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

Efficient production of Antrodin C by microparticle-enhanced cultivation of medicinal mushroom Antrodia cinnamomea

The microparticle-enhanced cultivation (MPEC) was used to enhance the production of Antrodin C by submerged fermentation of medicinal mushroom Antrodia cinnamomea. The crucial factors such as types, sizes, concentrations, and addition time of microparticles were optimized. The mechanism of MPEC on the membrane permeability and fluidity of A. cinnamomea and the expression of key genes in Antrodin C were investigated. When talc (18 μm, 2 g/L) was added into the fermentation liquid at 0 h, the promoting effect on Antrodin C was the best. The maximum yield of Antrodin C was 1615.7 mg/L, which was about 2.98 times of the control (541.7 mg/L). Talc slightly damaged the mycelia of A. cinnamomea, increased the release of intracellular constituents, and enhanced the index of unsaturated fatty acid. In addition, the key genes (IDI, E2.3.3.10, HMGCR, atoB) that might play an important role in the synthesis of the triquine-type sesquiterpene Antrodin C, were upregulated. In conclusion, talc increased the permeability and fluidity of cell membrane, upregulated the key genes and improved the biosynthesis process to enhance the yield of Antrodin C in the submerged fermentation of A. cinnamomea.

Genetic evidence for the requirements of antroquinonol biosynthesis by Antrodia camphorata during liquid-state fermentation

The solid-state fermentation of Antrodia camphorata could produce a variety of ubiquinone compounds, such as antroquinonol (AQ). However, AQ is hardly synthesized during liquid-state fermentation (LSF). To investigates the mechanism of AQ synthesis, three precursors (ubiquinone 0 UQ0, farnesol and farnesyl diphosphate FPP) were added in LSF. The results showed that UQ0 successfully induced AQ production; however, farnesol and FPP could not induce AQ synthesis. The precursor that restricts the synthesis of AQ is the quinone ring, not the isoprene side chain. Then, the Agrobacterium-mediated transformation system of A. camphorata was established and the genes for quinone ring modification (coq2-6) and isoprene synthesis (HMGR, fps) were overexpressed. The results showed that overexpression of genes for isoprene side chain synthesis could not increase the yield of AQ, but overexpression of coq2 and coq5 could significantly increase AQ production. This is consistent with the results of the experiment of precursors. It indicated that the A. camphorata lack the ability to modify the quinone ring of AQ during LSF. Of the modification steps, prenylation of UQ0 is the key step of AQ biosynthesis. The result will help us to understand the genetic evidence for the requirements of AQ biosynthesis in A. camphorata.

Promotion of monacolin K production in Monascus extractive fermentation: the variation in fungal morphology and in the expression levels of biosynthetic gene clusters

BACKGROUND

Monacolin K, an important secondary metabolite of Monascus, possesses a cholesterol-lowering effect and is widely used in the manufacture of antihypertensive drugs. In the present study, we constructed an extractive fermentation system by adding non-ionic surfactant and acquired a high monacolin K yield. The mechanism was determined by examining both cell morphology and the transcription levels of the related mokA-I genes in the monacolin K biosynthetic gene cluster.

RESULTS

The monacolin K yield was effectively increased to 539.59 mg L^-1 during extraction, which was an increase of 386.16% compared to that in the control group fermentation. The non-ionic surfactant showed good biocompatibility with Monascus. Electron scanning microscopy revealed alterations in the morphology of Monascus. The loosened mycelial structure and increased number of cell surface wrinkles were found to be related to the increased cell-membrane permeability and extracellular accumulation of monacolin K. Gene expression levels were measured via a quantitative reverse transciptase-polymerase chain reaction. By contrast, in the control group, mokA, mokB, mokC, mokD and mokF showed higher-level and longer-term expression in the extractive fermentation group, whereas mokE and mokG did not present a similar trend. The expression levels of mokH and mokI, encoding a transcription factor and efflux pump, respectively, were also higher than the control levels.

CONCLUSION

The addition of a non-ionic surfactant to Monascus fermentation effectively increases the yield of monacolin K by transforming the fungus morphology and promoting the expression of monacolin K biosynthesis genes. © 2021 Society of Chemical Industry.

Enhancement of antroquinonol production via the overexpression of 4-hydroxybenzoate polyprenyltransferase biosynthesis-related genes in Antrodia cinnamomea

Antroquinonol (AQ) as one of the most potent bioactive components in Antrodia cinnamomea (Fomitopsidaceae) shows a broad spectrum of anticancer effects. The lower yield of AQ has hampered its possible clinical application. AQ production may potentially be improved by genetic engineering. In this study, the protoplast-polyethylene glycol method combined with hygromycin as a selection marker was used in the genetic engineering of A. cinnamomea S-29. The optimization of several crucial parameters revealed that the optimal condition for generating maximal viable protoplasts was digestion of 4-day-old germlings with a mixture of enzymes (lysing enzyme, snailase, and cellulase) and 1.0 M MgSO₄ for 4 h. The ubiA and CoQ2 genes, which are involved in the synthesis of 4-hydroxybenzoate polyprenyltransferase, were cloned and overexpressed in A. cinnamomea. The results showed that ubiA and CoQ2 overexpression significantly increased AQ production in submerged fermentation. The overexpressing strain produced maximum AQ concentrations of 14.75 ± 0.41 mg/L and 19.25 ± 0.29 mg/L in pCT74-gpd-ubiA and pCT74-gpd-CoQ2 transformants, respectively. These concentrations were 2.00 and 2.61 times greater than those produced by the control, respectively. This research exemplifies how the production of metabolites may be increased by genetic manipulation, and will be invaluable to guide the genetic engineering of other mushrooms that produce medically useful compounds.

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.