Effect of physicochemical characteristics of cellulosic substrates on enzymatic hydrolysis by means of a multi-stage process for cellobiose production

in Applied Biochemistry and Biotechnology (2012), 166(6), 1423-1432

The effect of two types of cellulose, microcrystalline cellulose and paper pulp, on enzymatic hydrolysis for cellobiose production was investigated. The particle size, the relative crystallinity index and ... [more ▼]

The effect of two types of cellulose, microcrystalline cellulose and paper pulp, on enzymatic hydrolysis for cellobiose production was investigated. The particle size, the relative crystallinity index and the water retention value were determined for both celluloses. A previously studied multistage hydrolysis process that proved to enhance the cellobiose production was studied with both types of celluloses. The cellobiose yield exhibited a significant improvement (120% for the microcrystalline cellulose and 75% for the paper pulp) with the multistage hydrolysis process compared to continuous hydrolysis. The conversion of cellulose to cellobiose was greater for the microcrystalline cellulose than for the paper pulp. Even with high crystallinity, microcrystalline cellulose achieved the highest cellobiose yield probably due to its highest specific surface area accessible to enzymes and quantity of adsorbed protein. [less ▲]

Effect of Additives on Freeze-Drying and Storage of Yarrowia lipolytica Lipase.

in Applied Biochemistry and Biotechnology (2012)

The extracellular lipase of Yarrowia lipolytica presents numerous potentialities for biotechnological applications. This work describes the development and storage of powders obtained from supernatants ... [more ▼]

The extracellular lipase of Yarrowia lipolytica presents numerous potentialities for biotechnological applications. This work describes the development and storage of powders obtained from supernatants containing Y. lipolytica lipase by freeze-drying as downstream process that is important in obtaining a stable lipase powder with high enzymatic activity. Lipase was produced by Y. lipolytica U6 mutant strain in 20-L bioreactor. Non-concentrated cell-free culture supernatant samples were supplemented with different concentrations (0.5-1 %) of maltodextrin and glycerol as additives to freeze-drying. Effects of additives, temperature, pH, and storage time on lipase powders were determined. After addition of additives, freeze-drying yield increased 3.5-fold compared to supernatant without additive. Maltodextrin with 0.5 % concentration gave the best protection of lipase during dehydration treatment and its freeze-drying yield (77 %) is better than other formulations. Lipase powders were stored at 4 and 25 degrees C for 46 weeks without loss of lipase activity. A common impediment to the production of commercial enzyme is their low-stability aqueous solutions. The present study shows that freeze-dried lipase powders of Y. lipolytica have good stability for storage and various applications. [less ▲]

The utilization of gum tragacanth to improve the growth of Rhodotorula aurantiaca and the production of γ-decalactone in large scale

in Applied Biochemistry and Biotechnology (2009)

The production of γ-decalactone and 4-hydroxydecanoic acid by the psychrophilic yeast R. aurantiaca was studied. The effect of both compounds on the growth of R. aurantiaca was also investigated and our ... [more ▼]

The production of γ-decalactone and 4-hydroxydecanoic acid by the psychrophilic yeast R. aurantiaca was studied. The effect of both compounds on the growth of R. aurantiaca was also investigated and our results show that γ-decalactone must be one of the limiting factors for its production. The addition of gum tragacanth to the medium at concentrations of 3 and 4 g/l seems to be an adequate strategy to enhance γ-decalactone production and to reduce its toxicity towards the cell. The production of γ-decalactone and 4- hydroxydecanoic acid was significantly higher in 20-l bioreactor than in 100-l bioreactor. By using 20 g/l of castor oil, 6.5 and 4.5 g/l of γ-decalactone were extracted after acidification at pH 2.0 and distillation at 100 °C for 45 min in 20- and 100-l bioreactors, respectively. We propose a process at industrial scale using a psychrophilic yeast to produce naturally γ-decalactone from castor oil which acts also as a detoxifying agent; moreover the process was improved by adding a natural gum. [less ▲]

Xylanase Production by Penicillium canescens on Soya Oil Cake in Solid-State Fermentation.

in Applied biochemistry and biotechnology (2009), (2),

There is an increasing interest for the organic residues from various sectors of agriculture and industries over the past few decades. Their application in the field of fermentation technology has ... [more ▼]

There is an increasing interest for the organic residues from various sectors of agriculture and industries over the past few decades. Their application in the field of fermentation technology has resulted in the production of bulk chemicals and value-added products such as amino acid, enzymes, mushroom, organic acids, single-cell protein, biologically active secondary metabolites, etc. (Ramachandran et al., Bioresource Technology 98:2000–2009, 2007). In this work, the production of extracellular xylanase by the fungus Penicillium canescens was investigated in solid-state fermentation using five agro-industrial substrates (soya oil cake, soya meal, wheat bran, whole wheat bran, and pulp beet). The best substrate was the soya oil cake. In order to optimize the production, the most effective cultivation conditions were investigated in Erlenmeyer flasks and in plastic bags with 5 and 100 g of soya oil cake, respectively. The initial moisture content, initial pH, and temperature of the culture affected the xylanase synthesis. The optimal fermentation medium was composed by soya oil cake crushed to 5 mm supplemented with 3% and 4% (w/w) of casein peptone and Na2HPO4.2H2O. After 7 days of incubation at 30 °C and under 80% of initial moisture, a xylanase production level of 18,895±778 U/g (Erlenmeyer flasks) and 9,300± 589 U/g (plastic bags) was reached. The partially purified enzyme recovered by ammonium sulfate fractionation was completely stable at freezing and refrigeration temperatures up to 6 months and reasonably stable at room temperature for more than 3 months. [less ▲]

Study on mass transfer of isopropylbenzene and oxygen in a two-phase partitioning bioreactor in the presence of silicone oil.

in Applied Biochemistry and Biotechnology (2009), 153

A two-phase partitioning bioreactor (TPPB) to treat gas effluents polluted by volatile organic compound (VOC) has been developed. In this work, both the mass transfer of isopropylbenzene (IPB) and oxygen ... [more ▼]

A two-phase partitioning bioreactor (TPPB) to treat gas effluents polluted by volatile organic compound (VOC) has been developed. In this work, both the mass transfer of isopropylbenzene (IPB) and oxygen have been considered in relation to their influence on the hydrodynamics of the reactor and the type of silicone oils used as a second phase. The synergistic effect of silicone oil and stirrer speed on the global oxygen mass transfer coefficient (KLa) and gas-hold-up (up to 12%) have been investigated. The addition of 10% of low viscosity silicone oil (10 centistokes) in the reactor does not significantly affect the oxygen transfer rate. The very high solubility of IPB in the silicone oil leads to an enhancement of driving force term, especially for high fraction of silicone oil. However, it does not seem useful to exceed a volume fraction of 10% since KLaIPB decreases sharply at higher proportions of silicone oil. KLaIPB and KLa O2 evolve in the same way with the proportion of silicone oil. These results confirm the potentialities of our bioreactor to improve both the oxygen and pollutant gas transfer in the field of the treatment of gaseous pollutants, even for highly concentrated effluents. [less ▲]

Solid-state fermentation of xylanase from Penicillium canescens 10-10c in a multi-layer packed bed reactor

in Applied Biochemistry and Biotechnology (2008), 145

THE TWO-PHASE BIOREACTOR WATER / SILICON - OIL : PROSPECTS IN THE OFF- GAS TREATMENT

in Applied Biochemistry and Biotechnology (2005), 122(1-3), 707-719

ABSTRACT: A research was carried out to develop a biphasic biological reactor able to clean the gas effluents polluted by volatile organic compounds (V.O.C). Initially, Rhodococcus erythropolis T 902.1 ... [more ▼]

ABSTRACT: A research was carried out to develop a biphasic biological reactor able to clean the gas effluents polluted by volatile organic compounds (V.O.C). Initially, Rhodococcus erythropolis T 902.1 had been selected on the basis of its capacity to degrade isopropyl-benzene (IPB). The effect of gas flow and IPB concentration on the biodegadation of IPB was evaluated. The results show that the use of silicon-oil allows large quantities of IPB to be absorbed within the medium of biological abatement. On the other hand, the biodegradation rate is directly correlated to the inlet flow of IPB. Thus, the reactor presents interesting opportunities in the biological treatment of gas effluents. [less ▲]

Estimation of bioreactor efficiency through structured hydrodynamic modeling case study of a Pichia pastoris fed-batch process.

in Applied Biochemistry and Biotechnology (2005), 121-124

In this article, two theories are unified to investigate the effect of hydrodynamics on a specific bioprocess: the network-of-zones (NOZ) hydrodynamic structured modeling approach (developed by several ... [more ▼]

In this article, two theories are unified to investigate the effect of hydrodynamics on a specific bioprocess: the network-of-zones (NOZ) hydrodynamic structured modeling approach (developed by several researchers but applied to only a few bioprocesses) and the effectiveness factor eta approach. Two process scales were investigated (20 and 500 L), and for each, hydrodynamics were quantified using an NOZ validated by homogeneity time measurements. Several impeller combinations inducing quite different hydrodynamics were tested at the 20-L scale. After this step, effectiveness factors were determined for each fermentation run. To achieve this, a perfectly mixed microbial kinetic model was evaluated by using simple Monod kinetics with a fed-batch mass balance. This methodology permitted determination of the effectiveness factor with more accuracy because of the relation with the perfect case deduced from the Monod kinetics. It appeared that for the small scale, eta decreased until reaching a value of approx 0.7 (30% from the ideal case) for the three impeller systems investigated. However, stirring systems that include hydrofoils seemed to maintain higher effectiveness factors during the course of the fermentation. This effect can be attributed to oxygen transfer performance or to homogenization efficiency exhibited by the hydrofoils. To distinguish the oxygen transfer from the homogenization component of the effectiveness factor, these phenomena were analyzed separately. After determining the evolution of etaO2 linked to oxygen transfer for each of the fermentation runs, the NOZ model was employed to quantify substrate gradient appearance. After this step, another effectiveness factor, etamix, related to mixing was defined. Consequently, it is possible to distinguish the relative importance of the mixing effect and oxygen transfer on a given bioprocess. The results have highlighted an important scale effect on the bioprocess that can be analyzed using the NOZ model. [less ▲]

Xylanase Production By Penicillium Canescens 10-10c In Solid-State Fermentation

in Applied Biochemistry and Biotechnology (2003), 105

Purification and characterization of a microbial dehydrogenase - A vanillin : NAD(P)(+) oxidoreductase

in Applied Biochemistry and Biotechnology (2002), 98-100(Spring), 415-428

Pseudomonas fluorescens (strain BTP9) was found to have at least two NAD(P)-dependent vanillin dehydrogenases: one is induced by vanillin, and the other is constitutive. The constitutive enzyme was ... [more ▼]

Pseudomonas fluorescens (strain BTP9) was found to have at least two NAD(P)-dependent vanillin dehydrogenases: one is induced by vanillin, and the other is constitutive. The constitutive enzyme was purified by ammonium sulfate fractionation, gel-filtration, and Q-Sepharose chromatography. The subunit Mr value was 55,000, determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The native M, value estimated by gel-filtration chromatography gave a value of 210,000. The enzyme made use of NAD(+) less effectively than NADP(+). Benzaldehyde, 4-hydroxybenzaldehyde, hexanal, and acetaldehyde were not oxidized at detectable rates in the presence of NAD(+) or NADP(+). The ultraviolet absorption spectrum indicated that there is no cofactor or prosthetic group bound. The vanillin oxidation reaction was essentially irreversible. The pH optimum was 9.5 and the pI of the enzyme was 4.9. Enzyme activity was not affected when assayed in the presence of salts, except FeCl2. The enzyme was inhibited by the thiol-blocking reagents 4-chloromercuribenzoate and N-ethylmaleimide. NAD(+) and NADP(+) protected the enzyme against such a type of inhibition along with vanillin to a lesser extent. The enzyme exhibited esterase activity with 4-nitrophenyl acetate as substrate and was activated by low concentrations of NAD(+) or NADP(+). We compared the properties of the enzyme with those of some well-characterized microbial benzaldehyde dehydrogenases. [less ▲]