Gluconic Acid Concentration Research Articles

Diversity and activity of phosphate bioleaching bacteria from a high-phosphorus iron ore

Many of the current world iron ore resources contain over 0.08 w% of P, making this material out-of-standard for the manufacture of metallic iron and steel. Solubilization of phosphatic minerals can be performed by some bacteria, which in turn become useful in developing environmental friendly solutions for various human activities, such as agriculture and mining. When artificially inoculated in a particular environment, indigenous microorganisms, as a general rule, compete better in terms of adaptation and cause fewer ecological distortions than exogenous microorganisms. In this way, the aims of this study were to isolate and characterize phosphate-solubilizing bacteria associated to a high-phosphorous iron ore located in the Brazilian region of Minas Gerais and to determine the mechanisms by which they solubilize phosphorous moieties. Phosphorus content of the ore material is 0.18% (w:w) and, therefore, it is considered as a high-phosphorus iron ore. Among the culturable bacteria associated to the iron ore, four morphologically distinct bacterial strains showed high phosphate-solubilizing activity. They were identified by 16S rRNA gene sequencing as four different species: Leifsonia xyli FeGl 02, Burkholderia cenocepacia FeSu 01, Burkholderia caribensis FeGl 03 and Burkholderia ferrariae FeGl 01. In addition to tricalcium phosphate [Ca 3(PO 4) 2] solubilization activity, the two later strains were also tested for solubilization of berlinite [AlPO 4] and turquoise [CuAl 6(PO 4) 4(OH) 8·5H 2O] in plate culture. Although both strains were able to growth in the berlinite-amended medium, none showed solubilizing activity. Neither B. caribensis FeGl 03 nor B. ferrariae FeGl 01 grew in the turquoise-amended medium. The rates of P solubilization and production of gluconic acid, 2-ketogluconic acid, acetic acid and citric acid were assayed in flask-shake cultures growing in a medium supplemented with hydroxyapatite [Ca 5(PO 4) 3(OH)]. There was no appreciable difference in the rate of P solubilization between these two strains. Although neither 2-ketogluconic nor citric acid were detected in the broth media, both strains produced gluconic acid and acetic acid. However, a remarkable difference in the evolution of the gluconic acid concentration was observed between B. caribensis FeGl 03 and B. ferrariae FeGl 01.

Continuous gluconic acid production by the yeast-like Aureobasidium pullulans in a cascading operation of two bioreactors

The application of a new developed process for the continuous production of gluconic acid using a cascade of two bioreactors in a continuous process is shown reaching the highest concentration of gluconic acid described in the literature for continuous culture fermentation. Very high gluconic acid concentrations of 272-308 g/l have been achieved under continuous cultivation of free-growing cells of Aureobasidium pullulans in the first bioreactor at residence times (RT) between 19.5 and 24 h with formation rates for the generic product between 12.7 and 13.9 g/(l h). Gluconic acid, 350-370 g/l, was continuously reached in the second bioreactor at a total RT of 30.8-37 h with R (j) of 9.2-12 g/(l h). The highest specific gluconic acid production (m (p)) of 3.6 g/(g h) was found in the first bioreactor at the lowest RT of 19.5 h. The highest selectivity of 93.6% was determined in the first bioreactor as well. Complete glucose consumption was obtained at 37 h total residence time in the second bioreactor. Gluconic acid, 433 g/l, was continuously produced in the second bioreactor at a total RT of 37 h.

Process optimization of continuous gluconic acid fermentation by isolated yeast‐like strains of Aureobasidium pullulans

This study was focused on the optimization of a new fermentation process for continuous gluconic acid production by the isolated yeast-like strain Aureobasidium pullulans DSM 7085 (isolate 70). Operational fermentation parameters were optimized in chemostat cultures, using a defined glucose medium. Different optima were found for growth and gluconic acid production for each set of operation parameters. Highest productivity was recorded at pH values between 6.5 and 7.0 and temperatures between 29 and 31 degrees C. A gluconic acid concentration higher than 230 g/L was continuously produced at residence times of 12 h. A steady state extracellular gluconic acid concentration of 234 g/L was measured at pH 6.5. 122% air saturation yielded the highest volumetric productivity and product concentration. The biomass-specific productivity increased steadily upon raising air saturation. An intracellular gluconic acid concentration of about 159 g/L (0.83 mol) was determined at 31 degrees C. This is to be compared with an extracellular concentration of 223 g/L (1.16 mol), which indicates the possible existence of an active transport system for gluconic acid secretion, or the presence of extracellular glucose oxidizing enzymes. The new process provides significant advantages over the traditional discontinuous fungi operations. The process control becomes easier, thus offering stable product quality and quantity.

Potential Application of a Glucose-Transport-Deficient Mutant ofSchizosaccharomyces pombefor Removing Gluconic Acid from Grape Must

Musts from rotten grapes typically contain high levels of gluconic acid, which can raise severe problems in winemaking processes. In this work, the ability of the glucose-transport-deficient mutant YGS-5 of Schizosaccharomyces pombe to completely or partly remove gluconic acid from a synthetic glucose-containing medium and the potential use of this yeast strain for the same purpose in musts and wines were examined. Surprisingly, the S. pombe YGS-5 strain successfully removed 93% of the initial gluconic acid (2.5 gL(-1)) and 80% of the initial malic acid (1.0 gL(-1)) within 30 h after inoculation. Also, the yeast strain produced no volatile compounds other than those obtained in fermentations conducted with the wine yeast Saccharomyces cerevisiae. S. pombe YGS-5 could thus be used to remove gluconic acid present in musts from rotten grapes. On the basis of these results, various ways of using S. pombe YGS-5 to treat musts containing gluconic acid in order to solve the problems due to the high gluconic acid concentrations in botrytized grape must are proposed.

Aromatic series in sherry wines with gluconic acid subjected to different biological aging conditions by Saccharomyces cerevisiae var. capensis

Wines from healthy grapes supplemented with gluconic acid were subjected to biological aging under two experimental conditions. The first one was carried out under flor yeast velum as in the traditional biological aging and the second one under submerged cultures. The highest gluconic acid consumption was observed in aged wines in submerged cultures. Nine aromatic series were obtained by grouping the 48 volatile compounds quantified in wines. The aroma profile based on the aromatic series allows comparison of the changes due to the gluconic acid consumption and the changes due to the different aging conditions assayed. Only the herbaceous and fatty series showed diminished values of consequence of gluconic acid consumption. The fatty, herbaceous and roasty series show highest values, whereas the fruity, floral, solvent and medicinal series reached lower values in the submerged cultures assay. The application of the assay conditions to winemaking can reduce the gluconic acid concentration in wines obtained from rotten grapes.

Optimisation on bioleaching of incinerator fly ash by Aspergillus niger – use of central composite design

Previous work has shown that heavy metals may be bioleached from municipal solid waste (MSW) incinerator fly ash. The bioleaching of heavy metals from the ash depends on physical, chemical and biological factors. Our research objective is to establish the factors that exert a greater impact on the bioleaching process, and to determine the optimal bioleaching conditions in order to achieve the maximum metal leaching efficiency for selected metals. Four factors were investigated: sucrose concentration, inoculum spore concentration, fly ash pulp density, and the time of addition of fly ash to the fungus Aspergillus niger. Using the central composite design (CCD), 31 batch bioleaching tests were run under high and low values of these four factors. Empirical models obtained through second-order (Taylor series approximation) regression provided the optimal bioleaching conditions. Results showed that sucrose concentration and pulp density were more important factors than spore concentration and the time of addition of the fly ash. The concentration of Al, Fe, Zn, citric acid, and gluconic acid attained in the leached liquor was 12.3, 12.3, 77.6 ppm, 51 and 281 mM, respectively.

Gluconic acid consumption in wines by Schizosaccharomyces pombe and its effect on the concentrations of major volatile compounds and polyols.

Schizosaccharomyces pombe 1379 (ATCC 26760) yeast strain in wine substantially increases acetaldehyde and 1,1-diethoxyethane concentrations and to decreases levo-2,3-butanediol, glycerol, acetoin, and gluconic acid concentrations. In this study, S. pombe has been used for the first time to reduce gluconic acid in wine under aerobic conditions. Only acetaldehyde and acetoin exhibited significantly higher levels in the wines containing gluconic acid. The high in vitro specific activity of alcohol dehydrogenase observed may be directly related to the high production of acetaldehyde by the studied fission yeast.

Multicriteria optimization of gluconic acid production using net flow.

The biochemical process industry is often confronted with the challenge of making decisions in an atmosphere of multiple and conflicting objectives. Recent innovations in the field of operations research and systems science have yielded rigorous multicriteria optimization techniques that can be successfully applied to the field of biochemical engineering. These techniques incorporate the expert's experience into the optimization routine and provide valuable information about the zone of possible solutions. This paper presents a multicriteria optimization strategy that generates a Pareto domain, given a set of conflicting objective criteria, and determines the optimal operating region for the production of gluconic acid using the net flow method (NFM). The objective criteria include maximizing the productivity and concentration of gluconic acid, while minimizing the residual substrate. Three optimization strategies are considered. The first two strategies identify the optimal operating region for the process inputs. The results yielded an acceptable compromise between productivity, gluconic acid concentration and residual substrate concentration. Fixing the process inputs representing the batch time, initial substrate concentration and initial biomass equal to their optimal values, the remaining simulations were used to study the sensitivity of the optimum operating region to changes in the oxygen mass transfer coefficient, K(L) a, by utilizing a multi-level K(L) a strategy. The results show that controlling K(L) a during the reaction reduced the production of biomass, which in turn resulted in increased productivity and concentration of gluconic acid above that of a fixed K(L) a.

Continuous gluconic acid production by isolated yeast-like mould strains of Aureobasidium pullulans.

By extensive microbial screening, about 50 strains with the ability to secrete gluconic acid were isolated from wild flowers. The strains belong to the yeast-like mould Aureobasidium pullulans (de Bary) Arnaud. In shake flask experiments, gluconic acid concentrations between 23 and 140 g/l were produced within 2 days using a mineral medium. In batch experiments, various important fermentation parameters influencing gluconic acid production by A. pullulans isolate 70 (DSM 7085) were identified. Continuous production of gluconic acid with free-growing cells of the isolated yeast-like microorganisms was studied. About 260 g/l gluconic acid at total glucose conversion could be achieved using continuous stirred tank reactors in defined media with residence times (RT) of about 26 h. The highest space-time-yield of 19.3 g l(-1) x h(-1)) with a gluconic acid concentration of 207.5 g/l was achieved with a RT of 10.8 h. The possibility of gluconic acid production with biomass retention by immobilised cells on porous sinter glass is discussed. The new continuous gluconate fermentation process provides significant advantages over traditional discontinuous operation employing Aspergillus niger. The aim of this work was the development of a continuous fermentation process for the production of gluconic acid. Process control becomes easier, offering constant product quality and quantity.

High-performance electrolyte in the presence of dextrose and its derivatives for aluminum electrolytic capacitors

Dextrose and its derivatives (e.g. glucose, gluconic acid and gluconic lactone) are added to modify the characteristics of electrolytes used in aluminum electrolytic capacitors. The results show that the conductivity and sparking voltage of the electrolytes are severely affected by the concentration of dextrose gluconic acid and gluconic lactone. In addition, the pH of the electrolyte is only slightly affected by the quantity of gluconic acid and gluconic lactone. The capacitance, dissipation factor, and leakage current of capacitors impregnated with the electrolytes prepared in this work are periodically measured under storage conditions and loading at 105 °C.

OPTIMIZATION STUDY FOR THE PRODUCTION OF CITRIC AND GLUCONIC ACID FROM FIG WATER EXTRACT BY ASPERGILLUS NIGER IN SURFACE FERMENTATION

ABSTRACT The production of citric and gluconic acid from fig extract by Aspergillus niger ATCC 10577 and A. niger B60 in surface fermentation was investigated. The strain 10577 gave higher concentration of citric and gluconic acid than strain B60. A maximum citric and gluconic acid concentration (20.5 and 97.0 g/L, respectively), citric acid yield (12%), biomass dry weight (18.5 g/L), and sugar utilization (85%) was achieved at an initial sugar concentration of 200 g/L and a pH of 7.0. On the other hand, the highest gluconic acid yield (79.7%) was obtained in culture grown at initial sugar concentration 100 g/L. The addition of 4% (v/v) methanol in the fig extract increased the concentration of citric and gluconic acid from 20.5 and 97.0 g/L to 30.7 and 145.5 g/L, respectively. Citric acid was separated from the gluconic acid by extraction with diethyl ether or ethyl acetate.

Binding of cobalt and zinc by organic acids and culture filtrates of Aspergillus niger grown in the absence or presence of insoluble cobalt or zinc phosphate

The ability of commercially-available citric, oxalic and gluconic acids to bind Co 2+ and Zn 2+ was investigated and compared with culture filtrates from Aspergillus niger , a fungus capable of citric, gluconic and oxalic acid production, grown in the presence and absence of cobalt or zinc phosphate. This work demonstrated that citric and oxalic acid and the A. niger culture filtrates can bind Co 2+ and Zn 2+ and in some cases, the culture filtrates were more efficient than commercial organic acids. Gluconic acid did not bind Co 2+ or Zn 2+ under the conditions used in this study. The presence of insoluble metal phosphates in the growth medium was found to markedly influence the production of organic acids and, while large concentrations of gluconic acid were produced in the presence of Co 3 (PO 4)2 , the culture filtrate was unable to bind Zn 2+ . The production of oxalic acid by A. niger when grown in the presence of Zn 3 (PO 4 ) 2 led to the precipitation of insoluble zinc oxalate, a phenomenon with implications for metal tolerance and toxicity. The significance of these findings in relation to the environmental mobility of metals and phosphate, and the role of fungi in such transformations are discussed.

Citric and gluconic acid production from fig by Aspergillus niger using solid-state fermentation.

The production of citric and gluconic acids from fig by Aspergillus niger ATCC 10577 in solid-state fermentation was investigated. The maximal citric and gluconic acids concentration (64 and 490 g/kg dry figs, respectively), citric acid yield (8%), and gluconic acid yield (63%) were obtained at a moisture level of 75%, initial pH 7.0, temperature 30 degrees C, and fermentation time in 15 days. However, the highest biomass dry weight (40 g/kg wet substrate) and sugar utilization (90%) were obtained in cultures grown at 35 degrees C. The addition of 6% (w/w) methanol into substrate increased the concentration of citric and gluconic acid from 64 and 490 to 96 and 685 g/kg dry fig, respectively.

The nutraceutical benefit, part iii: honey

The nutraceutical benefit, part iii: honey

Phosphate solubilisation in solution culture by the soil fungus Penicillium radicum

Phosphorus is a plant nutrient which is rapidly made immobile and less available for plant use after addition to the soil as a soluble fertiliser. Phosphate-solubilising microorganisms may be able to improve the P nutrition of plants and thus stimulate plant growth. Penicillium radicum, a phosphate-solubilising fungus isolated from the rhizosphere of wheat roots, has shown promise in plant growth promotion. Its ability to solubilise inorganic phosphate was studied in vitro. The fungus was grown in liquid medium culture containing either ammonium or nitrate as the sole source of N. Insoluble, or sparingly-soluble P (1000 mg P l −1) was supplied as calcium monohydrogen phosphate (CaHPO 4), calcium orthophosphate (Ca 3(PO 4) 2), crystalline ferric phosphate (FePO 4·4H 2O), crystalline aluminium phosphate (AlPO 4), colloidal ferric phosphate or colloidal aluminium phosphate. The titratable acidity, pH and concentrations of organic acids and soluble phosphate were determined periodically during a 20 or 31 d incubation. Phosphate solubilisation was highest from CaHPO 4 (475 mg P l −1), Ca 3(PO 4) 2 (360 mg P l −1) and colloidal aluminium phosphate (207 mg P l −1). Phosphate solubilisation was generally higher when ammonium rather than nitrate was the sole source of N. Soluble phosphate concentrations in the culture medium were directly proportional to the titratable acidity and organic acid (principally gluconic acid) concentration and inversely related to pH. The main mechanism for phosphate solubilisation was acid production leading to a decrease in pH. Evidence from an abiotic study using HCl and gluconic acid to solubilise P also indicated that chelation of Al 3+ by gluconic acid may have been a factor in the solubilisation of colloidal aluminium phosphate.

Chemiluminescence Determination of Gluconic Acid in Pharmaceutical Formulations using Ru(bipy)3 2+ – KIO4 – Ce(IV) System

ABSTRACT A new chemiluminescence method for determination of gluconic acid is described. The method is based on the chemiluminescence reaction of gluconic acid with KlO4, Ru(bipy)3 2+ (bipy=2,2'-pyridyl) and Ce(IV) in sulfuric acid medium. Under the optimum conditions, the concentration of gluconic acid is proportional to the CL intensity in the range of 7.6x10−8 ˜1.5x10−5 mol/L. The limit of detection is 1.5x10−8 mol/L and the relative standard deviation is 3.5% for 5.0x10−7 mol/L gluconic solution (n=11). The method is relatively free from interferences from common excipients and co-existing drugs and has been successfully applied to the analysis of gluconic acid in pharmaceutical formulations.

Optimising glucose conversion in the production of reduced alcohol wine using glucose oxidase

The use of a glucose oxidase (GOX)-catalase enzyme system for the production of reduced-alcohol white wine is investigated. The process reduces alcohol potential by converting glucose to gluconic acid. Trials were conducted with grape juice and model solution to determine key factors affecting the activity of the GOX system, and to optimise the process for use with grape juice. Under our processing conditions, the low pH of grape juice was found to be a dominant limiting factor in the rate and extent of glucose conversion by GOX. An optimised process for glucose conversion (up to 87%) was developed after investigation of the effects of enzyme dosage, sparging, aeration and mixing rates, and temperature. Maximum GOX activity was observed during the first 4 to 6h of treatment, after which a significant decrease in the rate of gluconic acid formation and glucose degradation occurred. An expected increase in titratable acidity and concurrent decrease in pH during GOX treatment was also observed, and is attributable to an increase in the juice gluconic acid concentration of ca 73g/l.

Solubilization of zinc phosphate by a strain of Pseudomonas fluorescens isolated from a forest soil

A strain of Pseudomonas fluorescens, able to solubilize zinc phosphate, was isolated from a forest soil. Colonies of the microorganism produced clear haloes on solid medium incorporating zinc phosphate, but only when glucose was provided as the carbon source. Solubilization of zinc phosphate occurred by both an increase in the H+ concentration of the medium, probably a consequence of ammonia assimilation, and the production of gluconic acid. High concentrations of gluconic acid were produced when P. fluorescens 3a was cultured in the presence of zinc phosphate. Although under some conditions gluconic acid is purportedly able to solubilize metals by the formation of chelates, no evidence of zinc chelation was obtained in our experiments. Furthermore, the increased Zn2+ concentration caused by the solubilization process resulted in the manifestation of toxic effects on the culture. A sample of the culture, sonicated to disrupt cells, still possessed the ability to produce gluconic acid from glucose, in the presence and absence of zinc phosphate. The lack of gluconic acid overproduction in cultures of P. fluorescens 3a which were not amended with zinc phosphate suggests that at least some of the glucose oxidation required for the zinc solubilization occurred as a result of the toxic stress caused by the high Zn2+ concentration.

Biotransformation of glucose to free gluconic acid by Gluconobacter oxydans: substrate and product inhibition situtations

Microbial oxidation of glucose to free gluconic acid by Gluconobacter oxydans batch cultures was studied with a special reference to substrate and product inhibition. Process kinetics were evaluated by comparing different inhibition models. Substrate inhibition can be best described by the equation of Tseng and Wayman predicting linear inhibition of growth above a characteristic threshold glucose concentration. Non-linear inhibition kinetics was observed, however, for product inhibition and the model of Levenspiel was found to fit the experimental data. The biokinetic model parameters, productivities and conversion degrees on media with different glucose and gluconic acid concentrations were calculated and compared regarding the principal limits of process efficiency. Probable mechanisms of inhibition and possible techniques for their minimization are also discussed.

Optimization of the growth parameters of Aspergillus foetidus

AbstractThe batch production of gluconic acid in the presence of glucose, sucrose and molasses was investigated using free mycelia of Aspergillus foetidus NRRL 337 in shake flasks. Eight growth parameters were chosen as independent variables. The temperature, pH, substrate type and initial concentrations, inoculum percentage and shake rate directly affected the specific microorganism growth and gluconic acid production rates. The optimum temperature and initial pH values were found to be 33°C and five to six, respectively. The maximum specific growth and gluconic acid production rates were established as 57 g/dm3 of glucose, 75 g/dm3 of sucrose and 150 g/dm3 of molasses. The optimum values of the shake rate, inoculum percentage and initial ammonium nitrate concentration were determined as 100 1/min, 0.5% and 1.5 g/dm3, respectively. The maximum gluconic acid concentrations corresponding to these initial substrate concentrations were observed to be 8.3 g/dm3, 17.4 g/dm3 37.0 g/dm3, respectively. The optimum specific microbial growth and gluconic acid production rates were found as 0.0145 1/h and 0.0375 g/g × h, respectively, for the fermentation conditions of SGo = 57 g/dm3, T = 28°C, initial pH = 6.5, N = 84 1/min, A = 0.5 g/dm3 and I = 0.5%.