Synthesis of xylooligosaccharides of daidzein and their anti-oxidant and anti-allergic activities

The biocatalytic synthesis of xylooligosaccharides of daidzein was investigated using cultured cells of Catharanthus roseus and Aspergillus sp. β-xylosidase. The cultured cells of C. roseus converted daidzein into its 4'-O-β-glucoside, 7-O-β-glucoside, and 7-O-β-primeveroside, which was a new compound. The 7-O-β-primeveroside of daidzein was further xylosylated by Aspergillus sp. β-xylosidase to daidzein trisaccharide, i.e., 7-O-[6-O-(4-O-(β-d-xylopyranosyl))-β-d-xylopyranosyl]-β-d-glucopyranoside, which was a new compound. The 4'-O-β-glucoside, 7-O-β-glucoside, and 7-O-β-primeveroside of daidzein exerted DPPH free-radical scavenging and superoxide radical scavenging activity. On the other hand, 7-O-β-glucoside and 7-O-β-primeveroside of daidzein showed inhibitory effects on IgE antibody production.     

固定化生物催化剂用于污水厂污泥减量的研究

目前,剩余污泥的处理与处置已成为困扰污水厂的难题之一.采用固定化生物催化剂(IBC)在某城市污水处理厂进行污泥减量试验,结果表明:投加IBC的CASS池污泥减量效果明显,投药1个月后,外排剩余污泥量及产泥量均大幅减少,第3,4个月没有外排剩余污泥,且MLSS维持在1500 mg/L左右,有效地从源头实现了污泥减量.同时,投加IBC对出水水质无负面影响,且能够提高水质净化效果,投药池对COD、NH3-N、TP的平均去除率分别为84.18%、94.39%、63.17%,较对照池的79.88%、92.80%、49.61%均有所提高,出水水质优于对照池.     

SERR Spectroelectrochemistry as a Guide for Rational Design of DyP-Based Bioelectronics Devices

Immobilised dye-decolorizing peroxidases (DyPs) are promising biocatalysts for the development of biotechnological devices such as biosensors for the detection of H₂O₂. To this end, these enzymes have to preserve native, solution properties upon immobilisation on the electrode surface. In this work, DyPs from Cellulomonas bogoriensis (CboDyP), Streptomyces coelicolor (ScoDyP) and Thermobifida fusca (TfuDyP) are immobilised on biocompatible silver electrodes functionalized with alkanethiols. Their structural, redox and catalytic properties upon immobilisation are evaluated by surface-enhanced resonance Raman (SERR) spectroelectrochemistry and cyclic voltammetry. Among the studied electrode/DyP constructs, only CboDyP shows preserved native structure upon attachment to the electrode. However, a comparison of the redox potentials of the enzyme in solution and immobilised states reveals a large discrepancy, and the enzyme shows no electrocatalytic activity in the presence of H₂O₂. While some immobilised DyPs outperform existing peroxidase-based biosensors, others fail to fulfil the essential requirements that guarantee their applicability in the immobilised state. The capacity of SERR spectroelectrochemistry for fast screening of the performance of immobilised heme enzymes places it in the front-line of experimental approaches that can advance the search for promising DyP candidates.     

Impact of glycated pea proteins on the activity of free‐swimming and immobilised bacteria

BACKGROUND: Glycation (non‐enzymatic glycosylation), a spontaneously occurring process, is responsible for alteration of the structures and biological activities of proteins, making them highly active. Regrettably, information regarding the impact of glycated food proteins on intestinal bacteria still remains sparse. Pea seeds are considered to be a biological material of a high nutritional value, low content of anti‐nutritional substances and proven health‐promoting action and therefore they were used in this study. Since glycated pea proteins are proven to display a lowered susceptibility to the enzymatic digestion, their impact on the activity of both free‐swimming and immobilised bacteria was studied. RESULTS: In vitro model systems were used to prove the stimulatory impact of glycated pea proteins on the proliferation rate and survival, as well as on the metabolic activity of free‐swimming and immobilised bacteria. CONCLUSIONS: This phenomenon is of great importance because glycated food proteins are not only a source of nutrients and energy but also display new properties and increased biological activities. Additionally, they are able to modify the bacterial intestinal ecosystem, thus affecting the general health status of a consumer. Copyright © 2010 Society of Chemical Industry     

High Gravity Brewing by Continuous Process Using Immobilised Yeast: Effect of Wort Original Gravity on Fermentation Performance

The present work evaluated the influence of all‐malt wort original gravity on fermentative parameters and flavour‐active compound formation during primary fermentation of high gravity brewing by a continuous process using a lager yeast immobilised on a natural carrier obtained from brewer's spent grain (the main brewery by‐product). The all‐malt worts with original gravity (OG) ranging from 13.4 to 18.5°Plato were prepared by diluting a very‐high‐gravity wort (20°Plato) with sterile brewery water. The continuous assay was carried out in a bubble column bioreactor with a total working volume of 5.2 litres, at 15°C, using a constant gas flow rate of 250 mL/min (200 mL/min of CO₂ and 50 mL/min of air) and a dilution rate of 0.04 h^?1 (residence time of 25 h). The results indicated that as the wort OG was increased, the ethanol concentration of the outflowing beer increased. On the other hand, the continuous fermentation of the most concentrated worts (16.6 and 18.5°Plato) resulted in beers with unbalanced flavour profiles due to excessive ethyl acetate formation. The immobilised cell concentration appeared to be nearly independent from increasing wort OG.     

Direct nanoHPLC-ESI-QTOF MS/MS analysis of tryptic caseinophosphopeptides

Caseinophosphopeptides (CPPs) were generated following tryptic hydrolysis of sodium caseinate. Hydrolysate peptides were separated and identified using nano-HPLC ESI-QTOF MS/MS. Sequence coverage in the 3 h hydrolysate was 79.4%, 55.6%, 80.9% and 68.1% for α_s1-, α_s2-, β- and κ-casein (CN), respectively. Variable levels of serine phosphorylation in β-CN f1–25 were observed in the 3 h hydrolysate. Analysis of β-CN f1–25 4P demonstrated that this peptide was stable during the course of hydrolysis. The effect of heat treatment (75 °C, 45 min) at pH 6.0, 7.0 and 8.0 on the peptide profile of the 3 h hydrolysate was studied. Compared to pH 6.0 and 8.0, least modification in phosphopeptide profiles was observed for the hydrolysate sample heated at pH 7.0. Different dephosphorylation and oxidation patterns were also observed following heat treatment at the three pH values. These results demonstrate that heat treatment, in addition to pH, has a major effect on both the phosphorylated and non-phosphorylated peptide profiles of CN hydrolysates.     

Integrated chemo- and biocatalytic processes: a new fashion toward renewable chemicals production from lignocellulosic biomass

Concerns over climate change and environmental pollution resulting from petroleum refining has spurred the exploitation of green replacements for producing chemicals and fuels. Valorization of lignocellulosic biomass into chemicals represents a promising alternative to petroleum refining. Biological and chemical catalysis are two leading routes for lignocellulose variolization, but strategies relying simply on biological or chemical conversion have shown limitations. Integrating biocatalysts with chemocatalysts could leverage the inherent strengths of both while circumventing their respective disadvantages, benefiting product yield and selectivity, and reducing cost and waste generation. This review focuses on the coupled chemocatalytic and biocatalytic synthesis of renewable chemicals from polysaccharides and their derived platform chemicals. In addition, strategies for producing value-added products from lignin via integrated chemical depolymerization and biological conversion are highlighted. The techno-economics of integrating chemocatalysts and biocatalysts in producing chemicals in the context of biorefinery are also discussed. Finally, perspectives on designing integrated chemical and biological catalysis for renewable chemicals production are provided. © 2022 Society of Chemical Industry (SCI).     

Enantioselective Synthesis of α‐Hydroxy Ketones via Benzaldehyde Lyase‐Catalyzed C−C Bond Formation Reaction

(R)‐Benzoins and (R)‐2‐hydroxypropiophenone derivatives are formed on a preparative scale by benzaldehyde lyase (BAL)‐catalyzed C−C bond formation from aromatic aldehydes and acetaldehyde in aqueous buffer/DMSO solution with remarkable ease in high chemical yield and high optical purity. The substrate range of this thiamin diphosphate‐dependent enzyme was examined with respect to a broad applicability of this benzoin condensation‐type reaction in stereoselective synthesis.     

A Four-Step Enzymatic Cascade for Efficient Production of L-Phenylglycine from Biobased L-Phenylalanine

Enantiopure amino acids are of particular interest in the agrochemical and pharmaceutical industries. Here, we report a multi-enzyme cascade for efficient production of L-phenylglycine (L-Phg) from biobased L-phenylalanine (L-Phe). We first attempted to engineer Escherichia coli for expressing L-amino acid deaminase (LAAD) from Proteus mirabilis, hydroxymandelate synthase (HmaS) from Amycolatopsis orientalis, (S)-mandelate dehydrogenase (SMDH) from Pseudomonas putida, the endogenous aminotransferase (AT) encoded by ilvE and L-glutamate dehydrogenase (GluDH) from E. coli. However, 10 mM L-Phe only afforded the synthesis of 7.21±0.15 mM L-Phg. The accumulation of benzoylformic acid suggested that the transamination step might be rate-limiting. We next used leucine dehydrogenase (LeuDH) from Bacillus cereus to bypass the use of L-glutamate as amine donor, and 40 mM L-Phe gave 39.97±3.84 mM (6.04±0.58 g/L) L-Phg, reaching 99.9 % conversion. In summary, this work demonstrates a concise four-step enzymatic cascade for L-Phg synthesis from biobased L-Phe, with a potential for future industrial applications.