Integrated omics-based analysis reveals the role of ferulic acid activating a co-production of 4-vinyl guaiacol and fumaric acid by Rhizopus oryzae.

ABSTRACTThe potential of a laccase from the fungus Pycnoporus cinnabarinus to cross‐link feruloylated soluble wheat arabinoxylans was investigated using capillary viscometry, size‐exclusion HPLC, and reverse‐phase HPLC of phenolic compounds. The laccase results were compared with those for a hydrogen peroxide/horseradish peroxidase system. The oxidants provoked an increase in viscosity of a 0.2% (w/v) arabinoxylan solution. A gel was formed after 30 min with laccase. Hydrogen peroxide was consumed rapidly before a gel could be formed. Free ferulic acid, methyl ferulate, and vanillic acid inhibited the gelation, whereas fumaric acid had no effect. This suggests that the aromatic ring, and not the propenoic chain of ferulic acid, was the initiating site for arabinoxylan cross‐linking. Ferulic acid and its 8‐O‐4′, 8‐5′, and 5‐5′ dehydrodimers were present in nonoxidized arabinoxylans. Upon oxidation, the 8‐8′ and 8‐5′ benzofuran dehydrodimers appeared and the 8‐O‐4′ and 8‐5′ dimers increased. The production of dimers was proportional to the consumption of ester‐bound ferulic acid. In cross‐linked arabinoxylans, the major dimers were 8‐5′ benzofuran, 8‐8′, and 8‐O‐4′, whereas the 5‐5′ dehydrodimer remained at the same level as in the nonoxidized solution.

Combined effects of fumaric, lactic, and ferulic acid against food-borne pathogenic biofilms

The feruloyl esterase B gene (faeB) is specifically induced by hydroxycinnamic acids (e.g. ferulic acid, caffeic acid and coumaric acid) but the transcriptional regulation network involved in faeB induction and ferulic acid metabolism has only been partially addressed. To identify transcription factors involved in ferulic acid metabolism we constructed and screened a transcription factor knockout library of 239 Aspergillus niger strains for mutants unable to utilize ferulic acid as a carbon source. The ΔfarA transcription factor mutant, already known to be involved in fatty acid metabolism, could not utilize ferulic acid and other hydroxycinnamic acids. In addition to screening the transcription factor mutant collection, a forward genetic screen was performed to isolate mutants unable to express faeB. For this screen a PfaeB-amdS and PfaeB-lux613 dual reporter strain was engineered. The rationale of the screen is that in this reporter strain ferulic acid induces amdS (acetamidase) expression via the faeB promoter resulting in lethality on fluoro-acetamide. Conidia of this reporter strain were UV-mutagenized and plated on fluoro-acetamide medium in the presence of ferulic acid. Mutants unable to induce faeB are expected to be fluoro-acetamide resistant and can be positively selected for. Using this screen, six fluoro-acetamide resistant mutants were obtained and phenotypically characterized. Three mutants had a phenotype identical to the farA mutant and sequencing the farA gene in these mutants indeed showed mutations in FarA which resulted in inability to growth on ferulic acid as well as on short and long chain fatty acids. The growth phenotype of the other three mutants was similar to the farA mutants in terms of the inability to grow on ferulic acid, but these mutants grew normally on short and long chain fatty acids. The genomes of these three mutants were sequenced and allelic mutations in one particular gene (NRRL3_09145) were found. The protein encoded by NRRL3_09145 shows similarity to the FarA and FarB transcription factors. However, whereas FarA and FarB contain both the Zn(II)2Cys6 domain and a fungal-specific transcription factor domain, the protein encoded by NRRL3_09145 (FarD) lacks the canonical Zn(II)2Cys6 domain and possesses only the fungal specific transcription factor domain.

Activation of glycerol metabolic pathway by evolutionary engineering of Rhizopus oryzae to strengthen the fumaric acid biosynthesis from crude glycerol

Ferulic acid triggering a co-production of 4-vinyl guaiacol and fumaric acid from lignocellulose-based carbon source by Rhizopus oryzae

Production of organic acids through fermentation of biomass feedstock is a potent strategy for co-product generation and improving economics in lignocellulose biorefinery. Sugar cane trash (SCT), a surplus available agro-residue, was exploited for the production of fumaric acid - a dicarboxylic acid with applications in the synthesis of polyester resins, as mordant and as a food additive. The isolate NIIST 1 which showed the production of fumaric acid was identified as Rhizopus oryzae. Media engineering was carried out and a maximum production of fumaric acid in SCT hydrolysate incorporated media was 5.2 g/L. Response surface analyses of the interaction of parameters indicated the importance of maintaining a high C/N ratio. Results indicate the scope for developing the Rhizopus oryzae strain NIIST 1 as a potent organism for fumaric acid production, since only a few microorganisms have the ability to produce industrially relevant compounds using lignocellulose biomass hydrolysates.

The ability of Rhizopus oryzae to produce fumaric acid in the presence of glycerol and/or various monosaccharides as carbon sources was examined for seventeen different strains of this fungi. These strains were tested in shake-flask cultures on media containing glycerol and seven different carbohydrates, including glucose, fructose, galactose, mannose, xylose, arabinose, and rhamnose. An interesting and applicationally useful phenomenon was observed. This work presents a new approach to the conventional microbiological method of producing fumaric acid. In the presence of 40 g/l glycerol as the sole carbon source, fumaric acid production reached 0.16–6.1 g/l after 192 h. When monosaccharides were used as a single carbon source, the maximum fumaric acid concentration was much higher; for example, 19.8 g/l was achieved when 40 g/l xylose was used. In the co-fermentation of xylose (40 g/l) and glycerol (20 g/l), post-culture broth contained approx. 28.0 g/l of fumaric acid with a process yield of 0.90 g/g after 168 h. The production of fumaric acid by Rhizopus oryzae was also increased in the dual presence of glycerol and monosaccharides like fructose, galactose, and mannose. However, results obtained on glucose-glycerol-based medium did not follow this trend, showing instead complete utilization of glucose with significant glycerol consumption, but unexpectedly low final amounts of fumaric acid and process yields. Understanding how Rhizopus oryzae utilize various carbon sources may provide alternative avenues of fumaric acid fermentation.

Fumaric acid is an important four-carbon dicarboxylic acid as a potential biorefinery target. A high-throughput screening method for fumaric acid overproduction strains was established. Nystatin (50 mg/L) was added into the production medium to restrict the spread of Rhizopus oryzae hyphae on agar plates. With bromocerol green as a pH indicator in the agar plates, the capability of fumaric acid biosynthesis by single colony was positively correlated with the diameter ratio of the colored ring and the colony. With this novel strategy, one high-yield mutant (Rhizopus oryzae ZJU11) was isolated from a large colony library of Rhizopus oryzae after UV irradiation. Starting with an optimized glucose concentration of 85 g/L, Rhizopus oryzae ZJU11 can produce 57.4 g/L fumaric acid in flask and 41.1 g/L in 5-L fermentor, which were 205% and 160% higher than that of the parent strain, respectively. Further studies showed that the production of fumaric acid by Rhizopus oryzae ZJU11 remained at the same level after three consecutive generations on the fermentation medium.

The production of ferulic acid esterase involved in the release of ferulic acid side groups from xylan was investigated in strains of Aspergillus tubingensis, Aspergillus carneus, Aspergillus niger and Rhizopus oryzae. The highest activity on triticale bran as sole carbon source was observed with the A. tubingensis T8.4 strain, which produced a type A ferulic acid esterase active against methyl p-coumarate, methyl ferulate and methyl sinapate. The activity of the A. tubingensis ferulic acid esterase (AtFAEA) was inhibited twofold by glucose and induced twofold in the presence of maize bran. An initial accumulation of endoglucanase was followed by the production of endoxylanase, suggesting a combined action with ferulic acid esterase on maize bran. A genomic copy of the A. tubingensis faeA gene was cloned and expressed in A. niger D15#26 under the control of the A. niger gpd promoter. The recombinant strain has reduced protease activity and does not acidify the media, therefore promoting high-level expression of recombinant enzymes. It produced 13.5 U/ml FAEA after 5 days on autoclaved maize bran as sole carbon source, which was threefold higher than for the A. tubingensis donor strain. The recombinant AtFAEA was able to extract 50 % of the available ferulic acid from non-pretreated maize bran, making this enzyme suitable for the biological production of ferulic acid from lignocellulosic plant material.

Ferulic acid (FA) is one of a common ingredients in Chinese herbal medicine. FA has the interesting property of promoting growth and improving meat quality in livestock, but the mechanism is not understood. This study evaluated both safety and mechanism of efficacy in zebrafish model. At 15μg/mL or above, FA led to pericardial oedema and delayed growth in zebrafish embryos. Dietary FA promoted growth and feed assimilation in male adult zebrafish. Genes related to myogenic development (myod1, myog and myf5) were significantly upregulated by FA and muscle fibre width in skeletal muscle was increased. At 20µg/g, FA significantly increased number of goblet cells in zebrafish intestinal tissue, and gut microbiota composition also changed. Based on 16s rRNA gene sequences, 20μg/g FA decreased Firmicutes and increased Bacteroides. 20μg/g FA also stimulated the expression of PPAR-α, a gene associated with fat metabolism, and decreased the expression of PPAR-β and PPAR-γ. These gene expression changes were beneficial to fatty acid synthesis and metabolism and decreased fat deposition. Our overall results indicated that FA can be a safe growth promotor in fish particularly in skeletal muscles.

Fumaric Acid

Fumaric Acid

Fumaric, malic, and succinic acids have been selectively separated from their mixture obtained by Rhizopus oryzae fermentation using reactive extraction with Amberlite LA-2 dissolved in three solvents with different dielectric constants (n-heptane, n-butyl acetate, and dichloromethane). This technique allows recovering preferentially fumaric acid from the mixture, the raffinate containing only malic and succinic acids. The extractant concentration and organic phase polarity control the efficiency and selectivity of acids extraction. The increase of aqueous phase viscosity reduces the extraction yield for all studied acids, but exhibits a positively effect on separation selectivity. By using Amberlite LA-2 concentration equal to that stoichiometrically required for interfacial reaction with fumaric acid and mixing intensity which does not allow higher diffusion rates for larger molecules (malic and succinic acids), the maximum value of fumaric acid extraction rate exceeds 90%, while the selectivity factor value becomes 20. Regardless of the extraction system, the complete separation of fumaric acid from their mixture is possible by multi-stage extraction process, adjusting the extractant concentration in each stage. At higher values of aqueous phase viscosity, more extraction stages are required, while the increase of solvent polarity reduce the required number of stages for total recovery of fumaric acid.

The effects and mechanisms of dietary ferulic acid (FA) and dihydromyricetin (DMY) on growth and physiological responses of the shrimp (Litopenaeus vannamei)

Ensuring a suitable pH is a major problem in industrial organic acid fermentation. To circumvent this problem, we used a metabolic profiling approach to analyze metabolite changes in Rhizopus oryzae under different pH conditions. A correlation between fumaric acid production and intracellular metabolic characteristics of R. oryzae was revealed by principal component analysis. The results showed that to help cell survival in the presence of low pH, R. oryzae altered amino acid and fatty acid metabolism and promoted sugar or sugar alcohol synthesis, corresponding with a suppressing of energy metabolism, phenylalanine, and tyrosine synthesis and finally resulting in the low performance of fumaric acid production. Based on this observation, 1% linoleic acid was added to the culture medium in pH 3.0 to decrease the carbon demand for cell survival, and the fumaric acid titer was enhanced by 39.7% compared with the control (pH3.0 without linoleic acid addition), reaching 18.3g/L after 84h of fermentation. These findings provide new insights into the mechanism by which R. oryzae responds to acidic stress and would be helpful for the development of efficient strategies for fumaric acid production at low pH.