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The discovery of a novel enzyme from a microbial source takes anywhere between months to years, and therefore, there has been an immense interest in modifying the existing microbial enzymes to suit the present day needs of the industry. The redesigning of industrially useful enzymes for improving their performance has become a challenge because bioinformatics databases have been revealing new facts on a day-to-day basis. Modification of the existing enzymes has become a trend for fine tuning of biocatalysts in the biotech industry. Hydrolases are employed in pharmaceutical, biofuel, detergent, food and feed industries that significantly contribute to the global annual revenue, and therefore, the emphasis has been on engineering them. Although a large data is accumulating on making alterations in microbial enzymes, there is a lack of definite information on redesigning industrial enzymes. This review focuses on the recent developments in improving the characteristics of various biotechnologically important enzymes., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

Xylan is the second most abundant polysaccharide after cellulose in the plant organic matter, and it is a linear backbone of β-1, 4-linked D-xylopyranose residues with acetyl, arabinosyl, glucuronosyl, mannosyl, and uronosyl groups in the side chains. The complete hydrolysis of this heteropolymer, thus, requires the synergistic action of several enzymes, among which xylanases play a key role. A wide variety of microorganisms produce xylanolytic enzymes and most of the commercially available xylanases are from mesophiles. Immense interest in xylanases is due to their multiple applications in pulping and bleaching processes, textile processing and food and feed industries, saccharification of lignocellulosic materials to produce bioethanol, and waste treatment. Thermophilic bacteria and fungi are very important sources of thermostable xylanases. [ABSTRACT FROM AUTHOR]

Acidophiles are ecologically and economically important group of microorganisms, which thrive in acidic natural (solfataric fields, sulfuric pools) as well as artificial man-made (areas associated with human activities such as mining of coal and metal ores) environments. They possess networked cellular adaptations to regulate pH inside the cell. Several extracellular enzymes from acidophiles are known to be functional at much lower pH than the cytoplasmic pH. Enzymes like amylases, proteases, ligases, cellulases, xylanases, α-glucosidases, endoglucanases, and esterases stable at low pH are known from various acidophilic microbes. The possibility of improving them by genetic engineering and directed evolution will further boost their industrial applications. Besides biocatalysts, other biomolecules such as plasmids, rusticynin, and maltose-binding protein have also been reported from acidophiles. Some strategies for circumventing the problems encountered in expressing genes encoding proteins from extreme acidophiles have been suggested. The investigations on the analysis of crystal structures of some acidophilic proteins have thrown light on their acid stability. Attempts are being made to use thermoacidophilic microbes for biofuel production from lignocellulosic biomass. The enzymes from acidophiles are mainly used in polymer degradation. [ABSTRACT FROM AUTHOR]

Aims: Whole cell permeabilization of Pichia anomala to ameliorate the cell-bound phytase activity and usability of permeabilized cells in dephytinization of soymilk. Methods and Results: The cells of P. anomala were subjected to permeabilization using the surfactant Triton X-100 to overcome the permeability barrier and prepare whole cell biocatalysts with high phytase activity. The statistical approach, response surface methodology (RSM) was used to optimize the operating conditions for permeabilization. The treatment of cells with 5% Triton X-100 for 30 min resulted in c. 15% enhancement in cell-bound phytase activity. The shrinkage of protoplast was observed, although cell viability and phytase stability were not significantly altered. The free as well as immobilized permeabilized cells hydrolysed soymilk phytate, and the latter could be reused over four consecutive cycles. Conclusions: Whole cell permeabilization of P. anomala using Triton X-100 led to enhancement in cell-bound phytase activity. The viability and integrity of yeast cells were not significantly affected because of permeabilization. The permeabilized P. anomala cells effectively dephytinized soymilk, and the permeabilized cells immobilized in alginate could be reused because of sustained phytase activity. Significance and Impact of the Study: This is the first report on the use of permeabilized yeast cells for mitigating phytate content of soymilk. Alginate entrapment of permeabilized P. anomala allows reuse of cells for soymilk dephytinization, thus suggesting a potential application in food industry. [ABSTRACT FROM AUTHOR]

Aims: Phytase production by Sporotrichum thermophile in a cost-effective cane molasses medium in submerged fermentation and its application in bread. Methods and Results: The production of phytase by a thermophilic mould S. thermophile was investigated using free and immobilized conidiospores in cane molasses medium in shake flasks, and stirred tank and air-lift fermenters. Among surfactants tested, Tweens (Tween-20, 40 and 80) and sodium oleate increased phytase accumulation, whereas SDS and Triton X-100 inhibited the enzyme production. The mould produced phytase optimally at aw 0·95, and it declined sharply below this aw value. The enzyme production was comparable in air-lift and stirred tank reactors with a marked reduction in fermentation time. Among the matrices tried, Ca-alginate was the best for conidiospore immobilization, and fungus secreted sustained levels of enzyme titres over five cycles. The phytic acid in the dough was efficiently hydrolysed by the enzyme accompanied by the liberation of soluble phosphate in the bread. Conclusions: The phytase production by S. thermophile was enhanced in the presence of Tween-80 in cane molasses medium. A peak in enzyme production was attained in 48 h in the fermenter when compared with that of 96 h in shake flasks. Ca-alginate immobilized conidiospores germinated to produce fungal growth that secreted sustained levels of phytase over five cycles. The bread made with phytase contained reduced level of phytic acid and a high-soluble phosphate. Significance and Impact of the Study: The phytase accumulation by S. thermophile was increased by the surfactants. The sustainability of enzyme production in stirred tank and air-lift fermenters suggested the possibility for scaling up of phytase. The bread made with phytase contained low level of antinutrient, i.e. phytic acid. [ABSTRACT FROM AUTHOR]

Abstract: Alginate-entrapped sporangiospores of Thermomucor indicae-seudaticae were used for the production of glucoamylase. The critical variables that affected glucoamylase production were identified by Plackett–Burman design (sucrose, yeast-extract, K2HPO4 and asparagine) and further optimized by using a four factor central composite design (CCD) of response surface methodology (RSM). Immobilized sporangiospores secreted 41% and 60% higher glucoamylase titers in shake flasks and airlift fermenter, respectively, when the variables were used at their optimum levels (sucrose 3.0%, yeast-extract 0.2%, K2HPO4 0.1% and asparagine 0.35%). Glucoamylase production (26.3Uml−1) in the optimized medium was in good agreement with the values predicted by the quadratic model (26.7Uml−1), thereby confirming its validity. The enzyme production was sustainable in flasks of higher volume and also airlift fermenter, and attained a peak within 32h in the fermenter as compared to that of 48h in shake flasks. [Copyright &y& Elsevier]

Abstract: Statistical experimental designs were applied for the optimization of cell-bound phytase production by Pichia anomala in a cost-effective cane molasses medium. Using Plackett–Burman design, cane molasses, urea and inoculum density were identified as significant factors and these factors were subsequently optimized using a central composite design. The optimum variables that supported maximum enzyme titre were 8% cane molasses, 0.4% urea and 2% inoculum density. The validity of the optimized variables was verified in shake-flasks as well as in a laboratory fermenter. An overall 5- and 1.6-fold enhancement in phytase titres (324–1689U/g DYB) and biomass production (6.4–10g/l) were attained due to optimization, respectively. [Copyright &y& Elsevier]

a. vohra and t. satyanarayana. 2004. Formulation of an inexpensive cane molasses medium for improved cell-bound phytase production by Pichia anomala. Cell-bound phytase production by Pichia anomala was compared in synthetic glucose–beef extract and cane molasses media. The yeast was cultivated in 250 ml flasks containing 50 ml of the medium, inoculated with a 12 h-old inoculum (3 × 106 CFU ml−1) and incubated at 25°C for 24 h at 250 rev min−1. Different cultural parameters were optimized in cane molasses medium in batch fermentation. The cell-bound phytase content increased significantly in cane molasses medium (176 U g−1 dry biomass) when compared with the synthetic medium (100 U g−1 dry biomass). In fed-batch fermentation, a marked increase in biomass (20 g l−1) and the phytase yield (3000 U l−1) were recorded in cane molasses medium. The cost of production in cane molasses medium was £0·006 per 1000 U, which is much lower when compared with that in synthetic medium (£0·25 per 1000 U). An overall 86·6% enhancement in phytase yield was attained in optimized cane molasses medium using fed-batch fermentation when compared with that in synthetic medium. Furthermore, the production in cane molasses medium is cost-effective. Phytase yield was improved in cane molasses when compared with the synthetic medium, and the cost of production was also significantly reduced. This enzyme can find application in the animal feed industry for improving the nutritional status of feed and combating environmental pollution. [ABSTRACT FROM AUTHOR]

Pichia anomala, isolated from dried flower buds of Woodfordia fruticosa, produced a high activity of an intracellular phytase, at 68 U per g dry biomass, when grown at 20 °C for 24 h in a medium containing glucose (40 g l-1) and beef extract (10 g l-1) supplemented with Fe2+ (0.15 mM). Partially purified phytase was optimally active at 60 °C and pH 4 with a half life of 7 days at 60 °C. It retained 85% of its activity at 80 °C for 15 min. The enzyme is suitable for supplementing animal feeds to improve the availability of phosphate from phytate. [ABSTRACT FROM AUTHOR]

Review: 107 refs. [ABSTRACT FROM AUTHOR]

This article presents the highlights of the Second International Congress on Bioprocesses in Food Industries held at the University of Patras in Greece from June 18 to 21, 2006. Studies conducted since 1881 has shown the presence of an estimated 60 different enzymes in milk. Some of them are of interest due to their beneficial activity, some as indices of processing and some for their positive/negative effects on the quality of dairy products.