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Summary: Kombucha has gained global attention for its beneficial bioactive compounds. This study aimed to evaluate Thunbergia laurifolia tea as a potential substrate for Kombucha production due to its rich polyphenol content and biological properties, including antioxidant and anticancer properties, through monoculture and simultaneous mixed coculture fermentation. The pH and brix of the teas decreased significantly during fermentation, indicating sugar hydrolysis and organic acid synthesis by fermenting microbes. The alcohol content was higher in yeast monocultures (45.80 ± 0.00¬50.23 ± 0.08 g L−1) compared to mixed coculture fermented (CBY) tea (20.16 ± 0.00 g L−1). Total phenolic and flavonoid contents and antioxidant activity increased significantly in CBY tea compared to non‐fermented and monoculture teas. CBY also exhibited the highest cumulative phenolic compound content, including rosmarinic acid, caffeic acid, gallic acid, rutin, catechin, and quercetin, compared to monoculture teas. Overall, Thunbergia laurifolia tea shows promise as a substrate for kombucha production, with improved bioactive constituents and antioxidant activity. [ABSTRACT FROM AUTHOR]

Vitamin B12 is a critical nutrient in vegan and vegetarian lifestyles as plant-based vitamin sources are rare. Traditional fermented foods could be enriched by adding vitamin B12-producing bacteria to offer non-animal vitamin sources. The aim was to isolate a vitamin B12 producer that is capable of producing the human-active vitamin even at low pH values so that it can be used in fruit juice fortification. Therefore, fermented foods (homemade and industrial) and probiotics were screened for vitamin B12 production strains. A modified microbiological vitamin B12 assay based on Lactobacillus delbrueckii subsp. lactis DSM 20355 was used to identify vitamin B12-containing samples and the presence of vitamin B12-producing strains. The screening resulted in isolating several positive strains for vitamin B12 formation derived from sourdough. Mass spectrometry confirmed the biosynthesis of solely the human physiologically active form. Species identification carried out by the German Strain Collection of Microorganisms and Cell Cultures resulted in two species: Acetobacter orientalis and Acetobacter malorum, of which two isolates were further characterised. The potential for cobalamin biosynthesises in food matrixes was demonstrated for A. malorum HFD 3141 and A. orientalis HFD 3031 in apple juice at different pH values (2.85–3.80). The isolates synthesised up to 18.89 µg/L and 7.97 µg/L vitamin B12 at pH 3.80. The results of this study suggest that acetic acid bacteria (AAB) and fermented acetic acid foods are promising resources for vitamin B12 and its producers, which might have been overlooked in the past. [ABSTRACT FROM AUTHOR]

Gluconobacter oxydans succinic semialdehyde reductase (GoxSSAR) and Acetobacter aceti glyoxylate reductase (AacGR) represent a novel class in the β-hydroxyacid dehydrogenases superfamily. Kinetic analyses revealed GoxSSAR's activity with both glyoxylate and succinic semialdehyde, while AacGR is glyoxylate specific. GoxSSAR K167A lost activity with succinic semialdehyde but retained some with glyoxylate, whereas AacGR K175A lost activity. These findings elucidate differences between these homologous enzymes. [ABSTRACT FROM AUTHOR]

Copyright of China Condiment is the property of China Condiment and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Vitamin B12 is a critical nutrient in vegan and vegetarian lifestyles as plant-based vitamin sources are rare. Traditional fermented foods could be enriched by adding vitamin B12-producing bacteria to offer non-animal vitamin sources. The aim was to isolate a vitamin B12 producer that is capable of producing the human-active vitamin even at low pH values so that it can be used in fruit juice fortification. Therefore, fermented foods (homemade and industrial) and probiotics were screened for vitamin B12 production strains. A modified microbiological vitamin B12 assay based on Lactobacillus delbrueckii subsp. lactis DSM 20355 was used to identify vitamin B12-containing samples and the presence of vitamin B12-producing strains. The screening resulted in isolating several positive strains for vitamin B12 formation derived from sourdough. Mass spectrometry confirmed the biosynthesis of solely the human physiologically active form. Species identification carried out by the German Strain Collection of Microorganisms and Cell Cultures resulted in two species: Acetobacter orientalis and Acetobacter malorum, of which two isolates were further characterised. The potential for cobalamin biosynthesises in food matrixes was demonstrated for A. malorum HFD 3141 and A. orientalis HFD 3031 in apple juice at different pH values (2.85–3.80). The isolates synthesised up to 18.89 µg/L and 7.97 µg/L vitamin B12 at pH 3.80. The results of this study suggest that acetic acid bacteria (AAB) and fermented acetic acid foods are promising resources for vitamin B12 and its producers, which might have been overlooked in the past.

In fermented foods, acetic acid bacteria (AAB), kinds of bacteria with a long history of utilization, contribute to safety, nutritional, and sensory properties primarily through acetic acid fermentation. AAB are commonly found in various fermented foods such as vinegar, sour beer, fermented cocoa and coffee beans, kefir beverages, kombucha, and sourdough. They interact and cooperate with a variety of microorganisms, resulting in the formation of diverse metabolites and the production of fermented foods with distinct flavors. Understanding the interactions between AAB and other microbes is crucial for effectively controlling and utilizing AAB in fermentation processes. However, these microbial interactions are influenced by factors such as strain type, nutritional conditions, ecological niches, and fermentation duration. In this review, we examine the relationships and research methodologies of microbial interactions and interaction studies between AAB and yeasts, lactic acid bacteria (LAB), and bacilli in different food fermentation processes involving these microorganisms. The objective of this review is to identify key interaction models involving AAB and other microorganisms. The insights gained will provide scientific guidance for the effective utilization of AAB as functional microorganisms in food fermentation processes. [ABSTRACT FROM AUTHOR]

Port wine vinegar, a product of the esteemed Port wine, is renowned for its intricate blend of flavors and aromas, a result of complex microbial interactions. This study delves into the fascinating world of yeast and acetic acid bacteria (AAB) interactions during fermentation, which significantly influence the vinegar's chemical composition and sensory properties. We specifically investigate the role of yeasts in fermenting sugars into ethanol, a process that AAB then converts into acetic acid. The impact of these interactions on the production of secondary metabolites, such as gluconic acid, ketones, aldehydes, and esters, which contribute to the vinegar's unique sensory profile, is thoroughly examined. Advanced analytical techniques, including GC-MS and e-nose technology, alongside sensory evaluation, are employed to assess these effects. The research underscores the significance of ethanol tolerance in AAB and other production challenges in determining vinegar quality and underscores the importance of optimizing fermentation conditions and sustainable practices. The findings of this study underscore the importance of strain interactions and production techniques, which can significantly enhance the quality and market appeal of Port wine vinegar, providing valuable insights for the industry. This review also identifies exciting and critical areas for future research, inspiring further exploration and proposing strategies for advancing production and application in culinary, health, and industrial contexts. [ABSTRACT FROM AUTHOR]

Sourdough is one of the oldest technologies employed by humans to leaven bread because of its ability to enhance the flavour and structure of bread using micro-organisms. However, there is a lack of comprehensive information in Botswana regarding the diversity of sourdough starters and the fermentative micro-organisms responsible for spontaneous fermentation. The present study aimed to explore the microbial species diversity of sourdoughs in Botswana and gain insight into the unique microbial communities involved in sourdough production. A total of nine samples were collected from different areas in Botswana. The microbial diversity in sourdoughs was characterized through the sequencing of amplicons of the 16S ribosomal DNA and internal transcribed spacer regions. In silico polymerase chain reaction–restriction fragment length polymorphism and phylogenetics were utilized to determine the genetic diversity among the isolates. The dominant yeast species identified were Saccharomyces cerevisiae, Wickerhamomyces anomamlus, Pichia kudriazverii and kazachstania humilis. Additionally, the presence of Lactiplantibacillus plantarum, Lacticaseibacillus paracasei, Liquorilactobacillus nageli and Bacillus cereus was also detected. It is worth noting that two species of acetic acid bacteria (AAB), namely Acetobacter pasteurianus and A. indonesiensis, were isolated, though in low levels, but the finding is significant in sourdough fermentation. The low occurrence of AAB (acetic acid bacteria) species observed in this study could be an important finding, as these bacteria are considered understudied, yet they are known to contribute significantly to the final product. [ABSTRACT FROM AUTHOR]

Acetic acid bacteria (AAB) are major contributors to the production of fermented vinegar, offering various cultural, culinary, and health benefits. Although the residual unpasteurized AAB after vinegar production are not pathogens, these are necessary and require safety evaluations, including antibiotic resistance, before use as a starter. In this research, we investigated the antibiotic resistance profiles of 26 AAB strains, including various species of Komagataeibacter and Acetobacter, against 10 different antibiotics using the E-test method. All strains exhibited resistance to aztreonam and clindamycin. Komagataeibacter species demonstrated a 50% resistance rate to ciprofloxacin, analogous to Acetobacter species, but showed twice the resistance rates to chloramphenicol and erythromycin. Genomic analysis of K. saccharivorans CV1 identified intrinsic resistance mechanisms, such as multidrug efflux pumps, thereby enhancing our understanding of antibiotic resistance in acetic acid-producing bacteria. These findings enhance understanding of antibiotic resistance in AAB for food safety and new antimicrobial strategies, suggesting the need for standardized testing methods and molecular genetic study. [ABSTRACT FROM AUTHOR]

Copyright of China Condiment is the property of China Condiment and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Lipopolysaccharide (LPS), a cell surface component of Gram‐negative bacteria, activates innate immunity. Its active principle is the terminal glycolipid lipid A. Acetobacter pasteurianus is a Gram‐negative bacterium used in the fermentation of traditional Japanese black rice vinegar (kurozu). In this study, we focused on A. pasteurianus lipid A, which is a potential immunostimulatory component of kurozu. The active principle structure of A. pasteurianus lipid A has not yet been identified. Herein, we first systematically synthesized three types of A. pasteurianus lipid As containing a common and unique tetrasaccharide backbone. We developed an efficient method for constructing the 2‐trehalosamine skeleton utilizing borinic acid‐catalyzed glycosylation to afford 1,1'‐α,α‐glycoside in high yield and stereoselectivity. A common tetrasaccharide intermediate with an orthogonal protecting group pattern was constructed via [2+2] glycosylation. After introducing various fatty acids, all protecting groups were removed to achieve the first chemical synthesis of three distinct types of A. pasteurianus lipid As. After evaluating their immunological function using both human and murine cell lines, we identified the active principles of A. pasteurianus LPS. We also found the unique anomeric structure of A. pasteurianus lipid A contributes to its high chemical stability. [ABSTRACT FROM AUTHOR]

Acetic acid bacteria (AAB) and other members of the complex microbiotas, whose activity is essential for vinegar production, display biodiversity and richness that is difficult to study in depth due to their highly selective culture conditions. In recent years, liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) has emerged as a powerful tool for rapidly identifying thousands of proteins present in microbial communities, offering broader precision and coverage. In this work, a novel method based on LC–MS/MS was established and developed from previous studies. This methodology was tested in three studies, enabling the characterization of three submerged acetification profiles using innovative raw materials (synthetic alcohol medium, fine wine, and craft beer) while working in a semicontinuous mode. The biodiversity of existing microorganisms was clarified, and both the predominant taxa (Komagataeibacter, Acetobacter, Gluconacetobacter, and Gluconobacter) and others never detected in these media (Asaia and Bombella, among others) were identified. The key functions and adaptive metabolic strategies were determined using comparative studies, mainly those related to cellular material biosynthesis, energy-associated pathways, and cellular detoxification processes. This study provides the groundwork for a highly reliable and reproducible method for the characterization of microbial profiles in the vinegar industry. [ABSTRACT FROM AUTHOR]

This study focuses on optimizing the medium composition for cellular biomass production and bioconversion of ethylene glycol (EG) to glycolic acid (GA) using Gluconobacter oxydans CCT 0552. The improvement in cellular growth in the presence of yeast extract and peptone led to a 35.7% and 32.7% increase, respectively, compared to the medium with each of these carbon sources separately. Negligible growth was produced when (NH4)2SO4 and urea were used. Optimal bioconversion results were very similar for both the stirred tank and bubble column bioreactors, with GA concentrations reaching 49.4 g/L and 47.7 g/L, volumetric productivities of 0.35 g/L∙h and 0.33 g/L∙h, and product yield factors of 1.08 g/g and 0.94 g/g, respectively. An extended fed-batch strategy using a STR-type bioreactor achieved a concentration of glycolic acid of 94.2 g/L, corresponding to a volumetric productivity of 0.41 g/L∙h and a yield factor of 1.19 g/g. The resulting efficiency of this biological transformation process achieved a remarkable value of 97.3%, simultaneously with a significant decrease in the substrate amount by 90.5%. This study demonstrates the efficiency of G. oxydans in producing GA, offering a cost-effective and environmentally sustainable production method. [ABSTRACT FROM AUTHOR]

Fermentation of pumpkin puree and mature coconut water using water kefir grains is a potential method for producing a novel functional non-dairy-based probiotic drink. In the present study, response surface methodology based on Box–Behnken design (RSM-BBD) was used to optimise fermentation temperature and substrates' concentrations. The optimised fermentation temperature, pumpkin puree, and brown sugar concentrations of pumpkin-based mature coconut water kefir beverage (PWKC) were 27 °C, 20%, and 10% w/v, respectively. The optimised PWKC (PWKCopt) obtained an overall acceptability (OA) score of 4.03, with a desirable Lactobacillus count (6.41 Log CFU/mL), 0.68% v/v lactic acid content, 31% of water kefir grains' biomass growth rate, and fermentation time (to reach pH 4.5) of 4.5 h. The optimized beverage, PWKCopt, contained 3.26% proteins, 2.75% dietary fibre, 2186.33 mg/L of potassium, 180.67 mg/L phosphorus, and 137.33 mg/L calcium and had a total phenolic content of 89.93 mg GAE/100 mL, flavonoid content of 49.94 mg QE/100 mL, and carotenoid content of 33.24 mg/100 mL, with antioxidant activity (FRAP: 169.17 mM Fe(II)/100 mL, IC50 value of DPPH free radicals scavenging activity: 27.17 mg/mL). Water kefir microorganisms in PWKCopt remained stable for at least 56 days at 4 °C. Therefore, PWKCopt might potentially serve as a value-added product, offering a basis for sustainable development within both the coconut and pumpkin industries. [ABSTRACT FROM AUTHOR]

Background: This study explored the utilization of luffa sponge (LS) in enhancing acetification processes. LS is known for having high porosity and specific surface area, and can provide a novel means of supporting the growth of acetic acid bacteria (AAB) to improve biomass yield and acetification rate, and thereby promote more efficient and sustainable vinegar production. Moreover, the promising potential of LS and luffa sponge coated with κ-carrageenan (LSK) means they may represent effective alternatives for the co-production of industrially valuable bioproducts, for example bacterial cellulose (BC) and acetic acid. Methods: LS and LSK were employed as adsorbents for Acetobacter pasteurianus UMCC 2951 in a submerged semi-continuous acetification process. Experiments were conducted under reciprocal shaking at 1 Hz and a temperature of 32 °C. The performance of the two systems (LS-AAB and LSK-AAB respectively) was evaluated based on cell dry weight (CDW), acetification rate, and BC biofilm formation. Results: The use of LS significantly increased the biomass yield during acetification, achieving a CDW of 3.34 mg/L versus the 0.91 mg/L obtained with planktonic cells. Coating LS with κ-carrageenan further enhanced yield, with a CDW of 4.45 mg/L. Acetification rates were also higher in the LSK-AAB system, reaching 3.33 ± 0.05 g/L d as opposed to 2.45 ± 0.05 g/L d for LS-AAB and 1.13 ± 0.05 g/L d for planktonic cells. Additionally, BC biofilm formation during the second operational cycle was more pronounced in the LSK-AAB system (37.0 ± 3.0 mg/L, as opposed to 25.0 ± 2.0 mg/L in LS-AAB). Conclusions: This study demonstrates that LS significantly improves the efficiency of the acetification process, particularly when enhanced with κ-carrageenan. The increased biomass yield, accelerated acetification, and enhanced BC biofilm formation highlight the potential of the LS-AAB system, and especially the LSK-AAB variant, in sustainable and effective vinegar production. These systems offer a promising approach for small-scale, semi-continuous acetification processes that aligns with eco-friendly practices and caters to specialized market needs. Finally, this innovative method facilitates the dual production of acetic acid and bacterial cellulose, with potential applications in biotechnological fields. [ABSTRACT FROM AUTHOR]

The corrosion of diesel fuel storage tanks in the US was first reported in 2007, when the transition to more sustainable fuels, such as E10 and biodiesel, was underway, along with the adoption of ultra-low-sulfur diesel. Corrosion is caused by acetic acid produced by contaminating bacteria in fuel storage tanks. This study aimed to investigate the relationship between fuel improvements and microbiologically influenced corrosion in diesel fuel storage tanks by isolating acetic acid-producing bacteria and examining their effects on the deterioration of diesel-related fuels. The results revealed that the bacterium isolated from the two samples was Gluconacetobacter sp. (named as strain US-001). Among the carbon sources tested relevant to recent fuels, ethanol was dissimilated with acetic acid production and decreasing pH. Furthermore, the presence of 0.5% ethanol enabled the deterioration of n-dodecane, although it did not affect the pH. Dibenzothiophene, among the tested sulfur compounds present in previous low-sulfur diesel, inhibited the growth of the isolated strain US-001. In a sealed cup with a limited oxygen supply, the culture of strain US-001 experimentally induced severe steel corrosion when ethanol/n-dodecane was used as the carbon source. In conclusion, we speculate that ethanol contamination through E10 gasoline in diesel fuel tanks facilitates the growth of acetic acid bacteria, leading to the accumulation of acetic acid and a decrease in the pH of the sludge. Simultaneously, the introduction of ultra-low-sulfur diesel created more favorable growth conditions by removing their growth inhibitors, thereby resulting in microbiologically influenced corrosion of diesel fuel storage tanks. [ABSTRACT FROM AUTHOR]

ABSTRACT While research on the sourdough microbiome has primarily focused on lactic acid bacteria (LAB) and yeast, recent studies have found that acetic acid bacteria (AAB) are also common members. However, the ecology, genomic diversity, and functional contributions of AAB in sourdough remain unknown. To address this gap, we sequenced 29 AAB genomes, including three that represent putatively novel species, from a collection of over 500 sourdough starters surveyed globally from community scientists. We found variations in metabolic traits related to carbohydrate utilization, nitrogen metabolism, and alcohol production, as well as in genes related to mobile elements and defense mechanisms. Sourdough AAB genomes did not cluster when compared to AAB isolated from other environments, although a subset of gene functions was enriched in sourdough isolates. The lack of a sourdough-specific genomic cluster may reflect the nomadic lifestyle of AAB. To assess the consequences of AAB on the emergent function of sourdough starter microbiomes, we constructed synthetic starter microbiomes, varying only the AAB strain included. All AAB strains increased the acidification of synthetic sourdough starters relative to yeast and LAB by 18.5% on average. Different strains of AAB had distinct effects on the profile of synthetic starter volatiles. Taken together, our results begin to define the ways in which AAB shape emergent properties of sourdough and suggest that differences in gene content resulting from intraspecies diversification can have community-wide consequences on emergent function.IMPORTANCEThis study is a comprehensive genomic and ecological survey of acetic acid bacteria (AAB) isolated from sourdough starters. By combining comparative genomics with manipulative experiments using synthetic microbiomes, we demonstrate that even strains with >97% average nucleotide identity can shift important microbiome functions, underscoring the importance of species and strain diversity in microbial systems. We also demonstrate the utility of sourdough starters as a model system to understand the consequences of genomic diversity at the strain and species level on multispecies communities. These results are also relevant to industrial and home-bakers as we uncover the importance of AAB in shaping properties of sourdough starters that have direct impacts on sensory notes and the quality of sourdough bread.

Kombucha is a fermented tea beverage containing live microorganisms, mostly beneficial strains of yeast and acetic acid bacteria (AAB), but empirical evidence is limited supporting the probiotic potential of kombucha. This study reports the in vitro probiotic potential of 36 AAB strains isolated from three Kombucha samples commercially available in New Zealand. Nine representative AAB strains, belonging to three species (Komagataeibacter rhaeticus, Acetobacter musti and Gluconobacter potus), were examined for their primary probiotic characteristics such as tolerance to bile salts, NaCl, and low pH, and temperature. Three non-cellulose forming strains (A. musti LOAAB1, G. potus LOAAB2 and G. potus GBAAB3) were assayed for their cell surface characteristics such as auto-aggregation, co-aggregation with pathogenic bacteria, and hydrophobicity. Antimicrobial, antioxidant activities and enzymatic activities were also investigated for the strains of interest. Results indicated that nine strains were able to grow under low pH in the presence of bile salts, suggesting their potential to survive in the human gut. Six K. rhaeticus strains produced cellulosic pellicles, a potential source of prebiotics for beneficial bacteria. The three AAB strains LOAAB1, LOAAB2 and GBAAB3 showed promising cell surface characteristics, such as auto-aggregation rates (>80 %), co-aggregation with four pathogenic bacteria (13.24–43.47 %), hydrophobicity (42.12 % to 50.20 %), and antioxidant activities (>90 %). All nine strains tested negative for enzymatic activities (haemolytic, proteolytic, phospholipase, and gelatinase), suggesting that they are safe to consume. Together, these data indicate the potential for the three AAB strains to be further investigated as probiotic sources with more in vivo tests for applications in the food and beverages industry.

The aim of this study was to assess the impact of production parameters on the reproducibility of kombucha fermentation over several production cycles based on backslopping. Six conditions with varying oxygen accessibility (specific interface surface) and initial acidity (through the inoculation rate) of the cultures were carried out and compared to an original kombucha consortium and a synthetic consortium assembled from yeasts and bacteria isolated from the original culture. Output parameters monitored were microbial populations, biofilm weight, key physico-chemical parameters and metabolites. Results highlighted the existence of phases in microbial dynamics as backslopping cycles progressed. The transitions between phases occurred faster for the synthetic consortium compared to the original kombucha. This led to microbial dynamics and fermentative kinetics that were reproducible over several cycles but that could also deviate and shift abruptly to different behaviors. These changes were mainly induced by an increase in the Saccharomyces cerevisiae population, associated with an intensification of sucrose hydrolysis, sugar consumption and an increase in ethanol content, without any significant acceleration in the rate of acidification. The study suggests that the reproducibility of kombucha fermentations relies on high biodiversity to slow down the modulations of microbial dynamics induced by the sustained rhythm of backslopping cycles. [ABSTRACT FROM AUTHOR]

The production of gueuze beers through refermentation and maturation of blends of lambic beer in bottles is a way for lambic brewers to cope with the variability among different lambic beer batches. The resulting gueuze beers are more carbonated than lambic beers and are supposed to possess a unique flavor profile that varies over time. To map this refermentation and maturation process for gueuze production, a blend of lambic beers was made and bottled, whereby one of them was produced with the old wheat landrace Zeeuwse Witte. Through the use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and high-throughput sequencing of bacterial and fungal amplicons, in combination with metabolite target analysis, new insights into gueuze production were obtained. During the initial stages of refermentation, the conditions in the bottles were similar to those encountered during the maturation phase of lambic beer productions in wooden barrels, which was also reflected microbiologically (presence of Brettanomyces species, Pediococcus damnosus, and Acetobacter lambici) and biochemically (ethanol, higher alcohols, lactic acid, acetic acid, volatile phenolic compounds, and ethyl esters). However, after a few weeks of maturation, a switch from a favorable environment to one with nutrient and dissolved oxygen depletion resulted in several changes. Concerning the microbiology, a sequential prevalence of three lactic acid bacterial species occurred, namely, P. damnosus, Lentilactobacillus buchneri, and Lactobacillus acetotolerans, while the diversity of the yeasts decreased. Concerning the metabolites produced, mainly those of the Brettanomyces yeasts determined the metabolic profiles encountered during later stages of the gueuze production. IMPORTANCE Gueuze beers are the result of a refermentation and maturation process of a blend of lambic beers carried out in bottles. These gueuze beers are known to have a long shelf life, and their quality typically varies over time. However, knowledge about gueuze production in bottles is scarce. The present study provided more insights into the varying microbial and metabolite composition of gueuze beers during the first 2 years of this refermentation and maturation process. This will allow gueuze producers to gain more information about the influence of the refermentation and maturation time on their beers. These insights can also be used by gueuze producers to better inform their customers about the quality of young and old gueuze beers. [ABSTRACT FROM AUTHOR]

This review critically examines the multifaceted role of acetic acid bacteria (AAB) in the intricate production process of port wine vinegar, particularly in its transformative process from port wine. With the emergence of port wine vinegar as a distinctive agricultural product in 2018, producers have been faced with a diverse array of challenges, ranging from reducing the high alcohol content to preserving the inherent sweetness. Through an exhaustive exploration of acetic fermentation processes and the indispensable role of AAB, this review meticulously elucidates the complex biochemistry underlying vinegar formation, delving into the nuanced interactions between microbial activity and chemical composition. Furthermore, this review underscores the importance of sensory characteristics and consumer perception derived from vinegar production, providing invaluable insights into these fermented products' sensory profiles and marketability. In summary, this study offers valuable insights into the evolution of port wine into vinegar, highlighting its significance in agricultural and culinary contexts. [ABSTRACT FROM AUTHOR]

ABSTRACT Acetic acid bacteria are used in many industrial processes such as the production of vinegar, vitamin C, the antidiabetic drug miglitol, and various artificial flavorings. These industrially important reactions are primarily carried out by an arsenal of periplasmic-facing membrane-bound dehydrogenases that incompletely oxidize their substrates and shuttle electrons directly into the respiratory chain. Among these dehydrogenases, GOX1969 in Gluconobacter oxydans was predicted to be a pyrroloquinoline quinone-dependent dehydrogenase of unknown function. However, after multiple analysis by a number of labs, no dehydrogenase activity has been detected. Reanalysis of GOX1969 sequence and structure reveals similarities to Escherichia coli BamB, which functions as a subunit of the β-barrel assembly machinery complex that is responsible for the assembly of β-barrel outer membrane proteins in Gram-negative bacteria. To test if the physiological function of GOX1969 is similar to BamB in E. coli, we introduced the gox1969 gene into an E. coli ∆bamB mutant. Growth deficiencies in the ∆bamB mutant were restored when gox1969 was expressed on the plasmid pGox1969. Furthermore, increased membrane permeability conferred by bamB deletion was restored upon gox1969 expression, which suggests a direct link between GOX1969 and a role in maintaining outer membrane stability. Together, this evidence strongly suggests that GOX1969 is functionally acting as a BamB in G. oxydans. As such, functional information on uncharacterized genes will provide new insights that will allow for more accurate modeling of acetic acid bacterial metabolism and further efforts to design rational strains for industrial use.IMPORTANCEGluconobacter oxydans is an industrially important member of the acetic acid bacteria. Experimental characterization of putative genes is necessary to identify targets for further engineering of rational acetic acid bacteria strains that can be used in the production of vitamin C, antidiabetic compounds, artificial flavorings, or novel compounds. In this study, we have identified an undefined dehydrogenase GOX1969 with no known substrate and defined structural similarities to outer membrane biogenesis protein BamB in E. coli K12. Furthermore, we demonstrate that GOX1969 is capable of complementing bamB knockout phenotypes in E. coli K12. Taken together, these findings enhance our understanding of G. oxydans physiology and expand the list of potential targets for future industrial strain design.

Background This study explored the utilization of luffa sponge (LS) in enhancing acetification processes. LS is known for having high porosity and specific surface area, and can provide a novel means of supporting the growth of acetic acid bacteria (AAB) to improve biomass yield and acetification rate, and thereby promote more efficient and sustainable vinegar production. Moreover, the promising potential of LS and luffa sponge coated with κ-carrageenan (LSK) means they may represent effective alternatives for the co-production of industrially valuable bioproducts, for example bacterial cellulose (BC) and acetic acid. Methods LS and LSK were employed as adsorbents for Acetobacter pasteurianus UMCC 2951 in a submerged semi-continuous acetification process. Experiments were conducted under reciprocal shaking at 1 Hz and a temperature of 32 °C. The performance of the two systems (LS-AAB and LSK-AAB respectively) was evaluated based on cell dry weight (CDW), acetification rate, and BC biofilm formation. Results The use of LS significantly increased the biomass yield during acetification, achieving a CDW of 3.34 mg/L versus the 0.91 mg/L obtained with planktonic cells. Coating LS with κ-carrageenan further enhanced yield, with a CDW of 4.45 mg/L. Acetification rates were also higher in the LSK-AAB system, reaching 3.33 ± 0.05 g/L d as opposed to 2.45 ± 0.05 g/L d for LS-AAB and 1.13 ± 0.05 g/L d for planktonic cells. Additionally, BC biofilm formation during the second operational cycle was more pronounced in the LSK-AAB system (37.0 ± 3.0 mg/L, as opposed to 25.0 ± 2.0 mg/L in LS-AAB). Conclusions This study demonstrates that LS significantly improves the efficiency of the acetification process, particularly when enhanced with κ-carrageenan. The increased biomass yield, accelerated acetification, and enhanced BC biofilm formation highlight the potential of the LS-AAB system, and especially the LSK-AAB variant, in sustainable and effective vinegar production. These systems offer a promising approach for small-scale, semi-continuous acetification processes that aligns with eco-friendly practices and caters to specialized market needs. Finally, this innovative method facilitates the dual production of acetic acid and bacterial cellulose, with potential applications in biotechnological fields.

Kombucha is a traditional beverage produced by a living culture known as SCOBY or “symbiotic culture of bacteria and yeast”. Culture-dependent production is essential for stable kombucha fermentation. The aim of this study was to design a microbial community and to determine the effect of that community on the flavor and chemical properties of kombucha. The fermentations were carried out using combinations of selected species including Pichia kudriavzevii, Brettanomyces bruxellensis, Dekkera bruxellensis, Komagataeibacter saccharivorans, Komagataeibacter xylinus, and Acetobacter papayae, which were previously isolated from kombucha. The effects of monocultures and cocultures on fermentation were investigated. The highest acetic acid producer was A. papayae, which has strong antioxidant properties. In the monoculture and coculture fermentations, aldehydes, acids, and esters were generally observed at the end of fermentation. This study confirms that microbiota reconstruction is a viable approach for achieving the production of kombucha with increased bioactive constituents and consumer acceptance.

Abstract Background Bacterial cellulose (BC) is a biocompatible material with unique mechanical properties, thus holding a significant industrial potential. Despite many acetic acid bacteria (AAB) being BC overproducers, cost-effective production remains a challenge. The role of pyrroloquinoline quinone (PQQ)-dependent membrane dehydrogenases (mDH) is crucial in the metabolism of AAB since it links substrate incomplete oxidation in the periplasm to energy generation. Specifically, glucose oxidation to gluconic acid substantially lowers environmental pH and hinders BC production. Conversely, ethanol supplementation is known to enhance BC yields in Komagataeibacter spp. by promoting efficient glucose utilization. Results K. sucrofermentans ATCC 700178 was engineered, knocking out the four PQQ-mDHs, to assess their impact on BC production. The strain KS003, lacking PQQ-dependent glucose dehydrogenase (PQQ-GDH), did not produce gluconic acid and exhibited a 5.77-fold increase in BC production with glucose as the sole carbon source, and a 2.26-fold increase under optimal ethanol supplementation conditions. In contrast, the strain KS004, deficient in the PQQ-dependent alcohol dehydrogenase (PQQ-ADH), showed no significant change in BC yield in the single carbon source experiment but showed a restrained benefit from ethanol supplementation. Conclusions The results underscore the critical influence of PQQ-GDH and PQQ-ADH and clarify the effect of ethanol supplementation on BC production in K. sucrofermentans ATCC 700178. This study provides a foundation for further metabolic pathway optimization, emphasizing the importance of diauxic ethanol metabolism for high BC production.

Acetic acid bacteria synthesized microbial cellulose were isolated from various citrus fruits, enabled by increased cellulose production to develop a biodegradable polymer as a food wrapper. The objective of the research cynosures on the isolation, enrichment, identification, and optimization of bacteria that produce cellulose, characterization, and cytotoxic study of the obtained cellulose. Two highly effective cellulose producers, Acetobacter lovaniensis (A1) and Acetobacter fabarum (A2), were isolated based on their morphology, biochemical analysis, and 16s rRNA sequencing. Studies were conducted to optimize pH, temperature, inoculum size, nitrogen, and carbon sources. Strain A1 produced 0.715 g/100 ml, whereas A2 produced 0.856 g/100 ml of cellulose under optimum growth conditions. The characteristics of microbial cellulose were examined using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). A cytotoxicity study for the obtained cellulose has been conducted with mouse embryo fibroblast cells (3T3-L1) and showed 97% viability of cells with the lowest concentration of 12.5 µg/ml. These isolates could be employed in fermentation technology to produce cellulose polymer-based sustainable biodegradable food wrappers.

Background: Bacterial cellulose (BC) is a biocompatible material with unique mechanical properties, thus holding a significant industrial potential. Despite many acetic acid bacteria (AAB) being BC overproducers, cost-effective production remains a challenge. The role of pyrroloquinoline quinone (PQQ)-dependent membrane dehydrogenases (mDH) is crucial in the metabolism of AAB since it links substrate incomplete oxidation in the periplasm to energy generation. Specifically, glucose oxidation to gluconic acid substantially lowers environmental pH and hinders BC production. Conversely, ethanol supplementation is known to enhance BC yields in Komagataeibacter spp. by promoting efficient glucose utilization. Results: K. sucrofermentans ATCC 700178 was engineered, knocking out the four PQQ-mDHs, to assess their impact on BC production. The strain KS003, lacking PQQ-dependent glucose dehydrogenase (PQQ-GDH), did not produce gluconic acid and exhibited a 5.77-fold increase in BC production with glucose as the sole carbon source, and a 2.26-fold increase under optimal ethanol supplementation conditions. In contrast, the strain KS004, deficient in the PQQ-dependent alcohol dehydrogenase (PQQ-ADH), showed no significant change in BC yield in the single carbon source experiment but showed a restrained benefit from ethanol supplementation. Conclusions: The results underscore the critical influence of PQQ-GDH and PQQ-ADH and clarify the effect of ethanol supplementation on BC production in K. sucrofermentans ATCC 700178. This study provides a foundation for further metabolic pathway optimization, emphasizing the importance of diauxic ethanol metabolism for high BC production. [ABSTRACT FROM AUTHOR]

Sichuan Baoning vinegar, a typical representative of Sichuan bran vinegar, is a famous traditional fermented food made from cereals in China. At present, there are few studies on microbial characterization of culturable microorganisms in solid-state fermentation of Sichuan bran vinegar. To comprehensively understand the diversity of lactic acid bacteria, acetic acid bacteria and yeasts, which play an important role in the fermentation of Sichuan bran vinegar, traditional culture-dependent methods combined with morphological, biochemical, and molecular identification techniques were employed to screen and identify these isolates. A total of 34 lactic acid bacteria isolates, 39 acetic acid bacteria isolates, and 48 yeast isolates were obtained. Lactic acid bacteria were dominated by Enterococcus durans, Leuconostoc citreum, Lactococcus lactis, and Lactiplantibacillus plantarum, respectively. Latilactobacillus sakei was the first discovery in cereal vinegar. Acetic acid bacteria were mainly Acetobacter pomorum and A. pasteurianus. The dominant yeast isolates were Saccharomyces cerevisiae, in addition to four non-Saccharomyces yeasts. DNA fingerprinting revealed that isolates belonging to the same species exhibited intraspecific diversity, and there were differences between phenotypic and genotypic classification results. This study further enriches studies on cereal vinegar and lays a foundation for the development of vinegar starters. [ABSTRACT FROM AUTHOR]

We evaluated the suitability of Komagataeibacter europaeus , a vinegar production organism adept at synthetic media growth, as a host for heterologous gene expression. Cryptic plasmids (pGE1 and pGE2 derivatives) from K. europaeus strain KGMA0119 were employed as vectors for heterologous gene expression. The focus was placed on the groES promoter as a potential inducible switch. The groES promoter was fused with the EGFP gene and introduced into a pGE1 derivative to assess its suitability. Ethanol, acetic acid, and heat stresses were examined under various conditions for induction. EGFP transcription surged 600-fold when late logarithmic phase K. europaeus cells, cultured at 30 °C, endured heat stress at 40 °C, coupled with 20% acetic acid and 30% ethanol stress after an additional 6-hour cultivation. This robust induction system was then applied to express two proteins, Tth pol from the thermophilic bacterium Thermus thermophilus strain M1 and UPV230, a restriction enzyme from the acid-tolerant microorganism Ureaplasma parvum , known to cause vaginal infections and miscarriages. Both Tth pol and UPV230 were successfully expressed in K. europaeus cells and purified. The recovery of Tth pol from K. europaeus cells (480 µg protein per liter culture) was approximately half that from E. coli (960 µg protein per liter culture). In contrast, UPV230 recovery from K. europaeus cells (640 µg protein per liter culture) was nearly 10 times higher than that from Escherichia coli (66 µg protein per liter). The data highlights the potential of acetic acid bacteria as a host for producing acidophilic proteins. The shift in recognition from a 6-base sequence to a 4-base sequence of UPV230 was observed, accompanied by a change in structure as the pH transitioned from acidic pH to near-neutral pH. • The groES promoter in Komagataeibacter europaeus induced robust expression in response to heat shock, ethanol, and acetic acid. • K. europaeus plasmids enabled the expression of foreign proteins from the thermophile Thermus thermophilus and the acid-tolerant Ureaplasma parvum. • K. europaeus outperformed E. coli as a host system, yielding impressive amounts of the restriction enzyme UPV230 from the acid-tolerant U. parvum. • The shift in recognition a 6-base sequence to a 4-base sequence of UPV230 was observed as pH transitions from acidic to near neutral. [ABSTRACT FROM AUTHOR]

Acetic acid bacteria synthesized microbial cellulose were isolated from various citrus fruits, enabled by increased cellulose production to develop a biodegradable polymer as a food wrapper. The objective of the research cynosures on the isolation, enrichment, identification, and optimization of bacteria that produce cellulose, characterization, and cytotoxic study of the obtained cellulose. Two highly effective cellulose producers, Acetobacter lovaniensis (A1) and Acetobacter fabarum (A2), were isolated based on their morphology, biochemical analysis, and 16s rRNA sequencing. Studies were conducted to optimize pH, temperature, inoculum size, nitrogen, and carbon sources. Strain A1 produced 0.715 g/100 ml, whereas A2 produced 0.856 g/100 ml of cellulose under optimum growth conditions. The characteristics of microbial cellulose were examined using scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). A cytotoxicity study for the obtained cellulose has been conducted with mouse embryo fibroblast cells (3T3-L1) and showed 97% viability of cells with the lowest concentration of 12.5 µg/ml. These isolates could be employed in fermentation technology to produce cellulose polymer-based sustainable biodegradable food wrappers. [ABSTRACT FROM AUTHOR]

The symbiotic effect of acetic acid bacteria and yeast on bacterial cellulose (BC) synthesis in kombucha was explored. Firstly, the optimal culture ratio of acetic acid bacteria and yeast was optimised through single factor and orthogonal test. The results showed that when Komagataeibacter intermedius:Brettanomyces bruxellensis:Zygosaccharomyces bisporus ratio was 1:10:10, and the inoculation amounts of K. intermedius, B. bruxellensis, and Z. bisporus were 104, 105, and 105 CFU/mL, respectively, the yield of BC was the highest, and the dry basis was 5.51 g/L. It was determined that the metabolites of B. bruxellensis and Z. bisporus could promote the synthesis of BC by K. intermedius. In addition, the composition of yeast filtrate was analysed by amino acid analyser, gas chromatography-mass spectrometry (GC-MS), and high performance liquid chromatograph (HPLC). Results showed that 16 amino acids were detected in yeast filtrate, and cysteine was only detected in yeast filtrate. The increase in isoleucine before and after fermentation was the highest, which was 11.64 times that of the control group. The increase in aspartic acid and glycine were second and third, accounting for 60.00 and 41.67%, respectively. The main volatile substances were alcohols, accounting for 84.89%, of which the relative content of ethanol was the highest at 77.35%. The relative contents of 3-methyl-1-butanol and phenylethanol were also high, accounting for 4.13 and 3.14%, respectively. Tartaric, citric, and succinic acids were detected in the yeast filtrate. The chemical species did not change before and after fermentation, but the content decreased. Vitamins B2 and B6 were detected in yeast filtrate, and the species and content did not change significantly before and after fermentation. A theoretical basis for kombucha fermentation and BC synthesis was provided. [ABSTRACT FROM AUTHOR]

In this study, acetic acid bacteria strains were investigated for their ability to oxidize different carbon sources producing the corresponding oxidative products. Bacterial strains were cultivated in seven designed media and their acetification ability was assessed. The most performing strains were further tested to evaluate gluconic acid production in cooked grape must. Organic acids, sugars, and ethanol concentrations were assayed by high-pressure liquid chromatography. Overall, the findings showed high variability amongst strains of the same species, especially amongst Gluconobacter oxydans strains. However, strains ATCC 621H and DSM 3503T resulted to be the highest gluconic acid producers in all tested conditions. This study shows that grape must can be further valorized by selective fermentations for the production of gluconic based products.

Hardaliye is a traditional beverage produced by fermenting red grapes with mustard seeds and sour cherry leaves in the Thrace region of Turkey. There are few studies that have determined the microorganisms responsible for hardaliye fermentation, and these are limited to lactic acid bacteria (LAB) using culture-dependent techniques. The aim of this study was to determine the bacterial dynamics of hardaliye fermentation using a culture-independent approach, high-throughput sequencing of 16S rRNA amplicons. Hardaliye was produced using the traditional method, and samples were taken and analyzed on days 0, 2, 4, 6, and 10 of fermentation. During the fermentation period, pH decreased from 3.65 to 3.23. Amplicon sequencing showed that bacterial diversity was highest at 2 d, and lowest at 10 d, the final day. Although Enterobacteriaceae was the most dominant family at 0 and 2 d, Acetobacteriaceae, specifically Gluconobacter frateurii, became dominant with ~50% relative abundance at 4 d, and increased its abundance to >98% at 6 and 10 d. Although a slight increase in the relative abundance of ~1% (0 d) to ~5% (4 d) was observed in LAB, their presence was limited. This study showed that acetic acid bacteria should not be overlooked in hardaliye fermentation.

In fermented foods, acetic acid bacteria (AAB), kinds of bacteria with a long history of utilization, contribute to safety, nutritional, and sensory properties primarily through acetic acid fermentation. AAB are commonly found in various fermented foods such as vinegar, sour beer, fermented cocoa and coffee beans, kefir beverages, kombucha, and sourdough. They interact and cooperate with a variety of microorganisms, resulting in the formation of diverse metabolites and the production of fermented foods with distinct flavors. Understanding the interactions between AAB and other microbes is crucial for effectively controlling and utilizing AAB in fermentation processes. However, these microbial interactions are influenced by factors such as strain type, nutritional conditions, ecological niches, and fermentation duration. In this review, we examine the relationships and research methodologies of microbial interactions and interaction studies between AAB and yeasts, lactic acid bacteria (LAB), and bacilli in different food fermentation processes involving these microorganisms. The objective of this review is to identify key interaction models involving AAB and other microorganisms. The insights gained will provide scientific guidance for the effective utilization of AAB as functional microorganisms in food fermentation processes.

Sourdough is one of the oldest technologies employed by humans to leaven bread because of its ability to enhance the flavour and structure of bread using micro-organisms. However, there is a lack of comprehensive information in Botswana regarding the diversity of sourdough starters and the fermentative micro-organisms responsible for spontaneous fermentation. The present study aimed to explore the microbial species diversity of sourdoughs in Botswana and gain insight into the unique microbial communities involved in sourdough production. A total of nine samples were collected from different areas in Botswana. The microbial diversity in sourdoughs was characterized through the sequencing of amplicons of the 16S ribosomal DNA and internal transcribed spacer regions. In silico polymerase chain reaction–restriction fragment length polymorphism and phylogenetics were utilized to determine the genetic diversity among the isolates. The dominant yeast species identified were Saccharomyces cerevisiae, Wickerhamomyces anomamlus, Pichia kudriazverii and kazachstania humilis. Additionally, the presence of Lactiplantibacillus plantarum, Lacticaseibacillus paracasei, Liquorilactobacillus nageli and Bacillus cereus was also detected. It is worth noting that two species of acetic acid bacteria (AAB), namely Acetobacter pasteurianus and A. indonesiensis, were isolated, though in low levels, but the finding is significant in sourdough fermentation. The low occurrence of AAB (acetic acid bacteria) species observed in this study could be an important finding, as these bacteria are considered understudied, yet they are known to contribute significantly to the final product.

Port wine vinegar, a product of the esteemed Port wine, is renowned for its intricate blend of flavors and aromas, a result of complex microbial interactions. This study delves into the fascinating world of yeast and acetic acid bacteria (AAB) interactions during fermentation, which significantly influence the vinegar’s chemical composition and sensory properties. We specifically investigate the role of yeasts in fermenting sugars into ethanol, a process that AAB then converts into acetic acid. The impact of these interactions on the production of secondary metabolites, such as gluconic acid, ketones, aldehydes, and esters, which contribute to the vinegar’s unique sensory profile, is thoroughly examined. Advanced analytical techniques, including GC-MS and e-nose technology, alongside sensory evaluation, are employed to assess these effects. The research underscores the significance of ethanol tolerance in AAB and other production challenges in determining vinegar quality and underscores the importance of optimizing fermentation conditions and sustainable practices. The findings of this study underscore the importance of strain interactions and production techniques, which can significantly enhance the quality and market appeal of Port wine vinegar, providing valuable insights for the industry. This review also identifies exciting and critical areas for future research, inspiring further exploration and proposing strategies for advancing production and application in culinary, health, and industrial contexts.

Acetic acid bacteria (AAB) are major contributors to the production of fermented vinegar, offering various cultural, culinary, and health benefits. Although the residual unpasteurized AAB after vinegar production are not pathogens, these are necessary and require safety evaluations, including antibiotic resistance, before use as a starter. In this research, we investigated the antibiotic resistance profiles of 26 AAB strains, including various species of Komagataeibacter and Acetobacter, against 10 different antibiotics using the E-test method. All strains exhibited resistance to aztreonam and clindamycin. Komagataeibacter species demonstrated a 50% resistance rate to ciprofloxacin, analogous to Acetobacter species, but showed twice the resistance rates to chloramphenicol and erythromycin. Genomic analysis of K. saccharivorans CV1 identified intrinsic resistance mechanisms, such as multidrug efflux pumps, thereby enhancing our understanding of antibiotic resistance in acetic acid-producing bacteria. These findings enhance understanding of antibiotic resistance in AAB for food safety and new antimicrobial strategies, suggesting the need for standardized testing methods and molecular genetic study.

This study focuses on optimizing the medium composition for cellular biomass production and bioconversion of ethylene glycol (EG) to glycolic acid (GA) using Gluconobacter oxydans CCT 0552. The improvement in cellular growth in the presence of yeast extract and peptone led to a 35.7% and 32.7% increase, respectively, compared to the medium with each of these carbon sources separately. Negligible growth was produced when (NH4)2SO4 and urea were used. Optimal bioconversion results were very similar for both the stirred tank and bubble column bioreactors, with GA concentrations reaching 49.4 g/L and 47.7 g/L, volumetric productivities of 0.35 g/L∙h and 0.33 g/L∙h, and product yield factors of 1.08 g/g and 0.94 g/g, respectively. An extended fed-batch strategy using a STR-type bioreactor achieved a concentration of glycolic acid of 94.2 g/L, corresponding to a volumetric productivity of 0.41 g/L∙h and a yield factor of 1.19 g/g. The resulting efficiency of this biological transformation process achieved a remarkable value of 97.3%, simultaneously with a significant decrease in the substrate amount by 90.5%. This study demonstrates the efficiency of G. oxydans in producing GA, offering a cost-effective and environmentally sustainable production method.

Co-culture of yeast and acetic acid bacteria (AAB) is consortium which be useful on food and beverage fermentation. The various fermented beverages; alcoholic and non-alcoholic drinks, are obtained by these microbial communities and their interactions. The activities of co-culture of yeasts and acetic acid bacteria during pineapple juice fermentation, including the growth of starters, physicochemical and key compounds changes during pineapple juice fermentation were investigated. The specific characteristics of initial pineapple juice was appropriate for using as a raw material for single and dual yeast and AAB fermentation with no chaptalization. The adding of AAB could encourage the growth and ethanol production of allochthonous and autochthonous yeasts during pineapple juice fermentation, concurrently, the growth of AAB slowly decreased throughout the fermentation. In order to better understand the relationship between yeast and AAB during pineapple juice fermentation. The influence of pineapple juice properties on the growth of AAB during pineapple fermentation was further investigated.

Acetic acid bacteria (AAB) are ubiquitous wine spoilage microorganisms causing significant economic damage to winemakers. Considering difficulties in their isolation through traditional microbiological methods, it would be advantageous to detect them using molecular methods at all stages of winemaking and, thus, prevent wine spoilage. In this research, we analyzed wines, musts and grapes of 13 varieties grown in different regions of the Republic of Moldova. The DNA was extracted and analyzed via PCR using home-designed primers to detect Acetobacter aceti and Acetobacter pasteurianus. Generally, samples with no detectable amounts of AAB in either musts or wine had volatile acidity within the acceptable limits. Only one grape (Rara Neagra) had detectable amounts of AAB (A. pasteurianus) at all analyzed stages (grape, must, wine), and this sample had the highest amount of volatile acidity (2.11 g/L), exceeding the maximum acceptable limit for red wines of 1.2 g/L. A. pasteurianus was more common than A. aceti, both in musts and wines. Samples positive for AAB but containing low amounts of them in wine (Cq value > 35) did not have volatile acidity above the acceptable level. Samples that were wine-negative but must-positive for AAB had volatile acidity close to the acceptable limit. This study shows the utility of PCR diagnostics for predicting the risks of wine spoilage by AAB. [ABSTRACT FROM AUTHOR]

Background: This study aimed to evaluate microbial counts of beverage samples fermented using kombucha, including total acetic acid bacteria (AAB), total lactic acid bacteria (LAB), yeasts, and total microbial count (TMC). Methods: A fermented orange beverage was produced using yogurt whey at three different concentrations (0 %, 10 %, and 20 % v/v) and kombucha at four different concentrations (1 %, 2 %, 3 %, and 4 % w/v) as the starter culture. Next, the microbial counts of the produced samples were evaluated at the end of the incubation and during cold storage at 4 °C. The results were expressed as log CFU/mL. Results: The results indicated a significant increase in the viability of AAB, TMC, and yeasts with increasing yogurt whey concentrations in the samples (p < 0.05). Furthermore, increasing the kombucha percentage in beverage samples resulted in the viability increment of TMC, AAB, LAB, and yeasts. Over time, the number of yeasts and viability of LAB increased in the samples. Moreover, the viability of TMC and AAB increased in the samples from days 7 to 10 and decreased from days 10 to 14 (p < 0.05). Conclusion: Increasing yogurt whey and kombucha percentages affect microbial counts of beverage samples fermented using kombucha. [ABSTRACT FROM AUTHOR]

Fine-aroma cocoa (Theobroma cacao) is one of Ecuador's most iconic export products and comprises 63% of world production. Nevertheless, few advances have been made to improve fermentation processes that might benefit the development of chocolate's organoleptic characteristics. The study of starter cultures, which seek to improve organoleptic properties or decrease fermentation time, has been investigated in other countries. The aim of this study was to analyze the effect of a native microbial cocktail based on two yeasts (Torulaspora delbrueckii and Hanseniaspora uvarum), a lactic acid bacterium (LAB) (Limosilactobacillus plantarum), and an acetic acid bacterium (AAB) (Acetobacter ghanensis) inoculated at the beginning of the fermentative process while tracking physical and biochemical variables, microbial population dynamics, and bean fermentation time. The starter culture caused changes in sugar and acid content and increased polyphenols, which in turn generated temperature and pH changes in the dough. The dynamics of yeast, AAB, and mesophilic microorganisms remain higher than the controls throughout the process. A decrease in filamentous fungi that affect the flavor and quality of beans was observed due to the production of acetic acid or secondary metabolites from yeasts and LAB, and resulted in 24% greater fermentation than spontaneous fermentation in only 96 h. [ABSTRACT FROM AUTHOR]

In this study, microbiological analyses were performed on 41 samples of homemade vinegar to obtain information on the microbiota that might play a role in its fermentation. For this aim total aerobic mesophilic bacteria, yeasts and moulds, enterococci, coliform bacteria, probable acetic acid bacteria counts, pH and titratable acidity were investigated. Ninety-eight bacterial isolates were obtained from glucose-yeast-extract-calcium carbonate (GYC) medium. The isolates were classified using repetitive-element polymerase chain reaction (rep-PCR) technique with GTG5 primer. Identification of the isolates was performed by partial 16S rDNA sequencing. Bacillus, Brevibacillus parabrevis, Acetobacter okinawensis, Paenibacillus, Lactobacillus casei, Acetobacter pasteurianus and Acinetobacter johnsonii were found in the microbiota of vinegar samples. Low acidity of the product and the composition of the microbiota suggested that the production of vinegar at home was often not successful and the product obtained was actually not vinegar. [ABSTRACT FROM AUTHOR]

Vinegar is one of the most appreciated fermented foods in European and Asian countries. In industry, its elaboration depends on numerous factors, including the nature of starter culture and raw material, as well as the production system and operational conditions. Furthermore, vinegar is obtained by the action of acetic acid bacteria (AAB) on an alcoholic medium in which ethanol is transformed into acetic acid. Besides the highlighted oxidative metabolism of AAB, their versatility and metabolic adaptability make them a taxonomic group with several biotechnological uses. Due to new and rapid advances in this field, this review attempts to approach the current state of knowledge by firstly discussing fundamental aspects related to industrial vinegar production and then exploring aspects related to AAB: classification, metabolism, and applications. Emphasis has been placed on an exhaustive taxonomic review considering the progressive increase in the number of new AAB species and genera, especially those with recognized biotechnological potential. [ABSTRACT FROM AUTHOR]

Fermentation of pumpkin puree and mature coconut water using water kefir grains is a potential method for producing a novel functional non-dairy-based probiotic drink. In the present study, response surface methodology based on Box–Behnken design (RSM-BBD) was used to optimise fermentation temperature and substrates’ concentrations. The optimised fermentation temperature, pumpkin puree, and brown sugar concentrations of pumpkin-based mature coconut water kefir beverage (PWKC) were 27 °C, 20%, and 10% w/v, respectively. The optimised PWKC (PWKCopt) obtained an overall acceptability (OA) score of 4.03, with a desirable Lactobacillus count (6.41 Log CFU/mL), 0.68% v/v lactic acid content, 31% of water kefir grains’ biomass growth rate, and fermentation time (to reach pH 4.5) of 4.5 h. The optimized beverage, PWKCopt, contained 3.26% proteins, 2.75% dietary fibre, 2186.33 mg/L of potassium, 180.67 mg/L phosphorus, and 137.33 mg/L calcium and had a total phenolic content of 89.93 mg GAE/100 mL, flavonoid content of 49.94 mg QE/100 mL, and carotenoid content of 33.24 mg/100 mL, with antioxidant activity (FRAP: 169.17 mM Fe(II)/100 mL, IC50 value of DPPH free radicals scavenging activity: 27.17 mg/mL). Water kefir microorganisms in PWKCopt remained stable for at least 56 days at 4 °C. Therefore, PWKCopt might potentially serve as a value-added product, offering a basis for sustainable development within both the coconut and pumpkin industries.

Acetic acid bacteria (AAB) and other members of the complex microbiotas, whose activity is essential for vinegar production, display biodiversity and richness that is difficult to study in depth due to their highly selective culture conditions. In recent years, liquid chromatography coupled with tandem mass spectrometry (LC–MS/MS) has emerged as a powerful tool for rapidly identifying thousands of proteins present in microbial communities, offering broader precision and coverage. In this work, a novel method based on LC–MS/MS was established and developed from previous studies. This methodology was tested in three studies, enabling the characterization of three submerged acetification profiles using innovative raw materials (synthetic alcohol medium, fine wine, and craft beer) while working in a semicontinuous mode. The biodiversity of existing microorganisms was clarified, and both the predominant taxa (Komagataeibacter, Acetobacter, Gluconacetobacter, and Gluconobacter) and others never detected in these media (Asaia and Bombella, among others) were identified. The key functions and adaptive metabolic strategies were determined using comparative studies, mainly those related to cellular material biosynthesis, energy-associated pathways, and cellular detoxification processes. This study provides the groundwork for a highly reliable and reproducible method for the characterization of microbial profiles in the vinegar industry.

This review critically examines the multifaceted role of acetic acid bacteria (AAB) in the intricate production process of port wine vinegar, particularly in its transformative process from port wine. With the emergence of port wine vinegar as a distinctive agricultural product in 2018, producers have been faced with a diverse array of challenges, ranging from reducing the high alcohol content to preserving the inherent sweetness. Through an exhaustive exploration of acetic fermentation processes and the indispensable role of AAB, this review meticulously elucidates the complex biochemistry underlying vinegar formation, delving into the nuanced interactions between microbial activity and chemical composition. Furthermore, this review underscores the importance of sensory characteristics and consumer perception derived from vinegar production, providing invaluable insights into these fermented products’ sensory profiles and marketability. In summary, this study offers valuable insights into the evolution of port wine into vinegar, highlighting its significance in agricultural and culinary contexts.