Search

Exopolysaccharides (EPSs) from lactic acid bacteria have great effect on the quality of fermented milk products. However, the mechanism for the quality improvement has not been well described. This study aimed to investigate the molecular binding kinetics and interactions between EPS obtained from Streptococcus thermophilus AR333 (EPS333) and casein of milk (CM) in a simulated acidifying process. The results indicated that EPS333 had a significant effect on the stability of casein micelles at acidic pH (6.0-4.5) according to the turbidity, ζ-potential, particle size and distribution analysis. The adsorption-desorption study by bio-layer interferometry identified the direct affinity binding between EPS333 and CM, the interactive moiety of casein was α-casein, rather than β- or κ-casein. Fluorescence quenching analysis revealed that the force types of interaction between EPS333 and CM were dynamically changeable during the acidifying process, mainly from electrostatic interaction at pH 7.0-6.5, to hydrophobic or hydrogen bonding at pH 6.5-5.5, and then transferred to electrostatic interaction again at pH 5.5-5.0. Conclusively, EPS333 could bind with CM directly via different binding forces during acidifying process to stabilize the properties of casein micelles., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Producing alcoholic beverages with novel flavor are desirable for winemakers. We created fermenting yeast with superior ethanol tolerance and fermentation activity to improve the flavor profiles of Chinese rice wine. Strategies of ethanol domestication, ultraviolet mutagenesis (UV) and protoplast fusion were conducted to create yeast hybrids with excellent oenological characteristic. The obtained diploid hybrid F23 showed a cell viability of 6.2% under 25% ethanol, whereas its diploid parental strains could not survive under 20% ethanol. During Chinese rice wine-making, compared to diploid parents, F23 produced 7.07%-12.44% higher yield of ethanol. Flavor analysis indicated that the total content of flavor compounds in F23 wine was 19.99-26.55% higher than that of parent wines. Specifically, F23 exhibited higher capacity in producing 2-phenylethanol, short-chain and long-chain fatty-acid ethyl-ester than diploid parents. Compared to diploid parents, F23 introduced more flavor contributors with odor activity values (OAVs) above one to Chinese rice wine, and those contributors were found with higher OAVs. Based on principal component analysis (PCA), the flavor characteristic of F23 wine was similar to each of parent wine. Additionally, sensory evaluation showed that F23 wine was highly assessed for its intensive levels in fruit-aroma, alcohol-aroma and mouthfeel. Hybrid F23 not only displayed superior flavor production and oenological performance in making Chinese rice wine, but also could act as potential "mixed-like" starter to enrich wine style and differentiation., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Erythritol, a natural sweetener, is widely used in the food, medicinal and chemical industries because of its advantages of low calorie, good stability and high food safety. Yarrowia lipolytica is widely used as an efficient fermentation strain for erythritol production. However, the current research on erythritol production by Yarrowia lipolytica concentrates on control of the fermentation process and metabolic pathway regulation and has bottlenecks in the yield of erythritol and the fermentation process. On this basis, this article reviews recent progress in research on erythritol production by Yarrowia lipolytica from three aspects: fermentation substrate utilization, fermentation process control and metabolic pathway modification by genetic engineering. This review is expected to provide a reference for breaking the bottlenecks in erythritol production by Yarrowia lipolytica.

There have been many studies on the activities and polysaccharide production of Sanghuangporus vaninii. However, few studies have looked at triterpene production from S. vaninii using liquid‐state fermentation. A method for enhancing the production of triterpenes by in situ extractive fermentation (ISEF) was studied. Eight solvents were investigated as extractants for triterpene production in the ISEF system. The results showed that using vegetable oil as an extractant significantly increased the yield of total triterpenes and biomass of S. vaninii YC‐1, reaching 18.98 ± 0.71 and 44.67 ± 2.21 g/L, respectively. In 5 L fermenter experiments, the added vegetable oil improved the dissolved oxygen condition of the fermentation broth and promoted the growth of S. vaninii YC‐1. Furthermore, adding vegetable oil increased the expression of fatty acid synthesis‐related genes such as FAD2 and SCD, thereby increasing the synthesis of unsaturated fatty acids in the cell membrane of S. vaninii YC‐1. Therefore, the cell membrane permeability of S. vaninii YC‐1 increased by 19%. Our results indicated that vegetable oil increased the permeability of S. vaninii YC‐1 cell membranes to promote the production of total triterpenes. The use of vegetable oil as an extractant was thus effective in increasing the yield of triterpenes in the ISEF system. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Huangjiu (Chinese rice wine) has been consumed for centuries in Asian countries and is known for its unique flavor and subtle taste. The flavor compounds of Huangjiu are derived from a wide range of sources, such as raw materials, microbial metabolic activities during fermentation, and chemical reactions that occur during aging. Of these sources, microorganisms have the greatest effect on the flavor quality of Huangjiu. To enrich the microbial diversity, Huangjiu is generally fermented under an open environment, as this increases the complexity of its microbial community and flavor compounds. Thus, understanding the formation of flavor compounds in Huangjiu will be beneficial for producing a superior flavored product. In this paper, a critical review of aspects that may affect the formation of Huangjiu flavor compounds is presented. The selection of appropriate raw materials and the improvement of fermentation technologies to promote the flavor quality of Huangjiu are discussed. In addition, the effects of microbial community composition, metabolic function of predominant microorganisms, and dynamics of microbial community on the flavor quality of Huangjiu are examined. This review thus provides a theoretical basis for manipulating the fermentation process by using selected microorganisms to improve the overall flavor quality of Huangjiu. [ABSTRACT FROM AUTHOR]

BACKGROUND In situ extractive fermentation (ISEF) is an important technique for improving metabolite productivity. The different extractants can induce the synthesis of different bioactive metabolites of Antrodia camphorata during ISEF. However, a lack of research on the molecular genetics of A. camphorata during ISEF currently hinders such studies on metabolite biosynthetic mechanisms. RESULTS: To clarify the differentially expressed genes during ISEF, the gene transcriptional expression features of A. camphorata S‐29 were analysed. The addition of n‐tetradecane as an extractant during ISEF showed more pronounced up‐regulation of ubiquinone and other terpenoid‐quinone biosynthesis pathway genes (CoQ2, wrbA and ARO8). When oleic acid was used as an extractant, the terpenoid backbone biosynthesis and ubiquinone and other terpenoid‐quinone biosynthesis pathways were significantly enriched, and genes (IDI, E2.3.3.10, HMGCR atoB, and CoQ2) related to these two pathways were also significantly up‐regulated. The CoQ2 genes encode puru‐hydroxybenzoate:polyprenyltransferase, playing an important role in antroquinonol synthesis. The IDI, E2.3.3.10, HMGCR and atoB genes of the terpenoid backbone biosynthesis pathway might play an important role in the synthesis of the triquine‐type sesquiterpene antrodin C. CONCLUSION: This investigation advances our understanding of how two different extractants of n‐tetradecane and oleic acid affect the biosynthesis of metabolites in A. camphorata. It is beneficial to provide potential strategies for improving antrodin C and antroquinonol production by genetic means. © 2020 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

This study describes the application of in situ extractive fermentation (ISEF) to increase the yields of antroquinonol (AQ) and antrodin C (AC) from Antrodia camphorata S-29. In initial screening experiments, nine solvents were tested to identify the most suitable extractant for the in situ extraction of AQ and AC. These solvents included n-tetradecane, n-dodecane, n-decane, heavy paraffin, light paraffin, oleyl alcohol, oleic acid, butyl oleate, and isopropyl myristate. Of these, oleic acid was the most suitable solvent for the in situ extraction of AQ and AC. The use of oleic acid as an in situ extractant significantly improved AQ and AC productions, which were approximately 5-fold and 8-fold that of the control, respectively. The recovered oleic acid was treated with a silica gel solid-phase extraction column, which was able to rapidly adsorb the bioactive metabolites. The separated solvent hardly contained fermentation products and could be directly reused in ISEF. AQ and AC were obtained with purities of over 75% by silica gel column chromatography. The recoveries of AQ and AC reached 70.7 ± 0.8% and 81.5 ± 1.2%, respectively. [ABSTRACT FROM AUTHOR]

BACKGROUND: Antroquinonol, a ubiquinone derivative that shows anticancer and anti‐inflammatory activities, is produced during solid‐state fermentation of Antrodia camphorata; however, it cannot be biosynthesized via conventional submerged fermentation. RESULTS: A method for enhancing the biosynthesis of antroquinonol by controlling pH and adding an oxygen vector in a 7 L bioreactor was studied. In shake‐flask experiments, a maximum antroquinonol production of 31.39 ± 0.78 mg L−1 was obtained by fermentation with adding 0.2 g L−1 coenzyme Q0 (CoQ0), at the 96th hour. Following kinetic analysis of the fermentation process, pH control strategies were investigated. A maximum antroquinonol production of 86.47 ± 3.65 mg L−1 was achieved when the pH was maintained at 5.0, which exhibited an increase of 348.03% higher than the batch without pH regulation (19.30 ± 0.88 mg L−1). The conversion rate of CoQ0 improved from 1.51% to 20.20%. Further research revealed that the addition of n‐tetradecane could increase the production of antroquinonol to 115.62 ± 4.87 mg L−1 by increasing the dissolved oxygen in the fermentation broth. CONCLUSION: The results demonstrated that pH played an important role in antroquinonol synthesis in the presence of the effective precursor CoQ0. It was a very effective strategy to increase the yield of antroquinonol by controlling pH and adding oxygen vector. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Oenological properties, volatile profiles, and sensory characteristics between Chinese Hong Qu rice wine (HQW) and Chinese Wheat Qu rice wine (WQW) were investigated. Forty and thirty-five volatile compounds in HQW and WQW were, respectively, identified. According to the door activity values (OAVs > 1), isoamyl acetate, ethyl octanoate, ethyl tetradecanoate, nonanal, and 2-methoxy-phenol were the major flavour contributors for HQW and WQW. Principal component analysis (PCA) showed that middle-chain fatty-acid (C6-C12) ethyl esters were the dominant representative flavour in HQW and WQW. Sensory evaluation indicated that the aroma of esters and alcohols differed largely between HQW and WQW. By partial least squares regression (PLSR), middle-chain fatty-acid-ethyl-esters (FAEEs) had a strong impact on the sensory attributes of fruit aroma, continuation, and full body in HQW and WQW. [ABSTRACT FROM AUTHOR]

BACKGROUND Antroquinonol have significantly anti-tumour effects on various cancer cells. There is still lack of reports on regulation of environmental factors on antroquinonol production by Antrodia camphorata. RESULTS An effective submerged fermentation method was employed to induce antroquinonol with adding H2O2. The production of antroquinonol was 57.81 mg L−1 after fermentation for 10 days when adding 25 mmol L−1 H2O2 at day 4 of the fermentation process. Then, antroquinonol was further increased to 80.10 mg L−1 with cell productivity of 14.94 mg g−1 dry mycelium when the feeding rate of H2O2 was adjusted to 0.2 mmol L−1 h−1 in the 7 L fermentation bioreactor. After inhibiting the generation of reactive oxygen species with the inhibitor diphenyleneiodoium, the synthesis of antroquinonol from A. camphorata was significantly reduced, and the yield was only 3.3 mg L−1. ConcluSION The results demonstrated that addition of H2O2 was a very effective strategy to induce and regulate the synthesis of antroquinonol in submerged fermentation. Reactive oxygen species generated by H2O2 during fermentation caused oxidative stress, which induced the synthesis of antroquinonol and other chemical compounds. Moreover, it is very beneficial process to improve production and diversity of the active compounds during liquid fermentation of A. camphorata mycelium. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

A lactic acid bacteria strain AR333 with high - production of exopolysaccharides (EPS) was screened out from 350 bacteria strains isolated from naturally fermented dairy products. It was identified as Streptococcus thermophilus by morphological observation, physiological and biochemical characteristics, and 16S rDNA sequence determination. The EPS from AR333 were purified through DEAE-Sepharose Fast Flow and Sepharose CL-6B, and the purified fraction was designated as EPS333. In vitro test showed that EPS333 could stimulate macrophage RAW 264.7 to release NO significantly ( p < 0.05). The further work tried to elucidate the structural features of EPS333 via FT-IR spectrum, high-performance anion exchange chromatography (HPAEC) and high-performance size exclusion chromatography (HPSEC). The results showed that EPS333 was a pure neutral polysaccharide with monosaccharide composition of galactose and glucose in a molar ratio of 6:5. A certain amount of acetyl groups might exist in EPS333 according to the FT-IR spectrum. The molecular weight (Mw) was estimated to be 332 kDa. Current study suggested that the lactic bacteria strain AR333 could be a potential source of immunoregulatory polysaccharide. [ABSTRACT FROM AUTHOR]

Antrodia camphorata is a medicinal fungus and antrodin C is one of the main bioactive components of A. camphorata in the submerged fermentation (SmF). To optimize the culture conditions, the factors influencing the production of antrodin C by A. camphorata under solid-state fermentation (SSF) were investigated in this study. Different solid substrates and external nitrogen sources were tested for their efficiency in producing antrodin C. The response surface methodology was applied to evaluate the influence of several variables, namely, the concentrations of soybean meal, initial moisture content, and inoculum density on antrodin C production in solid-state fermentation. The experimental results show that the optimum fermentation medium for antrodin C production by A. camphorata was composed of 0.578 g soybean meal, 0.05 g Na2HPO4, 0.05 g MgSO4 for 100 g rice, with 51.83% initial moisture content, 22 day culture time, 28 °C culture temperature, and 35.54% inoculum density. At optimized conditions, 6,617.36 ± 92.71 mg kg−1 yield of antrodin C was achieved. Solid-state fermentation is one good cultural method to improve the production of antrodin C by A. camphorata. [ABSTRACT FROM AUTHOR]

Huangjiu (Chinese rice wine), flavor compounds, microbial community, raw material, yeast starter, fungi, fermentation technology Keywords: Huangjiu (Chinese rice wine); flavor compounds; microbial community; raw material; fermentation technology; yeast starter; fungi EN Huangjiu (Chinese rice wine) flavor compounds microbial community raw material fermentation technology yeast starter fungi N.PAG N.PAG 2 03/03/21 20210225 NES 210225 In the original article, there was a mistake in Figure 2 as published. [Extracted from the article]

An exopolysaccharide EPS333 was produced by a ropy Streptococcus thermophilus strain AR333 when grown on reconstituted skim milk. The molecular weight, radius of gyration (Rg), hydrodynamic radius (R h ) and intrinsic viscosity ([ η ]) of EPS333 were determined as 313.7 kDa, 33.96 nm, 25.98 nm, and 1.874 dL/g, respectively by high performance size exclusion chromatography (HPSEC). The conformational analysis demonstrated that EPS333 presented as compact and semi-stiff or stiff chain in aqueous solution. Monosaccharide analysis identified that EPS333 was composed of galactose, glucose and galactosamine in a molar ratio of 3: 2: 1. The backbone of EPS333 consisted of β-(1→3)-Gal p , β-(1→3,6)-Glc p , α-(1→3)-2-Gal p NAc, and α-(1→4)-Glc p . The branch chain was terminated at O -6 position of β-(1→3,6)-Glc p by α-T-Gal p . With the help of 1D & 2D NMR spectroscopy, the repeating unit of EPS333 was proposed. Further studies revealed that the in situ produced EPS333 could improve the quality of fermented milk to be close to the commercial product. [ABSTRACT FROM AUTHOR]