Immobilization of bakers yeast on jute fabric through adhesion using polyethylenimine: application in an annular column reactor for the inversion of sucrose

One-pot green synthesis of eumelanin: process optimization and its characterization

Herein, we propose the importance of Taguchi’s design of experiment methodology for increasing the yield of eumelanin using l-Dopa as the substrate and tyrosinase enzyme from Amorphophallus campanulatus as the biocatalyst.

Highly efficient production of inverted syrup in an analytical column with immobilized invertase

This paper presents a procedure by which a simple and economical analytical column containing immobilized invertase was developed. This column has high efficiency of converting sucrose into inverted syrup rapidly. Gelatine beads were used for the immobilization of invertase. The enzyme was entrapped efficiently and was found to be stable and retained its activity over a period of 3 months. Immobilization parameters for maximum enzyme activity were estimated as temperature optima at 60 °C, pH optima 7.0 and 30 mg/mL enzyme concentration was found to give maximum immobilization (72 %). The reusability of the gelatine immobilized invertase was found to be seven times with a time interval of 24 h. The immobilized invertase presented a KM of 51.28 mM and Vmax of 0.334 mM/min. The time required to hydrolyse 50 % sucrose solution by a column of length 10 cm and diameter of 1.5 cm was found to be 15 min at room temperature. The column was found effective for inversion of biological samples like sugar cane juice.

Denitrification of high nitrate wastewater in a cloth strip bioreactor with immobilized sludge

Denitrification of synthetic high nitrate wastewater containing 40,000 ppm NO(3) (9,032 ppm NO(3)-N) was achieved using immobilized activated sludge in a column reactor. Active anoxic sludge adsorbed onto Terry cloth was used in the denitrification of high nitrate wastewater. The operational stability of the immobilized sludge system was studied both in a batch reactor and in a continuous reactor. The immobilized sludge showed complete degradation of different concentrations of NO(3)-N (1,129, 1,693, 3,387, 6,774, and 9,032 ppm) in a batch process. The reactors were successfully run for 90 days without any loss in activity. The immobilized cell process has yielded promising results in attaining high denitrifying efficiency.

Enhanced growth of lactobacilli in soymilk upon immobilization on agrowastes

Cell immobilization is an alternative to microencapsulation for the maintenance of cells in a liquid medium. The objective of this study was to evaluate the effects of agrowastes from durian (Durio zibethinus), cempedak (Artocarpus champeden), and mangosteen (Garcinia mangostana) as immobilizers for lactobacilli grown in soymilk. Rinds from the agrowastes were separated from the skin, dried, and ground (150 microm) to form powders and used as immobilizers. Scanning electron microscopy revealed that lactobacilli cells were attached and bound to the surface of the immobilizers. Immobilized cells of Lactobacillus acidophilus FTDC 1331, L. acidophilus FTDC 2631, L. acidophilus FTDC 2333, L. acidophilus FTDC 1733, and L. bulgaricus FTCC 0411 were inoculated into soymilk, stored at room temperature (25 degrees C) and growth properties were evaluated over 168 h. Soymilk inoculated with nonimmobilized cells was used as the control. Utilization of substrates, concentrations of lactic and acetic acids, and changes in pH were evaluated in soymilk over 186 h. Immobilized lactobacilli showed significantly better growth (P < 0.05) compared to the control, accompanied by higher production of lactic and acetic acids in soymilk. Soymilk containing immobilized cells showed greater reduction of soy sugars such as stachyose, raffinose, sucrose, fructose, and glucose compared to the control (P < 0.05).

Covalent immobilization of invertase on polyurethane, plast-film and ferromagnetic Dacron

Invertase was covalently immobilized on polyurethane (PU), inox plate covered with plast-film layer and ferromagnetic azide-Dacron. The immobilization processes, physico-chemical parameters and a model for coupling reactions were studied. The preliminary studies for selection of the support showed that the best activity was obtained for PU treated with HCl, polyethylenimine and glutaraldehyde (156.7+/-4.9 U/g support). All plast-film-invertase derivatives did not show activity and the Dacron-invertase derivative showed an activity of 105.39 U/g support. The invertase immobilized in presence of substrate (10% w/v sucrose) was the most efficient (832.74+/-1.48 U/g support). The optimal pH was shifted from 4.5 (free enzyme) to 5.0 (immobilized derivative) and optimal temperature was not affected. Activation energy values of free enzyme, Dacron-invertase and PU-invertase were 32.4+/-0.34 kJ/mol, 33.4+/-0.36 kJ/mol and 44.0+/-0.67 kJ/mol, respectively. The PU-invertase could be used over 2 months without considerable activity loss (68.5% activity retention) and retained 12.6% (287.97+/-27.9U/g support) of the activity after five cycles.

Immobilization of bioluminescent Escherichia coli cells using natural and artificial fibers treated with polyethyleneimine

Biosensors based on whole-cell bioluminescence have the potential to become a cost-effective alternative to conventional detection methods upon validation of target selectivity and sensitivity. However, quantitative analysis of bioluminescence is greatly hindered due to lack of control over the total number of cells in a suspending culture. In this study, the effect of surface properties of genetically engineered luminous E. coli cells and fibrous matrices on the immobilization capacity and effectiveness under various environmental conditions were characterized. Four different fibers, including cotton, polyester, viscose rayon, and silk, were investigated. Although cell adhesion was observed on untreated viscose and cotton fibers, viscose fiber pretreated with 0.667% polyethyleneimine (PEI) was found capable of immobilizing the most viable E. coli DPD2234 cells, followed by viscose treated with 0.33% and 1% PEI. The cells immobilized on PEI-treated viscose remained viable and yielded 20% or more bioluminescence signals immediately upon contact with the inducer up to 72 h without feeding nutrients to the cells, suggesting that viscose treated with 0.667% PEI could provide a stable immobilization mechanism for bioluminescent E. coli cells with long sensing period, quick response time, and good signal reproducibility.

Bioprocess for solubilization of rock phosphate on starch based medium by Paecilomyces marquandii immobilized on polyurethane foam

Paecilomyces marquandii, a phosphate-solubilizing, starch-utilizing filamentous fungus, was immobilized on polyurethane foam (PUF). The immobilized fungus was applied in a repeated batch (six batches) fermentation process to solubilize Hirapur rock phosphate. The fungus was immobilized on PUF cubes and was used for phosphate solubilization in shake flask repeated batch cultivations. The fungus was also immobilized on PUF sheet and utilized in an airlift bioreactor in a repeated batch process. Maximum soluble phosphate (370 microg/ml) was recorded after third batch with 8 g rock phosphate/l. After 12 days of fermentation, a total production of 1,643 microg phosphate/ml was achieved.

Immobilization of recombinant invertase (re-INVB) from Zymomonas mobilis on D-sorbitol cinnamic ester for production of invert sugar

The recombinant invertase (re-INVB) from Zymomonas mobilis was immobilized by adsorption onto the totally cinnamoylated derivative of D-sorbitol. The polymerization and cross-linking of the derivative initially obtained was achieved by irradiation in the ultraviolet region, where this prepolymer shows maximum sensitivity. Immobilization of re-INVB on this support involves a process of physical adsorption and intense hydrophobic interactions between the cinnamoyl groups of the support and related groups of the enzyme. Enzyme concentration, immobilization time, and irradiation time were important parameters affecting the immobilization efficiency. The optimum reaction pH of immobilized enzyme was 5, and the optimal reaction temperature was 40 degrees C. The apparent Michaelis constant and the apparent catalytic constant of re-INVB immobilized on the SOTCN derivative acting on sucrose was 78+/-5 mM and 5x10(4)+/-3x10(2) s(-1), respectively, while for the free enzyme, it was 98.0+/-4 mM and 1.2x10(4)+/-2.5x10(2) s(-1), respectively, suggesting a better apparent affinity of the enzyme for the substrate and a better hydrolysis rate when immobilized than when in solution. Immobilized re-INVB also showed good thermal stability and good operational stability (40% of the initial activity remaining after 45 cyles of 1 min duration and 90.6 mg of sucrose being hydrolyzed in 45 min per 2.5 mg of immobilized protein). The results showed that cinnamic carbohydrate esters of D-sorbitol are an appropriate support for re-INVB immobilization and the production of invert sugar.

Research and application of microbial enzymes--India's contribution

Enzymes have attracted the attention of scientists world over due to their wide range of physiological, analytical and industrial applications. Although enzymes have been isolated, purified and studied from microbial, animal and plant sources, microorganisms represent the most common source of enzymes due to their broad biochemical diversity, feasibility of mass culture and ease of genetic manipulation. With the advent of molecular biology techniques, a number of genes of industrially important enzymes has been cloned and expressed in order to improve the production of enzymes, substrate utilization and other commercially useful properties. Special attention has been focused on enzymes isolated from thermophiles due to their inherent stability and industrial applications. In addition, a variety of methods have been employed to modify enzymes for their industrial usage including strain improvement, chemical modifications, modification of reaction environment, immobilization and protein engineering. A wide range of applications of enzymes in different bioprocess industries is discussed.

A cloth strip bioreactor with immobilized glucoamylase

Glucoamylase was immobilized on polyethylenimine (PEI)-coated cotton cloth by adsorption followed by cross-linking with 0.2% glutaraldehyde in the presence of starch. Optimal adsorption of the enzyme was seen when cloth treated with 2% PEI was contacted with the enzyme for 50 min. pH and temperature optima profiles were not changed appreciably on immobilization. However, the bound enzyme exhibited a higher thermal stability. The enzyme-bound cloth strips were used in a specially designed bioreactor for the continuous hydrolysis of starch. The reactor could be operated for over 21 days retaining about 70% of the original activity. An operational temperature of 45 degrees C was found to be optimal.