Industrial Vinegar Production Research Articles

Recent advances in applying omic technologies for studying acetic acid bacteria in industrial vinegar production: A comprehensive review.

Vinegar and related bioproducts containing acetic acid as the main component are among the most appreciated fermented foodstuffs in numerous European and Asian countries because of their exceptional organoleptic and bio-healthy properties. Regarding the acetification process and obtaining of final products, there is still a lack of knowledge on fundamental aspects, especially those related to the study of biodiversity and metabolism of the present microbiota. In this context, omic technologies currently allow for the massive analysis of macromolecules and metabolites for the identification and characterization of these microorganisms working in their natural media without the need for isolation. This review approaches comprehensive research on the application of omic tools for the identification of vinegar microbiota, mainly acetic acid bacteria, with subsequent emphasis on the study of the microbial diversity, behavior, and key molecular strategies used by the predominant groups throughout acetification. The current omics tools are enabling both the finding of new vinegar microbiota members and exploring underlying strategies during the elaboration process. The species Komagataeibacter europaeus may be a model organism for present and future research in this industry; moreover, the development of integrated meta-omic analysis may facilitate the achievement of numerous of the proposed milestones. This work might provide useful guidance for the vinegar industry establishing the first steps towards the improvement of the acetification conditions and the development of new products with sensory and bio-healthy profiles adapted to the agri-food market.

Latest Trends in Industrial Vinegar Production and the Role of Acetic Acid Bacteria: Classification, Metabolism, and Applications-A Comprehensive Review.

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.

Bacterial microbiota and metabolic characteristics of traditional Zhangjiajie Jiuqu aromatic ester vinegar in China

Aged vinegars are popular acidic condiments worldwide, used for their flavour and nutritional value; they also have a rich microbial diversity. This study combined the ultra-performance liquid chromatography-quadrupole-time of flight mass spectrometry (UPLC-Q-TOF-MS) technology with Pacific Biosciences (PacBio) single-molecule real-time (SMRT) sequencing to analyze the microbial population and associated metabolism in six traditional Zhangjiajie Jiuqu aromatic ester vinegars (JAEVs) in China. A total of 265 species and subspecies from 170 bacterial genera and 14 phyla were identified; among these Lactococcus lactis (18.23%) and Acinetobacter johnsonii (17.18%) were the predominant species. A total of 1352 metabolites were detected in the metabolomes of all samples. In addition, occurrence of 40 metabolites detected were significantly different among six samples. Based on correlation analyses between the prevalent bacterial species and main differentially recorded metabolites, we conclude that there were significant correlations (P < 0.05) between 20 metabolites and five bacterial species. Limosilactobacillus fermentum and Hyphomicrobium zavarzinii were the main regulatory strains caused differential metabolites. Some potential functional metabolites were also identified, mainly chlorogenic acid and trans-piceid. This study revealed the relationship between the unique flavour of JAEVs and the microbial community, and provided a basis for industrial production of traditional aged vinegar.

Unraveling the Role of Acetic Acid Bacteria Comparing Two Acetification Profiles From Natural Raw Materials: A Quantitative Approach in Komagataeibacter europaeus.

The industrial production of vinegar is carried out by the activity of a complex microbiota of acetic acid bacteria (AAB) working, mainly, within bioreactors providing a quite specific and hard environment. The “omics” sciences can facilitate the identification and characterization analyses of these microbial communities, most of which are difficult to cultivate by traditional methods, outside their natural medium. In this work, two acetification profiles coming from the same AAB starter culture but using two natural raw materials of different alcoholic origins (fine wine and craft beer), were characterized and compared and the emphasis of this study is the effect of these raw materials. For this purpose, the composition and natural behavior of the microbiota present throughout these profiles were analyzed by metaproteomics focusing, mainly, on the quantitative protein profile of Komagataeibacter europaeus. This species provided a protein fraction significantly higher (73.5%) than the others. A submerged culture system and semi-continuous operating mode were employed for the acetification profiles and liquid chromatography with tandem mass spectrometry (LC-MS/MS) for the protein analyses. The results showed that neither of two raw materials barely modified the microbiota composition of the profiles, however, they had an effect on the protein expression changes in different biological process. A molecular strategy in which K. europaeus would prevail over other species by taking advantage of the different features offered by each raw material has been suggested. First, by assimilating the excess of inner acetic acid through the TCA cycle and supplying biosynthetic precursors to replenish the cellular material losses; second, by a previous assimilation of the excess of available glucose, mainly in the beer medium, through the glycolysis and the pentose phosphate pathway (PPP); and third, by triggering membrane mechanisms dependent on proton motive force to detoxify the cell at the final moments of acetification. This study could complement the current knowledge of these bacteria as well as to expand the use of diverse raw materials and optimize operating conditions to obtain quality vinegars.Clinical Trial Registration:[www.ClinicalTrials.gov], identifier [PXD031147].

Acetobacter senegalensis isolated from mango fruits: Its polyphasic characterization and adaptation to protect against stressors in the industrial production of vinegar: A review.

It has been more than a decade since Acetobacter senegalensis was isolated, identified and described as a thermotolerant strain of acetic acid bacteria. It was isolated from mango fruits in Senegal and used for industrial vinegar production in developing countries, mainly in sub-Saharan Africa. The strain was tested during several spirit vinegar fermentation processes at relatively high temperatures in accordance with African acclimation. The upstream fermentation process had significant stress factors, which are highlighted in this review so that the fermentation process can be better controlled. Due to its high industrial potential, this strain was extensively investigated by diverse industrial microbiologists worldwide; they concentrated on its microbiological, physiological and genomic features. A research group based in Belgium proposed an important project for the investigation of the whole-genome sequence of A. senegalensis. It would use a 454-pyrosequencing technique to determine and corroborate features that could give this strain significant diverse bio-industrial applications. For instance, its application in cocoa bean fermentation has made it a more suitable acetic acid bacterium for the making of chocolate than Acetobacter pasteurianus. Therefore, in this paper, we present a review that summarizes the current research on A. senegalensis at its microbial and genomic levels and also its specific bio-industrial applications, which can provide economic opportunities for African agribusiness. This review summarizes the physiological and genomic characteristics of Acetobacter senegalensis, a thermotolerant strain isolated from mango fruits and intended to be used in industrial vinegar fermentation processes. It also explores other bio-industrial applications such as cocoa fermentation. Vinegar fermentation is usually performed with mesophilic strains in temperate regions of the world. Developing countries, such as Senegal, import vinegar or make 'fake' vinegar by diluting acetic acid obtained from petrochemicals. The use of a thermotolerant Acetobacter senegalensis strain as a solid functional starter culture, as well as the design of a new adapted bioreactor, has significantly contributed to food security and the creation of small- to medium-sized enterprises that produce mango vinegar in West Africa.

Transcriptome Analysis of Komagataeibacter europaeus CGMCC 20445 Responses to Different Acidity Levels During Acetic Acid Fermentation.

In the industrial production of high-acidity vinegar, the initial ethanol and acetic acid concentrations are limiting factors that will affect acetic acid fermentation. In this study, Komagataeibacter europaeus CGMCC 20445 was used for acetic acid shake flask fermentation at an initial ethanol concentration of 4.3% (v/v). We conducted transcriptome analysis of K. europaeus CGMCC 20445 samples under different acidity conditions to elucidate the changes in differentially expressed genes throughout the fermentation process. We also analyzed the expression of genes associated with acid-resistance mechanisms. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis showed that the differentially expressed genes were enriched in ribosomes, citrate cycle, butanoate metabolism, oxidative phosphorylation, pentose phosphate, and the fatty acid biosynthetic pathways. In addition, this study found that K. europaeus CGMCC 20445 regulates the gene expression levels of cell envelope proteins and stress-responsive proteins to adapt to the gradual increase in acidity during acetic acid fermentation. This study improved the understanding of the acid resistance mechanism of K. europaeus and provided relevant reference information for the further genetic engineering of this bacterium.

Analysis of alcohol dehydrogenase activity and fermentation characteristics of Acetobacter pasteurianus JST-S strain

Alcohol dehydrogenase activity (ADH), acetic acid yield, and tolerance to temperature and acid-induced stress are important bacterial strain parameters for the industrial production of acetic acid or vinegar. In this study, we evaluated and compared multiple features between A. pasteurianus JST-S strain, screened in the laboratory, and A. pasteurianus CICC 20001, a commonly used industrial strain. The ADH enzyme activity peaked at 8.22 U mg−1 for JST-S compared with the 7.62 U mg−1 for CICC 20001. Further, the ADH protein level was higher in JST-S than in the CICC 20001 strain. Comparative analysis of growth and cell morphology of the two strains indicated that the acetic acid tolerance of JST-S is superior to that of CICC 20001. Further, when the two strains were used for semi-continuous fermentation in 4 batches, the total acid production in fermentation broth with the JST-S peaked at 62.96 ± 1.42 g L−1 compared with 56.83 ± 1.12 g L−1 for the CICC 20001 strain. Thus, the JST-S strain seems to have better fermentation characteristics than the commonly used industrial strain. Based on all our observations, we propose that A. pasteurianus JST-S may be applied for cost-effective industrial production to obtain a high concentration of acetic acid.

Metaproteomics of microbiota involved in submerged culture production of alcohol wine vinegar: A first approach

Acetic acid bacteria form a complex microbiota that plays a fundamental role in the industrial production of vinegar through the incomplete oxidation reaction from ethanol to acetic acid. The organoleptic properties and the quality of vinegar are influenced by many factors, especially by the raw material used as acetification substrate, the microbial diversity and the technical methods employed in its production. The metaproteomics has been considered, among the new methods employed for the investigation of microbial communities, since it may provide information about the microbial biodiversity and behaviour by means of a protein content analysis. In this work, alcohol wine vinegar was produced through a submerged culture of acetic acid bacteria using a pilot acetator, operated in a semi-continuous mode, where the main system variables were monitored and the cycle profile throughout the acetification was obtained. Through a first approach, at qualitative level, of a metaproteomic analysis performed at relevant moments of the acetification cycle (end of fast and discontinuous loading phases and just prior to unloading phase), it is aimed to investigate the microbiota existent in alcohol wine vinegar as well as its changes during the cycle; to our knowledge, this is the first metaproteomics report carried out in this way on this system. A total of 1723 proteins from 30 different genera were identified; 1615 out of 1723 proteins (93.73%) belonged to the four most frequent (%) genera: Acetobacter, Gluconacetobacter, Gluconobacter and Komagataeibacter. Around 80% of identified proteins belonged to the species Komagataeibacter europaeus. In addition, GO Term enrichment analysis highlighted the important role of catalytic activity, organic cyclic compound binding, metabolic and biosynthesis processes throughout acetic acid fermentation. These findings provide the first step to obtain an AAB profile at omics level related to the environmental changes produced during the typical semi-continuous cycles used in this process and it would contribute to the optimization of operating conditions and improving the industrial production of vinegar.

DISEÑO DE UN BIORREACTOR PARA LA PRODUCCIÓN INDUSTRIAL DE VINAGRE DE MANZANA

El ácido acético tiene una gran importancia ya que se utiliza como aromatizante en ensaladas y otros alimentos, y debido a su acidez, también se emplea en la elaboración de encurtidos, por esta razón la presente investigación tiene como objetivo el diseño de un biorreactor para la producción industrial de vinagre de manzana, teniendo en cuenta las diversas variables que se puedan presentar, lo cual garantiza un mayor rendimiento de producción. El método empleado para el proceso de fermentación acética es el método Orleans, para poder así determinar los coeficientes de la ecuación de cultivo celular, los coeficientes de rendimientos del proceso, balance de materia y energía del proceso, y de esta forma desarrollar los cálculos para un diseño del biorreactor. Los resultados obtenidos fueron un YP/Smax=1,95 y un YB/Smax=5,342 con un diseño de biorreactor con 0,14 m3 y con una altura de 1 m, con lo que se pudo llegar a concluir que las bacterias transformaron el 60% del sustrato alcohólico, lo cual es referente para generar una propuesta del diseño de un biorreactor a escala industrial. Palabras clave: biorreactor, vinagre, fermentación, ácido acético.

Mycofactocin Is Associated with Ethanol Metabolism in Mycobacteria.

Mycofactocin (MFT) belongs to the class of ribosomally synthesized and posttranslationally modified peptides conserved in many ActinobacteriaMycobacterium tuberculosis assimilates cholesterol during chronic infection, and its in vitro growth in the presence of cholesterol requires most of the MFT biosynthesis genes (mftA, mftB, mftC, mftD, mftE, and mftF), although the reasons for this requirement remain unclear. To identify the function of MFT, we characterized MFT biosynthesis mutants constructed in Mycobacterium smegmatis, M. marinum, and M. tuberculosis We found that the growth deficit of mft deletion mutants in medium containing cholesterol-a phenotypic basis for gene essentiality prediction-depends on ethanol, a solvent used to solubilize cholesterol. Furthermore, functionality of MFT was strictly required for growth of free-living mycobacteria in ethanol and other primary alcohols. Among other genes encoding predicted MFT-associated dehydrogenases, MSMEG_6242 was indispensable for M. smegmatis ethanol assimilation, suggesting that it is a candidate catalytic interactor with MFT. Despite being a poor growth substrate, ethanol treatment resulted in a reductive cellular state with NADH accumulation in M. tuberculosis During ethanol treatment, mftC mutant expressed the transcriptional signatures that are characteristic of respirational dysfunction and a redox-imbalanced cellular state. Counterintuitively, there were no differences in cellular bioenergetics and redox parameters in mftC mutant cells treated with ethanol. Therefore, further understanding of the function of MFT in ethanol metabolism is required to identify the cause of growth retardation of MFT mutants in cholesterol. Nevertheless, our results establish the physiological role of MFT and also provide new insights into the specific functions of MFT homologs in other actinobacterial systems.IMPORTANCE Tuberculosis is caused by Mycobacterium tuberculosis, and the increasing emergence of multidrug-resistant strains renders current treatment options ineffective. Although new antimycobacterial drugs are urgently required, their successful development often relies on complete understanding of the metabolic pathways-e.g., cholesterol assimilation-that are critical for persistence and for pathogenesis of M. tuberculosis In this regard, mycofactocin (MFT) function appears to be important because its biosynthesis genes are predicted to be essential for M. tuberculosisin vitro growth in cholesterol. In determining the metabolic basis of this genetic requirement, our results unexpectedly revealed the essential function of MFT in ethanol metabolism. The metabolic dysfunction thereof was found to affect the mycobacterial growth in cholesterol which is solubilized by ethanol. This knowledge is fundamental in recognizing the bona fide function of MFT, which likely resembles the pyrroloquinoline quinone-dependent ethanol oxidation in acetic acid bacteria exploited for industrial production of vinegar.

Production of vinegar from purple sweet potato in a liquid fermentation process and investigation of its antioxidant activity.

Acetobacter pasteurianus JST-S was screened from solid fermented grains of vinegar in China, identified by molecular analysis, and used for the production of purple sweet potato vinegar using purple sweet potato as the substrate. By orthogonal experiment, maximum total acid concentration (4.26% [v/v]) was achieved under optimized conditions as follows: fermentation time, 3.5days; ethanol content, 9% v/v; and inoculum size, 8% v/v. During the production of purple potato vinegar, the anthocyanin concentration decreased from 652.07 to 301.73μg/mL. The antioxidant activity of products, including diphenyl-picryl hydrazide radical-scavenging capacity (above 60%), reducing power (above 0.47), and hydroxyl radical-scavenging capacity (above 46%), showed positive linear regression (P<0.01), which could be related with the changes in anthocyanin concentration and antioxidant activities at different stages of vinegar fermentation. The acetic acid and other non-phenolic antioxidants in purple sweet potato vinegar may have contributed to the antioxidant activities. Results of these studies may provide a reference for the industrial production of vinegar by liquid fermentation of purple sweet potato.

Feasible acetic acid fermentations of alcoholic and sugary substrates in combined operation mode

Starting from small-scale batch cultivations, acetic acid fermentations in static and submerged systems have been performed by a single acetic acid bacterial strain. To provide user-friendly selected starter cultures for industry, the versatility of these cultures in using different oxidation substrates under different conditions was assessed. In all cases, vinegars with the desired acetic acid, residual ethanol and reducing sugar contents were obtained.An appropriate small-scale batch cultivation subjected to strict process control was pivotal for obtaining the desired acetic acid concentrations and an active culture for submerged fermentation. This achievement enabled the generation of selected starter cultures for submerged vinegar production, which reached an acetic acid content of 8.00–9.00% (w/v), as well as prototype-scale vinegar production. The production of vinegars with reducing sugars in the range of 15.00–27.00 (% w/v) was achieved, and cellulose production was avoided. The dominance of the microbial culture in this process was shown via (GTG)5-PCR. These results are valuable for introducing the use of selected acetic acid bacteria cultures in industrial vinegar production.

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.

16S rRNA in situ Hybridization Followed by Flow Cytometry for Rapid Identification of Acetic Acid Bacteria Involved in Submerged Industrial Vinegar Production.

Acetic acid bacteria are involved in many biotechnological processes such as vitamin C, gluconic acid, miglitol or acetic acid production, and others. For a technologist trying to control the industrial process, the ability to follow the microbiological development of the process is thus of importance. During the past few years hybridization in a combination with flow cytometry has often been used for this purpose. Since vinegar is a liquid, it is an ideal matrix for flow cytometry analysis. In this work we have constructed a specific probe for highly acetic acid-resistant species of the acetic acid bacteria and a protocol for in situ hybridization, which in combination with flow cytometry enables direct monitoring of bacteria producing vinegar with >10% of acetic acid. The approach was successfully applied for monitoring microbiota during industrial vinegar production.

Comparative Proteome of Acetobacter pasteurianus Ab3 During the High Acidity Rice Vinegar Fermentation.

As a traditional Asian food for several centuries, vinegar is known to be produced by acetic acid bacteria. The Acetobacter species is the primary starter for vinegar fermentation and has evolutionarily acquired acetic acid resistance, in which Acetobacter pasteurianus Ab3 is routinely used for industrial production of rice vinegar with a high acidity (9%, w/v). In contrast to the documented short-term and low acetic acid effects on A. pasteurianus, here we investigated the molecular and cellular signatures of long-term and high acetic acid responses by proteomic profiling with bidimensional gel electrophoresis and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI TOF/MS) analyses. Protein spots of interest were selected based on the threshold ANOVA p value of 0.05 and minimal twofold of differential expression, leading to the identification of 26 proteins that are functionally enriched in oxidoreductase activity, cell membrane, and metabolism. The alterations in protein functioning in respiratory chain and protein denaturation may underlay cellular modifications at the outer membrane. Significantly, we found that at higher acidity fermentation phase, the A. pasteurianus Ab3 cells would adapt to distinct physiological processes from that of an ordinary vinegar fermentation with intermediate acidity, indicating increasing energy requirement and dependency of membrane integrity during the transition of acetic acid production. Together, our study provided new insights into the adaptation mechanisms in A. pasteurianus to high acetic acid environments and yield novel regulators and key pathways during the development of acetic acid resistance.

Isolation, identification and fermentation conditions of highly acetoin-producing acetic acid bacterium from Liangzhou fumigated vinegar in China

Liangzhou fumigated vinegar is famous in China for its distinct flavor. How to enhance flavor in traditional fermented foods, such as vinegar, has attracted a large interest in recent years. Acetoin (ACT) is a precursor of tetramethylpyrazine (TTMP), a popular food flavor found in different traditional fermented foods. We obtained 200 acid-producing isolates from the solid fermentative substrate of Liangzhou fumigated vinegar by the method of forming transparent zones on GYC agar, and 28 bacteria producing ACT by Voges–Proskauer colorimetric assay and gas chromatography analysis, including 15 strains of Acetobacter, eight strains of Lactobacillus and five strains of Staphylococcus. Based on ACT level, the isolate C92 with the highest yield was selected for further analysis. It was identified as Acetobacter pasteurianus by physiological and biochemical characteristics, as well as 16S rRNA gene sequence similarities. We examined the ACT level of strain C92 under different conditions, and found that a temperature of 31.31 °C, pH of 6.67, shaking speed of 209 rpm, and inoculation volume of 8.27 % were the best conditions for strain C92 to produce a yield of 19.04 g/L at 40 h post-culture. In a time–ACT curve, ACT reached the maximum value at 40 h and then decreased afterward, suggesting that ACT produced by C92 is a growth-associated primary metabolite from sugar. Therefore, the C92 isolate is regarded as a strain with promising ACT-production ability in vinegar. More studies are needed before C92 is applied in the industrial production of vinegar.

Banana Vinegars Production Using Thermotolerant Acetobacter pasteurianus Isolated From Ivorian Palm Wine

&lt;p&gt;Vinegar or sour wine is a product of alcoholic and subsequent acetous fermentation of sugary precursors. Among acetic acid producing bacteria, only few genera (&lt;em&gt;Acetobacter and Gluconobacter&lt;/em&gt;) are used in vinegar industry. In this paper, we intended to produce vinegar at 37 °C using two &lt;em&gt;Acetobacter&lt;/em&gt; &lt;em&gt;pasteurianus&lt;/em&gt; strains (S3 and S32). These species were isolated from palm (&lt;em&gt;Elaeis guineensis&lt;/em&gt;) wine and presented potentialities for industrial vinegar production at 37 °C. Successive fermentations were carried up and semi-continuous acetous fermentation was performed to increase acid production. Concentrated bananas (&lt;em&gt;Musa ssp.&lt;/em&gt;) juice (11°Brix) was fermented using &lt;em&gt;Saccharomyces cerevisae&lt;/em&gt; within 7 days, yielding 6.4% alcohol. After fermentation, 60 and 58 g/L acetic acid were produced in vinegars obtained using S3 and S32 stains respectively in 34 days and 5 flow cycles. Malic and acetic acids were the most substantial acids produced in alcoholic juice with 5 631.473 and 2 833.055 mg/L respectively. Among the eight organic acids responsible for vinegars total acidity, acetic acid was major compound with 23 459.416 and 21 268.407 mg/L for S3 and S32 strains respectively. Alcohol and acetic acid fermentation efficiency were 90.9% and 85.39 - 87.63% respectively. All the results above showed that S3 and S32 strains revealed great potentialities for successful industrial vinegar production from overripe banana.&lt;/p&gt;

Plasmid analysis of high acetic acid-resistant bacterial strains by two-dimensional agarose gel electrophoresis and insights into the phenotype of plasmid pJK2-1

Plasmid profiling can be used for quick molecular characterization of bacteria. In the study reported here, this method was used to compare the plasmid profiles of strains of Gluconacetobacter europaeus, one of the dominant species in industrial vinegar production. Further analysis of three selected strains by two-dimensional agarose gel electrophoresis showed that the plasmid profiles are composed of different forms of plasmids of the same size. One of these plasmids, pJK2-1, was introduced into Gluconacetobacter oboediens JK3 as a chimeric plasmid (pJT2) with pUC18. The recombinant strain showed a shorter lag phase in a medium with 3 and 5 % (v/v) acetic acid. Deletion of a part of plasmid pJK2-1 allowed a region that contributes to this novel phenotype of G. oboediens JK3 pJT2 to be identified. Non-problematic handling of G. oboediens JK3 warrants further study in elucidating the function of plasmids involved in the production of vinegar.

An Overview on the Biological Production of Vinegar

Vinegar contains about 5% acetic acid in water, varying amounts of fixed fruit acids, colouring matter, salts and a few other fermentation products which impart characteristic flavour and aroma to the product. Vinegar traditionally has been used as a food preservative. Vinegar production methods could range from traditional methods employing wooden casks (Orleans Process) and surface culture (Generator Process) to submerged fermentation. Vinegar is the product made from the conversion of ethyl alcohol to acetic acid by a genus of bacteria Acetobacter. Many technical devices have been developed to improve the industrial production of vinegar. Generally, these improvements increase the speed of the transformation of ethanol into acetic acid in the presence of acetic acid bacteria. In this review a detailed description on vinegar production, methods of production, different substrates and microorganisms used for its production, and the chemistry of vinegar is presented.

Prediction of influence of stepwise increment of initial acetic acid concentration in charging medium on acetification rate of semi-continuous process by artificial neural network

Based on industrial vinegar production, ethanol concentration in charging medium is normally considered as a strong variable influencing the acetification for a given initial acetic acid concentration. Moreover, high initial acetic acid concentration is considered when higher than 100 g L−1 of acetic acid as finished product is obtained. This study assessed the effect of a stepwise increment of initial acetic acid concentration in fermentation medium of 45, 55, and 65 g L−1 after charging at constant ethanol concentration of 35 g L−1 on acetification rate (ETA) by high acid-tolerant strain of Acetobacter aceti WK. Average ETA was 8.144 + 0.09 g L−1 d−1 at 45 g L−1 and 8.655 + 0.09 g L−1 d−1 at 55 g L−1, and significant decreased to 6.819 + 0.23 g L−1 d−1 at 65 g L−1. An artificial neural network (ANN) model was applied to predict the ETA in semi-continuous acetification under the conditions of the study. The optimized ANN structure was revealed to contain two hidden layers and seven neurons per layer. The experimental acetification correlated to the predicted data with R2 of training and testing data set of 0.858 and validation data set of 0.831, respectively. Results indicated that the inputs as acetic acid and ethanol concentrations successfully predicted the ETA of semi-continuous acetification process.