Metabolomics-Driven Elucidation of Interactions between Saccharomyces cerevisiae and Lactobacillus panis from Chinese Baijiu Fermentation Microbiome

Recent advances in yeast and bacteria co-cultivation for bioprocess applications

Yeast and bacteria co-cultures can be found in nature and have multiple advantages that can be exploited, nowadays also in a controlled bioproduction environment. Various types of co-cultivation have been used for food applications such as production of flavor compounds in dairy products and alcoholic beverages. Co-cultures can broaden the substrate spectrum for microbial food and feed production, they can increase productivity and efficiency, and the nutritional value. Workflows have been developed from plate to bioreactor scale to increase reproducibility and optimize benefits of individual co-cultivation strategies. Nonetheless, certain limitations need to be overcome for industrial application. Many interactions of microbes, in particular in suspension cultures, are not sufficiently understood or even explored. While more possibilities arose from on-line monitoring of individual populations or even single cells, off-line measurement techniques are still typically applied in order to assess growth and product formation. Promising advances have been achieved, however, by methods for single-cell at-line and on-line analysis in co-cultures which are accounted for to emphasize the current opportunities and challenges in monitoring and controlling co-cultures. This review aims to summarize the recent advances with a particular focus on cultivation procedures and process analysis in bacteria, yeast and bacteria-yeast co-cultures. The implementation of suitable monitoring methods to enable (remote) control and contribute to quality assurance will accelerate the development and optimization of industrial co-culture bioprocesses. This will support transferability and process standardization across world regions adding to the advancement of bioproduction. The applicability of some relevant technology is, however, in its infancy.

Enhancing blueberry wine quality and antioxidant capacity through mixed fermentation with S. cerevisiae and O. oeni

This study investigates the impact of O. oeni on the quality of blueberry wine, employing various analytical methods to determine parameters such as alcohol content, antioxidant capacity, organic acids, amino acids, and volatile components. The results demonstrated that co-inoculation with O. oeni significantly decreased the titratable acidity of blueberry wine. Among the organic acids, the malic acid content of ST and SE groups decreased by (26.24 ± 1.24)% and (35.75 ± 4.02)%, respectively. The main consumed amino acids were aspartate, lysine, and arginine after co-inoculation with O. oeni. Additionally, co-inoculation with O. oeni significantly increased the content of medium-chain fatty acid ethyl esters, especially isoamyl acetate content. The antioxidant capacity of blueberry wine was significantly enhanced by co-inoculation with O. oeni, particularly in terms of measurement of 1,1-diphenyl-2-picryl-hydrazyl (DPPH) clearance. The findings of this study provide a solid basis for improving the quality of blueberry wine and promoting the growth of blueberry wine industry.

Evaluation of the nutritional value of fermented pangasius fish waste and its potential as a poultry feed supplement

Background and Aim

The increasing global demand for sustainable and nutrient-dense poultry feed necessitates innovative approaches to utilize byproducts such as pangasius fish waste. This study explores the potential of bioconverted fermented pangasius fish waste (FPW) produced through microbial fermentation as a poultry feed supplement.

Materials and Methods

The study was conducted in two stages. In the first stage, bioconversion of pangasius fish waste utilized a microbial consortium (PaRmYl: Pseudomonas aeruginosa, Rhizopus microsporus, and Yarrowia lipolytica) at varying inoculum doses (5%, 10%, and 20%) and fermentation durations (2, 4, and 8 days). Nutritional content, enzyme activity, and antioxidant properties were analyzed. The second stage involved biological testing on 90 broiler chickens (randomized into three treatment groups with 30 replications each) to assess digestibility and nitrogen retention of FPW-based feed.

Results

Fermentation with a 10% inoculum dose over 4 days yielded the optimal nutritional composition, with crude protein content increasing to 37.27%, enhanced amino acid (EAA/NEAA ratio: 0.88), and fatty acid profiles (notably ω-3 and ω-6). Protease and lipase activity peaked at 1.49 U/mL and 1.21 U/mL, respectively, with antioxidant activity showing an IC50 value of 39.84 ppm. Biological tests demonstrated significantly higher dry matter digestibility (75.53%) and nitrogen retention (75.53%) in broilers fed FPW compared to non-fermented feed.

Conclusion

FPW, produced through microbial bioconversion, offers a sustainable and cost-effective poultry feed supplement, enhancing digestibility and nutrient retention while addressing environmental concerns related to fish processing waste.

The insights into sour flavor and organic acids in alcoholic beverages

Alcoholic beverages have developed unique flavors over millennia, with sourness playing a vital role in their sensory perception and quality. Organic acids, as crucial flavor compounds, significantly impact flavor. This paper reviews the sensory attribute of sour flavor and key organic acids in alcoholic beverages. Regarding sour flavor, research methods include both static and dynamic sensory approaches and summarize the interaction of sour flavor with aroma, taste, and mouthfeel. In addition, this review focuses on identifying key organic acids, including sample extraction, chromatography, olfactometry/taste, and mass spectrometry. The key organic acids in alcoholic beverages, such as wine, Baijiu, beer, and Huangjiu, and their primary regulatory methods are discussed. Finally, future avenues for the exploration of sour flavor and organic acids by coupling machine learning, database, sensory interactions and electroencephalography are suggested. This systematic review aims to enhance understanding and serve as a reference for further in-depth studies on alcoholic beverages.

Unraveling the regional environmental ecology dominated baijiu fermentation microbial community succession and associated unique flavor

Chinese baijiu as one of the famous distilled liquor in which fermented in open environments, with various microorganisms (i.e., bacteria, fungi, and yeast) involved in their brewing process, and created corresponding unique flavor. However, the sources of environmentally enriched microbial communities associated with liquor fermentation are still being characterized yet. Given the dependence of microbial growth and reproduction on environmental ecology, it is important to understand the correlation between baijiu fermentation microbial community and surrounding environmental ecology (i.e., temperature, humidity, wind, and precipitation). This study systematically overviewed the sources of microorganisms in the Jiang-flavor-Baijiu fermentation system. The results showed that microorganisms in baijiu brewing (i.e., mold, lactic acid bacteria, and yeast) mainly originated from surrounding environmental matrices, including the air (i.e., Yeast, Streptomyces and Bacillus), soil (i.e., Xanthomonas, Methanococcus and Comamonas) and water (i.e., Flavobacterium, Acinetobacter, and Pseudomonas) via atmospheric transport, raw material transfer and surface runoff. In addition, the unique baijiu fermentation microbial community diversity depends on local geology and meteorological conditions, highlighting that the structural stability and diversity of the microorganisms in the Baijiu brewing process dominated by local environmental ecology. We also explored the regional environmental conditions on the microbial community and found that the unique Jiang-flavor-Baijiu fermentation microbial community diversity depends on local geology and meteorological conditions. The Jiang-flavor-Baijiu workshop is located in the basin of the middle-and low latitude mountainous areas, with sufficient solar irradiation and rainfall, high air humidity, and low wind speed that favor the growth and propagation of Baijiu fermentation microorganisms. Therefore, the obtained conclusions provide new insights unraveling the key factor controlling the unique flavor of Chinese Baijiu, where protecting the ecology of baijiu brewing-regions is fundamental for maintaining the long-term quality of baijiu.

Correlational analysis of physicochemical indexes, microbial communities, and volatile components in light-flavor Daqu from north and south regions of China

Daqu is of great significance to the brewing process of Baijiu, and there are variations in the light-flavor Baijiu Daqu in different regions. However, few studies have been conducted on light-flavor Daqu from the north and south regions of China. In this study, the physicochemical indices, volatile flavor components, and microbial community structure of two types of Daqu from the north and south regions of China were comparatively analyzed. The study findings reveal that Daqu originating from the southern region of China (HB) exhibits superior moisture content, acidity, starch content, and saccharification power. In contrast, Daqu from the northern region of China (SX) displays higher fermentation, esterification, and liquefaction power. The analysis of the microbial community structure revealed that HB was dominated by Bacillus, Kroppenstedtia, Saccharomycopsis, and Thermoascus, while SX was dominated by Bacillus, Prevotella, and Saccharomycopsis. The analysis detected a total of 47 volatile components in both HB Daqu and SX Daqu. The volatile components of pyrazine were significantly more abundant in HB Daqu than in SX Daqu, while alcohol compounds were more prominent in SX Daqu than in HB Daqu. In addition, the RDA analysis established a correlation between dominant microorganisms and volatile components. Cyanobacteria, Fusobacteriota, Ascomycota, Blastocladiomycota, Basidiomycota, and Mucormyce exhibited positive correlations with a significant proportion of the key volatile compounds. This study establishes a scientific foundation for improving the quality of light-flavor Daqu liquor in different regions of China.

Enhanced probiotic potential of Lactobacillus kefiranofaciens OSU-BDGOA1 through co-culture with Kluyveromyces marxianus bdgo-ym6

Introduction

Due to the increasing consumer demand for the development and improvement of functional foods containing probiotics, new probiotic candidates need to be explored as well as novel means to enhance their beneficial effects. Lactobacillus kefiranofaciens OSU-BDGOA1 is a strain isolated from kefir grains that has demonstrated probiotic traits. This species is the main inhabitant of kefir grains and is responsible for the production of an exopolysaccharide (EPS) whit vast technological applications and potential bioactivities. Research has shown that interkingdom interactions of yeast and lactic acid bacteria can enhance metabolic activities and promote resistance to environmental stressors.

Methods

Comparative genomic analyses were performed to distinguish OSU-BDGOA1 from other strains of the same species, and the genome was mined to provide molecular evidence for relevant probiotic properties. We further assessed the cumulative effect on the probiotic properties of OSU-BDGOA1 and Kluyveromyces marxianus bdgo-ym6 yeast co-culture compared to monocultures.

Results

Survival during simulated digestion assessed by the INFOGEST digestion model showed higher survival of OSU-BDGOA1 and bdgo-ym6 in co-culture. The adhesion to intestinal cells assessed with the Caco-2 intestinal cell model revealed enhanced adhesion of OSU-BDGOA1 in co-culture. The observed increase in survival during digestion could be associated with the increased production of EPS during the late exponential and early stationary phases of co-culture that, by enhancing co-aggregation between the yeast and the bacterium, protects the microorganisms from severe gastrointestinal conditions as observed by SEM images. Immune modulation and barrier function for recovery and prevention of flagellin-mediated inflammation by Salmonella Typhimurium heat-killed cells (HKSC) in Caco-2 cells were also measured. OSU-BDGOA1 in mono- and co-culture regulated inflammation through downregulation of pro-inflammatory cytokine expression and increased membrane barrier integrity assessed by TEER, FD4 permeability, and expression of tight junctions.

Discussion

The results of the study warrant further research into the application of co-cultures of yeast and LAB in functional probiotic products and the potential to increase EPS production by co-culture strategies.

Peptidomics analysis of Jiang-Flavor Daqu from high-temperature fermentation to mature and in different preparation season

Jiang-Flavor Daqu (JFDQ) is a grain-type fermented starter for brewing Chinese liquor. Peptides, the metabolites of proteins in JFDQ, are important for the quality and flavor of JFDQ or even the liquor. The peptide variations in the progress of JFDQ preparation were investigated using RPLC-MS/MS. The JFDQ after high-temperature fermenting (HTF_SU) and after ripening (M_SU), as well as the mature JFDQ prepared in spring (M_SP) and in summer (M_SU), were compared respectively. These two groups were investigated from peptides, precursor proteins, abundance, interactions, and potential antimicrobial peptides (pAMPs). A total of 177, 158, and 262 peptides from HTF_SU, M_SP, and M_SU were identified, respectively. Significant differences (P < 0.01) in the abundance of shared peptides were found in different fermentation stage group (HTF_M), and stronger positive correlations were observed in different preparation season group (MSP_MSU). The interactions of the shared peptides in HTF_M and in MSP_MSU were investigated respectively. In addition, 8 pAMPs in HTF_SU, 5 in M_SP, and 22 in M_SU were predicted using CAMPR3, and their core functional regions were analyzed. This systematic study demonstrated the influences of fermentation stage and preparation season on the peptide profiles in JFDQ, which would provide theoretical guidance and be helpful for JFDQ production. SIGNIFICANCE: Peptidomics analysis showed that the peptide profiles of JFDQ varied in different fermentation stages and different preparation seasons, which mainly resulted from the peptides with high abundance, high interaction degrees, and potential antimicrobial activity, as well as the important precursor proteins such as glutens. This systematic study would benefit for the insufficiency of peptide research of JFDQ till now, and provide theoretical guidance for JFDQ production.