An efficient phthalate ester-degrading Bacillus subtilis: Degradation kinetics, metabolic pathway, and catalytic mechanism of the key enzyme

Xu, Youqiang; Liu, Xiao; Zhao, Jingrong; Huang, Huiqin; Wu, Mengqin; Li, Xiuting; Li, Weiwei; Sun, Xiaotao; Sun, Baoguo

doi:10.1016/j.envpol.2021.116461

Cited by 54 publications

(17 citation statements)

References 47 publications

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“…The Microorganisms are one of the deciding factors affecting baijiu quality (Jin et al, 2017;Wang et al, 2020Wang et al, , 2021. They not only metabolically synthesize flavor chemicals but also degrade some of the harmful chemicals in the raw materials, thus contributing greatly to the flavor and quality of the products (Xu Y. Q. et al, 2020;Xu et al, 2021aXu et al, , 2022a. A. niger was generally recognized as an important functional microorganism in baijiu manufacture (Wu et al, 2015).…”

Section: Methodsmentioning

confidence: 99%

Characterization of an Aspergillus niger for Efficient Fatty Acid Ethyl Ester Synthesis in Aqueous Phase and the Molecular Mechanism

Huang

et al. 2022

Front. Microbiol.

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Fatty acid ethyl esters are important flavor chemicals in strong-flavor baijiu. Microorganisms are the main contributors to ester synthesis during baijiu manufacture. However, the ester synthesis was unstable between batches. This was owing to a limited knowledge of the mechanisms for ester synthesis by microorganisms. In this work, a fatty acid ethyl ester synthesizing Aspergillus niger strain CGMCC (China General Microbiological Culture Collection) 3.4309 was identified. The conversion ratios of ethyl valerate, ethyl caproate, ethyl caprylate, and ethyl caprate were 7.87, 29.20, 94.80, and 85.20%, respectively, under the optimized conditions. A comparison of transcriptomes under the initial and optimized ester synthetic conditions indicated that 23 genes were upregulated in transcription level and encoded enzymes with potential abilities for ester synthesis. Eleven of the enzymes were expressed, and three of them, numbered An605, An1097, and An3131, showed the ability to catalyze fatty acid ethyl ester synthesis under aqueous phase, with capric acid as the preferred substrate. The possible enzymatic catalytic mechanism was proposed based on homology modeling and molecular docking. This study reported for the first time that A. niger showed the ability to efficiently catalyze the synthesis of short- and medium-chain fatty acid ethyl esters in aqueous phase, identified the key enzymes, and analyzed the basic enzymatic properties. This is helpful to promote the application of related microorganisms and enzyme resources in the baijiu industry.

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Section: Methodsmentioning

confidence: 99%

Characterization of an Aspergillus niger for Efficient Fatty Acid Ethyl Ester Synthesis in Aqueous Phase and the Molecular Mechanism

Huang

et al. 2022

Front. Microbiol.

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“…A total of 96 volatile compounds were detected in three samples; BQ contained 55, WQ contained 59, and YQ contained 61. As indicated in Table S1, they were categorized into seven groups based on their chemical structural properties, including esters (19), alcohols (16), acids (16), aldehydes (5), phenols (7), ketones (5), pyrazines (7) and ethers (4), as well as others (17). Similarly to Daqu for manufacturing strong-and light-flavored baijiu [36,37], esters were also dominant volatile compounds in high-temperature Daqu.…”

Section: Analysis Of the Volatile Flavor Compounds In The Three Daqu ...mentioning

confidence: 99%

“…In addition to metabolically synthesizing a variety of flavor compounds, the microbes in Daqu also break down some of the hazardous chemicals present in the raw materials. [7][8][9]. Therefore, Daqu plays an essential role in the manufacturing of sauce-flavored baijiu [10,11].…”

Section: Introductionmentioning

confidence: 99%

Correlational Analysis of the Physicochemical Indexes, Volatile Flavor Components, and Microbial Communities of High-Temperature Daqu in the Northern Region of China

Pang

Hao

et al. 2023

Foods

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Daqu is a microbial-rich baijiu fermentation starter. The high-temperature Daqu plays an essential role in the manufacturing of sauce-flavored baijiu. However, few studies have focused on three kinds of high-temperature Daqu (white, yellow, and black Daqu) in northern China. In this study, the physicochemical indexes, volatile flavor compounds, and microbial characteristics of the three different colors of high-temperature Daqu in northern China were comparatively analyzed to reveal their potential functions. White Daqu (WQ) exhibited the highest liquefying power and starch, and black Daqu (BQ) showed the highest saccharifying and esterifying powers. A total of 96 volatile components were identified in the three types of Daqu, and the contents of the volatile components of yellow Daqu (YQ) were the highest. The microbial community structure analysis showed that Bacillus and Byssochlamys were dominant in BQ, Kroppenstedtia and Thermoascus were dominant in WQ, and Virgibacillus and Thermomyces dominated the YQ. The RDA analysis revealed the correlation between the dominant microorganisms and different physicochemical indexes. The Spearman correlation analysis indicated that Oceanobacillus, Saccharopolyspora, Staphylococcus, Pseudogracilibacillus, Byssochlamys, and Thermomyces showed positive correlations with part of the majority of the key volatile flavor compounds. This work provides a scientific basis for the actual production of different colors of high-temperature Daqu in the northern region of China for sauce-flavored baijiu.

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“…Recent studies found that PAEs acted as endocrine disruptors, and brought serious negative effects to human health by causing abnormal lipid metabolism, childhood obesity, immune response interference, and neuropsychological disease ( Xu et al, 2020 ). According to the latest assessment by the European Food Safety Agency in 2019, the limitation of human tolerance to PAEs was lower than 50 μg/(Kg·d) ( Xu et al, 2021b ). As there were no covalent bonds between PAEs and the plastic backbone, PAEs were easily escaped into the environment, such as farmland and water ( Xu et al, 2021b ).…”

Section: Introductionmentioning

confidence: 99%

“…According to the latest assessment by the European Food Safety Agency in 2019, the limitation of human tolerance to PAEs was lower than 50 μg/(Kg·d) ( Xu et al, 2021b ). As there were no covalent bonds between PAEs and the plastic backbone, PAEs were easily escaped into the environment, such as farmland and water ( Xu et al, 2021b ). Studies found that the concentrations of PAEs in some surface water and soil were as high as 500 mg/l and 63 mg/Kg, respectively ( Net et al, 2015 ).…”

Section: Introductionmentioning

confidence: 99%

Enzyme catalyzes ester bond synthesis and hydrolysis: The key step for sustainable usage of plastics

et al. 2023

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Petro-plastic wastes cause serious environmental contamination that require effective solutions. Developing alternatives to petro-plastics and exploring feasible degrading methods are two solving routes. Bio-plastics like polyhydroxyalkanoates (PHAs), polylactic acid (PLA), polycaprolactone (PCL), poly (butylene succinate) (PBS), poly (ethylene furanoate) s (PEFs) and poly (ethylene succinate) (PES) have emerged as promising alternatives. Meanwhile, biodegradation plays important roles in recycling plastics (e.g., bio-plastics PHAs, PLA, PCL, PBS, PEFs and PES) and petro-plastics poly (ethylene terephthalate) (PET) and plasticizers in plastics (e.g., phthalate esters, PAEs). All these bio- and petro-materials show structure similarity by connecting monomers through ester bond. Thus, this review focused on bio-plastics and summarized the sequences and structures of the microbial enzymes catalyzing ester-bond synthesis. Most of these synthetic enzymes belonged to α/β-hydrolases with conserved serine catalytic active site and catalyzed the polymerization of monomers by forming ester bond. For enzymatic plastic degradation, enzymes about PHAs, PBS, PCL, PEFs, PES and PET were discussed, and most of the enzymes also belonged to the α/β hydrolases with a catalytic active residue serine, and nucleophilically attacked the ester bond of substrate to generate the cleavage of plastic backbone. Enzymes hydrolysis of the representative plasticizer PAEs were divided into three types (I, II, and III). Type I enzymes hydrolyzed only one ester-bond of PAEs, type II enzymes catalyzed the ester-bond of mono-ester phthalates, and type III enzymes hydrolyzed di-ester bonds of PAEs. Divergences of catalytic mechanisms among these enzymes were still unclear. This review provided references for producing bio-plastics, and degrading or recycling of bio- and petro-plastics from an enzymatic point of view.

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An efficient phthalate ester-degrading Bacillus subtilis: Degradation kinetics, metabolic pathway, and catalytic mechanism of the key enzyme

Cited by 54 publications

References 47 publications

Characterization of an Aspergillus niger for Efficient Fatty Acid Ethyl Ester Synthesis in Aqueous Phase and the Molecular Mechanism

Characterization of an Aspergillus niger for Efficient Fatty Acid Ethyl Ester Synthesis in Aqueous Phase and the Molecular Mechanism

Correlational Analysis of the Physicochemical Indexes, Volatile Flavor Components, and Microbial Communities of High-Temperature Daqu in the Northern Region of China

Enzyme catalyzes ester bond synthesis and hydrolysis: The key step for sustainable usage of plastics

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