Sphingopyxis Sp Research Articles

Heterologous expression of mlrA in a photoautotrophic host – Engineering cyanobacteria to degrade microcystins

In this report, we establish proof-of-principle demonstrating for the first time genetic engineering of a photoautotrophic microorganism for bioremediation of naturally occurring cyanotoxins. In model cyanobacterium Synechocystis sp. PCC 6803 we have heterologously expressed Sphingopyxis sp. USTB-05 microcystinase (MlrA) bearing a 23 amino acid N-terminus secretion peptide from native Synechocystis sp. PCC 6803 PilA (sll1694). The resultant whole cell biocatalyst displayed about 3 times higher activity against microcystin-LR compared to a native MlrA host (Sphingomonas sp. ACM 3962), normalized for optical density. In addition, MlrA activity was found to be almost entirely located in the cyanobacterial cytosolic fraction, despite the presence of the secretion tag, with crude cellular extracts showing MlrA activity comparable to extracts from MlrA expressing E. coli. Furthermore, despite approximately 9.4-fold higher initial MlrA activity of a whole cell E. coli biocatalyst, utilization of a photoautotrophic chassis resulted in prolonged stability of MlrA activity when cultured under semi-natural conditions (using lake water), with the heterologous MlrA biocatalytic activity of the E. coli culture disappearing after 4 days, while the cyanobacterial host displayed activity (3% of initial activity) after 9 days. In addition, the cyanobacterial cell density was maintained over the duration of this experiment while the cell density of the E. coli culture rapidly declined. Lastly, failure to establish a stable cyanobacterial isolate expressing native MlrA (without the N-terminus tag) via the strong cpcB560 promoter draws attention to the use of peptide tags to positively modulate expression of potentially toxic proteins.

Further Investigation of the Enzymatic Pathway for Microcystins Biodegradation by Sphingopyxis sp.USTB-05

Based on the isolation of a promising bacterial strain of Sphingopyxis sp. USTB-05 for biodegrading MCs, the genes USTB-05-A (HM245411), USTB-05-B (KC513423) and USTB-05-C (KC573527) that are responsible for the biodegradation of MCs were cloned and expressed for the first time. After purification, the MC-degrading enzymes encoded by these genes were used for the catalytic degradation of MC-LR. The results demonstrated that the second enzyme encoded by USTB-05-B could convert linear MC-LR to a tetrapeptide by breaking the Ala–Arg bond. The third enzyme encoded by USTB-05-C could cleave Adda-Glu peptide bonds of both linear MC-LR and the tetrapeptide of Adda-Glu-Mdha-Ala, producing Adda as their common product. These findings will help better understand the biodegradation mechanism of MCs by Sphingopyxis sp. USTB-05.

A Novel and Native Microcystin-Degrading Bacterium of Sphingopyxis sp. Isolated from Lake Taihu.

A native, highly efficient microcystin-LR (MC-LR)-degrading bacterium named a7 was isolated from Lake Taihu and identified as Sphingopyxis sp. by 16S rDNA sequence analysis. The strain a7 could totally degrade MC-LR at a rate of 3.33 mg/(L·h), as detected by high-performance liquid chromatography (HPLC). The mlrA, mlrC, and mlrD genes were detected in the strain a7 by sequence analysis. Tetrapeptide and Adda—which are the middle metabolites of MC-LR—were analyzed via liquid chromatography time-of-flight mass spectrometry (LC-TOF-MS) during degradation. These metabolites were degraded completely, which suggested that the native Sphingopyxis sp. a7 was highly efficient in MC-LR degradation under bench conditions. Thus, strain a7 exhibited a significant potential application for bioremediation in water bodies contaminated by MC-LR produced by harmful cyanobacterial blooms.

Microbial Interspecies Interactions Affect Arsenic Fate in the Presence of MnII.

Biotransformation of arsenic (As) plays an important role in its environmental fate. However, the impact of direct microbial interspecies interactions on valence state and migration of As is rarely reported and cognized. Here, by co-cultivating two aerobic AsV-reducing bacteria (Arthrobacter sp. QXT-31 and Sphingopyxis sp. QXT-31) in a culture medium containing initial AsV (10μM) and bivalent manganese (MnII, 175μM), we demonstrated how the interactions between strains affect valence state and partition of As. The results showed that both the strains first reduced AsV to AsIII via a detoxification mechanism during aerobic growth, with participation of AsV-reducing gene arsC; the expression of a MnII-oxidizing gene of Arthrobacter sp. QXT-31 was then triggered in the presence of Sphingopyxis sp. QXT-31, and emerging MnII-oxidizing activity oxidized 90% of MnII to Mn oxides; the formed Mn oxides oxidized AsIII to AsV and adsorbed AsV; MnII-oxidizing activity decreased significantly in the later stage, resulting to desorption of AsV from Mn oxides and subsequent bioreduction in aqueous phase. Considering the universality of the two bacterial genera and the interspecies interactions, our study hints at the pervasive impact of direct microbial interspecies interactions on the environmental fate of As in an aquatic ecosystem containing Mn.

Cometabolic biodegradation of 1,2,3-trichloropropane by propane-oxidizing bacteria

1,2,3-Trichloropropane (TCP) is an emerging groundwater pollutant and suspected human carcinogen. TCP, a recalcitrant contaminant, has been detected in the subsurface near TCP manufacture facilities and many superfund sites. Considering the toxicity and the occurence of TCP, there is a need to seek for cost-effective treatment technologies for TCP-contaminated sites. This paper investigated TCP biodegradation by propane-oxidizing bacteria (PrOB) which are known to express propane monooxygenase (PrMO). PrMO can cometabolically degrade many different contaminants. Four PrOB, Rhodococus jostii RHA1, Mycobacterium vaccae JOB5, Rhodococcus rubber ENV425 and one isolate Sphingopyxis sp. AX-A were examined for their ability to degrade TCP. All the four PrOB resting cells were able to degrade TCP. Strain JOB5 exhibited the best TCP degradation ability (vinitial = 9.7 ± 0.7 μg TCP (mg protein)−1h−1). No TCP was degraded in the presence of acetylene (an inhibitor for PrMO), suggesting that PrMO might be responsible for TCP degradation. Furthermore, competitive inhibition was observed between propane and TCP, and between trichloroethylene (TCE) and TCP.

Presence or Absence of mlr Genes and Nutrient Concentrations Co-Determine the Microcystin Biodegradation Efficiency of a Natural Bacterial Community.

The microcystin biodegradation potential of a natural bacterial community coexisting with a toxic cyanobacterial bloom was investigated in a water reservoir from central Spain. The biodegradation capacity was confirmed in all samples during the bloom and an increase of mlrA gene copies was found with increasing microcystin concentrations. Among the 24 microcystin degrading strains isolated from the bacterial community, only 28% showed presence of mlrA gene, strongly supporting the existence and abundance of alternative microcystin degradation pathways in nature. In vitro degradation assays with both mlr+ and mlr− bacterial genotypes (with presence and absence of the complete mlr gene cluster, respectively) were performed with four isolated strains (Sphingopyxis sp. IM-1, IM-2 and IM-3; Paucibacter toxinivorans IM-4) and two bacterial degraders from the culture collection (Sphingosinicella microcystinivorans Y2; Paucibacter toxinivorans 2C20). Differences in microcystin degradation efficiencies between genotypes were found under different total organic carbon and total nitrogen concentrations. While mlr+ strains significantly improved microcystin degradation rates when exposed to other carbon and nitrogen sources, mlr− strains showed lower degradation efficiencies. This suggests that the presence of alternative carbon and nitrogen sources possibly competes with microcystins and impairs putative non-mlr microcystin degradation pathways. Considering the abundance of the mlr− bacterial population and the increasing frequency of eutrophic conditions in aquatic systems, further research on the diversity of this population and the characterization and conditions affecting non-mlr degradation pathways deserves special attention.

Mercury remediation potential of a mercury resistant strain Sphingopyxis sp. SE2 isolated from contaminated soil

A mercury resistant bacterial strain SE2 was isolated from contaminated soil. The 16s rRNA gene sequencing confirms the strain as Sphingopyxis belongs to the Sphingomonadaceae family of the α-Proteobacteria group. The isolate showed high resistance to mercury with estimated concentrations of Hg that caused 50% reduction in growth (EC50) of 5.97 and 6.22mg/L and minimum inhibitory concentrations (MICs) of 32.19 and 34.95mg/L in minimal and rich media, respectively. The qualitative detection of volatilized mercury and the presence of mercuric reductase enzyme proved that the strain SE2 can potentially remediate mercury. ICP-QQQ-MS analysis of the remaining mercury in experimental broths indicated that a maximum of 44% mercury was volatilized within 6hr by live SE2 culture. Furthermore a small quantity (23%) of mercury was accumulated in live cell pellets. While no volatilization was caused by dead cells, sorption of mercury was confirmed. The mercuric reductase gene merA was amplified and sequenced. Homology was observed among the amino acid sequences of mercuric reductase enzyme of different organisms from α-Proteobacteria and ascomycota groups.

Stenotrophomonas maltophilia isolated from gasoline-contaminated soil is capable of degrading methyl tert-butyl ether

Background: Methyl tert-butyl ether (MTBE) is a pollutant that causes deleterious effects on human and environmental health. Certain microbial cultures have shown the ability to degrade MTBE, suggesting that a novel bacterial species capable of degrading MTBE could be recovered. The goal of this study was to isolate, identify and characterize the members of a bacterial consortium capable of degrading MTBE. Results: The IPN-120526 bacterial consortium was obtained through batch enrichment using MTBE as the sole carbon and energy source. The cultivable fraction of the consortium was identified; of the isolates, only Stenotrophomonas maltophilia IPN-TD and Sphingopyxis sp. IPN-TE were capable of degrading MTBE. To the best of our knowledge, this report is the first demonstrating that S. maltophilia and Sphingopyxis sp. are capable of degrading MTBE. The degradation kinetics of MTBE demonstrated that S. maltophilia IPN-TD had a significantly higher overall MTBE degradation efficiency and rate (48.39 ± 3.18% and 1.56 ± 0.12 mg L -1 h -1 , respectively) than the IPN-120526 consortium (38.59 ± 2.17% and 1.25 ± 0.087 mg L -1 h -1 , respectively). The kinetics of MTBE removal by both cultures fit first-order and pseudo-first-order reaction models. Conclusions: These findings suggest that S. maltophilia IPN-TD in axenic culture has considerable potential for the detoxification of MTBE-contaminated water. Normal 0 21 false false false ES-TRAD JA X-NONE /* Style Definitions */ table.MsoNormalTable {mso-style-name:Tabla normal; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-parent:; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:Cambria,serif; mso-ascii-font-family:Cambria; mso-ascii-theme-font:minor-latin; mso-hansi-font-family:Cambria; mso-hansi-theme-font:minor-latin; mso-ansi-language:ES-TRAD;}

Emergence of Antagonism Against the Pathogenic Fungus Fusarium oxysporum by Interplay Among Non‐Antagonistic Bacteria in a Hydroponics Using Multiple Parallel Mineralization

AbstractThe rhizosphere microbial community in a multiple parallel mineralization (MPM) system contributes to suppression of root‐borne diseases. We hypothesized this phenomenon can be attributed to the interplay of non‐antagonistic bacteria rather than to a single antagonistic microbe. In this study, we tested this hypothesis by investigating the potential roles of bacterial interplay in a subset of MPM microbiota in the suppression of the fungal phytopathogen Fusarium oxysporum. Bacterial strains isolated from the MPM system were subjected to in vitro and in planta tests on F. oxysporum. A community of seven bacterial strains (Kaistia sp. TBD58, Sphingopyxis sp. TBD84, Bosea sp. TBD101, Ancylobacter sp. TBD132, Cupriavidus sp. TBD162, Brevibacillus sp. TBD179 and Sphingopyxis sp. TBD181) suppressed F. oxysporum growth. None of the strains alone was antagonistic against F. oxysporum, whereas several pairs of those non‐antagonistic strains inhibited its growth. Morphological observations showed the formation of swollen F. oxysporum cells in the presence of these bacterial pairs. The same bacterial pairs also suppressed Fusarium wilt disease in Arabidopsis thaliana. These results indicate that a complex bacterial interplay among non‐antagonistic bacteria can significantly contribute to the development of antagonism against F. oxysporum in the context of the MPM system.

Pathway for Biodegrading Nodularin (NOD) by Sphingopyxis sp. USTB-05.

Nodularin (NOD) is greatly produced by Nodularia spumigena and released into the environment when toxic cyanobacterial blooms happened in natural water body, which is seriously harmful to human and animals. The promising bacterial strain of Sphingopyxis sp. USTB-05 was found to have an ability in biodegrading NOD. Initially, 11.6 mg/L of NOD could be completely eliminated within 72 h by whole cells of USTB-05, and within 36 h by its crude enzymes (CEs) of 570 mg/L, respectively. During the enzymatic biodegradation process of NOD, two products were observed on the profiles of HPLC. Based on the analysis of m/z ratios of NOD and its two products on a rapid-resolution liquid chromatogram-mass spectrum (RRLC-MS), we suggested that at least two enzymes of USTB-05 participated in biodegrading NOD. The first enzyme hydrolyzed Arg-Adda peptide bond of cyclic NOD and converted it to linear NOD as the first product. The second enzyme was found to cut off the target peptide bond between Adda and Glu of linearized NOD, and Adda was produced as a second and dead-end product. This finding is very important in both basic research and the application of USTB-05 on the removal of NOD from a water environment.

Cyanotoxin degradation activity and mlr gene expression profiles of a Sphingopyxis sp. isolated from Lake Champlain, Canada.

A bacterium capable of degrading five microcystin (MC) variants, microcystin-LR, YR, LY, LW and LF at an initial total concentration of 50 μg l-1 in less than 16 hours was isolated from Missisquoi Bay, in the south of Quebec, Canada. Phylogenetic analysis of the 16S rRNA gene sequence identified the bacterium as Sphingopyxis sp., designated strain MB-E. It was shown that microcystin biodegradation activity was reduced at acidic and basic pH values. Even though no biodegradation occurred at pH values of 5.05 and 10.23, strain MB-E was able to degrade MCLR and MCYR at pH 9.12 and all five MCs variants tested at pH 6.1. Genomic sequencing revealed that strain MB-E contained the microcystin degrading gene cluster, including the mlrA, mlrB, mlrC and mlrD genes, and transcriptomic analysis demonstrated that all of these genes were induced during the degradation of MCLR alone or in the mixture of all five MCs. This novel transcriptomic analysis showed that the expression of the mlr gene cluster was similar for MCLR alone, or the mixture of MCs, and appeared to be related to the total concentration of substrate. The results suggested that the bacterium used the same pathway for the degradation of all MC variants.

Cooperative Mn(II) oxidation between two bacterial strains in an aquatic environment

In natural or engineered environments, diverse interspecific interactions among two or more microbial taxa may profoundly affect the transformation of organic compounds in the media. Little is known, however, about how these organisms and interactions affect the transformation of heavy metals. Recently, we found an interaction between two non-Mn(II)-oxidizing (when in monoculture) strains, Arthrobacter sp. QXT-31 and Sphingopyxis sp. QXT-31, which, when cultured in combination, resulted in Mn(II)-oxidizing activity in synthetic media. In order to study the occurrence likelihood of cooperative Mn(II) oxidation in natural water and discharged effluent, we initially identified an optimal ratio of the two strains in a combined culture, as well as the impacts of external factors on the cooperative oxidation. Once preferred initial conditions were established, we assessed the degree and rate of Mn(II) oxidation mediated by the combined QXT-31 strains (henceforth referred to as simply ‘QXT-31’) in three different water types: groundwater, domestic sewage and coking wastewater. Results showed that Mn(II) oxidation only occurred when the two strains were within a specific ratios range. When introduced to the test waters at the preferred ratio, QXT-31 demonstrated high Mn(II)-oxidizing activities, even when relative abundance of QXT-31 was very low (roughly 1.6%, calculated by 454 pyrosequencing events on 16S rcDNA). Interestingly, even under low relative abundance of QXT-31, removal of total organic carbon and total nitrogen in the test waters was significantly higher than the control treatments that were not inoculated with QXT-31. Data from our study indicate that cooperative Mn(II) oxidation is most likely to occur in natural aquatic ecosystems, and also suggests an alternative method to treat wastewater containing high concentrations of Mn(II).

Zincmethylphyrins and coproporphyrins, novel growth factors released by Sphingopyxis sp., enable laboratory cultivation of previously uncultured Leucobacter sp. through interspecies mutualism.

We have identified coproporphyrins including structurally new zincmethylphyrins I and III as growth factors A-F for the previously uncultured bacterial strain, Leucobacter sp. ASN212, from a supernatant of 210 l of Sphingopyxis sp. GF9 culture. Growth factors A-F induced significant growth of strain ASN212 at the concentrations of picomolar to nanomolar which would otherwise be unculturable in liquid medium or on agar plate. More interestingly, we found that the growth factors functioned as self-toxic compounds for the growth-factor producing strain GF9 at the picomolar to nanomolar levels. As a variety of bacteria could potentially produce coproporphyrins, our findings suggest that these compounds function as a novel class of signal molecules across a boundary at phylum level in the complex bacterial communities.

Whole-Genome Sequence of the Microcystin-Degrading Bacterium Sphingopyxis sp. Strain C-1.

This report describes the whole-genome sequence of an alkalitolerant microcystin-degrading bacterium, Sphingopyxis sp. strain C-1, isolated from a lake in China.

Pathway for Biodegrading Microcystin-YR by Sphingopyxis sp. USTB-05.

Harmful cyanobacterial blooms in waters have become a global environmental problem, this mainly due to the production and release of various microalgal toxins, in which microcystins (MCs) are distributed widely. Here, we focused on the study of a typical form of microcystins called microcystin-YR (MC-YR). It was found that initial 14.8 mg/L of MC-YR could be completely eliminated within 10 hr by the crude enzymes (CEs) of Sphingopyxis sp. USTB-05, a promising bacterial strain we isolated and identified in our previous study. During the enzymatic biodegradation of MC-YR with time course, the peaks of two intermediate and two final products were observed on the profiles of HPLC at the wavelengths of 238 nm and 230 nm, respectively. Based on the analysis of m/z ratios of MC-YR and its four products by LC-MS/MS, we suggested that at least four enzymes were involved in the biodegradation of MC-YR by Sphingopyxis sp. USTB-05. The first enzyme microcystinase converted cyclic MC-YR to linear MC-YR as the first product. Then the second enzyme serine protease was found to cleave the target peptide bond between alanine (Ala) and tyrosine (Tyr) of linearized MC-YR, producing a tetrapeptide and a tripeptide as second products, which were Adda-Glu-Mdha-Ala and Tyr-Masp-Arg, respectively. Next, the third enzyme peptidase converted the tetrapeptide of Adda-Glu-Mdha-Ala to Adda. And the fourth enzyme cleaved the tripeptide of Tyr-Masp-Arg to produce Tyr and dipeptide (Masp-Arg), which has never been reported. These findings will help us better understand the biodegradation pathway of MC-YR by Sphingopyxis sp. USTB-05.

Co-metabolic formation of substituted phenylacetic acids by styrene-degrading bacteria

Some soil bacteria are able to metabolize styrene via initial side-chain oxygenation. This catabolic route is of potential biotechnological relevance due to the occurrence of phenylacetic acid as a central metabolite.The styrene-degrading strains Rhodococcus opacus 1CP, Pseudomonas fluorescens ST, and the novel isolates Sphingopyxis sp. Kp5.2 and Gordonia sp. CWB2 were investigated with respect to their applicability to co-metabolically produce substituted phenylacetic acids. Isolates were found to differ significantly in substrate tolerance and biotransformation yields. Especially, P. fluorescens ST was identified as a promising candidate for the production of several phenylacetic acids. The biotransformation of 4-chlorostyrene with cells of strain ST was shown to be stable over a period of more than 200 days and yielded about 38mmolproductgcelldryweight−1 after nearly 350 days. Moreover, 4-chloro-α-methylstyrene was predominantly converted to the (S)-enantiomer of the acid with 40% enantiomeric excess.

Density-dependent enhancement of methane oxidation activity and growth of Methylocystis sp. by a non-methanotrophic bacterium Sphingopyxis sp

Methanotrophs are a biological resource as they degrade the greenhouse gas methane and various organic contaminants. Several non-methanotrophic bacteria have shown potential to stimulate growth of methanotrophs when co-cultured, and however, the ecology is largely unknown. Effects of Sphingopyxis sp. NM1 on methanotrophic activity and growth of Methylocystis sp. M6 were investigated in this study. M6 and NM1 were mixed at mixing ratios of 9:1, 1:1, and 1:9 (v/v), using cell suspensions of 7.5×1011 cellsL−1. Methane oxidation of M6 was monitored, and M6 population was estimated using fluorescence in situ hybridization (FISH). Real-time PCR was applied to quantify rRNA and expression of transcripts for three enzymes involved in the methane oxidation pathway. NM1 had a positive effect on M6 growth at a 1:9 ratio (p<0.05), while no significant effects were observed at 9:1 and 1:1 ratios. NM1 enhanced the methane oxidation 1.34-fold at the 1:9 ratio. NM1 increased the population density and relative rRNA level of M6 by 2.4-fold and 5.4-fold at the 1:9 ratio, indicating that NM1 stimulated the population growth of M6. NM1 increased the relative transcriptional expression of all mRNA targets only at the 1:9 ratio. These results demonstrated that NM1 enhanced the methanotrophic activity and growth of M6, which was dependent on the proportion of NM1 present in the culture. This stimulation can be used as management and enhancement strategies for methanotrophic biotechnological processes.

Pichia pastoris Aft1--a novel transcription factor, enhancing recombinant protein secretion.

BackgroundThe methylotrophic yeast Pichia pastoris is frequently used for the production of recombinant proteins. However, expression levels can vary depending on the target protein. Allowing for simultaneous regulation of many genes, which may elicit a desired phenotype like increased protein production, overexpression of transcription factors can be used to overcome expression bottlenecks. Here, we present a novel P. pastoris transcription factor currently annotated as Aft1, activator of ferrous transport.ResultsThe promoter regions of key secretory P. pastoris genes were screened for fungal transcription factor binding sites, revealing Aft1 as an interesting candidate for improving secretion. Genome wide analysis of transcription factor binding sites suggested Aft1 to be involved in the regulation of many secretory genes, but also indicated possible novel functions in carbohydrate metabolism. No Aft binding sites were found in promoters of characteristic iron homeostasis genes in P. pastoris. Microarrays were used to study the Aft1 regulon in detail, confirming Aft1 involvement in the regulation of carbon-responsive genes, and showing that iron regulation is dependent on FEP1, but not AFT1 expression levels. The positive effect of AFT1 overexpression on recombinant protein secretion was demonstrated for a carboxylesterase from Sphingopyxis sp. MTA144, for which secretion was improved 2.5-fold in fed batch bioreactor cultivations.ConclusionThis study demonstrates that the transcription factor Aft1 can be used to improve recombinant protein secretion in P. pastoris. Furthermore, we discovered possible novel functions of Aft1 in carbohydrate metabolism and provide evidence arguing against a direct role of Aft1 in P. pastoris iron regulation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12934-014-0120-5) contains supplementary material, which is available to authorized users.

Styrene oxide isomerase of Sphingopyxis sp. Kp5.2.

Styrene oxide isomerase (SOI) catalyses the isomerization of styrene oxide to phenylacetaldehyde. The enzyme is involved in the aerobic styrene catabolism via side-chain oxidation and allows the biotechnological production of flavours. Here, we reported the isolation of new styrene-degrading bacteria that allowed us to identify novel SOIs. Out of an initial pool of 87 strains potentially utilizing styrene as the sole carbon source, just 14 were found to possess SOI activity. Selected strains were classified phylogenetically based on 16S rRNA genes, screened for SOI genes and styrene-catabolic gene clusters, as well as assayed for SOI production and activity. Genome sequencing allowed bioinformatic analysis of several SOI gene clusters. The isolate Sphingopyxis sp. Kp5.2 was most interesting in that regard because to our knowledge this is the first time it was shown that a member of the family Sphingomonadaceae utilized styrene as the sole carbon source by side-chain oxidation. The corresponding SOI showed a considerable activity of 3.1 U (mg protein)(-1). Most importantly, a higher resistance toward product inhibition in comparison with other SOIs was determined. A phylogenetic analysis of SOIs allowed classification of these biocatalysts from various bacteria and showed the exceptional position of SOI from strain Kp5.2.

Biotransformation of Ginsenoside Rc into C-Mc1 by the Bacterium Sphingopyxis sp. BG97

The principal biologically active compounds of Panax ginseng C. A. Meyer are triterpenoid glycosides, ginsenosides [1], which exhibit immunostimulating, anti-inflammatory, anticarcinogenic, antitumor, antidiabetic, hepatoprotective, neuromodulating, and other properties [2]. Greater than 50 different ginsenosides have been isolated from P. ginseng. Six of these (Rb1, Rb2, Rc, Rd, Re, and Rg1) make up >80% of total saponins and have protopanaxadiol or protopanaxatriol as the aglycon [1]. Furthermore, it is well known that minor glycosides of P. ginseng in several instances have broader spectra of biological activity or are more active than them [2]. This stimulates great interest in producing the minor ginsenosides, including biotransformation of the principal ginsenosides using various microorganisms [3, 4]. We reported earlier the transformation of ginsenoside Rb1 into the minor glycoside F-2 and compound K [5] and glycoside Rd into minor ginsenoside (20S)-Rg3 [6] using bacteria isolated from soil samples taken from a ginseng field. Among these, strains belonging to the genus Sphingopyxis were identified [7]. Herein we communicate data on the transformation of principal ginsenoside Rc (1) into minor compound C-Mc1 (2) by the bacterium Sphingopyxis sp. BG97.