RESUMO
Zhenjiang vinegar, the grains of which contain a unique microbial flora, is one of the four famous traditional Chinese vinegars. We investigated the components of Zhenjiang vinegar grains. Unique acetic acid bacteria were randomly isolated from Zhenjiang vinegar grains, and the obtained strains were qualitatively analyzed to compare their capacities for acetate decomposition and acid production. Acetic acid bacteria with a high acid-producing rate were identified by 16S rDNA sequencing, and further confirmation was performed using the Basic Local Alignment Search Tool comparison method. Six significant strains of acetic acid bacteria were isolated. Qualitative analysis showed that these strains produced no brown precipitate and had a capacity for acetate decomposition. Based on physiological and biochemical evaluation, the two strains with the highest acid yield were sequenced, and the results identified strain W1 as Acetobacter aceti and strain W6 as A. pasteurianus.
Assuntos
Ácido Acético/metabolismo , Acetobacter/metabolismo , DNA Ribossômico/genética , RNA Ribossômico 16S/genética , Acetobacter/classificação , Acetobacter/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Fermentação , Filogenia , Plasmídeos/química , Plasmídeos/metabolismo , Análise de Sequência de DNARESUMO
Acetic acid bacteria (AAB) are considered fastidious microorganisms because they are difficult to isolate and cultivate. Different molecular approaches were taken to detect AAB diversity, independently of their capacity to grow in culture media. Those methods were tested in samples that originated during traditional vinegar production. Bacterial diversity was assessed by analysis of 16S rRNA gene, obtained by PCR amplifications of DNA extracted directly from the acetification container. Bacterial composition was analyzed by RFLP-PCR of 16S rRNA gene, Temporal Temperature Gradient Gel Electrophoresis (TTGE) separation of amplicons containing region V3-V5 of 16S rRNA gene and cloning of those amplicons. TTGE bands and clones were grouped based on their electrophoretic pattern similarity and sequenced to be compared with reference strains. The main microorganism identified in vinegar was Acetobacter pasteurianus, which at the end of the acetification process was considered to be the only microorganism present. The diversity was the highest at 2% acetic acid, where indefinite species of Gluconacetobacter xylinus/europaeus/intermedius were also present.
Assuntos
Ácido Acético/metabolismo , Acetobacteraceae/classificação , Contagem de Colônia Microbiana/métodos , Filogenia , Polimorfismo de Fragmento de Restrição , Acetobacter/classificação , Acetobacter/genética , Acetobacter/metabolismo , Acetobacteraceae/genética , Acetobacteraceae/metabolismo , Clonagem Molecular , DNA Bacteriano/genética , Eletroforese em Gel de Ágar , Microbiologia de Alimentos , Gluconobacter/classificação , Gluconobacter/genética , Gluconobacter/metabolismo , Dados de Sequência Molecular , Reação em Cadeia da Polimerase/métodos , RNA Bacteriano/genética , RNA Ribossômico 16S/genética , Especificidade da EspécieRESUMO
Nitrogen is an essential plant nutrient, widely applied as N-fertilizer to improve yield of agriculturally important crops. An interesting alternative to avoid or reduce the use of N-fertilizers could be the exploitation of plant growth-promoting bacteria (PGPB), capable of enhancing growth and yield of many plant species, several of agronomic and ecological significance. PGPB belong to diverse genera, including Azospirillum, Azotobacter, Herbaspirillum, Bacillus, Burkholderia, Pseudomonas, Rhizobium, and Gluconacetobacter, among others. They are capable of promoting plant growth through different mechanisms including (in some cases), the biological nitrogen fixation (BNF), the enzymatic reduction of the atmospheric dinitrogen (N(2)) to ammonia, catalyzed by nitrogenase. Aerobic bacteria able to oxidize ethanol to acetic acid in neutral or acid media are candidates of belonging to the family Acetobacteraceae. At present, this family has been divided into ten genera: Acetobacter, Gluconacetobacter, Gluconobacter, Acidomonas, Asaia, Kozakia, Saccharibacter, Swaminathania, Neoasaia, and Granulibacter. Among them, only three genera include N(2)-fixing species: Gluconacetobacter, Swaminathania and Acetobacter. The first N(2)-fixing acetic acid bacterium (AAB) was described in Brazil. It was found inside tissues of the sugarcane plant, and first named as Acetobacter diazotrophicus, but then renamed as Gluconacetobacter diazotrophicus. Later, two new species within the genus Gluconacetobacter, associated to coffee plants, were described in Mexico: G. johannae and G. azotocaptans. A salt-tolerant bacterium named Swaminathania salitolerans was found associated to wild rice plants. Recently, N(2)-fixing Acetobacter peroxydans and Acetobacter nitrogenifigens, associated with rice plants and Kombucha tea, respectively, were described in India. In this paper, recent advances involving nitrogen-fixing AAB are presented. Their natural habitats, physiological and genetic aspects, as well as their association with different plants and contribution through BNF are described as an overview.
Assuntos
Acetobacter/metabolismo , Acetobacteraceae/metabolismo , Produtos Agrícolas/microbiologia , Nitrogênio/metabolismo , Filogenia , Acetobacter/classificação , Acetobacteraceae/classificação , Produtos Agrícolas/crescimento & desenvolvimento , Gluconacetobacter/classificação , Gluconacetobacter/metabolismo , Fixação de Nitrogênio , Raízes de Plantas/microbiologia , Microbiologia do Solo , SimbioseRESUMO
The presence of acetic acid bacteria populations on grape surfaces from several Chilean valleys is reported. The bacteria were analysed at both the species and the strain level by molecular methods such as RFLP-PCR 16S rRNA gene, RFLP-PCR ITS 16S-23S rRNA gene regions and Arbitrary Primed (AP) PCR. Our results show that there are limited numbers of species of acetic acid bacteria in the grapes and that there is a need for an enrichment medium before plating to recover the individual colonies. In the Northernmost region analysed, the major species recovered was a non-acetic acid bacteria, Stenotrophomonas maltophila. Following the North-South axis of Chilean valleys, the observed distribution of acetic acid bacteria was zonified: Acetobacter cerevisiae was only present in the North and Gluconobacter oxydans in the South. Both species were recovered together in only one location. The influence of the grape cultivar was negligible. Variability in strains was found to be high (more than 40%) for both Acetobacteraceae species.