kg^?1 in samples from the northern lowlands. Moniliformin (MON) was detected from all agroecological zones in the two seasons (5–320 μg kg^?1 in 2009/10; 15–1,205 μg kg^?1 in 2010/11). Emerging toxins such as fusaproliferin (FUS) and beauvericin (BEA) were also detected. OTA was not detected in any of the samples analysed. Only one 2009/10 sample in the Senqu river valley was positive for AFB₁. This is the first report on toxigenic fungi and multi-mycotoxin contamination of maize samples from subsistence farmers’ stores in different agroecological zones of Lesotho.     

Isolation and characterization of novel ginsenoside-hydrolyzing glycosidase from Microbacterium esteraromaticum that transforms ginsenoside Rb2 to rare ginsenoside 20(S)-Rg3

Ginsenoside Rb2 was transformed by recombinant glycosidase (Bgp2) into ginsenosides Rd and 20(S)-Rg3. The bgp2 gene consists of 2,430 bp that encode 809 amino acids, and this gene has homology to the glycosyl hydrolase family 2 protein domain. SDS-PAGE was used to determine that the molecular mass of purified Bgp2 was 87 kDa. Using 0.1 mg ml^?1 of enzyme in 20 mM sodium phosphate buffer at 40 °C and pH 7.0, 1.0 mg ml^?1 ginsenoside Rb2 was transformed into 0.47 mg ml^?1 ginsenoside 20(S)-Rg3 within 120 min, with a corresponding molar conversion yield of 65 %. Bgp2 hydrolyzed the ginsenoside Rb2 along the following pathway: Rb2 → Rd → 20(S)-Rg3. This is the first report of the biotransformation of ginsenoside Rb2 to ginsenoside 20(S)-Rg3 using the recombinant glycosidase.     

Hyphomonas beringensis sp. nov. and Hyphomonas chukchiensis sp. nov., isolated from surface seawater of the Bering Sea and Chukchi Sea

Two Gram-negative, non-spore-forming, oval to pear shaped motile strains, designated 25B14_1^T and BH-BN04-4^T, isolated from surface seawater from the Bering Sea and Chukchi Sea, respectively, were subjected to polyphasic taxonomic study. Phylogenetic analysis based on 16S rRNA gene sequences demonstrated that strains 25B14_1^T and BH-BN04-4^T clustered together with Hyphomonas atlanticus 22II1-22F38^T and Hyphomonas oceanitis DSM 5155^T, respectively, within genus Hyphomonas. Based on whole genome sequence analysis, the calculated DDH and ANIm values between strain 25B14_1^T and BH-BN04-4^T are 18.8 and 83.19 % respectively. The calculated DDH values of strain 25B14_1^T and BH-BN04-4^T with seven type strains ranged from 18.2 to 19.9 % and from 18.4 to 40.4 %, respectively. The ANIm values of strain 25B14_1^T and BH-BN04-4^T with seven type strains ranged from 83.00 to 84.67 % and from 83.14 to 90.58 %, respectively. Both isolates were found to contain Q-11 as the predominant respiratory quinone. The major fatty acids of strain 25B14_1^T were identified as C_16:0, C_17:0, C_18:1 ω7c-methyl and Summed Feature 8 (C_18:1 ω6c/ω7c as defined by MIDI), while in the case of strain BH-BN04-4^T they were identified as C_16:0, C_18:1 ω7c-methyl and Summed Feature 8 (C_18:1 ω6c/ω7c). The G+C contents of 25B14_1^T and BH-BN04-4^T were determined to be 58.4 and 61.0 mol%, respectively. The combined phenotypic and genotypic data show that the two isolates each represent novel species of the genus Hyphomonas, for which the names Hyphomonas beringensis sp. nov. and Hyphomonas chukchiensis sp. nov. are proposed, with the type strain 25B14_1^T (=MCCC 1A07321^T = LMG 27914^T) and BH-BN04-4^T (=MCCC 1A07481^T = LMG 27915^T), respectively.