A chlorogenic acid esterase with a unique substrate specificity from Ustilago maydis

Comparative analysis of lipolytic enzymes involved in the surface fermentation of dried katsuobushi by xerophilic molds

BACKGROUND

Fermented katsuobushi, a traditional Japanese seasoning, is produced from skipjack tuna through smoking, drying and fermentation by xerophilic Aspergillus molds, primarily Aspergillus chevalieri and Aspergillus pseudoglaucus. In this study, we characterized lipolytic enzymes (cLip_1 to cLip_5 and pLip_1 to pLip_3) to clarify their roles in lipid hydrolysis during katsuobushi production under low water activity.

RESULTS

The enzymes showed significant diversity in their activity, stability and substrate specificity, and in the hydrolysis profiles of their reactions with fish oil. Phylogenetic analyses revealed that cLip_5 showed a high identity with pLip_2 (94%) and these enzymes formed a phylogenetic cluster with filamentous fungal lipases. Purified recombinant enzymes (rcLip_1, rcLip_2, rcLip_4 and rcLip_5) and wild-type enzymes (cLip_3 and pLip_3) showed varying substrate preferences toward p-nitrophenyl esters. The addition of glycerol to reduce the water activity in the reaction mixture led to increased activities of rcLip_1 and rcLip_4, but it did not affect the activity of the other three enzymes. Among the tested six enzymes, cLip_5 showed the highest hydrolytic activity toward fish oil. The cLip_5 and pLip_2 gene transcript levels were moderately high in strains MK86 and MK88, respectively.

CONCLUSION

cLip_5 and its homolog pLip_2 were identified as the most promising enzymes for katsuobushi fermentation, because of their high hydrolytic activities toward fish oil and adaptability to low water activity conditions. These findings support the selection of optimal Aspergillus strains as starter cultures to potentially shorten the fermentation time and improve the quality and shelf life of katsuobushi. © 2025 Society of Chemical Industry.

The structure of a Lactobacillus helveticus chlorogenic acid esterase and the dynamics of its insertion domain provide insights into substrate binding

Chlorogenic acid esterases (ChlEs) are a useful class of enzymes that hydrolyze chlorogenic acid (CGA) into caffeic and quinic acids. ChlEs can break down CGA in foods to improve their sensory properties and release caffeic acid in the digestive system to improve the absorption of bioactive compounds. This work presents the structure, molecular dynamics, and biochemical characterization of a ChlE from Lactobacillus helveticus (Lh). Molecular dynamics simulations suggest that substrate access to the active site of LhChlE is modulated by two hairpin loops above the active site. Docking simulations and mutational analysis suggest that two residues within the loops, Gln145 and Lys164 , are important for CGA binding. Lys164 provides a slight substrate preference for CGA, whereas Gln145 is required for efficient turnover. This work is the first to examine the dynamics of a bacterial ChlE and provides insights on substrate binding preference and turnover in this type of enzyme.

Mycelium-bound chlorogenate hydrolase of Aspergillus niger AKU 3302 as a stable immobilized biocatalyst

CHase catalyzes chlorogenic acid (CGA) hydrolysis to yield equimolar quinic (QA) and caffeic (CA) acids, products of high value and keen industrial interest. We proposed the preparation and characterization of the nonviable mycelium of Aspergillus niger AKU 3302 containing a cell-associated CHase (CHase biocatalyst) for application in hydrolyzing the CGA from yerba mate residues to produce QA and CA. When the vegetative mycelium was heated at 55 °C for 30 min, no loss of CHase activity occurred, but vegetative mycelial growth and spore germination ended. The CHase biocatalyst did not limit mass transfer above 100 strokes min^-1. The reaction rate increased with catalyst loading and was kinetically controlled. The CHase biocatalyst exhibited suitable biochemical properties (optimum pH 6.5 at 50 °C) and high thermal stability (remaining stable at up to 50 °C for 8 h). The cations in yerba mate extracts did not affect CHase activity. We observed no apparent loss in the activity of the CHase biocatalyst after even 11 batch cycles of continuous use. The biocatalyst retained 85% of its initial activity after 25 days of storage at pH 6.5 and 5 °C. When a yerba mate extract was passed through a glass column packed with the biocatalyst, an effective bioconversion of CGA into CA and QA occurred. CHase activity produced a natural biocatalysis with considerable operational and storage stability; which capability, being a novel biotechnological process, can be used in the bioconversion of CGA from yerba mate residues into CA and QA at a substantially reduced cost.

Huitlacoche (Ustilago maydis), an Iconic Mexican Fungal Resource: Biocultural Importance, Nutritional Content, Bioactive Compounds, and Potential Biotechnological Applications

Worldwide, the fungus known as huitlacoche (Ustilago maydis (DC.) Corda) is a phytopathogen of maize plants that causes important economic losses in different countries. Conversely, it is an iconic edible fungus of Mexican culture and cuisine, and it has high commercial value in the domestic market, though recently there has been a growing interest in the international market. Huitlacoche is an excellent source of nutritional compounds such as protein, dietary fiber, fatty acids, minerals, and vitamins. It is also an important source of bioactive compounds with health-enhancing properties. Furthermore, scientific evidence shows that extracts or compounds isolated from huitlacoche have antioxidant, antimicrobial, anti-inflammatory, antimutagenic, antiplatelet, and dopaminergic properties. Additionally, the technological uses of huitlacoche include stabilizing and capping agents for inorganic nanoparticle synthesis, removing heavy metals from aqueous media, having biocontrol properties for wine production, and containing biosurfactant compounds and enzymes with potential industrial applications. Furthermore, huitlacoche has been used as a functional ingredient to develop foods with potential health-promoting benefits. The present review focuses on the biocultural importance, nutritional content, and phytochemical profile of huitlacoche and its related biological properties as a strategy to contribute to global food security through food diversification; moreover, the biotechnological uses of huitlacoche are also discussed with the aim of contributing to the use, propagation, and conservation of this valuable but overlooked fungal resource.

A highly active esterase from Lactobacillus helveticus hydrolyzes chlorogenic acid in sunflower meal to prevent chlorogenic acid induced greening in sunflower protein isolates

Chlorogenic acid (CGA) is an ester between caffeic and quinic acid. It is found in many foods and reacts with free amino groups in proteins at alkaline pH, leading to the formation of an undesirable green pigment in sunflower seed-derived ingredients. This paper presents the biochemical characterization and application of a highly active chlorogenic acid esterase from Lactobacillus helveticus. The enzyme is one of the most active CGA esterases known to date with a Km of 0.090 mM and a kcat of 82.1 s-1. The CGA esterase is easily expressed recombinantly in E. coli in large yields and is stable over a wide range of pH and temperatures. We characterized CGA esterase's kinetic properties in sunflower meal and demonstrated that the enzyme completely hydrolyzes CGA in the meal. Finally, we showed that CGA esterase treatment of sunflower seed meal enables the production of pale brown sunflower protein isolates using alkaline extraction. This work will allow for more widespread use of sunflower-derived products in applications where neutrally-colored food products are desired.

Improved Foods Using Enzymes from Basidiomycetes

Within the kingdom of fungi, the division Basidiomycota represents more than 30,000 species, some with huge genomes indicating great metabolic potential. The fruiting bodies of many basidiomycetes are appreciated as food (“mushrooms”). Solid-state and submerged cultivation processes have been established for many species. Specifically, xylophilic fungi secrete numerous enzymes but also form smaller metabolites along unique pathways; both groups of compounds may be of interest to the food processing industry. To stimulate further research and not aim at comprehensiveness in the broad field, this review describes some recent progress in fermentation processes and the knowledge of fungal genetics. Processes with potential for food applications based on lipases, esterases, glycosidases, peptidases and oxidoreductases are presented. The formation and degradation of colourants, the degradation of harmful food components, the formation of food ingredients and particularly of volatile and non-volatile flavours serve as examples. In summary, edible basidiomycetes are foods—and catalysts—for food applications and rich donors of genes to construct heterologous cell factories for fermentation processes. Options arise to support the worldwide trend toward greener, more eco-friendly and sustainable processes.

Untargeted Metabolomic Investigation of Wheat Infected with Stinking Smut Tilletia caries

Tilletia caries infection of wheat (Triticum aestivum) has become an increasing problem in organic wheat agriculture throughout the world. Little is known about how this pathogen alters host metabolism to ensure a successful infection. We investigated how T. caries allocates resources from wheat for its growth over the life cycle of the pathogen. An untargeted metabolomics approach that combined gas chromatography time-of-flight mass spectrometry and ultraperformance liquid chromatography tandem mass spectrometry platforms was used to determine which primary or specialized metabolite pathways are targeted and altered during T. caries infection. We found that T. caries does not dramatically alter the global metabolome of wheat but instead alters key metabolites for its own nutrient uptake and to antagonize host defenses by reducing wheat's sweet immunity response and other related pathways. Our results highlight metabolic characteristics needed for selecting wheat varieties that are resistant to T. caries infection for organic agriculture. In addition, several wheat metabolites were identified that could be used in developing a diagnostic tool for early detection of T. caries infection.

A novel esterase from a soil metagenomic library displaying a broad substrate range

A novel esterase gene was isolated from a soil metagenomic library. The gene encoded a protein of 520 amino acids which contained a 21 aa signal peptide. Primary structure analysis of the protein sequence revealed that it contained a conserved active site motif (SxSxG) and a structural motif (CS-D-HC). Then the esterase gene was cloned and expressed in Escherichia coli BL21(DE3). SDS-PAGE analysis of the purified esterase showed that it was expressed in a highly soluble form and its molecular mass was estimated to be 55 kDa. Characterization of the esterase revealed that it exhibited high activity toward p-nitrophenyl esters with short acyl chains and especially p-nitrophenyl acetate, suggesting that it was a typical carboxylesterase rather than a lipase. With p-nitrophenyl acetate as substrate, the enzyme showed its optimal activity at pH 7.0 and 30 °C, and it was stable at a broad pH range from 4.5 to 10.0 and temperature not higher than 50 °C. Furthermore, the enzyme showed different substrate specificity from known esterase, it was not only hydrolyzing against p-nitrophenyl esters, but also hydrolyzing all hydroxybenzoic esters and hydroxycinnamic ester assayed. As it was an enzyme active on a broad range of phenolic esters, simultaneously possessing feruloyl esterase, chlorogenate esterase and tannase activities, it could serve as a valuable candidate for applications in biotechnology.

Catabolism of hydroxycinnamic acids in contact with probiotic Lactobacillus

AIMS

The catabolism products of the fermentation process of selected hydroxycinnamic acids initiated by different species of Lactobacillus strains were identified.

METHODS AND RESULTS

Three dietary supplements (Sanprobi IBS^® , BioGaia ProTectis Baby^® and Dicoflor 60^® ) were used to isolate the Lactobacillus strains. The overnight bacterial cultures (18 h) were diluted and grown in a microaerophilic atmosphere at 37°C. Then, each phenolic acid was added to bacterial cultures and incubated for 24 h at 37°C. Samples were collected at specific intervals for a further 24 h of incubation. LC-MS/MS was used for the identification of metabolism products of selected phenolic acids.

CONCLUSIONS

The phenolic acids were resistant to the Lactobacillus rhamnosus GG. Lactobacillus plantarum 299v caused degradation of caffeic and ferulic acids. The former was degraded either to dihydrocaffeic acid or to 4-vinylcatechol and 4-ethylcatechol. Ferulic acid was degraded only to dihydroferulic acid. Lactobacillus reuteri DSM 17938 caused only the degradation of chlorogenic acid (5-caffeoylquinic acid, referred to IUPAC nomenclature) to caffeic acid.

SIGNIFICANCE AND IMPACT OF THE STUDY

Using of Lactobacilli as food additive should be taken into account that phenolic acids metabolism rate depends on not only the specific bacterial strain but also the structural properties of the acid.

Feruloyl Esterases for Biorefineries: Subfamily Classified Specificity for Natural Substrates

Feruloyl esterases (FAEs) have an important role in the enzymatic conversion of lignocellulosic biomass by decoupling plant cell wall polysaccharides and lignin. Moreover, FAEs release anti-oxidative hydroxycinnamic acids (HCAs) from biomass. As a plethora of FAE candidates were found in fungal genomes, FAE classification related to substrate specificity is an indispensability for selection of most suitable candidates. Hence, linking distinct substrate specificities to a FAE classification, such as the recently classified FAE subfamilies (SF), is a promising approach to improve the application of these enzymes for a variety of industrial applications. In total, 14 FAEs that are classified members of SF1, 5, 6, 7, 9, and 13 were tested in this research. All FAEs were investigated for their activity toward a variety of substrates: synthetic model substrates, plant cell wall-derived substrates, including lignin, and natural substrates. Released HCAs were determined using reverse phase-ultra high performance liquid chromatography coupled to UV detection and mass spectrometry. Based on this study, FAEs of SF5 and SF7 showed the highest release of FA, pCA, and diFAs over the range of substrates, while FAEs of SF6 were comparable but less pronounced for diFAs release. These results suggest that SF5 and SF7 FAEs are promising enzymes for biorefinery applications, like the production of biofuels, where a complete degradation of the plant cell wall is desired. In contrast, SF6 FAEs might be of interest for industrial applications that require a high release of only FA and pCA, which are needed as precursors for the production of biochemicals. In contrast, FAEs of SF1, 9 and 13 showed an overall low release of HCAs from plant cell wall-derived and natural substrates. The obtained results substantiate the previous SF classification as a useful tool to predict the substrate specificity of FAEs, which eases the selection of FAE candidates for industrial applications.

Carbohydrate Esterases: An Overview

Carbohydrate esterases are a group of enzymes which release acyl or alkyl groups attached by ester linkage to carbohydrates. The CAZy database, which classifies enzymes that assemble, modify, and break down carbohydrates and glycoconjugates, classifies all carbohydrate esterases into 16 families. This chapter is an overview of the research for nearly 50 years around the main groups of carbohydrate esterases dealing with the degradation of polysaccharides, their main biochemical and molecular traits, as well as its application for the synthesis of high added value esters.

A type D ferulic acid esterase from Streptomyces werraensis affects the volume of wheat dough pastries

A type D ferulic acid esterase (FAE) was identified in the culture supernatant of Streptomyces werraensis, purified, sequenced, and heterologously produced in E. coli BL21(DE3)Star by co-expressing chaperones groES-groEL (69 U L^-1). The unique enzyme with a mass of about 48 kDa showed no similarity to other FAEs, and only moderate homology (78.5%) to a Streptomycete β-xylosidase. The purified reSwFAED exhibited a temperature optimum of 40 °C, a pH optimum in the range from pH seven to eight and a clear preference for bulky natural substrates, such as 5-O-trans-feruloyl-L-arabinofuranose (FA) and β-D-xylopyranosyl-(1→2)-5-O-trans-feruloyl-L-arabinofuranose (FAX), compared to the synthetic standard substrate methyl ferulate. Treatment of wheat dough with as little as 0.03 U or 0.3 U kg^-1 reSwFAED activity resulted in a significant increase of the bun volume (8.0 or 9.7%, resp.) after baking when combined with polysaccharide-degrading enzymes from Aspergillus. For the first time, the long-standing, but rarely proven positive effect of a FAE in baking was confirmed.

Characterization and purification of a bacterial chlorogenic acid esterase detected during the extraction of chlorogenic acid from arbuscular mycorrhizal tomato roots

A Gram-negative bacterium able to grow using chlorogenic acid (5-caffeoylquinic acid) as sole carbon source has been isolated from the roots of tomato plants inoculated with the arbuscular mycorrhizal fungus Rhizophagus irregularis. An intracellular esterase exhibiting very high affinity (K_m = 2 μM) for chlorogenic acid has been extracted and purified by FPLC from the chlorogenate-grown cultures of this bacterium. The molecular mass of the purified esterase determined by SDS-PAGE was 61 kDa and its isoelectric point determined by chromatofocusing was 7.75. The esterase hydrolysed chlorogenic acid analogues (caffeoylshikimate, and the 4- and 3-caffeoylquinic acid isomers), feruloyl esterases substrates (methyl caffeate and methyl ferulate), and even caffeoyl-CoA in vitro but all of them were less active than chlorogenic acid, demonstrating that the esterase is a genuine chlorogenic acid esterase. It was also induced when the bacterial strain was cultured in the presence of hydroxycinnamic acids (caffeic, p-coumaric or ferulic acid) as sole carbon source, but not in the presence of simple phenolics such as catechol or protocatechuic acid, nor in the presence of organic acids such as succinic or quinic acids. The purified esterase was remarkably stable in the presence of methanol, rapid formation of methyl caffeate occurring when its activity was measured in aqueous solutions containing 10-60% methanol. Our results therefore show that this bacterial chlorogenase can catalyse the transesterification reaction previously detected during the methanolic extraction of chlorogenic acid from arbuscular mycorrhizal tomato roots. Data are presented suggesting that colonisation by Rhizophagus irregularis could increase chlorogenic acid exudation from tomato roots, especially in nutrient-deprived plants, and thus favour the growth of chlorogenate-metabolizing bacteria on the root surface or in the mycorhizosphere.

Feruloyl esterases from Schizophyllum commune to treat food industry side-streams

Agro-industrial side-streams are abundant and renewable resources of hydroxycinnamic acids with potential applications as antioxidants and preservatives in the food, health, cosmetic, and pharmaceutical industries. Feruloyl esterases (FAEs) from Schizophyllum commune were functionally expressed in Pichia pastoris with extracellular activities of 6000UL(-1). The recombinant enzymes, ScFaeD1 and ScFaeD2, released ferulic acid from destarched wheat bran and sugar beet pectin. Overnight incubation of coffee pulp released caffeic (>60%), ferulic (>80%) and p-coumaric acid (100%) indicating applicability for the valorization of food processing wastes and enhanced biomass degradation. Based on substrate specificity profiling and the release of diferulates from destarched wheat bran, the recombinant FAEs were characterized as type D FAEs. ScFaeD1 and ScFaeD2 preferably hydrolyzed feruloylated saccharides with ferulic acid esterified to the O-5 position of arabinose residues and showed an unprecedented ability to hydrolyze benzoic acid esters.

Heterologous production and characterization of a chlorogenic acid esterase from Ustilago maydis with a potential use in baking

Ustilago maydis, an edible mushroom growing on maize (Zea mays), is consumed as the food delicacy huitlacoche in Mexico. A chlorogenic acid esterase from this basidiomycete was expressed in good yields cultivating the heterologous host Pichia pastoris on the 5L bioreactor scale (reUmChlE; 45.9UL(-1)). In contrast to previously described chlorogenic acid esterases, the reUmChlE was also active towards feruloylated saccharides. The enzyme preferred substrates with the ferulic acid esterified to the O-5 position of arabinose residues, typical of graminaceous monocots, over the O-2 position of arabinose or the O-6 position of galactose residues. Determination of kcat/Km showed that the reUmChlE hydrolyzed chlorogenic acid 18-fold more efficiently than methyl ferulate, p-coumarate or caffeate. Phenolic acids were released by reUmChlE from natural substrates, such as destarched wheat bran, sugar beet pectin and coffee pulp. Treatment of wheat dough using reUmChlE resulted in a noticeable softening indicating a potential application of the enzyme in bakery and confectionery.

Diversity of fungal feruloyl esterases: updated phylogenetic classification, properties, and industrial applications

Feruloyl esterases (FAEs) represent a diverse group of carboxyl esterases that specifically catalyze the hydrolysis of ester bonds between ferulic (hydroxycinnamic) acid and plant cell wall polysaccharides. Therefore, FAEs act as accessory enzymes to assist xylanolytic and pectinolytic enzymes in gaining access to their site of action during biomass conversion. Their ability to release ferulic acid and other hydroxycinnamic acids from plant biomass makes FAEs potential biocatalysts in a wide variety of applications such as in biofuel, food and feed, pulp and paper, cosmetics, and pharmaceutical industries. This review provides an updated overview of the knowledge on fungal FAEs, in particular describing their role in plant biomass degradation, diversity of their biochemical properties and substrate specificities, their regulation and conditions needed for their induction. Furthermore, the discovery of new FAEs using genome mining and phylogenetic analysis of current publicly accessible fungal genomes will also be presented. This has led to a new subfamily classification of fungal FAEs that takes into account both phylogeny and substrate specificity.

Multifunctional roles of leader protein of foot-and-mouth disease viruses in suppressing host antiviral responses

Foot-and-mouth disease virus (FMDV) leader protein (L^pro) is a papain-like proteinase, which plays an important role in FMDV pathogenesis. L^pro exists as two forms, Lab and Lb, due to translation being initiated from two different start codons separated by 84 nucleotides. L^pro self-cleaves from the nascent viral polyprotein precursor as the first mature viral protein. In addition to its role as a viral proteinase, L^pro also has the ability to antagonize host antiviral effects. To promote FMDV replication, L^pro can suppress host antiviral responses by three different mechanisms: (1) cleavage of eukaryotic translation initiation factor 4 γ (eIF4G) to shut off host protein synthesis; (2) inhibition of host innate immune responses through restriction of interferon-α/β production; and (3) L^pro can also act as a deubiquitinase and catalyze deubiquitination of innate immune signaling molecules. In the light of recent functional and biochemical findings regarding L^pro, this review introduces the basic properties of L^pro and the mechanisms by which it antagonizes host antiviral responses.

Heterologous production of a feruloyl esterase from Pleurotus sapidus synthesizing feruloyl-saccharide esters

The feruloyl esterase (FAE) gene EST1 from the basidiomycete Pleurotus sapidus was heterologously expressed in Escherichia coli and Pichia pastoris. Catalytically active recombinant Est1 was secreted using P. pastoris as a host. For expression in P. pastoris, the expression vector pPIC9K was applied. The EST1 gene was cloned with an N-terminal α-mating factor pre-pro sequence and expressed under the control of a methanol inducible alcohol oxidase 1 promotor. Est1 was purified to homogeneity using ion exchange and hydrophobic interaction chromatography. The recombinant Est1 showed optima at pH 5.0 and 50 °C, and released ferulic acid from saccharide esters and from the natural substrate destarched wheat bran. Substrate specificity profile and descriptor-based analysis demonstrated unique properties, showing that Est1 did not fit into the current FAE classification model. Transferuloylation synthesis of feruloyl-saccharide esters was proven for mono- and disaccharides.