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Assessment of the efficiency of U-tube continuous bioreactor and immobilized enzyme beads for dye decolourization.

ABSTRACT: Two bioreactors (column and U-tube) were compared for continuous dye decolourization efficiency using a laccase-producing white rot fungus, Phlebia radiata. Column bioreactor containing immobilized crude enzyme beads and U-tube continuous bioreactor containing actively growing fungal biomass were established. Synthetic dye (coracryl blue C5G) solution treated with immobilized crude enzyme on alginate beads showed a maximum net decolourization up to 55% (flow rate 1 ml/min). The U-tube bioreactor was more efficient in decolorizing the dye, which showed a net decolourization up to 64% at faster flow rate (2.5 ml/min). The decolorization efficiency in both the systems was positively influenced by the slower flow rate. Thus, the study presents designing and operations of two continuous small-scale bioreactors one with immobilized enzyme while the another one with direct fungal contact.

SUBMITTER: Sharma RK

PROVIDER: S-EPMC5938218 | biostudies-literature | 2018 May

REPOSITORIES: biostudies-literature

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Assessment of the efficiency of U-tube continuous bioreactor and immobilized enzyme beads for dye decolourization.

Sharma Rakesh Kumar RK Sharma Richa R Arora Daljit Singh DS

3 Biotech 20180507 5

Two bioreactors (column and U-tube) were compared for continuous dye decolourization efficiency using a laccase-producing white rot fungus, <i>Phlebia radiata</i>. Column bioreactor containing immobilized crude enzyme beads and U-tube continuous bioreactor containing actively growing fungal biomass were established. Synthetic dye (coracryl blue C5G) solution treated with immobilized crude enzyme on alginate beads showed a maximum net decolourization up to 55% (flow rate 1 ml/min). The U-tube bio ...[more]

PMID: 29744273

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Project description:Recent advances in nanocellulose technology have revealed the potential of crystalline cellulose nanofibers to reinforce materials which are useful for tissue engineering, among other functions. However, the low biodegradability of nanocellulose can possess some problems in biomedical applications. In this work, alginate particles with encapsulated enzyme cellulase extracted from Trichoderma reesei were prepared for the biodegradation of crystalline cellulose nanofibers, which carrier system could be incorporated in tissue engineering biomaterials to degrade the crystalline cellulose nanoreinforcement in situ and on-demand during tissue regeneration. Both alginate beads and microparticles were processed by extrusion-dropping and inkjet-based methods, respectively. Processing parameters like the alginate concentration, concentration of ionic crosslinker Ca2+, hardening time, and ionic strength of the medium were varied. The hydrolytic activity of the free and encapsulated enzyme was evaluated for unmodified (CNFs) and TEMPO-oxidized cellulose nanofibers (TOCNFs) in suspension (heterogeneous conditions); in comparison to solubilized cellulose derivatives (homogeneous conditions). The enzymatic activity was evaluated for temperatures between 25-75 °C, pH range from 3.5 to 8.0 and incubation times until 21 d. Encapsulated cellulase in general displayed higher activity compared to the free enzyme over wider temperature and pH ranges and for longer incubation times. A statistical design allowed optimizing the processing parameters for the preparation of enzyme-encapsulated alginate particles presenting the highest enzymatic activity and sphericity. The statistical analysis yielded the optimum particles characteristics and properties by using a formulation of 2% (w/v) alginate, a coagulation bath of 0.2 M CaCl2 and a hardening time of 1 h. In homogeneous conditions the highest catalytic activity was obtained at 55 °C and pH 4.8. These temperature and pH values were considered to study the biodegradation of the crystalline cellulose nanofibers in suspension. The encapsulated cellulase preserved its activity for several weeks over that of the free enzyme, which latter considerably decreased and practically showed deactivation after just 10 d. The alginate microparticles with their high surface area-to-volume ratio effectively allowed the controlled release of the encapsulated enzyme and thereby the sustained hydrolysis of the cellulose nanofibers. The relative activity of cellulase encapsulated in the microparticles leveled-off at around 60% after one day and practically remained at that value for three weeks.

Project description:The lipase from Pseudomonas fluorescens (PFL) has been immobilized on octyl-agarose beads under 16 different conditions (varying pH, ionic strength, buffer, adding some additives) at two different loadings, 1 and 60 mg of enzyme/g of support with the objective of check if this can alter the biocatalyst features. The activity of the biocatalysts versus p-nitrophenyl butyrate and triacetin and their thermal stability were studied. The different immobilization conditions produced biocatalysts with very different features. Considering the extreme cases, using 1 mg/g preparations, PFL stability changed more than fourfolds, while their activities versus pNPB or triacetin varied a 50-60%. Curiously, PFL specific activity versus triacetin was higher using highly enzyme loaded biocatalysts than using lowly loaded biocatalysts (even by a twofold factor). Moreover, stability of the highly loaded preparations was higher than that of the lowly loaded preparations, in many instances even when using 5°C higher temperatures (e.g., immobilized in the presence of calcium, the highly loaded biocatalysts maintained after 24 h at 75°c a 85% of the initial activity, while the lowly loaded preparation maintained only 27% at 70°C). Using the highly loaded preparations, activity of the different biocatalysts versus pNPB varied almost 1.7-folds and versus triacetin 1.9-folds. In this instance, the changes in stability caused by the immobilization conditions were much more significant, some preparations were almost fully inactivated under conditions where the most stable one maintained more than 80% of the initial activity. Results suggested that immobilization conditions greatly affected the properties of the immobilized PFL, partially by individual molecule different conformation (observed using lowly loaded preparations) but much more relevantly using highly loaded preparations, very likely by altering some enzyme-enzyme intermolecular interactions. There is not an optimal biocatalyst considering all parameters. That way, preparation of biocatalysts using this support may be a powerful tool to tune enzyme features, if carefully controlled.

Dataset Information

Assessment of the efficiency of U-tube continuous bioreactor and immobilized enzyme beads for dye decolourization.

Publications

Assessment of the efficiency of U-tube continuous bioreactor and immobilized enzyme beads for dye decolourization.

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