H-NS involved in positive regulation of glycerol dehydratase gene expression in Klebsiella pneumoniae 2e.

Glycerol dehydratase is the key and rate-limiting enzyme in the 1,3-propanediol synthesis pathway of Klebsiella pneumoniae, which determined the producing rate and yield of 1,3-propanediol. However, the expression regulation mechanism of glycerol dehydratase gene dhaB remains poorly unknown. In this study, a histone-like nucleoid-structuring (H-NS) protein was identified and characterized as the positive transcription regulator for dhaB expression in K. pneumoniae 2e, which exhibited high tolerance against crude glycerol in our previous study. Deletion of hns gene significantly decreased the transcription level of dhaB in K. pneumoniae 2e, which led to a remarkable defect on strain growth, glycerol dehydratase activity, and 3-hydroxypropanal production during glycerol fermentation. The transcription level of dhaB was significantly up-regulated in crude glycerol relative to pure glycerol, while the inactivation of H-NS resulted in more negative effect for transcription level of dhaB in the former. Though the H-NS expression level was almost comparable in both substrates, its multimer state was reduced in crude glycerol relative to pure glycerol, suggesting that the oligomerization state of H-NS might have contributed for positive regulation of dhaB expression. Furthermore, electrophoretic mobility shift and DNase I footprinting assays showed that H-NS could directly bind to the upstream promoter region of dhaB by recognizing the AT-rich region. These findings provided new insight into the transcriptional regulation mechanism of H-NS for glycerol dehydratase expression in K. pneumoniae, which might offer new target for engineering bacteria to industrially produce 1,3-propanediol.IMPORTANCEThe biological production of 1,3-propanediol from glycerol by microbial fermentation shows great promising prospect on industrial application. Glycerol dehydratase catalyzes the penultimate step in glycerol metabolism and is regarded as one of the key and rate-limiting enzymes for 1,3-propanediol production. H-NS was reported as a pleiotropic modulator with negative effects on gene expression in most studies. Here, we reported for the first time that the expression of glycerol dehydratase gene is positively regulated by the H-NS. The results provide insight into a novel molecular mechanism of H-NS for positive regulation of glycerol dehydratase gene expression in K. pneumoniae, which holds promising potential for facilitating construction of engineering highly efficient 1,3-propanediol-producing strains.

Nondestructive and Quantitative Analysis of Cell Wall Regeneration in the Medicinal Macrofungus Ganoderma lingzhi by a Membrane-Fusing Fluorescent Probe.

Ganoderma is a prize medicinal macrofungus with a broad range of pharmaceutical values. To date, various attempts have been made to cultivate Ganoderma to improve the production of secondary metabolites with pharmacological activity. Among the adopted techniques, protoplast preparation and regeneration are indispensable. However, the evaluation of protoplasts and regenerated cell walls usually relies on electron microscopy assays, which require time-consuming and destructive sample preparation and merely provide localized information in the selected area. In contrast, fluorescence assays enable sensitive real-time detection and imaging in vivo. They can also be applied to flow cytometry, providing a collective overview of every cell in a sample. However, for macrofungi such as Ganoderma, the fluorescence analysis of protoplasts and regenerated cell walls is difficult owing to the hindrance of the homologous fluorescent protein expression and the lack of an appropriate fluorescence marker. Herein, a specific plasma membrane probe, TAMRA perfluorocarbon nucleic acid probe (TPFN), is proposed for the nondestructive and quantitative fluorescence analysis of cell wall regeneration. Exploiting the perfluorocarbon membrane-anchoring chains, hydrophilic nucleic acid linker, and fluorescent dye TAMRA, the probe is proven to be selective, soluble, and stable, enabling rapid fluorescence detection of a protoplast sample free of transgenic expression or immune staining. Based on the TPFN and flow cytometry techniques, a quantitative approach is constructed to monitor the process of cell wall growth in a fast, quantitative, and high-throughout manner, and the obtained results are consistent with those of conventional electron microscopy. In principle, with slight modifications or integration, the proposed probe and approach can be adapted to the preparation of cell protoplasts, inspection of cell wall integrity under environmental stress, and programmable membrane engineering for cytobiology and physiology research.

Angiotensin I-converting enzyme inhibitory peptide: an emerging candidate for vascular dysfunction therapy.

Abnormal vasoconstriction, inflammation, and vascular remodeling can be promoted by angiotensin II (Ang II) in the renin-angiotensin system (RAS), leading to vascular dysfunction diseases such as hypertension and atherosclerosis. Researchers have recently focused on angiotensin I-converting enzyme inhibitory peptides (ACEIPs), that have desirable efficacy in vascular dysfunction therapy due to Ang II reduction by inhibiting ACE activity. Promising methods for the large-scale preparation of ACEIPs include selective enzymatic hydrolysis and microbial fermentation. Thus far, ACEIPs have been widely reported to be hydrolyzed from protein-rich sources, including animals, plants, and marine organisms, while many emerging microorganism-derived ACEIPs are theoretically biosynthesized through the nonribosomal peptide synthase (NRPS) pathway. Notably, vasodilatation, anti-inflammation, and vascular reconstruction reversal of ACEIPs are strongly correlated. However, the related molecular mechanisms underlying signal transduction regulation in vivo remain unclear. We provide a comprehensive update of the ACE-Ang II-G protein-coupled type 1 angiotensin receptor (AT1R) axis signaling and its functional significance for potential translation into therapeutic strategies, particularly targeting AT1R by ACEIPs, as well as specific related signaling pathways. Future studies are expected to verify the biosynthetic regulatory mechanism of ACEIPs via the NRPS pathway, the effect of gut microbiota metabolism on vascular dysfunction and rigorous studies of ACE-Ang II-AT1R signaling pathways mediated by ACEIPs in large animals and humans.

Comprehensive understanding of Saccharomyces cerevisiae phenotypes with whole-cell model WM_S288C.

Biological network construction for Saccharomyces cerevisiae is a widely used approach for simulating phenotypes and designing cell factories. However, due to a complicated regulatory mechanism governing the translation of genotype to phenotype, precise prediction of phenotypes remains challenging. Here, we present WM_S288C, a computational whole-cell model that includes 15 cellular states and 26 cellular processes and which enables integrated analyses of physiological functions of Saccharomyces cerevisiae. Using WM_S288C to predict phenotypes of S. cerevisiae, the functions of 1140 essential genes were characterized and linked to phenotypes at five levels. During the cell cycle, the dynamic allocation of intracellular molecules could be tracked in real-time to simulate cell activities. Additionally, one-third of non-essential genes were identified to affect cell growth via regulating nucleotide concentrations. These results demonstrated the value of WM_S288C as a tool for understanding and investigating the phenotypes of S. cerevisiae.

Adaptability of Klebsiella pneumoniae 2e, a Newly Isolated 1,3-Propanediol-Producing Strain, to Crude Glycerol as Revealed by Genomic Profiling.

Crude glycerol is largely generated as the main by-product of the biodiesel industry and is unprofitable for industrial application without costly purification. The direct bioconversion of crude glycerol into 1,3-propanediol (1,3-PDO) by microorganisms is a promising alternative for effective and economic utilization. In this study, Klebsiella pneumoniae 2e was newly isolated for the conversion of crude glycerol into 1,3-PDO. Batch fermentation analysis confirmed that crude glycerol and its main impurities had slight impacts on the growth, key enzyme activity, and 1,3-PDO production of K. pneumoniae 2e. The 1,3-PDO yield from crude glycerol by K. pneumoniae 2e reached 0.64 mol 1,3-PDO/mol glycerol, which was higher than that by most reported 1,3-PDO-producing Klebsiella strains. Genomic profiling revealed that K. pneumoniae 2e possesses 30 genes involved in glycerol anaerobic metabolism and 1,3-PDO biosynthesis. Quantitative real-time PCR analysis of these genes showed that the majority of the genes encoding the key enzymes for glycerol metabolism and 1,3-PDO biosynthesis were significantly upregulated during culture in crude glycerol relative to that in pure glycerol. Further comparative genomic analysis revealed a novel glycerol uptake facilitator protein in K. pneumoniae 2e and a higher number of stress response proteins than in other Klebsiella strains. This work confirms the adaptability of a newly isolated 1,3-PDO-producing strain, K. pneumoniae 2e, to crude glycerol and provides insights into the molecular mechanisms involved in its crude glycerol tolerance, which is valuable for industrial 1,3-PDO production from crude glycerol.IMPORTANCE The rapid development of the biodiesel industry has led to tremendous crude glycerol generation. Due to the presence of complex impurities, crude glycerol has low value for industry without costly purification. Obtaining novel microorganisms capable of direct and efficient bioconversion of crude glycerol to value-added products has great economic potential for industrial application. In this work, we characterized a newly isolated strain, Klebsiella pneumoniae 2e, with the capacity to efficiently produce 1,3-propanediol (1,3-PDO) from crude glycerol and demonstrated its adaptation to crude glycerol. Our work provides insights into the molecular mechanisms of K. pneumoniae 2e adaptation to crude glycerol and the expression patterns of its genes involved in 1,3-PDO biosynthesis, which will contribute to the development of industrial 1,3-PDO production from crude glycerol.

Improved Production and Antitumor Properties of Triterpene Acids from Submerged Culture of Ganoderma lingzhi.

Triterpene acids (TAs) are the major bioactive constituents in the medicinal fungus Ganoderma lingzhi. However, fermentative production of TAs has not been optimized for commercial use, and whether the TAs isolated from G. lingzhi submerged culture mycelia possess antitumor activity needs to be further proven. In this study, enhanced TA yield and productivity were attained with G. lingzhi using response surface methodology. The interactions of three variables were studied using a Box-Benhnken design, namely initial pH, dissolved oxygen (DO) and fermentation temperature. The optimum conditions were an initial pH of 5.9, 20.0% DO and 28.6 °C. These conditions resulted in a TA yield of 308.1 mg/L in a 5-L stirred bioreactor. Furthermore, the optimized conditions were then successfully scaled up to a production scale of 200 L, and maximum TA production and productivity of 295.3 mg/L and 49.2 mg/L/day were achieved, which represented 80.9% and 111.5% increases, respectively, compared with the non-optimized conditions. Additionally, the triterpene acid extract (TAE) from G. lingzhi mycelia was found to be cytotoxic to the SMMC-7721 and SW620 cell lines in vitro, and the TAE exhibited dose-dependent antitumor activity against the solid tumor sarcoma 180 in vivo. Chemical analysis revealed that the key active triterpene compounds, ganoderic acid T and ganoderic acid Me, predominated in the extract.

The Protective Effects of Ganoderma lucidum Active Peptide GLP4 on Lung Injury Induced by Cadmium Poisoning in Mice.

Ganoderma triterpenes and spore powder have shown promising results in mitigating cadmium-induced renal and hepatic injuries. Ganoderma lucidum active peptide GLP4 is a natural protein with dual antioxidant activities derived from the mycelium of Ganoderma lucidum. However, its efficacy in alleviating cadmium-induced lung injury remains unexplored. This study aims to investigate the protective effects of GLP4 against cadmium-induced lung injury in mice. Mice were exposed to cadmium chloride via nebulization to induce lung injury. The protective effect of GLP4 was assessed by measuring the total cell count in BALF, levels of inflammatory cytokines, and the expression of NLRP3 in lung tissues a through histopathological examination of lung tissue changes. The results showed that GLP4 significantly mitigated histopathological damage in lung tissues, decreased the secretion of inflammatory cytokines, and reduced the expression of NLRP3, which was elevated in cadmium-exposed mice. In vitro studies further revealed that GLP4 inhibited the cadmium-induced activation of the NLRP3 inflammasome. Notably, acute cadmium exposure by the respiratory tract did not affect the liver and kidneys of the mice. The findings suggest that GLP4 reduces cadmium-induced lung injury in mice by inhibiting the activation of the NLRP3 inflammasome, which provides a theoretical foundation for using Ganoderma lucidum as a preventive and therapeutic agent against cadmium poisoning.

How social media sharing drives consumption intention: the role of social media envy and social comparison orientation.

BACKGROUND: Social media benign envy, an upward comparison-based and painful emotions associated with the motivation to improve oneself, has attracted increasing attention from researchers due to its ubiquitous and significant impact on social network users' intentions and behavior. However, the results of previous studies on whether material or experiential consumption is more likely to cause social media envy (treated as a single construct) have been inconsistent, and there is a lack of research on what triggers social media users to experience more intense benign envy and thus inspiring their consumption intentions. The purpose of this study is to investigate how the type and luxuriousness of shared consumption and viewer's social comparison orientation jointly affect social media users' consumption intentions through benign envy. METHODS: A 2 (type of consumption sharing: experiential vs. material) × 2 (luxuriousness of consumption sharing: luxury vs. non-luxury) × 2 (social comparison orientation: high vs. low) mixed-design experiment was conducted to test theoretical model with data from 544 undergraduates in China. SPSS 26.0 and the Process macro were used to test the model. RESULTS: The results revealed that luxury experiential consumption information shared on social media triggered more benign envy compared with other types of shared consumption information. When social media users shared non-luxury consumption, experiential consumption was more likely to inspire benign envy among users with high social comparison orientation than material consumption. However, when luxury consumption was shared, benign envy acted as a mediator between purchase type and participants' purchase intention regardless of whether participants' social comparison orientation was high or low. CONCLUSION: This study revealed that whether and how social comparison orientation of social media users who read the shared content influences the mechanism by which the type of consumption sharing on social media affects social media users' consumption intentions through benign envy as a mediator is dependent on the luxuriousness of the shared consumption. The findings not only provide new insights for researchers to better understand social media envy and the underlying psychological mechanism for social media readers' consumption intention, but also have practical implications for practitioners.

An alternative peptone preparation using Hermetia illucens (Black soldier fly) hydrolysis: process optimization and performance evaluation.

Background: Hermetia illucens (HI), commonly known as the black soldier fly, has been recognized for its prowess in resource utilization and environmental protection because of its ability to transform organic waste into animal feed for livestock, poultry, and aquaculture. However, the potential of the black soldier fly's high protein content for more than cheap feedstock is still largely unexplored. Methods: This study innovatively explores the potential of H. illucens larvae (HIL) protein as a peptone substitute for microbial culture media. Four commercial proteases (alkaline protease, trypsin, trypsase, and papain) were explored to hydrolyze the defatted HIL, and the experimental conditions were optimized via response surface methodology experimental design. The hydrolysate of the defatted HIL was subsequently vacuum freeze-dried and deployed as a growth medium for three bacterial strains (Staphylococcus aureus, Bacillus subtilis, and Escherichia coli) to determine the growth kinetics between the HIL peptone and commercial peptone. Results: The optimal conditions were 1.70% w/w complex enzyme (alkaline protease: trypsin at 1:1 ratio) at pH 7.0 and 54 °C for a duration of 4 h. Under these conditions, the hydrolysis of defatted HIL yielded 19.25% ±0.49%. A growth kinetic analysis showed no significant difference in growth parameters (µmax, Xmax, and λ) between the HIL peptone and commercial peptone, demonstrating that the HIL hydrolysate could serve as an effective, low-cost alternative to commercial peptone. This study introduces an innovative approach to HIL protein resource utilization, broadening its application beyond its current use in animal feed.

Isolation, structural elucidation and biosynthetic pathway of bioactive prenyl quinone compounds from Panus lecomtei based on untargeted metabolomics combined with molecular networking.

Panus lecomtei is a relatively unfamiliar and undeveloped mushroom. This study generated ethyl acetate extracts of P. lecomtei intracellular (I), extracellular (E) and total fermentation broth (T). Both E and T extracts demonstrated antioxidant and antibacterial activities at 100 to 200 µg/mL. The composition differences of metabolites of these extracts were further studied based on comparative metabolomics by LS/MS and molecular network analysis. The results revealed that there were over 2000 significantly distinct metabolites among the three extracts, with abundant prenyl quinone compounds. Furthermore, the molecular network clarified the conversion relationship of P. lecomtei metabolites. Seven known prenyl quinone derivatives (1-7) were isolated from the E extract. Among them, compound 3 displayed excellent antioxidant activity and modest antibacterial activity. Compound 5 was discovered in fungi for the first time. Finally, a potential biosynthetic route for prenyl quinone in P. lecomtei was suggested.

Energy flows through nematode food webs depending on the soil carbon and nitrogen contents after forest conversion.

The swift proliferation of forests converted into monoculture plantations has profound impacts on soil nutrients, microbial communities, and many ecological processes and functions. Nematodes are soil microfauna that play a pivotal role in biogeochemical cycling and in soil food web, whereas the response of soil nematode communities and energy flows to forest conversion remains unknown. Here, we assessed the community composition and the energy flows of the nematode food webs as a function of soil chemistry after conversion from natural forests (Forest) to four plantations (8-year-old): Amygdalus persica (Peach), Myrica rubra (Berry), Camellia oleifera (Oil), and Cunninghamia lanceolata (Fir). After forest conversion, soil organic carbon (SOC) and total nitrogen (TN) contents decreased by 65 % and 55 %, respectively. Forest conversion strongly reduced the abundance (particularly large-bodied omnivorous-predatory nematodes), diversity, maturity, and stability of the soil nematode community. The shifts in composition and structure of nematode communities after forest conversion are reflected in changes in the abundance of predominant genera and trophic taxa, especially bacterivorous, fungivorous, and omnivorous-predatory nematodes. Acrobeloides notably increased, whereas Plectus, Prismatolaimus, Tylencholaimus, and Tripyla decreased. Accordingly, the abundances of r-strategy nematodes (cp value = 1-2) increased, but that of the K-strategists (cp value = 3-5) declined. Additionally, the energy flow across the soil nematode food web was reduced by 36 % and flow uniformity declined by 24 % after forest conversion. These changes in nematode diversity and abundance were triggered by diminishing soil C and N contents, thereby affecting the energy flows via the nematode food webs. Thus, forest conversion affects soil biotas and multi-functions from the perspective of nematode food web structure and energy flows, and underlines the interconnections between ecosystem and energy dynamics across multi-trophic levels, which is crucial for sustainable forest management.

The Method of Screening and Identification of Transcription Factor in Klebsiella.

This protocol describes a method for verifying the specific transcription factor regulating glycerol dehydratase (GDH) expression in Klebsiella. DNA pull-down accompanied with mass spectrometry is used to screen and identify the transcription factor interacting with the promoter region of the key gene in Klebsiella. EMSA method is used to validate the specific binding of the transcription factor to the promoter region in vitro. In addition, the target DNA fragments are constructed by fusion PCR to prepare competent cells from Klebsiella for electrical transformation and further transformed to obtain key gene deletion strains to verify the transcription factor responsible for the target gene expression in Klebsiella.

Multi-omics analysis unravels positive effect of rotenone on the cordycepin biosynthesis in submerged fermentation of Cordyceps militaris.

Cordycepin is the key pharmacologically active compound of Cordyceps militaris, and various fermentation strategies have been developed to increase cordycepin production. This study aimed to investigate the effect of rotenone on cordycepin biosynthesis in submerged fermentation of C. militaris, and also to explore its possible induction mechanisms via multi-omics analysis. Adding 5 mg/L rotenone significantly increased the cordycepin production by 316.09 %, along with mycelial growth inhibition and cell wall destruction. Moreover, transcriptomic analysis and metabolomic analysis revealed the accumulation of cordycepin was promoted by alterations in energy metabolism and amino acid metabolism pathways. Finally, the integration analysis of the two omics confirmed rotenone altered the nucleotide metabolism pathway toward adenosine and up-regulated the cordycepin synthesis genes (cns1-3) to convert adenosine to cordycepin. This work reports, for the first time, rotenone could act as an effective inducer of cordycepin synthesis.

Biochemical and molecular characterization of a novel glycerol dehydratase from Klebsiella pneumoniae 2e with high tolerance against crude glycerol impurities.

BACKGROUND: The direct bioconversion of crude glycerol, a byproduct of biodiesel production, into 1,3-propanediol by microbial fermentation constitutes a remarkably promising value-added applications. However, the low activity of glycerol dehydratase, which is the key and rate-limiting enzyme in the 1,3-propanediol synthetic pathway, caused by crude glycerol impurities is one of the main factors affecting the 1,3-propanediol yield. Hence, the exploration of glycerol dehydratase resources suitable for crude glycerol bioconversion is required for the development of 1,3-propanediol-producing engineered strains. RESULTS: In this study, the novel glycerol dehydratase 2eGDHt, which has a tolerance against crude glycerol impurities from Klebsiella pneumoniae 2e, was characterized. The 2eGDHt exhibited the highest activity toward glycerol, with Km and Vm values of 3.42 mM and 58.15 nkat mg-1, respectively. The optimum pH and temperature for 2eGDHt were 7.0 and 37 °C, respectively. 2eGDHt displayed broader pH stability than other reported glycerol dehydratases. Its enzymatic activity was increased by Fe2+ and Tween-20, with 294% and 290% relative activities, respectively. The presence of various concentrations of the crude glycerol impurities, including NaCl, methanol, oleic acid, and linoleic acid, showed limited impact on the 2eGDHt activity. In addition, the enzyme activity was almost unaffected by the presence of an impurity mixture that mimicked the crude glycerol environment. Structural analyses revealed that 2eGDHt possesses more coil structures than reported glycerol dehydratases. Moreover, molecular dynamics simulations and site-directed mutagenesis analyses implied that the existence of unique Val744 from one of the increased coil regions played a key role in the tolerance characteristic by increasing the protein flexibility. CONCLUSIONS: This study provides insight into the mechanism for enzymatic action and the tolerance against crude glycerol impurities, of a novel glycerol dehydratase 2eGDHt, which is a promising glycerol dehydratase candidate for biotechnological conversion of crude glycerol into 1,3-PDO.

Acetylated rice starch nanocrystals improved the physical, mechanical, and structural properties of native rice starch based films.

Rice starch nanocrystals (SNC) and acetylated rice starch nanocrystals (ASNC) with three different substitution degrees (DS) for 0.22 (ASNCa), 0.56 (ASNCb), and 0.83 (ASNCc), respectively, were synthesized. Starch nanocrystals (SNC, ASNCa, ASNCb and ASNCc) with varying concentrations (0-25 %) were used in the production of composite rice starch-based films plasticized with glycerol using the solvent casting technique. Films were compared concerning their morphology, moisture content and solubility, transmittance, tensile strength, elongation at break. The SNC and ASNC content and acetylated DS had a significant effect (p ≤ 0.05) on all the properties investigated when compared to the control film. The addition of ASNC resulted in less hydrophilic films and UV light barrier properties, and the addition of SNC and ASNC increased the rigidity of starch film. There was an increase of 156.7 % in tensile strength for 10 % ASNCc composite films and a reduction of 68.1 % in water vapor permeability for 20 % ASNCc composite films. The rice starch/ASNCb nanocomposite films with the addition of 5 % and 10 % ASNCb exhibited a compact, smooth, and flat surface structure. Therefore, these results showed that ASNC significantly improved the mechanical properties, surface morphology and thermal stability of the films.

Chitinase Is Involved in the Fruiting Body Development of Medicinal Fungus Cordyceps militaris.

Cordyceps militaris is a famous traditional edible and medicinal fungus in Asia, and its fruiting body has rich medicinal value. The molecular mechanism of fruiting body development is still not well understood in C. militaris. In this study, phylogenetically analysis and protein domains prediction of the 14 putative chitinases were performed. The transcription level and enzyme activity of chitinase were significant increased during fruiting body development of C. militaris. Then, two chitinase genes (Chi1 and Chi4) were selected to construct gene silencing strain by RNA interference. When Chi1 and Chi4 genes were knockdown, the differentiation of the primordium was blocked, and the number of fruiting body was significantly decreased approximately by 50% compared to wild-type (WT) strain. The length of the single mature fruiting body was shortened by 27% and 38% in Chi1- and Chi4-silenced strains, respectively. In addition, the chitin content and cell wall thickness were significantly increased in Chi1- and Chi4-silenced strains. These results provide new insights into the biological functions of chitinase in fruiting body development of C. militaris.

The bHLH-zip transcription factor SREBP regulates triterpenoid and lipid metabolisms in the medicinal fungus Ganoderma lingzhi.

Ganoderic acids (GAs) are well recognized as important pharmacological components of the medicinal species belonging to the basidiomycete genus Ganoderma. However, transcription factors directly regulating the expression of GA biosynthesis genes remain poorly understood. Here, the genome of Ganoderma lingzhi is de novo sequenced. Using DNA affinity purification sequencing, we identify putative targets of the transcription factor sterol regulatory element-binding protein (SREBP), including the genes of triterpenoid synthesis and lipid metabolism. Interactions between SREBP and the targets are verified by electrophoretic mobility gel shift assay. RNA-seq shows that SREBP targets, mevalonate kinase and 3-hydroxy-3-methylglutaryl coenzyme A synthetase in mevalonate pathway, sterol isomerase and lanosterol 14-demethylase in ergosterol biosynthesis, are significantly upregulated in the SREBP overexpression (OE::SREBP) strain. In addition, 3 targets involved in glycerophospholipid/glycerolipid metabolism are upregulated. Then, the contents of mevalonic acid, lanosterol, ergosterol and 13 different GAs as well as a variety of lipids are significantly increased in this strain. Furthermore, the effects of SREBP overexpression on triterpenoid and lipid metabolisms are recovered when OE::SREBP strain are treated with exogenous fatostatin, a specific inhibitor of SREBP. Taken together, our genome-wide study clarify the role of SREBP in triterpenoid and lipid metabolisms of G. lingzhi.

Effect of cross-linking and enzymatic hydrolysis composite modification on the properties of rice starches.

Native rice starch lacks the versatility necessary to function adequately under rigorous industrial processing, so modified starches are needed to meet the functional properties required in food products. This work investigated the impact of enzymatic hydrolysis and cross-linking composite modification on the properties of rice starches. Rice starch was cross-linked with epichlorohydrin (EPI) with different concentrations (0.5%, 0.7%, 0.9% w/w, on a dry starch basis), affording cross-linked rice starches with the three different levels of cross-linking that were named R1, R2, and R3, respectively. The cross-linked rice starches were hydrolyzed by α-amylase and native, hydrolyzed, and hydrolyzed cross-linked rice starches were comparatively studied. It was found that hydrolyzed cross-linked rice starches showed a lower the degree of amylase hydrolysis compared with hydrolyzed rice starch. The higher the degree of cross-linking, the higher the capacity to resist enzyme hydrolysis. Hydrolyzed cross-linked rice starches further increased the adsorptive capacities of starches for liquids and decreased the trend of retrogradation, and it also strengthened the capacity to resist shear compared to native and hydrolyzed rice starches.

Evaluation of black tea polyphenol extract against the retrogradation of starches from various plant sources.

The effects of black tea polyphenol extract (BTPE) on the retrogradation of starches from different plant sources were studied using differential scanning calorimetry (DSC) and X-ray diffraction (XRD). DSC analysis shows that the gelatinization temperature of maize starch and starches from different rice varieties increased with increasing BTPE level. After storage at 4 °C, BTPE at a concentration of 15% markedly retarded the retrogradation of maize starch and starches from different rice varieties. Native maize starch and starches from different rice varieties showed typical A-type X-ray diffraction patterns, while native potato starch showed a typical B-type X-ray diffraction pattern. Adding BTPE significantly affected the crystalline region and intensities of X-ray diffraction peaks of maize and rice starch granules. It is concluded that adding BTPE markedly inhibits the retrogradation of maize starch and starches from different rice varieties, but has no significant influence on the gelatinization and retrogradation characteristics of potato starch.

Improving the fermentation production of the individual key triterpene ganoderic acid me by the medicinal fungus Ganoderma lucidum in submerged culture.

Enhanced ganoderic acid Me (GA-Me, an important anti-tumor triterpene) yield was attained with the medicinal fungus Ganoderma lucidum using response surface methodology (RSM). Interactions were studied with three variables, viz. glucose, peptone and culture time using a Central Composite Design (CCD). The CCD contains a total of 20 experiments with the first 14 experiments organized in a fractional factorial design, with the experimental trails from 15 to 20 involving the replications of the central points. A polynomial model, describing the relationships between the yield of GA-Me and the three factors in a second-order equation, was developed. The model predicted the maximum GA-Me yield of 11.9 mg·L−1 for glucose, peptone, culture time values of 44.4 g·L−1, 5.0 g·L−1, 437.1 h, respectively, and a maximum GA-Me yield of 12.4 mg·L−1 was obtained in the validation experiment, which represented a 129.6% increase in titre compared to that of the non-optimized conditions. In addition, 11.4 mg·L−1 of GA-Me was obtained in a 30-L agitated fermenter under the optimized conditions, suggesting the submerged culture conditions optimized in the present study were also suitable for GA-Me production on a large scale.