The Effect of Co-Fermentation with Lactobacillus plantarum HLJ29L2 and Yeast on Wheat Protein Characteristics in Sourdough and Crackers

Discovery and interaction of four key biosynthetic enzymes under co-regulation for dopamine biosynthesis with marine Meyerozyma guilliermondii GXDK6 and Bacillus aryabhattai NM1-A2

Dopamine has proven effective in treating conditions such as depression and myocardial infarction. The marine Meyerozyma guilliermondii GXDK6 and Bacillus aryabhattai NM1-A2, both known for their robust nitrogen conversion capabilities, were selected for co-fermentation to synthesize dopamine. The metabolic co-regulation mechanism was further elucidated, demonstrating that the synergistic interaction between GXDK6 and NM1-A2 significantly enhanced dopamine synthesis. Under optimized conditions, dopamine production reached 2019.22 mg/L in a bioreactor. Genome-wide analysis revealed that co-fermentation enriched proteins involved in the conversion of tyrosine to dopamine, including polyphenol oxidase (encoded by gene PPO) and tyrosine decarboxylase (encoded by gene BamfnA) from NM1-A2, as well as cytochrome P450 76AD1 (encoded by gene CYP76AD1) and tyrosine decarboxylase (encoded by gene MgmfnA) from GXDK6. These proteins strengthen the dopamine metabolic pathway, facilitating efficient dopamine expression. Heterologous expression of biosynthetic enzymes indicated that dual-gene expression was more effective in dopamine biosynthesis than individual gene expression, for which the synthesized L-dopa was used to catalyze the synthesis of dopamine. In vitro catalysis with purified PPO showed that 5 mM of tyrosine could be converted to 0.21 mM of L-dopa. This co-fermentation strategy provides a novel theoretical framework for the de novo microbial synthesis of dopamine.

Exploring Core fermentation microorganisms, flavor compounds, and metabolic pathways in fermented Rice and wheat foods

The unique flavors of fermented foods significantly influence consumer purchasing choices, prompting widespread scientific interest in the flavor development process. Fermented rice and wheat foods are known for their unique flavors and they occupy an important place in the global diet. Many of these are produced on an industrial scale using starter cultures, whereas others rely on spontaneous fermentation, homemade production, or traditional activities. Microorganisms are key in shaping the sensory properties of fermented products through different metabolic pathways, thus earning the title "the essence of fermentation." Therefore, this study systematically summarizes the key microbial communities and their interactions that contribute positively to iconic fermented rice and wheat foods, such as steamed bread, bread, Mifen, and rice wine. This study revealed the mechanism by which these core microbial communities affect flavor and revealed the strategies of core microorganisms and related enzymes to enhance flavor during fermentation.

Selenium-enriched yeast, a selenium supplement, improves the rheological properties and processability of dough: From the view of yeast metabolism and gluten alteration

This study investigated the effect mechanism of selenium (Se)-enriched yeast on the rheological properties of dough from the perspective of yeast metabolism and gluten alteration. As the yeast Se content increased, the gas production rate of Se-enriched yeast slowed down, and dough viscoelasticity decreased. The maximum creep of Se-enriched dough increased by 29%, while the final creep increased by 54%, resulting in a softer dough. Non-targeted metabolomics analyses showed that Se inhibited yeast energy metabolism and promoted the synthesis of stress-resistance related components. Glutathione, glycerol, and linoleic acid contributed to the rheological property changes of the dough. The fractions and molecular weight distribution of protein demonstrated that the increase in yeast Se content resulted in the depolymerization of gluten. The intermolecular interactions, fluorescence spectrum and disulfide bond analysis showed that the disruption of intermolecular disulfide bond induced by Se-enriched yeast metabolites played an important role in the depolymerization of gluten.

Dynamics of nutrients, sensory quality and microbial communities and their interactions during co-fermentation of pineapple by-products and whey protein

In this study, a new fermented food was developed using pineapple by-products and whey protein (2.6%) as raw materials through the co-fermentation of autochthonous lactic acid bacteria and yeast. To better understand the fermentation mechanism and the impact of microorganisms on the entire fermentation system, we tracked the changes in carbohydrate and amino acid profiles, organoleptic quality and microbial community during the fermentation process. Compared with unfermented samples, dietary fiber and free amino acids increased significantly as fermentation proceeded. The fermented samples were significantly lower in astringency and bitterness and significantly higher in sourness, umami and richness. The fermented products were richer in volatile compounds with floral, cheesy, fruity and other flavors. Relevant analyses showed that the core microbial community was highly correlated with the quality attributes of the fermented products. Microorganisms such as Lactococcus, Weissella, Hanseniaspora, Saccharomyces and Lachancea contributed significantly to the fermented products.

Understanding the nutritional benefits through plant proteins-probiotics interactions: mechanisms, challenges, and perspectives

The nutritional benefits of combining probiotics with plant proteins have sparked increasing research interest and drawn significant attention. The interactions between plant proteins and probiotics demonstrate substantial potential for enhancing the functionality of plant proteins. Fermented plant protein foods offer a unique blend of bioactive components and beneficial microorganisms that can enhance gut health and combat chronic diseases. Utilizing various probiotic strains and plant protein sources opens doors to develop innovative probiotic products with enhanced functionalities. Nonetheless, the mechanisms and synergistic effects of these interactions remain not fully understood. This review aims to delve into the roles of promoting health through the intricate interplay of plant proteins and probiotics. The regulatory mechanisms have been elucidated to showcase the synergistic effects, accompanied by a discussion on the challenges and future research prospects. It is essential to recognize that the interactions between plant proteins and probiotics encompass multiple mechanisms, highlighting the need for further research to address challenges in achieving a comprehensive understanding of these mechanisms and their associated health benefits.

Waste to Wealth: Dynamics and metabolic profiles of the conversion of jackfruit flake into value-added products by different fermentation methods

Thus far, little is known about whether jackfruit flake, a byproduct of jackfruit, can be used as a fermentation substrate to obtain value-added products through microbial fermentation. Here, jackfruit flake puree was fermented by three different ways: spontaneous fermentation (JF), inoculated with LAB (JFL), inoculated co-fermentation with LAB and yeast (JFC). In contrast to JF, the total polyphenol and flavonoid content and syndrome-associated enzyme inhibition are significantly increased in JFC at the end of fermentation. Electronic tongue analysis revealed that the JFC was significantly lower in astringency and higher in bitterness. 41 volatile compounds were identified during fermentation by HS-SPME-GC-MS, and JFC was richer in honey, rose, and fruity flavors. A total of 290 compounds were screened for discriminative pre- and post-fermentation differential metabolites by non-target metabolomics analysis. These results provide a potential reference for the conversion of jackfruit waste into functional products using fermentation.

Physicochemical, Rheological, and Sensory Characteristics of Yogurt Fermented by Lactic Acid Bacteria with Probiotic Potential and Bioprotective Properties

The applicability of two lactic acid bacterial strains with probiotic potential and bioprotective properties as additions in the starter culture in yogurt fermentation was examined. The studied strains, Lactobacillus delbrueckii subsp. bulgaricus KZM 2-11-3 and Lactiplantibacillus plantarum KC 5-12, inhibited the growth of Kluyveromyces lactis, Kluyveromyces marxianus, and Saccharomyces cerevisiae. The strain L. delbrueckii subsp. bulgaricus KZM 2-11-3 directly inhibited Escherichia coli. The important characteristics for the quality of the yogurt product, such as physicochemical parameters during fermentation and storage, rheological characteristics, and sensory changes during the storage of samples were determined. The yogurt samples with the strains did not differ in most parameters from the control yogurt with the commercial starter. The added strains showed stable viability in the yogurt samples during storage. The yogurt sample with L. delbrueckii subsp. bulgaricus KZM 2-11-3 and the sample with both strains based on the total evaluation were very similar to the control yogurt with the commercial starter. Using these strains as probiotic supplements to enrich the starter cultures in yogurt production will contribute to developing new products with benefits to human health.