Identification of acetic acid bacteria in traditionally produced vinegar and mother of vinegar by using different molecular techniques

Microbial Characterization of a Zambian Honey Vinegar

Forest Fruits Organic Honey Vinegar (FFOHV) is a spontaneously fermented (yeast) and acetified (Acetic Acid Bacteria-AAB) Miombo Woodland honey vinegar developed in Zambia. Live vinegars containing live microbial cultures are marketed for their probiotic health benefits. The correlation between a well-developed gut microbiome and human health is well studied and fermented products such as live vinegar containing AAB contribute to a healthy gut microbiome. This study details a metagenomic analysis of stable, bottled FFOHV (Zambia) alongside two commercially available live vinegar products: Bragg Organic Apple Cider Vinegar (BOACV) and Nature's Source Apple Cider Vinegar (NSACV). FFOHV contained representatives of five bacterial and nine fungal genera, compared to BOACV with two bacterial and five fungal, and NSACV containing no bacterial and six fungal genera. FFOHV and BOACV showed a dominance of Komagataeibacter bacterial species. The dominant yeast was Vanrija humicola present in all three vinegar samples. FFOHV contained greater diversity of genera, with the notable species Monascus purpureus-a microbe that produces several health-enhancing compounds. The analysis showed that FFOHV is a microbially diverse product containing several potentially health-enhancing microbes. Graphical Abstract Text: This study presents a metagenomic analysis of Forest Fruits Organic Honey Vinegar (FFOHV) from Zambia, compared with two commercial live cider vinegars: Bragg Organic Apple Cider Vinegar (BOACV) and Nature's Source Apple Cider Vinegar (NSACV). FFOHV exhibited a richer microbial diversity, containing five bacterial and nine fungal genera, including the health-promoting species Monascus purpureus. Both FFOHV and BOACV were dominated by Komagataeibacter species, with Vanrija humicola as the prevalent yeast across all samples. This confirmed FFOHV's unique potential probiotic benefits.

A Review on the Interaction of Acetic Acid Bacteria and Microbes in Food Fermentation: A Microbial Ecology Perspective

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.

Microbiome Analysis of Traditional Grain Vinegar Produced under Different Fermentation Conditions in Various Regions in Korea

The fermentation of traditional vinegar is a spontaneous and complex process that involves interactions among various microorganisms. Here, we used a microbiome approach to determine the effects of networks, such as fermentation temperature, location, physicochemical and sensory characteristics, and bacterial profile, within traditional grain vinegar samples collected from various regions of Korea. Acetic acid and lactic acid were identified as the major metabolites of grain vinegar, and sourness and umami were determined as taste fingerprints that could distinguish between vinegar samples. Acetobacter ghanensis and Lactobacillus acetotolerans were the predominant bacterial species, and the functional composition of the microbiota revealed that the nucleotide biosynthesis pathway was the most enriched. These results reveal that vinegar samples fermented outdoors are more similar to each other than vinegar samples fermented at 30 °C, when comparing the distance matrix for comprehending bacterial networks among samples. This study may help obtain high-quality vinegar through optimized fermentation conditions by suggesting differences in sensory characteristics according to the fermentation environment.

Screening and Characterization of New Acetobacter fabarum and Acetobacter pasteurianus Strains with High Ethanol−Thermo Tolerance and the Optimization of Acetic Acid Production

The production of vinegar on an industrial scale from different raw materials is subject to constraints, notably the low tolerance of acetic acid bacteria (AAB) to high temperatures and high ethanol concentrations. In this study, we used 25 samples of different fruits from seven Moroccan biotopes with arid and semi-arid environmental conditions as a basic substrate to isolate thermo- and ethanol-tolerant AAB strains. The isolation and morphological, biochemical and metabolic characterization of these bacteria allowed us to isolate a total number of 400 strains with characters similar to AAB, of which six strains (FAGD1, FAGD10, FAGD18 and GCM2, GCM4, GCM15) were found to be mobile and immobile Gram-negative bacteria with ellipsoidal rod-shaped colonies that clustered in pairs and in isolated chains. These strains are capable of producing acetic acid from ethanol, growing on peptone and oxidizing acetate to CO2 and H2O. Strains FAGD1, FAGD10 and FAGD18 show negative growth on YPG medium containing D-glucose > 30%, while strains GCM2, GCM4 and GCM15 show positive growth. These six strains stand out on CARR indicator medium as isolates of the genus Acetobacter ssp. Analysis of 16S rDNA gene sequencing allowed us to differentiate these strains as Acetobacter fabarum and Acetobacter pasteurianus. The study of the tolerance of these six isolates towards pH showed that most of the six strains are unable to grow at pH 3 and pH 9, with an ideal pH of 5. The behavior of the six strains at different concentrations of ethanol shows an optimal production of acetic acid after incubation at concentrations between 6% and 8% (v/v) of ethanol. All six strains tolerated an ethanol concentration of 16% (v/v). The resistance of the strains to acetic acid differs between the species of AAB. The optimum acetic acid production is obtained at a concentration of 1% (v/v) for the strains of FAGD1, FAGD10 and FAGD18, and 3% (v/v) for GCM2, GCM4 and GCM15. These strains are able to tolerate an acetic acid concentration of up to 6% (v/v). The production kinetics of the six strains show the highest levels of growth and acetic acid production at 30 °C. This rate of growth and acetic acid production is high at 35 °C, 37 °C and 40 °C. Above 40 °C, the production of acid is reduced. All six strains continue to produce acetic acid, even at high temperatures up to 48 °C. These strains can be used in the vinegar production industry to minimize the load on cooling systems, especially in countries with high summer temperatures.

Comparative Metabolite Profiling of Traditional and Commercial Vinegars in Korea

Vinegar, composed of various organic acids, amino acids, and volatile compounds, has been newly recognized as a functional food with health benefits. Vinegar is produced through alcoholic fermentation of various raw materials followed by acetic acid fermentation, and detailed processes greatly vary between different vinegar products. This study performed metabolite profiling of various vinegar products using gas chromatography-mass spectrometry to identify metabolites that are specific to vinegar production processes. In particular, seven traditional vinegars that underwent spontaneous and slow alcoholic and acetic acid fermentations were compared to four commercial vinegars that were produced through fast acetic acid fermentation using distilled ethanol. A total of 102 volatile and 78 nonvolatile compounds were detected, and the principal component analysis of metabolites clearly distinguished between the traditional and commercial vinegars. Ten metabolites were identified as specific or significantly different compounds depending on vinegar production processes, most of which had originated from complex microbial metabolism during traditional vinegar fermentation. These process-specific compounds of vinegars may serve as potential biomarkers for fermentation process controls as well as authenticity and quality evaluation.

Multi fragment melting analysis system (MFMAS) for one-step identification of lactobacilli

The accurate identification of lactobacilli is essential for the effective management of industrial practices associated with lactobacilli strains, such as the production of fermented foods or probiotic supplements. For this reason, in this study, we proposed the Multi Fragment Melting Analysis System (MFMAS)-lactobacilli based on high resolution melting (HRM) analysis of multiple DNA regions that have high interspecies heterogeneity for fast and reliable identification and characterization of lactobacilli. The MFMAS-lactobacilli is a new and customized version of the MFMAS, which was developed by our research group. MFMAS-lactobacilli is a combined system that consists of i) a ready-to-use plate, which is designed for multiple HRM analysis, and ii) a data analysis software, which is used to characterize lactobacilli species via incorporating machine learning techniques. Simultaneous HRM analysis of multiple DNA fragments yields a fingerprint for each tested strain and the identification is performed by comparing the fingerprints of unknown strains with those of known lactobacilli species registered in the MFMAS. In this study, a total of 254 isolates, which were recovered from fermented foods and probiotic supplements, were subjected to MFMAS analysis, and the results were confirmed by a combination of different molecular techniques. All of the analyzed isolates were exactly differentiated and accurately identified by applying the single-step procedure of MFMAS, and it was determined that all of the tested isolates belonged to 18 different lactobacilli species. The individual analysis of each target DNA region provided identification with an accuracy range from 59% to 90% for all tested isolates. However, when each target DNA region was analyzed simultaneously, perfect discrimination and 100% accurate identification were obtained even in closely related species. As a result, it was concluded that MFMAS-lactobacilli is a multi-purpose method that can be used to differentiate, classify, and identify lactobacilli species. Hence, our proposed system could be a potential alternative to overcome the inconsistencies and difficulties of the current methods.

Acetic Acid Fermentation of Soybean Molasses and Characterisation of the Produced Vinegar

Soybean molasses is a by-product from the production of protein concentrate from soybean meal that predominantly contains sugars, with sucrose as the major component. In Brazil, soybean molasses is used for animal feed or it is discarded, although some industries use it to produce ethanol. This study aims to evaluate the parameters required for the acetic acid fermentation of soybean molasses, and characterise the resultant vinegar. To study the most suitable parameters for the acetic acid fermentation, vinegar was produced from the alcohol fermentation of soybean molasses through eight fermentation cycles: five for adaptation and three for production. The average acidity of the acetic acid fermentation product was 50.60 g/L, with an acetic acid fermentation yield, total yield of acetic acid in broth and productivity 65.01%, 92.76% and 0.033 g/(L·h), respectively. The vinegar produced from soybean molasses has an acidity of 5.07% (m/V), residual ethanol content 0.17% (m/V), sugars 7.86% (m/V), dry extract 14.67% (m/V), ash 2.27% (m/V) and a density of 1.023 g/cm³. The contents of total phenolics and isoflavones decreased after the alcohol and acetic acid fermentations. Moreover, the isoflavones profile of the fermented product comprised only three forms: daidzein, glycitin and genistin. According to our results, 3460 L of vinegar can be produced for every tonne of soy molasses, with an acetic acid concentration of 40 g/L, the minimum required by the legislation on vinegar production. Thus, these findings demonstrate that soy molasses represents a useful raw material for the production of vinegar.

Genome Sequence of Komagataeibacter saccharivorans Strain JH1, Isolated from Fruit Flies

We present the genome sequence of Komagataeibacter saccharivorans strain JH1, which belongs to the acetic acid bacteria. The draft genome sequence consists of 3.7 Mb and contains 3,437 predicted protein-encoding genes. This organism contains putative genes involved in cellulose and levan biosynthesis.

We present the genome sequence of Komagataeibacter saccharivorans strain JH1, which belongs to the acetic acid bacteria. The draft genome sequence consists of 3.7 Mb and contains 3,437 predicted protein-encoding genes. This organism contains putative genes involved in cellulose and levan biosynthesis.

Bacterial community dynamics and physicochemical characteristics in natural fermentation of jiang-shui, a traditional food made in northwest China

BACKGROUND

Chinese jiang-shui is fermented food without salt. In consideration of the few studies of the bacterial community and dynamics of jiang-shui fermentation, the aim of this study was to investigate the microbial diversity and dynamics of jiang-shui fermentation using high-throughput sequencing (HTS), denaturing gradient gel electrophoresis (DGGE) and the culture-dependent method.

RESULTS

The culture-dependent method showed that pathogenic bacteria (Staphylococcus aureus, Salmonella and Escherichia coli) and yeast mainly existed in the early stage and lactic acid bacteria dominated until the end stage. HTS and DGGE revealed that Serratia marcescens, Serratia sp., Lactobacillus curvatus, Lactococcus lactis, uncultured bacterium and Bacillus thuringiensis started the fermentation, followed by the middle stage with Lactococcus lactis, Weissella sp. and Bacillus arthracis as the predominant species. The end stage was characterized with Lactobacillus pentosus, Weissella cibaria and Weissella sp. as the major bacteria.

CONCLUSIONS

The results showed that genera Serratia, Lactococcus, Weissella and Lactobacillus dominated the whole process of jiang-shui fermentation. This study provided a good analysis of the bacterial changes of jiang-shui fermentation, and future studies should consider the relationships among the sensory characteristics, microbial communities and metabolites. © 2019 Society of Chemical Industry.

Assessing the efficiency in assisted depuration of coffee processing wastewater from mixed wild microbial selected inoculum

This work evaluated the efficiency of bacterial bio-augmentation to the biological treatment of coffee processing wastewater (CPWW) in a pilot wastewater treatment plant (WTP). Biochemical oxygen demand (BOD) and chemical oxygen demand (COD) values were the basis for the treatment efficiency. Serratia marcescens CCMA 1010 and CCMA 1013, Corynebacterium flavescens CCMA 1006 and Acetobacter indonesiensis CCMA 1002 were previously selected. The microbial cocktail was inoculated and persisted in CPWW during all treatments. The richness of wild species was a little altered over time and up to nine species were found in each sampled season. The microbiota composition presented variation of a total of 13 species, despite the inoculation of the microbial inoculum. The biodegradability index of effluent, close to 0.5, was favourable to biological treatment. The pollution parameters of CPWW were decreased in function of the variation of community composition and microbial activity. The greatest reduction of BOD (~ 33%) and COD (~ 25%) was observed between 72 h and 8 days of the biological treatment. The CPWW toxicity in Allium cepa seeds was lower by up to 60%, and the germination index (GI) exceeded 100% in the treated CPWW. The results of the CPWW biological treatment by bio-augmentation from native micro-organisms in the pilot-scale WTP indicated the greatest efficiency relating to the spontaneous biological treatment of CPWW. After this treatment, the discharge of effluent in the environment would not have toxic effects on the plants.

Characterization and comparative analysis of toxin-antitoxin systems in Acetobacter pasteurianus

Bacterial toxin-antitoxin (TA) systems play important roles in diverse cellular regulatory processes. Here, we characterize three putative type II TA candidates from Acetobacter pasteurianus and investigate the profile of type II TA systems in the genus Acetobacter. Based on the gene structure and activity detection, two-pairs loci were identified as the canonical hicAB and higAB TA systems, respectively, and DB34_01190-DB34_01195 as a putative new one without a canonical TA architecture. Physiologically, the expression of the three pairs conferred E. coli with additional plasmid maintenance and survival when under acetic acid stress. Chromosomal TA systems can be horizontally transferred within an ecological vinegar microbiota by co-option, and there was a tendency for toxin module loss. The antitoxin retention in the genome is suggested to have a broad role in bacterial physiology. Furthermore, A. pasteurianus strains, universally domesticated and used for industrial vinegar fermentation, showed a higher number of type II TA loci compared to the host-associated ones. The amount of TA loci per genome showed little positive relationship to insertion sequences, although its prevalence was species-associated, to the extent of even being strain-associated. The TA system is a candidate of studying the resistant mechanistic network, the TAs-dependent translatome affords a real-time profile to explore stress adaptation of A. pasteurianus, promoting industrial development.

Profiling white wine seed vinegar bacterial diversity through viable counting, metagenomic sequencing and PCR-DGGE

The production of traditional vinegar is usually carried out using the so-called "seed vinegar" or "mother of vinegar" that is composed of an undefined and complex pool of microorganisms deriving from a previous vinegar production. To date, there have been relatively few studies on the microbiota of seed vinegars. The present study was carried out to discover the bacterial biota of seed vinegar samples used in the homemade production of local vinegars obtained from the acetic fermentation of white wine. The seed vinegar samples were subjected to viable counting and advanced molecular analyses, namely, Illumina sequencing and PCR-DGGE. The adopted polyphasic approach allowed the bacterial diversity of the analyzed samples to be profiled, thus revealing the presence of acetic acid bacteria ascribed to the genera Acetobacter, Gluconacetobacter, Gluconobacter and Komagataeibacter. Moreover, other microbial genera as Pseudomonas, Bacillus and Clostridium were abundantly found in almost all the samples, together with other minority genera. The results of viable counting confirmed the well-acknowledged limitations inherent with acetic acid bacteria recovery on plate growth media. The overall results confirmed that seed vinegars have a complex and heterogeneous biodiversity, thus encouraging their exploitation for the isolation and future technological characterization of cultures to be selected for the manufacture of mixed starter cultures.

Acetic Acid Bacteria in the Food Industry: Systematics, Characteristics and Applications

The group of Gram-negative bacteria capable of oxidising ethanol to acetic acid is called acetic acid bacteria (AAB). They are widespread in nature and play an important role in the production of food and beverages, such as vinegar and kombucha. The ability to oxidise ethanol to acetic acid also allows the unwanted growth of AAB in other fermented beverages, such as wine, cider, beer and functional and soft beverages, causing an undesirable sour taste. These bacteria are also used in the production of other metabolic products, for example, gluconic acid, l-sorbose and bacterial cellulose, with potential applications in the food and biomedical industries. The classification of AAB into distinct genera has undergone several modifications over the last years, based on morphological, physiological and genetic characteristics. Therefore, this review focuses on the history of taxonomy, biochemical aspects and methods of isolation, identification and quantification of AAB, mainly related to those with important biotechnological applications.

Diversity of microbiota found in coffee processing wastewater treatment plant

Cultivable microbiota presents in a coffee semi-dry processing wastewater treatment plant (WTP) was identified. Thirty-two operational taxonomic units (OTUs) were detected, these being 16 bacteria, 11 yeasts and 4 filamentous fungi. Bacteria dominated the microbial population (11.61 log CFU mL^- 1), and presented the highest total diversity index when observed in the WTP aerobic stage (Shannon = 1.94 and Simpson = 0.81). The most frequent bacterial species were Enterobacter asburiae, Sphingobacterium griseoflavum, Chryseobacterium bovis, Serratia marcescens, Corynebacterium flavescens, Acetobacter orientalis and Acetobacter indonesiensis; these showed the largest total bacteria populations in the WTP, with approximately 10 log CFU mL^- 1. Yeasts were present at 7 log CFU mL^- 1 of viable cells, with Hanseniaspora uvarum, Wickerhamomyces anomalus, Torulaspora delbrueckii, Saturnispora gosingensis, and Kazachstania gamospora being the prevalent species. Filamentous fungi were found at 6 log CFU mL^- 1, with Fusarium oxysporum the most populous species. The identified species have the potential to act as a biological treatment in the WTP, and the application of them for this purpose must be better studied.

A rapid, ideal, and eco-friendlier protocol for quantifying proline

Proline, a stress marker, is routinely quantified by a protocol that essentially uses hazardous toluene. Negative impacts of toluene on human health prompted us to develop a reliable alternate protocol for proline quantification. Absorbance of the proline-ninhydrin condensation product formed by reaction of proline with ninhydrin at 100 °C in the reaction mixture was significantly higher than that recorded after its transfer to toluene, revealing that toluene lowers sensitivity of this assay. λ _max of the proline-ninhydrin complex in the reaction mixture and toluene were 508 and 513 nm, respectively. Ninhydrin in glacial acetic acid yielded higher quantity of the proline-ninhydrin condensation product compared to ninhydrin in mixture of glacial acetic acid and H₃PO₄, indicating negative impact of H₃PO₄ on proline quantification. Further, maximum yield of the proline-ninhydrin complex with ninhydrin in glacial acetic acid and ninhydrin in mixture of glacial acetic acid and H₃PO₄ was achieved within 30 and 60 min, respectively. This revealed that H₃PO₄ has negative impact on the reaction rate and quantity of the proline-ninhydrin complex formed. In brief, our proline quantification protocol involves reaction of a 1-ml proline sample with 2 ml of 1.25 % ninhydrin in glacial acetic acid at 100 °C for 30 min, followed by recording absorbance of the proline-ninhydrin condensation product in the reaction mixture itself at 508 nm. Amongst proline quantification protocols known till date, our protocol is the most simple, rapid, reliable, cost-effective, and eco-friendlier.

Application of high-resolution melting analysis for differentiation of spoilage yeasts

A new method based on high resolution melting (HRM) analysis was developed for the differentiation and classification of the yeast species that cause food spoilage. A total 134 strains belonging to 21 different yeast species were examined to evaluate the discriminative power of HRM analysis. Two different highly variable DNA regions on the 26 rRNA gene were targeted to produce the HRM profiles of each strain. HRM-based grouping was compared and confirmed by (GTG)5 rep-PCR fingerprinting analysis. All of the yeast species belonging to the genera Pichia, Candida, Kazachstania, Kluyveromyces, Debaryomyces, Dekkera, Saccharomyces, Torulaspora, Ustilago, and Yarrowia, which were produced as species-specific HRM profiles, allowed discrimination at species and/or strain level. The HRM analysis of both target regions provided successful discrimination that correlated with rep-PCR fingerprinting analysis. Consequently, the HRM analysis has the potential for use in the rapid and accurate classification and typing of yeast species isolated from different foods to determine their sources and routes as well as to prevent contamination.

Vinegar Production from Jabuticaba (Myrciaria jaboticaba) Fruit Using Immobilized Acetic Acid Bacteria

Cell immobilization comprises the retention of metabolically active cells inside a polymeric matrix. In this study, the production of jabuticaba (Myrciaria jaboticaba) vinegar using immobilized Acetobacter aceti and Gluconobacter oxydans cells is proposed as a new method to prevent losses of jabuticaba fruit surplus. The pulp of jabuticaba was processed and Saccharomyces cerevisiae CCMA 0200 was used to ferment the must for jabuticaba wine production. Sugars, alcohols (ethanol and glycerol) and organic acids were assayed by high-performance liquid chromatography. Volatile compounds were determined by gas chromatography-flame ionization detector. The ethanol content of the produced jabuticaba wine was approx. 74.8 g/L (9.5% by volume) after 168 h of fermentation. Acetic acid fermentation for vinegar production was performed using a mixed culture of immobilized A. aceti CCT 0190 and G. oxydans CCMA 0350 cells. The acetic acid yield was 74.4% and productivity was 0.29 g/(L·h). The vinegar had particularly high concentrations of citric (6.67 g/L), malic (7.02 g/L) and succinic (5.60 g/L) acids. These organic acids give a suitable taste and flavour to the vinegar. Seventeen compounds (aldehydes, higher alcohols, terpene, acetate, diether, furans, acids, ketones and ethyl esters) were identified in the jabuticaba vinegar. In conclusion, vinegar was successfully produced from jabuticaba fruits using yeast and immobilized mixed cultures of A. aceti and G. oxydans. To the best of our knowledge, this is the first study to use mixed culture of immobilized cells for the production of jabuticaba vinegar.

Comparison of Cultivable Acetic Acid Bacterial Microbiota in Organic and Conventional Apple Cider Vinegar

Organic apple cider vinegar is produced from apples that go through very restricted treatment in orchard. During the first stage of the process, the sugars from apples are fermented by yeasts to cider. The produced ethanol is used as a substrate by acetic acid bacteria in a second separated bioprocess. In both, the organic and conventional apple cider vinegars the ethanol oxidation to acetic acid is initiated by native microbiota that survived alcohol fermentation. We compared the cultivable acetic acid bacterial microbiota in the production of organic and conventional apple cider vinegars from a smoothly running oxidation cycle of a submerged industrial process. In this way we isolated and characterized 96 bacteria from organic and 72 bacteria from conventional apple cider vinegar. Using the restriction analysis of the PCR-amplified 16S-23S rRNA gene ITS regions, we identified four different HaeIII and five different HpaII restriction profiles for bacterial isolates from organic apple cider vinegar. Each type of restriction profile was further analyzed by sequence analysis of the 16S-23S rRNA gene ITS regions, resulting in identification of the following species: Acetobacter pasteurianus (71.90%), Acetobacter ghanensis (12.50%), Komagataeibacter oboediens (9.35%) and Komagataeibacter saccharivorans (6.25%). Using the same analytical approach in conventional apple cider vinegar, we identified only two different HaeIII and two different HpaII restriction profiles of the 16S‒23S rRNA gene ITS regions, which belong to the species Acetobacter pasteurianus (66.70%) and Komagataeibacter oboediens (33.30%). Yeasts that are able to resist 30 g/L of acetic acid were isolated from the acetic acid production phase and further identified by sequence analysis of the ITS1-5.8S rDNA‒ITS2 region as Candida ethanolica, Pichia membranifaciens and Saccharomycodes ludwigii. This study has shown for the first time that the bacterial microbiota for the industrial production of organic apple cider vinegar is clearly more heterogeneous than the bacterial microbiota for the industrial production of conventional apple cider vinegar. Further chemical analysis should reveal if a difference in microbiota composition influences the quality of different types of apple cider vinegar.