Yeast Metabolic Engineering for Biosynthesis of Caffeic Acid-Derived Phenethyl Ester and Phenethyl Amide.

Caffeic acid (CA)-derived phenethyl ester (CAPE) and phenethyl amide (CAPA) are extensively investigated bioactive compounds with therapeutic applications such as antioxidant, anti-inflammatory, and anticarcinogenic properties. To construct microbial cell factories for production of CAPE or CAPA is a promising option given the limitation of natural sources for product extraction and the environmental toxicity of the agents used in chemical synthesis. We reported the successful biosynthesis of caffeic acid in yeast previously. Here in this work, we further constructed the downstream synthetic pathways in yeast for biosynthesis of CAPE and CAPA. After combinatorial engineering of yeast chassis based on the rational pathway engineering method and library-based SCRaMbLE method, we finally obtained the optimal strains that respectively produced 417 µg/L CAPE and 1081 µg/L CAPA. Two screened gene targets of ΔHAM1 and ΔYJL028W were discovered to help improve the product synthesis capacity. This is the first report of the de novo synthesis of CAPA from glucose in an engineered yeast chassis. Future work on enzyme and chassis engineering will further support improving the microbial cell factories for the production of CA derivatives.

Biological valorization of lignin to flavonoids.

Lignin is the most affluent natural aromatic biopolymer on the earth, which is the promising renewable source for valuable products to promote the sustainability of biorefinery. Flavonoids are a class of plant polyphenolic secondary metabolites containing the benzene ring structure with various biological activities, which are largely applied in health food, pharmaceutical, and medical fields. Due to the aromatic similarity, microbial conversion of lignin derived aromatics to flavonoids could facilitate flavonoid biosynthesis and promote the lignin valorization. This review thereby prospects a novel valorization route of lignin to high-value natural products and demonstrates the potential advantages of microbial bioconversion of lignin to flavonoids. The biodegradation of lignin polymers is summarized to identify aromatic monomers as momentous precursors for flavonoid synthesis. The biosynthesis pathways of flavonoids in both plants and strains are introduced and compared. After that, the key branch points and important intermediates are clearly discussed in the biosynthesis pathways of flavonoids. Moreover, the most significant enzyme reactions including Claisen condensation, cyclization and hydroxylation are demonstrated in the biosynthesis pathways of flavonoids. Finally, current challenges and potential future strategies are also discussed for transforming lignin into various flavonoids. The holistic microbial conversion routes of lignin to flavonoids could make a sustainable production of flavonoids and improve the feasibility of lignin valorization.

Yeast chromosomal engineering to improve industrially-relevant phenotypes.

Genome structural variations enable microbes to evolve quickly under environmental stress. Recent efforts in synthetic biology have shown the ability of yeast chromosomal engineering to generate a larger scale of genome structural variations, which require a high efficiency of DNA rearrangement technology. In this review, we summarize the recent development of the SCRaMbLE system, an evolutionary approach, and the CRISPR/Cas9 technology to generate yeast genome rearrangement. Both technologies exhibit the powerful applications of chromosomal engineering to accelerate phenotypic evolution. We highlight several studies where yeast genome rearrangement has successfully improved industrially-relevant phenotypes, including the production of novel medicine, nutrition supplements, anti-tumor molecules, and the tolerance of environmental stress and drug resistance.

High production of triterpenoids in Yarrowia lipolytica through manipulation of lipid components.

BACKGROUND: Lupeol exhibits novel physiological and pharmacological activities, such as anticancer and immunity-enhancing activities. However, cytotoxicity remains a challenge for triterpenoid overproduction in microbial cell factories. As lipophilic and relatively small molecular compounds, triterpenes are generally secreted into the extracellular space. The effect of increasing triterpene efflux on the synthesis capacity remains unknown. RESULTS: In this study, we developed a strategy to enhance triterpene efflux through manipulation of lipid components in Y. lipolytica by overexpressing the enzyme Δ9-fatty acid desaturase (OLE1) and disturbing phosphatidic acid phosphatase (PAH1) and diacylglycerol kinase (DGK1). By this strategy combined with two-phase fermentation, the highest lupeol production reported to date was achieved, where the titer in the organic phase reached 381.67 mg/L and the total production was 411.72 mg/L in shake flasks, exhibiting a 33.20-fold improvement over the initial strain. Lipid manipulation led to a twofold increase in the unsaturated fatty acid (UFA) content, up to 61-73%, and an exceptionally elongated cell morphology, which might have been caused by enhanced membrane phospholipid biosynthesis flux. Both phenotypes accelerated the export of toxic products to the extracellular space and ultimately stimulated the capacity for triterpenoid synthesis, which was proven by the 5.11-fold higher ratio of extra/intracellular lupeol concentrations, 2.79-fold higher biomass accumulation and 2.56-fold higher lupeol productivity per unit OD in the modified strains. This strategy was also highly efficient for the biosynthesis of other triterpenes and sesquiterpenes, including α-amyrin, ß-amyrin, longifolene, longipinene and longicyclene. CONCLUSIONS: In conclusion, we successfully created a high-yield lupeol-producing strain via lipid manipulation. We demonstrated that the enhancement of lupeol efflux and synthesis capacity was induced by the increased UFA content and elongated cell morphology. Our study provides a novel strategy to promote the biosynthesis of valuable but toxic products in microbial cell factories.

NVD-BM-mediated genetic biosensor triggers accumulation of 7-dehydrocholesterol and inhibits melanoma via Akt1/NF-ĸB signaling.

Aberrant activation of the cholesterol biosynthesis supports tumor cell growth. In recent years, significant progress has been made by targeting rate-limiting enzymes in cholesterol biosynthesis pathways to prevent carcinogenesis. However, precise mechanisms behind cholesterol degradation in cancer cells have not been comprehensively investigated. Here, we report that codon optimization of the orthologous cholesterol 7-desaturase, NVD-BM from Bombyx mori, significantly slowed melanoma cell proliferation and migration, and inhibited cancer cell engraftment in nude mice, by converting cholesterol to toxic 7-dehydrocholesterol. Based on these observations, we established a synthetic genetic circuit to induce melanoma cell regression by sensing tumor specific signals in melanoma cells. The dual-input signals, RELA proto-oncogene (RELA) and signal transducer and activator of transcription 1 (STAT1), activated NVD-BM expression and repressed melanoma cell proliferation and migration. Mechanically, we observed that NVD-BM decreased Akt1-ser473 phosphorylation and inhibited cytoplasmic RELA translocation. Taken together, NVD-BM was identified as a tumor suppressor in malignant melanoma, and we established a dual-input biosensor to promote cancer cell regression, via Akt1/NF-κB signaling. Our results demonstrate the potential therapeutic effects of cholesterol 7-desaturase in melanoma metabolism, and provides insights for genetic circuits targeting 7-dehydrocholesterol accumulation in tumors.

Rapid and Efficient CRISPR/Cas9-Based Mating-Type Switching of Saccharomyces cerevisiae.

Rapid and highly efficient mating-type switching of Saccharomyces cerevisiae enables a wide variety of genetic manipulations, such as the construction of strains, for instance, isogenic haploid pairs of both mating-types, diploids and polyploids. We used the CRISPR/Cas9 system to generate a double-strand break at the MAT locus and, in a single cotransformation, both haploid and diploid cells were switched to the specified mating-type at ∼80% efficiency. The mating-type of strains carrying either rod or ring chromosome III were switched, including those lacking HMLα and HMRa cryptic mating loci. Furthermore, we transplanted the synthetic yeast chromosome V to build a haploid polysynthetic chromosome strain by using this method together with an endoreduplication intercross strategy. The CRISPR/Cas9 mating-type switching method will be useful in building the complete synthetic yeast (Sc2.0) genome. Importantly, it is a generally useful method to build polyploids of a defined genotype and generally expedites strain construction, for example, in the construction of fully a/a/α/α isogenic tetraploids.

Comprehensive Profiling of Proteome Changes Provide Insights of Industrial Penicillium chrysogenum During Pilot and Industrial Penicillin G Fermentation.

The intracellular proteomes of the Penicillium chrysogenum throughout pilot and industrial processes were investigated by using 2-DE combined with MALDI-TOF-TOF MS, respectively. We detected a total of 223 spots corresponding to 154 proteins and 231 spots corresponding to 157 proteins throughout pilot and industrial processes, respectively. The levels of glyceraldehyde-3-phosphate dehydrogenase increased (5.1- and 2.5-fold) under the pilot process, while its levels were no significant changes under the industrial process at 140 and 170 h when compared with that at 2 h. The levels of isocitrate lyase and fumarate hydratase were increased significantly under the industrial process, while their levels had no obvious changes after 20 h of fermentation throughout the pilot process. These results indicate that there were remarkable differences in carbohydrate metabolism (including glycolysis, gluconeogenesis, pentose phosphate pathway, and tricarboxylic acid cycle) of P. chrysogenum during the pilot and industrial fermentations, which likely result in alterations of the primary metabolism and penicillin biosynthesis. Moreover, the differences in the levels of proteins involved in amino acid metabolisms (including valine, cysteine, and α-aminoadipic acid biosynthesis) indicated that the pilot and industrial processes influenced the supplies of penicillin precursors. Compared with that at 2 h, the maximum levels of superoxide (6.9-fold, at 32 h) and catalase (9-fold, at 80 h) during the industrial process and the maximum levels of superoxide (1.2-fold, at 20 h) and catalase (7.7-fold at 128 h) during the pilot process revealed the significant difference in cell redox homeostasis and stress responses during scale-up fermentation. Particularly, 10 spots corresponding to isopenicillin N synthetase and 4 spots corresponding to isopenicillin N (IPN) acyltransferase in pilot and industrial processes were identified, respectively. The levels of IPN acyltransferase (spots 197 and 198) and CoA ligase at 80 h during the industrial process were around 2-fold of that during the pilot process, indicating that the industrial process with a higher penicillin production per cell might provide available environments to induce over-expression of IPN acyltransferase and accelerate penicillin formation. These results provide new insights into the globally potential responses of P. chrysogenum to variations of environments in different fermentation scales so as to consequently regulate the penicillin production.

Engineered biosynthesis of natural products in heterologous hosts.

Natural products produced by microorganisms and plants are a major resource of antibacterial and anticancer drugs as well as industrially useful compounds. However, the native producers often suffer from low productivity and titers. Here we summarize the recent applications of heterologous biosynthesis for the production of several important classes of natural products such as terpenoids, flavonoids, alkaloids, and polyketides. In addition, we will discuss the new tools and strategies at multi-scale levels including gene, pathway, genome and community levels for highly efficient heterologous biosynthesis of natural products.

Feature selection for the identification of antitumor compounds in the alcohol total extracts of Curcuma longa.

Antitumor activity has been reported for turmeric, the dried rhizome of Curcuma longa. This study proposes a new feature selection method for the identification of the antitumor compounds in turmeric total extracts. The chemical composition of turmeric total extracts was analyzed by gas chromatography-mass spectrometry (21 ingredients) and high-performance liquid chromatography-mass spectrometry (22 ingredients), and their cytotoxicity was detected through an 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay against HeLa cells. A support vector machine for regression and a generalized regression neural network were used to research the composition-activity relationship and were later combined with the mean impact value to identify the antitumor compounds. The results showed that six volatile constituents (three terpenes and three ketones) and seven nonvolatile constituents (five curcuminoids and two unknown ingredients) with high absolute mean impact values exhibited a significant correlation with the cytotoxicity against HeLa cells. With the exception of the two unknown ingredients, the identified 11 constituents have been reported to exhibit cytotoxicity. This finding indicates that the feature selection method may be a supplementary tool for the identification of active compounds from herbs.

A novel approach to active compounds identification based on support vector regression model and mean impact value.

Traditionally, active compounds were discovered from natural product extracts by bioassay-guided fractionation, which was with high cost and low efficiency. A well-trained support vector regression model based on mean impact value was used to identify lead active compounds on inhibiting the proliferation of the HeLa cells in curcuminoids from Curcuma longa L. Eight constituents possessing the high absolute mean impact value were identified to have significant cytotoxicity, and the cytotoxic effect of these constituents was partly confirmed by subsequent MTT (3-(4, 5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assays and previous reports. In the dosage range of 0.2-211.2, 0.1-140.2, 0.2-149.9 µm, 50% inhibiting concentrations (IC50 ) of curcumin, demethoxycurcumin, and bisdemethoxycurcumin were 26.99 ± 1.11, 19.90 ± 1.22, and 35.51 ± 7.29 µm, respectively. It was demonstrated that our method could successfully identify lead active compounds in curcuminoids from Curcuma longa L. prior to bioassay-guided separation. The use of a support vector regression model combined with mean impact value analysis could provide an efficient and economical approach for drug discovery from natural products.

Comparison of the secondary metabolites in two scales of cephalosporin C (CPC) fermentation and two different post-treatment processes.

Cephalosporin C (CPC) is the precursor of a class of antibiotics that were more effective than traditional penicillins. CPC production is performed mainly through fermentation by Acremonium chrysogenum, whose secondary metabolism was sensitive to the environmental changes. In the present work, secondary metabolites were measured by ion-pair reversed-phase liquid chromatography tandemed with hybrid quadrupole time-of-flight mass spectrometry, and the disparity of them from two scales of CPC fermentations (pilot and industrial) and also two different post-treatment processes (oxalic acid and formaldehyde added and control) were investigated. When fermentation size was enlarged from pilot scale (50 l) to industrial scale (156,000 l), the remarkable disparities of concentrations and changing trends of the secondary metabolites in A. chrysogenum were observed, which indicated that the productivity of CPC biosynthesis was higher in the large scale of fermentation. Three environmental factors were measured, and the potential reasons that might cause the differences were analyzed. In the post-treatment process after industrial fermentation, the changes of these secondary metabolites in the tank where oxalic acid and formaldehyde were added were much less than the control tank where none was added. This indicated that the quality of the final product was more stable after the oxalic acid and formaldehyde were added in the post-treatment process. These findings provided new insight into industrial CPC production.

Comparative metabolomic study of Penicillium chrysogenum during pilot and industrial penicillin fermentations.

Comparative metabolomics was carried out to investigate the metabolic differences of Penicillium chrysogenum in the pilot and industrial fermentations that resulted from the scale-up. By principal component analysis, the early stages of two fermentation processes were clearly distinguished, whereas the middle and final stages were clustered together. It indicated that the different metabolisms of cells in the pilot and industrial fermentations mainly existed during the early stage. Furthermore, the levels of polyamines, polyols, glycolysis, and tricarboxylic acid cycle intermediates, which changed more dramatically during the pilot process, were all higher in the pilot than in the industrial fermentation during the early stage. This indicated that the fermentation conditions of the early stage should be the focus of process management which is aimed at increasing penicillin production. Additionally, the comparative accumulations of the precursors of penicillin (valine, cysteine, and lysine) revealed that penicillin biosynthesis in the industrial process was more affected during the middle stage of fermentation. These findings provide new insights to further regulate the industrial process and improve the production of penicillin. More generally, this study attempts to address the scarcity of studies that contrast the metabolic outcomes between commercial- and pilot-scale conditions.

Metabolomic analysis of the positive effects on Ketogulonigenium vulgare growth and 2-keto-L-gulonic acid production by reduced glutathione.

Ketogulonigenium vulgare has long been used in industry to produce 2-keto-L-gulonic acid (2KGA), the precursor of vitamin C. This fermentation process involves co-culture of K. vulgare and a Bacillus species. Early studies demonstrated that the presence of the Bacillus strain can enhance the cellular growth and 2KGA production of K. vulgare. However, the molecular mechanism behind how Bacillus affects the growth of K. vulgare and 2KGA production remains unclear. In addition, the inclusion of Bacillus in the fermentation process presents difficulties for the post-separation and purification of 2KGA. To address these issues, efforts have been made to replace the Bacillus strain with chemical compounds. In this study, we found that adding thiol compounds such as reduced glutathione (GSH) and dithiothreitol (DTT) to the K. vulgare mono-culture system can increase the growth of K. vulgare about twofold, and increase 2KGA production by about fivefold. The effects of thiols on the concentrations of some cellular metabolites were determined using gas chromatography coupled to time-of-flight mass spectrometry. The results showed that the levels of intracellular amino acids and intermediates in the pentose phosphate pathway increased significantly after thiol addition. Interestingly, when GSH was added, the levels of key intracellular metabolites in primary metabolic pathways and the cell biomass both reached their maximum in the first 36 h, and then decreased when the thiol was exhausted. These findings indicate that cell growth needs the assistance of a high concentration of thiols. This study is the first report that chemically defined compounds were used to enhance the growth of K. vulgare and 2KGA production. Furthermore, it also provides new insights into the possible cellular interaction between Bacillus species and K. vulgare.

Identification of antitumor constituents in curcuminoids from Curcuma longa L. based on the composition-activity relationship.

Using orthogonal partial least squares (OPLS), based on the Simca-p11.5 software, and canonical correlation analysis (CCA), performed on MatLab r2010 software, the correlation between curcuminoids extracted from Curcuma longa L. and the antitumor activity on HeLa cells was investigated to identify the significantly active constituents. Fingerprints from 31 batches of curcuminoids from C. longa L. were established using high performance liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS), and a total of 26 selected characteristic peaks were quantitatively analyzed. Afterward, the antitumor activities of the curcuminoids on HeLa cells were measured using an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. We found that 13 of the curcuminoids (peaks 9, 18, 14, 8, 16, 17, 24, 12, 4, 13, 10, 20 and 11) were significantly correlated with antitumor activity via a Loadings plot and VIP (variable importance in projection) in OPLS and a correlation coefficient in CCA. These results support a method for the discovery of antitumor active constituents.

Proteomic analysis of Ketogulonicigenium vulgare under glutathione reveals high demand for thiamin transport and antioxidant protection.

Ketogulonicigenium vulgare, though grows poorly when mono-cultured, has been widely used in the industrial production of the precursor of vitamin C with the coculture of Bacillus megaterium. Various efforts have been made to clarify the synergic pattern of this artificial microbial community and to improve the growth and production ability of K. vulgare, but there is still no sound explanation. In previous research, we found that the addition of reduced glutathione into K. vulgare monoculture could significantly improve its growth and productivity. By performing SEM and TEM, we observed that after adding GSH into K. vulgare monoculture, cells became about 4-6 folds elongated, and formed intracytoplasmic membranes (ICM). To explore the molecular mechanism and provide insights into the investigation of the synergic pattern of the co-culture system, we conducted a comparative iTRAQ-2-D-LC-MS/MS-based proteomic analysis of K. vulgare grown under reduced glutathione. Principal component analysis of proteomic data showed that after the addition of glutathione, proteins for thiamin/thiamin pyrophosphate (TPP) transport, glutathione transport and the maintenance of membrane integrity, together with several membrane-bound dehydrogenases had significant up-regulation. Besides, several proteins participating in the pentose phosphate pathway and tricarboxylic acid cycle were also up-regulated. Additionally, proteins combating intracellular reactive oxygen species were also up-regulated, which similarly occurred in K. vulgare when the co-cultured B. megaterium cells lysed from our former research results. This study reveals the demand for transmembrane transport of substrates, especially thiamin, and the demand for antioxidant protection of K. vulgare.

Comparative analysis of intracellular metabolites of Cephalosporium acremonium in pilot and industrial fermentation processes.

To get a better understanding of the characteristics of Cephalosporium acremonium with higher productivity, C. acremonium cells in pilot and industrial fermentation processes were analyzed using the profiles of metabolites. The different metabolic features of cells in pilot and industrial processes were caused by the different fermentation environments. The hierarchical cluster analysis of the data of metabolic profiling revealed that the concentrations of most of the metabolites were higher in the industrial process than in the pilot one, especially at the cephalosporin C accumulation stage. The analysis of important metabolites of primary metabolism indicated that the ability of the cephalosporin C biosynthesis was higher in the industrial process than that in the pilot one in C. acremonium. The analysis of the variations of cephalosporin C precursors and amino acids that were related to these precursors suggested that the metabolic flux changes of α-aminoadipic acid and cysteine between the primary metabolism and cephalosporin biosynthetic pathway in the industrial process. Furthermore, metabolites of C. acremonium, such as proline, spermine, inositol phosphate, and glycerol, were shown to respond to the fermentation environmental stress. These findings provide insights into the intracellular metabolite characteristics and feasible regulation scheme to improve the titer of cephalosporin C in the industrial process.

Lipidomic analysis of apoptotic hela cells induced by Paclitaxel.

Apoptosis has been shown to be accompanied by changes in cellular phospholipids. In this study, lipidomic strategy was applied to investigate the early changes in Hela cell phospholipid metabolism in response to paclitaxel-induced apoptosis. A total of 240 phospholipid species were profiled and 202 of them were quantified using the NPLC-ESI/MS(n) procedure. Principal component analysis and partial least squares combined with variable influence on projection were applied to find the potential biomarkers for discrimination between the control and paclitaxel-treated cells. Lysophosphatidylethanolamine and lysophosphatidylcholine species with strong decreasing trends after 6 h of treatment were identified as possible biomarkers for discrimination, which could be backed up by the decreased expression of cPLA(2). In addition, some of phosphatidylethanolamine, phosphatidylinositol, and phosphatidylcholine species with unsaturated fatty acid chains and phosphatidic acid species with saturated fatty acid chains were also indentified as potential biomarkers, and their changes might be closely related to the alteration of cell membrane fluidity happened in apoptotic process. These results showed clearly that phospholipids and related phospholipases played important roles in paclitaxel-induced apoptosis in Hela cells. Our study also demonstrates that lipidomics provide a powerful tool for better understanding anticancer mechanisms of chemotherapeutic agents and for biomarker screening.

Comparison of the secondary metabolites in Penicillium chrysogenum between pilot and industrial penicillin G fermentations.

The disparity of secondary metabolites in Penicillium chrysogenum between two scales of penicillin G fermentation (50 L as pilot process and 150,000 L as industrial one) was investigated by ion-pair reversed-phase liquid chromatography tandemed with hybrid quadrupole time-of-flight mass spectrometry. In industrial process, the pools of intracellular L-α-aminoadipyl-L-cysteinyl-D-valine (LLD-ACV) and isopenicillin N (IPN) were remarkably less than that in the pilot one, which indicated that the productivity of penicillin G might be higher in the large scale of fermentation. This conclusion was supported by the higher intracellular penicillin G concentration as well as its higher yield per unit biomass in industrial cultivation. The different changing tendencies of IPN, 6-aminopenicillanic acid and 6-oxopiperide-2-carboxylic acid between two processes also suggested the same conclusion. The higher content of intracellular LLD-ACV in pilot process lead to a similarly higher concentration of bis-δ-(L-α-aminoadipyl)-L-cysteinyl-D-valine, which had an inhibitory effect on ACV synthetase and also subdued the activity of IPN synthetase. The interconversion of secondary metabolites and the influence they put on enzymes would intensify the discrepancy between two fermentations more largely. These findings provided new insight into the changes and regulation of secondary metabolites in P. chrysogenum under different fermentation sizes.

Proteomic insights into adaptive responses of Saccharomyces cerevisiae to the repeated vacuum fermentation.

The responses and adaptation mechanisms of the industrial Saccharomyces cerevisiae to vacuum fermentation were explored using proteomic approach. After qualitative and quantitative analyses, a total of 106 spots corresponding to 68 different proteins were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The differentially expressed proteins were involved in amino acid and carbohydrate metabolisms, various signal pathways (Ras/MAPK, Ras-cyclic adenosine monophosphate, and HOG pathway), and heat shock and oxidative responses. Among them, alternations in levels of 17 proteins associated with carbohydrate metabolisms, in particular, the upregulations of proteins involved in glycolysis, trehalose biosynthesis, and the pentose phosphate pathway, suggested vacuum-induced redistribution of the metabolic fluxes. The upregulation of 17 heat stress and oxidative response proteins indicated that multifactors contributed to oxidative stresses by affecting cell redox homeostasis. Taken together with upregulation in 14-3-3 proteins levels, 22 proteins were detected in multispots, respectively, indicating that vacuum might have promoted posttranslational modifications of some proteins in S. cerevisiae. Further investigation revealed that the elevations of the differentially expressed proteins were mainly derived from vacuum stress rather than the absence of oxygen. These findings provide new molecular mechanisms for understanding of adaptation and tolerance of yeast to vacuum fermentation.

Analysis of phospholipids, sterols, and fatty acids in Taxus chinensis var. mairei cells in response to shear stress.

Plant cell culture has been developed as an alternative method for the production of an anticancer drug, paclitaxel. However, the sensitivity of plant cells to shear stress has been one of the main obstacles to the scale-up of the plant cell culture. To gain a better understanding of the mechanism of plant cells' response to hydrodynamic mechanical stress, lipid profiling of suspension-cultured Taxus chinensis (Chinese yew) var. mairei cells under shear stress was carried out using liquid chromatography-tandem MS and gas chromatography-time-of-flight MS. T. chinensis var. mairei cells cultured in a Couette-type shear reactor responded with an increase of cell membrane permeability compared with control cells, which indicated that the adaptation to shear stress altered membrane lipid composition. The main changes of lipid profiles in the shear-stress-induced cells were the following: (a) the total phospholipid content decreased, especially that of structural phospholipids such as phosphatidylglycerol, phosphatidylethanolamine and phosphatidylcholine; (b) cells showed increased stigmasterol at the expense of sitosterol and campesterol; (c) the stigmasterol/phospholipid ratio increased; (d) the mono-unsaturated-fatty-acid content increased; (e) the shear-stress-induced cells accumulated very-long-chain saturated fatty acids (C22:0, C23:0, C24:0 and C25:0). These findings suggested alterations in membrane composition and hinted at a possible molecular basis for the mechanotransduction processes induced by shear stress in T. chinensis var. mairei cells.