Abstract:From the pellicle formed on top of brewing coconut water vinegar in Sri Lanka, three Acetobacter strains (SL13E-2, SL13E-3, and SL13E-4) that grow at 42 °C and four Gluconobacter strains (SL13-5, SL13-6, SL13-7, and SL13-8) grow at 37 °C were identified as Acetobacter pasteurianus and Gluconobacter frateurii, respectively. Acetic acid production by the isolated Acetobacter strains was examined. All three strains gave 4% acetic acid from 6% initial ethanol at 37 °C, and 2.5% acetic acid from 4% initial ethanol … Show more
“…In fact, all the bacterial strains isolated from cactus fruits were subjected to API 50 CHL (Bio-Merieux, Craponne, France) assay according to the instructions provided by the manufacturer. The metabolism of catalase and oxidase, growth in peptone and production of acetic acid from ethanol were also evaluated according to the methodology of Perumpuli et al [16]. Finally, the pigmentation (brown) on YPG agar, overoxidation of ethanol to CO 2 plus water, and oxidation of acetate to CO 2 plus H 2 O were evaluated in order to distinguish between Acetobacter and Gluconobacter genera [21].…”
Section: Morphological and Biochemical Characterization Of Isolated Aabmentioning
confidence: 99%
“…For that, it is necessary to isolate AAB strains that can produce the acetic acid at least at 37 °C, which can be promising for the industrial production of vinegar. Therefore, the thermotolerant AAB screening from the regions characterized by raised temperature can be advantageous to isolate this type of strains, which may have acquired resistance to high temperatures and have obtained phenotypic proliferation under stress conditions by adapting to their habitats [16]. …”
Industrially, the sensitivity of acetic acid bacteria (AAB) to the high temperatures and the high ethanol concentrations is the major concerns for manufacturers. This study was conceived and designed to isolate and identify new thermo-and ethanol-tolerant AAB from Opuntia ficus-indica L. fruits. As a result, among 140 isolated bacterial strains, five selected strains (CR1, CR5, CR23, CZ2, and CZ15) exhibited important acetic acid production until 40°C. The use of 16S rDNA gene analysis was insufficient to identify selected bacteria. Indeed, except CR5 that presented 100% similarity to A. cerevisiae, the other strains presented similar homology rates simultaneously to the 16S rDNA sequences of A. cerevisiae and A. malorum. The reidentification by 16S-23S rDNA gene sequencing showed that CR1, CR23, and CZ15 were A. malorum, which were shown tolerance to the highest concentration of ethanol (12%) and produced elevated amount (40 g/L) of acetic acid at 37°C. In summary, we showed the thermotolerance and ethanol tolerant character of new A. malorum strains, which can be used as a starter for vinegar production. Furthermore, during the molecular characterization of the isolated strains, we concluded that 16S-23S rDNA internal transcribed spacer sequence is of great importance for discriminating between AAB species as a complement to the identification by 16S rDNA sequencing.
“…In fact, all the bacterial strains isolated from cactus fruits were subjected to API 50 CHL (Bio-Merieux, Craponne, France) assay according to the instructions provided by the manufacturer. The metabolism of catalase and oxidase, growth in peptone and production of acetic acid from ethanol were also evaluated according to the methodology of Perumpuli et al [16]. Finally, the pigmentation (brown) on YPG agar, overoxidation of ethanol to CO 2 plus water, and oxidation of acetate to CO 2 plus H 2 O were evaluated in order to distinguish between Acetobacter and Gluconobacter genera [21].…”
Section: Morphological and Biochemical Characterization Of Isolated Aabmentioning
confidence: 99%
“…For that, it is necessary to isolate AAB strains that can produce the acetic acid at least at 37 °C, which can be promising for the industrial production of vinegar. Therefore, the thermotolerant AAB screening from the regions characterized by raised temperature can be advantageous to isolate this type of strains, which may have acquired resistance to high temperatures and have obtained phenotypic proliferation under stress conditions by adapting to their habitats [16]. …”
Industrially, the sensitivity of acetic acid bacteria (AAB) to the high temperatures and the high ethanol concentrations is the major concerns for manufacturers. This study was conceived and designed to isolate and identify new thermo-and ethanol-tolerant AAB from Opuntia ficus-indica L. fruits. As a result, among 140 isolated bacterial strains, five selected strains (CR1, CR5, CR23, CZ2, and CZ15) exhibited important acetic acid production until 40°C. The use of 16S rDNA gene analysis was insufficient to identify selected bacteria. Indeed, except CR5 that presented 100% similarity to A. cerevisiae, the other strains presented similar homology rates simultaneously to the 16S rDNA sequences of A. cerevisiae and A. malorum. The reidentification by 16S-23S rDNA gene sequencing showed that CR1, CR23, and CZ15 were A. malorum, which were shown tolerance to the highest concentration of ethanol (12%) and produced elevated amount (40 g/L) of acetic acid at 37°C. In summary, we showed the thermotolerance and ethanol tolerant character of new A. malorum strains, which can be used as a starter for vinegar production. Furthermore, during the molecular characterization of the isolated strains, we concluded that 16S-23S rDNA internal transcribed spacer sequence is of great importance for discriminating between AAB species as a complement to the identification by 16S rDNA sequencing.
“…have been isolated from various sources around the world and they are the primary species used in vinegar fermentation due to their strong ability to oxidize ethanol and to tolerate high acetic acid concentrations (Gullo et al, 2014). They produce acetic acid from ethanol by two sequential oxidation reactions involving alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH) (Adachi et al, 2003;Perumpuli et al, 2014). In our laboratory, further studies are in progress for a complete characterization of the technological potential of the isolated strains (measurement of ethanol and lactic acid oxidizing power, amount of acetic acid produced, and tolerance to acid, heat, acetic acid, and ethanol) to establish their usefulness in industrial application.…”
Section: Genotypic Identification and Phylogenetic Analysismentioning
Date palm sap (Phoenix dactylifera L.), called Lagmi, is a sugary substrate that readily ferments through the activity of native microflora that consists mainly of yeasts, lactic acid bacteria and acetic acid bacteria (AAB). The aim of this work was to perform a preliminary step in the isolation and identification of AAB species from different samples of palm sap collected in Southern Tunisia, in order to use them as a starter in vinegar production. AAB were isolated on GEY agar from the fresh palm sap (day (D) 0) and following spontaneous fermentation at room temperature after 3 (D3) and 7 days (D7). A preliminary phenotypic identification of 18 isolates was made by means of Gram, catalase, oxidase and ethanol oxidation to acetic acid, and then further to CO 2 and H 2 O. Subsequently, genotypic identification was conducted by sequencing the gene coding for 16SrRNA and a phylogenetic analysis was obtained based on 16S rRNA sequences. Isolates were identified as Acetobacter tropicalis (11 strains), Acetobacter pasteurianus (3 strains), Acetobacter senegalensis (1 strain), Acetobacter indonesiensis (1 strain), Acetobacter cerevisiaie (1 strain), and Gluconacetobacter liquefacienes (1 strain). The application of selected strains as pure starter cultures for the production of vinegar from palm sap is under investigation in our laboratory.
“…High-temperature acetic acid fermentation has been described in a pioneering work by Beppu's group 8) , and it is still of industrial and scientific interest. 38) Industrial fermentation is carried out in a large-scale fermentor, which consequently generates fermentation heat. Moreover, large-scale fermentation in tropical areas and areas affected by climate change is more difficult to perform with proper temperature regulation.…”
Section: High-temperature Acetic Acid Fermentation With Thermally Adapted a Pasteurianusmentioning
Environmental adaptation is considered as one of the most challenging subjects in biology to understand evolutionary or ecological diversification processes and in biotechnology to obtain useful microbial strains. Temperature is one of the important environmental stresses; however, microbial adaptation to higher temperatures has not been studied extensively. For industrial purposes, the use of thermally adapted strains is important, not only to reduce the cooling expenses of the fermentation system, but also to protect fermentation production from accidental failure of thermal management. Recent progress in next-generation sequencing provides a powerful tool to track the genomic changes of the adapted strains and allows us to compare genomic DNA sequences of conventional strains with those of their closely related thermotolerant strains. In this article, we have attempted to summarize our recent approaches to produce thermotolerant strains by thermal adaptation and comparative genomic analyses of Acetobacter pasteurianus for high-temperature acetic acid fermentations, and Zymomonas mobilis and Kluyveromyces marxianus for high-temperature ethanol fermentations. Genomic analysis of the adapted strains has found a large number of mutations and/or disruptions in highly diversified genes, which could be categorized into groups related to cell surface functions, ion or amino acid transporters, and some transcriptional factors. Furthermore, several phenotypic and genetic analyses revealed that the thermal adaptation could lead to decreased ROS generation in cells that produce higher ROS levels at higher temperatures. Thus, it is suggested that the thermally adapted cells could become robust and resistant to many stressors, and thus could be useful for high-temperature fermentations.
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