scholarly journals Use of PEDOT:PSS/Graphene/Nafion Composite in Biosensors Based on Acetic Acid Bacteria

Biosensors ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 332
Author(s):  
Yulia Plekhanova ◽  
Sergei Tarasov ◽  
Anatoly Reshetilov

Immobilization of the biocomponent is one of the most important stages in the development of microbial biosensors. In this study, we examined the electrochemical properties of a novel PEDOT:PSS/graphene/Nafion composite used to immobilize Gluconobacter oxydans bacterial cells on the surface of a graphite screen-printed electrode. Bioelectrode responses to glucose in the presence of a redox mediator 2,6-dichlorophenolindophenol were studied. The presence of graphene in the composite reduced the negative effect of PEDOT:PSS on cells and improved its conductivity. The use of Nafion enabled maintaining the activity of acetic acid bacteria at the original level for 120 days. The sensitivity of the bioelectrode based on G. oxydans/PEDOT:PSS/graphene/Nafion composite was shown to be 22 μA × mM−1 × cm−2 within the linear range of glucose concentrations. The developed composite can be used both in designing bioelectrochemical microbial devices and in biotechnology productions for long-term immobilization of microorganisms.

2009 ◽  
Vol 75 (24) ◽  
pp. 7760-7766 ◽  
Author(s):  
Hiroshi Habe ◽  
Yuko Shimada ◽  
Toshiharu Yakushi ◽  
Hiromi Hattori ◽  
Yoshitaka Ano ◽  
...  

ABSTRACT Glyceric acid (GA), an unfamiliar biotechnological product, is currently produced as a small by-product of dihydroxyacetone production from glycerol by Gluconobacter oxydans. We developed a method for the efficient biotechnological production of GA as a target compound for new surplus glycerol applications in the biodiesel and oleochemical industries. We investigated the ability of 162 acetic acid bacterial strains to produce GA from glycerol and found that the patterns of productivity and enantiomeric GA compositions obtained from several strains differed significantly. The growth parameters of two different strain types, Gluconobacter frateurii NBRC103465 and Acetobacter tropicalis NBRC16470, were optimized using a jar fermentor. G. frateurii accumulated 136.5 g/liter of GA with a 72% d-GA enantiomeric excess (ee) in the culture broth, whereas A. tropicalis produced 101.8 g/liter of d-GA with a 99% ee. The 136.5 g/liter of glycerate in the culture broth was concentrated to 236.5 g/liter by desalting electrodialysis during the 140-min operating time, and then, from 50 ml of the concentrated solution, 9.35 g of GA calcium salt was obtained by crystallization. Gene disruption analysis using G. oxydans IFO12528 revealed that the membrane-bound alcohol dehydrogenase (mADH)-encoding gene (adhA) is required for GA production, and purified mADH from G. oxydans IFO12528 catalyzed the oxidation of glycerol. These results strongly suggest that mADH is involved in GA production by acetic acid bacteria. We propose that GA is potentially mass producible from glycerol feedstock by a biotechnological process.


2020 ◽  
Vol 104 (21) ◽  
pp. 9267-9282
Author(s):  
Philipp Moritz Fricke ◽  
Tobias Link ◽  
Jochem Gätgens ◽  
Christiane Sonntag ◽  
Maike Otto ◽  
...  

Abstract The acetic acid bacterium (AAB) Gluconobacter oxydans incompletely oxidizes a wide variety of carbohydrates and is therefore used industrially for oxidative biotransformations. For G. oxydans, no system was available that allows regulatable plasmid-based expression. We found that the l-arabinose-inducible PBAD promoter and the transcriptional regulator AraC from Escherichia coli MC4100 performed very well in G. oxydans. The respective pBBR1-based plasmids showed very low basal expression of the reporters β-glucuronidase and mNeonGreen, up to 480-fold induction with 1% l-arabinose, and tunability from 0.1 to 1% l-arabinose. In G. oxydans 621H, l-arabinose was oxidized by the membrane-bound glucose dehydrogenase, which is absent in the multi-deletion strain BP.6. Nevertheless, AraC-PBAD performed similar in both strains in the exponential phase, indicating that a gene knockout is not required for application of AraC-PBAD in wild-type G. oxydans strains. However, the oxidation product arabinonic acid strongly contributed to the acidification of the growth medium in 621H cultures during the stationary phase, which resulted in drastically decreased reporter activities in 621H (pH 3.3) but not in BP.6 cultures (pH 4.4). These activities could be strongly increased quickly solely by incubating stationary cells in d-mannitol-free medium adjusted to pH 6, indicating that the reporters were hardly degraded yet rather became inactive. In a pH-controlled bioreactor, these reporter activities remained high in the stationary phase (pH 6). Finally, we created a multiple cloning vector with araC-PBAD based on pBBR1MCS-5. Together, we demonstrated superior functionality and good tunability of an AraC-PBAD system in G. oxydans that could possibly also be used in other AAB. Key points • We found the AraC-PBADsystem from E. coli MC4100 was well tunable in G. oxydans. •  In the absence of AraC orl-arabinose, expression from PBADwas extremely low. • This araC-PBADsystem could also be fully functional in other acetic acid bacteria.


2016 ◽  
Vol 19 (4) ◽  
pp. 31-38
Author(s):  
Huong Thi Lan Vu ◽  
Oanh Thi Kim Nguyen ◽  
Van Thi Thu Bui ◽  
Uyen Thi Tu Bui ◽  
Nghiep Dai Ngo ◽  
...  

Sixty-six acetic acid bacteria (AAB) were isolated from fourty-five flowers and fruits collected in Hochiminh City, Vietnam. Of the sixty-six, thirty-one isolates were selected as dihydroxyacetone (DHA)-producing AAB based on the reaction with Fehling’s solution and grouped into three groups by routine identification with phenotypic features. Group I composed of fourteen isolates and was assigned to the genus Acetobacter, Group II composed of thirteen isolates and was assigned to the genus Gluconobacter and Group III was the remaining four isolates and was assigned to the genus Gluconacetobacter. Ten isolates among the thirteen isolates of Group II gave a larger amount of DHA (22.2–26.0 mg/mL) than Gluconobacter oxydans NBRC 14819T (19.8 mg/mL), promising for the potential use in producing DHA. In phylogenetic analysis based on 16S rRNA gene sequences, six isolates of the ten potential DHA producers were suggested to be candidates for new taxa in the genus Gluconobacter.


Microbiology ◽  
2010 ◽  
Vol 156 (6) ◽  
pp. 1890-1899 ◽  
Author(s):  
Jörn Voss ◽  
Armin Ehrenreich ◽  
Wolfgang Liebl

The growth of Gluconobacter oxydans DSM 7145 on meso-erythritol is characterized by two stages: in the first stage, meso-erythritol is oxidized almost stoichiometrically to l-erythrulose according to the Bertrand–Hudson rule. The second phase is distinguished from the first phase by a global metabolic change from membrane-bound meso-erythritol oxidation to l-erythrulose assimilation with concomitant accumulation of acetic acid. The membrane-associated erythritol-oxidizing enzyme was found to be encoded by a gene homologous to sldA known from other species of acetic acid bacteria. Disruption of this gene in the genome of G. oxydans DSM 7145 revealed that the membrane-bound polyol dehydrogenase not only oxidizes meso-erythritol but also has a broader substrate spectrum which includes C3–C6 polyols and d-gluconate and supports growth on these substrates. Cultivation of G. oxydans DSM 7145 on different substrates indicated that expression of the polyol dehydrogenase was not regulated, implying that the production of biomass of G. oxydans to be used as whole-cell biocatalysts in the biotechnological conversion of meso-erythritol to l-erythrulose, which is used as a tanning agent in the cosmetics industry, can be conveniently carried out with glucose as the growth substrate.


2002 ◽  
Vol 68 (5) ◽  
pp. 2619-2623 ◽  
Author(s):  
Hesham E. Mostafa ◽  
Knut J. Heller ◽  
Arnold Geis

ABSTRACT An efficient transformation protocol for Gluconobacter oxydans and Acetobacter liquefaciens strains was developed by preparation of electrocompetent cells grown on yeast extract-ethanol medium. Plasmid pBBR122 was used as broad-host-range vector to clone the Escherichia coli lacZY genes in G. oxydans and A. liquefaciens. Although both lac genes were functionally expressed in both acetic acid bacteria, only a few transformants were able to grow on lactose. However, this ability strictly depended on the presence of a plasmid expressing both lac genes. Mutations in the plasmids and/or in the chromosome were excluded as the cause of growth ability on lactose.


2020 ◽  
Vol 70 (7) ◽  
pp. 4351-4357 ◽  
Author(s):  
Pattaraporn Yukphan ◽  
Piyanat Charoenyingcharoen ◽  
Sukunphat Malimas ◽  
Yuki Muramatsu ◽  
Yasuyoshi Nakagawa ◽  
...  

Two bacterial strains, isolates AC10T and AC20, which were reported in a previous study on the diversity of acetic acid bacteria in Thailand, were subjected to a taxonomic study. The phylogenetic analysis based on the 16S rRNA gene sequences showed that the two isolates were located closely to the type strains of Gluconobacter oxydans and Gluconobacter roseus . However, the two isolates formed a separate cluster from the type strains of the two species. The genomic DNA of isolate AC10T was sequenced. The assembled genomes of the isolate were analysed for average nucleotide identity (ANI) and digital DNA–DNA hybridization (dDDH). The results showed that the highest ANI and dDDH values between isolate AC10T and G. oxydans DSM 3503T were 91.15 and 68.2 %, which are lower than the suggested values for species delineation. The genome-based tree was reconstructed and the phylogenetic lineage based on genome sequences showed that the lineage of isolate AC10T was distinct from G. oxydans DSM 3503T and its related species. The two isolates were distinguished from G. oxydans and their relatives by their phenotypic characteristics and MALDI-TOF profiles. Therefore, the two isolates, AC10T (=BCC 15749T=TBRC 11329T=NBRC 103576T) and AC20 (=BCC 15759=TBRC 11330=NBRC 103579), can be assigned to an independent species within the genus Gluconobacter , and the name Gluconobacter aidae sp. nov. is proposed for the two isolates.


1998 ◽  
Vol 64 (4) ◽  
pp. 1477-1483 ◽  
Author(s):  
Rosane Freitas Schwan

ABSTRACT Cocoa fermentations were performed in wooden boxes under the following four experimental regimens: beans naturally fermented with wild microflora; aseptically prepared beans with no inoculum; and beans inoculated with a defined cocktail containing microorganisms at a suitable concentration either at zero time or by using phased additions at appropriate times. The cocktail used consisted of a yeast,Saccharomyces cerevisiae var. chevalieri, two lactic acid bacterial species, Lactobacillus lactis andLactobacillus plantarum, and two acetic acid bacterial species, Acetobacter aceti and Gluconobacter oxydans subsp. suboxydans. The parameters measured were cell counts (for yeasts, filamentous fungi, lactic acid bacteria, acetic acid bacteria, and spore formers, including reisolation and identification of all residual cell types), sugar, ethanol, acetic acid, and lactic acid contents (and contents of other organic acids), pH, and temperature. A cut test for bean quality and a sensorial analysis of chocolate made from the beans were also performed. The natural fermentation mimicked exactly the conditions in 800-kg boxes on farms. The aseptic box remained largely free of microflora throughout the study, and no significant biochemical changes occurred. With the zero-time inoculum the fermentation was almost identical to the natural fermentation. The fermentation with the phased-addition inoculum was similar, but many changes in parameters were slower and less pronounced, which led to a slightly poorer end product. The data show that the nearly 50 common species of microorganisms found in natural fermentations can be replaced by a judicious selection and concentration of members of each physiological group. This is the first report of successful use of a defined, mixed starter culture in such a complex fermentation, and it should lead to chocolate of more reliable and better quality.


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Abeer Essam Noman ◽  
Naif S. Al-Barha ◽  
Abdul-Aziz M. Sharaf ◽  
Qais Ali Al-Maqtari ◽  
Amani Mohedein ◽  
...  

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