Acetobacter Aceti Cells Research Articles

The influence of cultivation conditions on the immobilized acetic acid bacteria metabolic activity

Brewing is an innovative sector of the food industry. Non-alcoholic beer production increases every year. The largest volumes of non-alcoholic beer are obtained by regular beer dialysis. The beer dialysate formed in production contains ethyl alcohol, which entails the need for its rational use. One of the effective ways to use beer dialysate is food biochemical vinegar production. The purpose of the work is to conduct research for biotechnology development of food vinegar from beer dialysates generation using acetic acid bacteria (AAB) immobilization on bio-carriers of various nature. The objects of research were samples of beer dialysates (BD), concentrated to a volume fraction of ethyl alcohol of 7.5%, Acetobacter aceti AAB, vinegar from BD. To study the changes in metabolic activity of immobilized AAB on a bio-carrier, acetic acid fermentation was performed using Acetobacter aceti cells, immobilized on beech shavings, zeolite, and high-pressure polyethylene. Air was supplied to a reservoir by a microcompressor from below through a finely porous ceramic nozzle, providing uniform air dispersion in cultural fluid. Graphs of the cells number and Acetobacter aceti biomass dependence on cultivation duration, nature of the bio-carrier and the aeration method when obtaining vinegar from beer dialysate are presented. The experimental data of the volatile components composition, organic acids and beer dialysate amino acids and vinegar from it are presented. Electron microscopic research of Acetobacter aceti AAB during beech shavings and zeolite cultivation is presented. The results of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) are presented.

Bioprocess Intensification Using Flow Reactors: Stereoselective Oxidation of Achiral 1,3-diols with Immobilized Acetobacter Aceti

Enantiomerically enriched 2-hydroxymethylalkanoic acids were prepared by oxidative desymmetrisation of achiral 1,3-diols using immobilized cells of Acetobacter aceti in water at 28 °C. The biotransformations were first performed in batch mode with cells immobilized in dry alginate, furnishing the desired products with high molar conversion and reaction times ranging from 2 to 6 h. The biocatalytic process was intensified using a multiphasic flow reactor, where a segmented gas–liquid flow regime was applied for achieving an efficient O2-liquid transfer; the continuous flow systems allowed for high yields and high biocatalyst productivity.

Upscaled Production of Sugarcane Vinegar by Adsorbed Cells of Acetobacter aceti Under Semi-Continuous Fermentation Conditions

Natural vinegar is a food supplement, tonic and nutraceutical produced by twin fermentation of sugar to acetic acid via ethanol. The fermentation of sugarcane juice carried out with Saccharomyces cerevisiae MTCC 11815 produced 9.11 % (v/v) of ethanol with a fermentation efficiency of 89.8 % in 72 h. Statistical optimization of acetic acid fermentation revealed that immobilized cells of Acetobacter aceti (grown in 2 g/L DAHP supplemented jaggery solution) adsorbed on 15-mm-sized Melona grandis wood shavings for 15 h had the highest adsorption rate (66.6 %) followed by Tectona grandis (44.4 %) and Castania sativa (21.4 %) with maximum viable count of 12.76 × 107 and 6.0 × 107 cfu/g in absence or presence of substrate, respectively. A 1L plastic fermenter packed up to half of its length produced sugarcane vinegar with 5.0 % (w/v) volatile acidity in 6 days. These optimized conditions scaled to 5 L in PVC column reactors and 50 L plastic fermenter produced 7.0 % (w/v) and 4.0 % (w/v) volatile acidity in 6–7 days and 7–10 days, respectively. The sugarcane vinegar had a mean sensory score of 8.61 ± 0.52 in comparison to commercial brands with sensory scores of 7.22 ± 0.76 and 7.47 ± 1.02.

Fermentative Production of Sugarcane Vinegar by Immobilized Cells of Acetobacter aceti Under Packed Bed conditions

Sugarcane juice (17 °Bx), the substrate of choice for vinegar production due to its high sugar content and easy availability was fermented to ethanol by Saccharomyces cerevisiae strain 35 producing 9.5 % (v/v) ethanol. This ethanol was used for vinegar production using immobilized cells of Acetobacter aceti AC1 (on wood shavings with cell to adsorbent ratio of 2:1) packed in an indigenously developed polyvinyl chloride column. Sugarcane ethanol (supplemented with mother vinegar) with an initial acidity of 2 % (w/v) was trickled at 50 ml/h through the packed bed at 2.5 l scale, that produced sugarcane vinegar in 72 h (compared to 13 days of batch cycle). The vinegar production was consistent over 25 cycles studied and had a volatile acidity of 4.08–6.84 % (w/v), fermentation efficiency (52.9–87.9 %), acetification rate (5.8–22.8 g/l/day) and yield factor (0.68–1.14). The sugarcane vinegar had a good sensory score (8.66 ± 0.33), improved total phenols (81.9 ± 0.14–138.6 ± 0.49 mg/100 ml) with retention of ascorbic acid (42.0 ± 1.13–86.5 ± 1.34 mg/100 ml).

Production of 2-phenylacetic acid and phenylacetaldehyde by oxidation of 2-phenylethanol with free immobilized cells of Acetobacter aceti

Acetobacter aceti MIM 2000/28 was employed for the oxidation of 2-phenyl-1-ethanol. Oxidation in aqueous systems gave phenylacetic acid with high yields, while the use of a two-liquid phase system (composed of water and isooctane) allowed for the production of the corresponding aldehyde. Free cells showed poor operational stability and were immobilized in calcium alginate; immobilized cells had specific activity, substrate tolerance and stability higher than that obtained with free cells. Simple fed-batch operation with immobilized cells in an air-lift reactor allowed for the production of 23 g l −1 phenylacetic acid in 9 days without foam formation.

Mediated catalytic current for the oxidation of ethanol produced by Acetobacter aceti cells suspended in solution

Mediated catalytic current for the oxidation of ethanol produced by Acetobacter aceti cells suspended in solution

Mediated catalytic current for the oxidation of ethanol produced by Acetobacter aceti cells suspended in solution

Mediated catalytic current for the oxidation of ethanol produced by Acetobacter aceti cells suspended in solution

Electrocatalytic properties of Acetobacter aceti cells immobilized on electrodes for the quinone-mediated oxidation of ethanol

Abstract Carbon paste electrodes on which intact cells of Acetobacter aceti (IFO3284) are immobilized behind a dialysis membrane produce a catalytic current for the oxidation of ethanol in the presence of 2-methyl-5,6-dimethoxy benzoquinone (Q 0 ). Analysis of the catalytic current reveals that the catalytic activity of the bacterial cells is due to alcohol dehydrogenase (ADH) existing in the cytoplasmic membranes. The membrane-bound ADH catalyzes the oxidation of ethanol by the use of Q 0 penetrating the membranes, in which Q 0 is reduced by accepting electrons from the enzyme. The reduced form of Q 0 , in turn, reaches the electrode and is oxidized there. Thus, Q 0 serves as an electron transfer mediator between the intact cells and the electrode. The mediated bioelectrocatalysis behavior can be described by an equation of the catalytic current derived for an enzyme-based electrocatalysis. Performance of the electrode as an ethanol sensor is compared with that of an electrode modified with purified ADH. An ADH deficient strain and the ADH mutant harboring ADH gene are also examined as biocatalysts in place of A. aceti .

Ethanol and acetic acid tolerance in free and immobilized cells of Saccharomyces cerevisiae and Acetobacter aceti

Saccharomyces cerevisiae and Acetobacter aceti cells were immobilized by entrapment in Ca-alginate or by adsorption on to preformed cellulose beads and were treated with 0-20% (v/v) ethanol and 0-10% (v/v) acetic acid. At 20% (v/v) ethanol, lethal for free yeast cells, 62-72% of the immobilized cells survived. In 10% (v/v) acetic acid, free and adsorbed Acetobacter aceti cells ceased to grow but 69% of entrapped cells survived. Cells released from the carrier showed an intermediate survival (20-60%).

Effects of immobilization on biomass production and acetic acid fermentation of Acetobacter aceti as a function of temperature and pH

Acetobacter aceti cells were immobilized using entrapment in Ca-alginate gel and adsorption on preformed cellulose beads. The cell number within the supports showed no significant alterations on changing temperature or pH, whereas the acetic acid production was slightly increased by immobilization.

Enhancement of acetic acid production in a high cell-density culture of Acetobacter aceti

The rate of production of acetic acid was greatly enhanced by a high cell-density culture of Acetobacter aceti. Acetobacter aceti cells were recycled through a hollow fiber filter module, and the high acetic acid production rate of 120 mg/ l/h (at an exit acetic acid concentration of 40 g/ l) at the dilution rate of 4.0 h −1 was obtained. High viable cell concentrations were maintained by using medium rich in yeast extract and controlling the DO concentration at an optimum level. Viable cell concentrations increased with increasing added amounts of yeast extract in the medium as long as the acetic acid concentration was not higher than 40 g/ l. When DO and yeast extract were not depleted from the culture, the correlation between the acetic acid production rate ( PD) and the dilution rate ( D) was given as, PD = 7.1 + 34.5 D (0.3 ≤ D ≤ 3)

Immobilization of Acetobacter acoti on cellulose ion exchangers: Adsorption isotherms

The adsorptive behavior of cells of Acetobacter aceti, ATCC 23746, on DEAE-, ECTEOLA-, TEAE-, and DEHPAE-cellulose ion exchangers in a modified Hoyer's medium at 30 degrees C was investigated. The maximum observed adsorption capacities varied from 46 to 64 mg dry wt/g resin. The Langmuir isotherm form was used to fit the data, since the cells formed a monolayer on the resin and exhibited saturation. The equilibrium constant in the Langmuir expression was qualitatively correlated with the surface charge density of the resin. The adsorption was also "normalized" by considering the ionic capacities of the resins. The exceptionally high normalized adsorption capacity of ECTEOLA-cellulose, 261 mg dry wt/meq, may be explained by an interaction between the cell wall and the polyglyceryl chains of the exchanging groups in addition to the electrostatic effects. The effect of pH on the bacterial adsorption capacity of ECTEOLA-, TEAE-, and phosphate-cellulose resins was studied and the pl of the bacteria was estimated to be 3.0.

Spheroplast of Acetic Acid Bacteria

A procedure, preparing spheroplast of acetic acid bacteria, was established to elucidate the membrane structure of the organisms. Of the acetic acid bacteria, only Acetobacter aceti cells were converted into spheroplasts by the sucrose-EDTA-lysozyme system. To Gluconobacter suboxydans, a method exchanging sucrose in the system for NaCl was indispensable. This NaCl-EDTA-lysozyme system was adequate for almost all acetic acid bacteria, which were converted efficiently into spheroplasts. The existence of EDTA was not essential to the genus Gluconobacter.

Oxaloacetate decarboxylase from Acetobacter aceti

An oxaloacetate (OAA) decarboxylase (EC 4.1.1.3) has been purified 72-fold from Acetobacter aceti cells grown on ethanol, and its molecular weight was estimated to be about 80,000 by gel filtration. Several properties distinguished this enzyme from the OAA decarboxylase from A. xylinum: a) It was not a constitutive enzyme; the activity was 6- to 20-fold higher in cells grown on a C2 substrate (acetate or ethanol) than in cells grown on a C3 compound (pyruvate or propionate). b) The optimum pH was 7.5; a value of 5.6 was reported for the enzyme from A. xylinum. c) The enzyme did not need a divalent cation and was not inhibited by EDTA. d) The Kmvalue for OAA was found to be 0.22 mM. It was not affected by the addition of nicotinamide adenine dinucleotide. e) The enzyme activity was neither inhibited by acetate nor by L-malate.