Changes in volatile compound composition of Antrodia camphorata during solid state fermentation

Correlation analysis and modeling application from objective indicators to subjective evaluation of scented tea: A case study of rose tea

Different scented teas provide various choices for consumers from appearance, aroma, flavor and others. Aiming to define advantages and market positions of different scented teas and promote optimization of market structure, characteristics for scented tea favored by consumers and outstanding attributes of different scented teas should be clarified. Rose tea was taken as study object. Sensory evaluation and consumer acceptance were investigated. GC-MS and HPLC fingerprints were established. Physicochemical characteristics were determined. RGB integration analysis was inventively proposed for correlation analysis. The volatile compounds with spicy, green or herbal odor as camphene, β-phenethyl acetate, eugenol, and physicochemical parameters as antioxidant capacity, reducing sugar content, pH showed positive correlation with popular sensory properties. Six models for consumer preference by objective description were built through GA-SVR (accuracy = 1), and APP was developed. The research mode of scented tea has been successfully established to study multiple subjective characteristics with measurable objective parameters.

Comparative Genomic and Metabolomic Analysis of Termitomyces Species Provides Insights into the Terpenome of the Fungal Cultivar and the Characteristic Odor of the Fungus Garden of Macrotermes natalensis Termites

Macrotermitinae termites have domesticated fungi of the genus Termitomyces as food for their colony, analogously to human farmers growing crops. Termites propagate the fungus by continuously blending foraged and predigested plant material with fungal mycelium and spores (fungus comb) within designated subterranean chambers. To test the hypothesis that the obligate fungal symbiont emits specific volatiles (odor) to orchestrate its life cycle and symbiotic relations, we determined the typical volatile emission of fungus comb biomass and Termitomyces nodules, revealing α-pinene, camphene, and d-limonene as the most abundant terpenes. Genome mining of Termitomyces followed by gene expression studies and phylogenetic analysis of putative enzymes related to secondary metabolite production encoded by the genomes uncovered a conserved and specific biosynthetic repertoire across strains. Finally, we proved by heterologous expression and in vitro enzymatic assays that a highly expressed gene sequence encodes a rare bifunctional mono-/sesquiterpene cyclase able to produce the abundant comb volatiles camphene and d-limonene.

IMPORTANCE The symbiosis between macrotermitinae termites and Termitomyces is obligate for both partners and is one of the most important contributors to biomass conversion in the Old World tropic’s ecosystems. To date, research efforts have dominantly focused on acquiring a better understanding of the degradative capabilities of Termitomyces to sustain the obligate nutritional symbiosis, but our knowledge of the small-molecule repertoire of the fungal cultivar mediating interspecies and interkingdom interactions has remained fragmented. Our omics-driven chemical, genomic, and phylogenetic study provides new insights into the volatilome and biosynthetic capabilities of the evolutionarily conserved fungal genus Termitomyces, which allows matching metabolites to genes and enzymes and, thus, opens a new source of unique and rare enzymatic transformations.

RNA-Seq transcriptomic analyses of Antrodia camphorata to determine antroquinonol and antrodin C biosynthetic mechanisms in the in situ extractive fermentation

BACKGROUND

In situ extractive fermentation (ISEF) is an important technique for improving metabolite productivity. The different extractants can induce the synthesis of different bioactive metabolites of Antrodia camphorata during ISEF. However, a lack of research on the molecular genetics of A. camphorata during ISEF currently hinders such studies on metabolite biosynthetic mechanisms.

RESULTS

To clarify the differentially expressed genes during ISEF, the gene transcriptional expression features of A. camphorata S-29 were analysed. The addition of n-tetradecane as an extractant during ISEF showed more pronounced up-regulation of ubiquinone and other terpenoid-quinone biosynthesis pathway genes (CoQ2, wrbA and ARO8). When oleic acid was used as an extractant, the terpenoid backbone biosynthesis and ubiquinone and other terpenoid-quinone biosynthesis pathways were significantly enriched, and genes (IDI, E2.3.3.10, HMGCR atoB, and CoQ2) related to these two pathways were also significantly up-regulated. The CoQ2 genes encode puru-hydroxybenzoate:polyprenyltransferase, playing an important role in antroquinonol synthesis. The IDI, E2.3.3.10, HMGCR and atoB genes of the terpenoid backbone biosynthesis pathway might play an important role in the synthesis of the triquine-type sesquiterpene antrodin C.

CONCLUSION

This investigation advances our understanding of how two different extractants of n-tetradecane and oleic acid affect the biosynthesis of metabolites in A. camphorata. It is beneficial to provide potential strategies for improving antrodin C and antroquinonol production by genetic means. © 2020 Society of Chemical Industry.

Comprehensive transcriptomic and proteomic analyses of antroquinonol biosynthetic genes and enzymes in Antrodia camphorata

Antroquinonol (AQ) has several remarkable bioactivities in acute myeloid leukaemia and pancreatic cancer, but difficulties in the mass production of AQ hamper its applications. Currently, molecular biotechnology methods, such as gene overexpression, have been widely used to increase the production of metabolites. However, AQ biosynthetic genes and enzymes are poorly understood. In this study, an integrated study coupling RNA-Seq and isobaric tags for relative and absolute quantitation (iTRAQ) were used to identify AQ synthesis-related genes and enzymes in Antrodia camphorata during coenzyme Q0-induced fermentation (FM). The upregulated genes related to acetyl-CoA synthesis indicated that acetyl-CoA enters the mevalonate pathway to form the farnesyl tail precursor of AQ. The metE gene for an enzyme with methyl transfer activity provided sufficient methyl groups for AQ structure formation. The CoQ2 and ubiA genes encode p-hydroxybenzoate polyprenyl transferase, linking coenzyme Q0 and the polyisoprene side chain to form coenzyme Q3. NADH is transformed into NAD+ and releases two electrons, which may be beneficial for the conversion of coenzyme Q3 to AQ. Understanding the biosynthetic genes and enzymes of AQ is important for improving its production by genetic means in the future.

An increase in cell membrane permeability in the in situ extractive fermentation improves the production of antroquinonol from Antrodia camphorata S-29

The goals of this study were to increase the production of antroquinonol (AQ) and to elucidate the response mechanism of the cell membrane during the in situ extractive fermentation (ISEF) of Antrodia camphorata S-29. Through ISEF, the concentration of AQ reached a maximum of 146.1 ± 2.8 mg/L, which was approximately (7.4 ± 0.1)-fold that of the control (coenzyme Q0-induced fermentation). Transcriptome sequencing showed that four genes (FAD2, fabG, SCD, and FAS1) related to fatty acid biosynthesis were upregulated. FAD2 and SCD may regulate the increase in oleic acid (C18:1) and linoleic acid (C18:2) in the cell membrane of A. camphorata S-29, resulting in an increase in cell membrane permeability. AQ was successfully transferred to the n-tetradecane phase through the cell membrane, reducing product feedback inhibition and improving the production of AQ from A. camphorata S-29.

Aroma Profile Analyses of Filamentous Fungi Cultivated on Solid Substrates

Filamentous fungi have been used since centuries in the production of food by means of solid substrate fermentation (SSF). The most applied SSF involving fungi is the cultivation of mushrooms, e.g., on tree stumps or sawdust, for human consumption. However, filamentous fungi are also key players during manufacturing of several processed foods, like mold cheese, tempeh, soy sauce, and sake. In addition to their nutritive values, these foods are widely consumed due to their pleasant flavors. Based on the potentials of filamentous fungi to grow on solid substrates and to produce valuable aroma compounds, in recent decades, several studies concentrated on the production of aroma compounds with SSF, turning cheap agricultural wastes into valuable flavors. In this review, we focus on the presentation of common analytical methods for volatile substances and highlight various applications of SSF of filamentous fungi dealing with the production of aroma compounds. Graphical Abstract.

Vanillin Promotes the Germination of Antrodia camphorata Arthroconidia through PKA and MAPK Signaling Pathways

Wild fruiting bodies of medicinal mushroom Antrodia camphorata are only found on the endemic species bull camphor tree, Cinnamomum kanehirae, in Taiwan. Despite the evident importance of the host components in promoting the growth of A. camphorata, insights into the underlying mechanisms are still lacking. Here, we first evaluated effects of the compounds from C. kanehirai, C. camphora, and A. camphorata, and their structural analogs on the germination rate of A. camphorata arthroconidia. Among the 54 tested compounds, vanillin (4-hydroxy-3-methoxybenzaldehyde) was determined as the optimum germination promoter, while o-vanillin and 1-octen-3-ol as major negative regulators of arthroconidia germination. Second, the protein patterns of arthroconidia after 24 h of incubation in the presence or absence of vanillin were compared via isobaric tags for relative and absolute quantitation (iTRAQ)-based proteomics. Via bioinformatic analysis, it was found that 61 proteins might relate to the germination of arthroconidia, in which 16 proteins might involve in two potential protein kinase A (PKA) and mitogen-activated protein kinase (MAPK) signaling pathways in the vanillin-promoted germination of A. camphorata arthroconidia. Last, the mRNA expression levels of the 16 germination-related genes in the potential PKA and MAPK signaling pathways were analyzed by quantitative real time PCR. Together, our results are beneficial for the elucidation of molecular mechanisms underlying the germination of A. camphorata arthroconidia.

Effect of cultural conditions on antrodin C production by basidiomycete Antrodia camphorata in solid-state fermentation

Antrodia camphorata is a medicinal fungus and antrodin C is one of the main bioactive components of A. camphorata in the submerged fermentation (SmF). To optimize the culture conditions, the factors influencing the production of antrodin C by A. camphorata under solid-state fermentation (SSF) were investigated in this study. Different solid substrates and external nitrogen sources were tested for their efficiency in producing antrodin C. The response surface methodology was applied to evaluate the influence of several variables, namely, the concentrations of soybean meal, initial moisture content, and inoculum density on antrodin C production in solid-state fermentation. The experimental results show that the optimum fermentation medium for antrodin C production by A. camphorata was composed of 0.578 g soybean meal, 0.05 g Na2 HPO4 , 0.05 g MgSO4 for 100 g rice, with 51.83% initial moisture content, 22 day culture time, 28 °C culture temperature, and 35.54% inoculum density. At optimized conditions, 6,617.36 ± 92.71 mg kg(-1) yield of antrodin C was achieved. Solid-state fermentation is one good cultural method to improve the production of antrodin C by A. camphorata.

Enhancement of 4-acetylantroquinonol B production by supplementation of its precursor during submerged fermentation of Antrodia cinnamomea

The antiproliferation activity of the ethanol extract of A. cinnamomea mycelium on hepatocellular cancer cells HepG2 was found to be associated with aroma intensity of the broth during fermentation. We hypothesized that some of the volatile compounds are the precursors of the key bioactive component 4-acetylantroquinonol B of this fungus. The major volatile compounds of A. cinnamomea were identified by GC/MS, and they are oct-1-en-3-ol, linalool, methyl phenylacetate, nerolidol, γ-cadinene and 2,4,5-trimethoxybenzaldehyde (TMBA). TMBA and nerolidol were further selected and used as supplements during fermentation. It was found that both of them could increase the production of 4-acetylantroquinonol B and enhance the antiproliferation activity of the fungus. In addition, the TMBA was identified as the most promising supplement for increasing the bioactivity of A. cinnamomea during cultivation.