Continuous gluconic acid production by Aureobasidium pullulans with and without biomass retention (original) (raw)
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Continuous gluconic acid production 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.
Gluconic acid, the oxidation product of glucose, is a mild neither caustic nor corrosive, non toxic and readily biodegradable organic acid of great interest for many applications. As a multifunctional carbonic acid belonging to the bulk chemicals and due to its physiological and chemical characteristics, gluconic acid itself, its salts (e.g. alkali metal salts, in especially sodium gluconate) and the gluconolactone form have found extensively versatile uses in the chemical, pharmaceutical, food, construction and other industries. Present review article presents the comprehensive information of patent bibliography for the production of gluconic acid and compares the advantages and disadvantages of known processes. Numerous manufacturing processes are described in the international bibliography and patent literature of the last 100 years for the production of gluconic acid from glucose, including chemical and electrochemical catalysis, enzymatic biocatalysis by free or immobilized enzymes in specialized enzyme bioreactors as well as discontinuous and continuous fermentation processes using free growing or immobilized cells of various microorganisms, including bacteria, yeast-like fungi and fungi. Alternatively, new superior fermentation processes have been developed and extensively described for the continuous and discontinuous production of gluconic acid by isolated strains of yeast-like mold Aureobasidium pullulans, offering numerous advantages over the traditional discontinuous fungi processes.
Biotechnological production of gluconic acid: future implications
Applied Microbiology and Biotechnology, 2007
Gluconic acid (GA) is a multifunctional carbonic acid regarded as a bulk chemical in the food, feed, beverage, textile, pharmaceutical, and construction industries. The favored production process is submerged fermentation by Aspergillus niger utilizing glucose as a major carbohydrate source, which accompanied product yield of 98%. However, use of GA and its derivatives is currently restricted because of high prices: about US$ 1.20–8.50/kg. Advancements in biotechnology such as screening of microorganisms, immobilization techniques, and modifications in fermentation process for continuous fermentation, including genetic engineering programmes, could lead to cost-effective production of GA. Among alternative carbohydrate sources, sugarcane molasses, grape must show highest GA yield of 95.8%, and banana must may assist reducing the overall cost of GA production. These methodologies would open new markets and increase applications of GA.
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 h) 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.
Production of gluconic acid from glucose by Aspergillus niger: growth and non-growth conditions
Process Biochemistry, 2004
Batch fermentation of glucose to gluconic acid was conducted using Aspergillus niger under growth and non-growth conditions using pure oxygen and air as a source of oxygen for the fermentation in 2 and 5 l stirred tank reactors (batch reactor). Production of gluconic acid under growth conditions was conducted in a 5 l batch reactor. Production and growth rates were higher during the period of supplying pure oxygen than that during supplying air, and the substrate consumption rate was almost constant. For the production of gluconic acid under non-growth conditions, conducted in the 2 l batch reactor, the effect of the pure oxygen flow rate and the biomass concentration on the gluconic acid production was investigated and an empirical equation suggested to show the dependence of the production rate r p on the biomass concentration C x and oxygen flow rate Q, at constant operating conditions (30 • C, 300 rpm and pH 5.5). Biomass concentration had a positive effect on the production rate r p , and the effect of Q on r p was positive at high biomass concentrations.
Production of free gluconic acid by cells ofGluconobacter oxydans
Biotechnology Letters, 1994
Microbial oxidation of glucose to free gluconic acid by growing G.oxyduns batch cultures was investigated. Kinetic data for the discussed process were obtained and attention was paid mainly to the influence of the initial glucose concentration and of the conversion degree on the course of the process. It was determined that relatively high maximum specific growth rates of about 0,39 h-l and gluconic acid volumetric productivities up to 53 mmol/h could be reached using G.oxyduns NBIMCC 1043 in nuts without pH control. A maximum conversion degree of 90,4 % was achieved.
Gluconic acid production under varying fermentation conditions byAspergillus niger
Journal of Chemical Technology and Biotechnology, 2003
The production of gluconic acid with respect to varying substrate concentrations in submerged (SmF), semisolid-state (SmSF), surface (SF), and solid-state surface (SSF) fermentations was analyzed. Under the various fermentation conditions the biomass and specific growth rate varied with different concentrations of glucose. The highest level of gluconic acid (106.5 g dm−3) with 94.7% yield was obtained under SSF conditions. In all cases the maximum degree of gluconic acid conversion was observed at on initial substrate concentration of 120 g dm−3. The rate of glucose uptake increased on increasing the initial glucose concentration and glucose utilization was observed to be highest (89–94%) in the SmSF process and was comparable with the SSF and SF processes. The maximum rate of cell growth was obtained in all processes at an initial glucose concentration of 120 g dm−3. The gluconic acid production and change in pH were analyzed at varying time intervals and it was observed that the SmF and SmSF processes were completed within 6 days of incubation whereas the highest yield was observed after 12 days of incubation and continued thereafter in the SSF process.© 2003 Society of Chemical Industry
Gluconic acid: Properties, applications and microbial production
Food Technology and Biotechnology
Gluconic acid is a mild organic acid derived from glucose by a simple oxidation reaction. The reaction is facilitated by the enzyme glucose oxidase (fungi) and glucose dehydrogenase (bacteria such as Gluconobacter). Microbial production of gluconic acid is the preferred method and it dates back to several decades. The most studied and widely used fermentation process involves the fungus Aspergillus niger. Gluconic acid and its derivatives, the principal being sodium gluconate, have wide applications in food and pharmaceutical industry. This article gives a review of microbial gluconic acid production, its properties and applications.
Amon g the seven isolated mi crobial strai ns from dumping sites of the sugarcane industry was te, a potent funga l strain Aspergilil/s lIiger ORS-4 was selected, th at gave 48 giL of glu co ni c acid wi th 74 per ce nt yield w hen glucose was used as the ca rbon source. Starch hydrol ysa te, molasses and th e banana must were evalu ated as th e cheaper ca rbohydrate sou rces 1 '01' glu co ni c acid production by A lIiger ORS-4 in surface cu lture fermen tati on process. The banana mu st was found to be a bett er source with signi licant glucon ic acid producti on (3 9.6 gi L, 40 per cent yield) aner 12 d incubati on. The untrea ted sugarca ne mo lasses gave margi nal production of gluco ni c acid (2.4 gi L), however, th e produ cti on increased signifi ca ntl y (34. 6 giL, yield 38.5 per cent) after th e molasses were subj ec ted to th e hexacynoferrate (HCF) trea tment. Starch hydro lysate on the other hand , resulted into co mparative prod ucti on (30.2 giL, yield 35.9 per cent) but lower th an th at ob tained with HCF treated mol asses , whereas the acid production was low (10 giL) with unh ydro lyzed starch. Gluconi c acid production from these substrates was comparab le to th at obtained wi th glu cose.