Enzyme-polysaccharide interaction: a method for improved stability of horseradish peroxidase.

With the advent of green technology, use of enzymes as biocatalyst has become increasingly popular. However, in doing so, enzymes can lose their structure and catalytic activity under conditions that might be necessary for other components of processes. Compared to other strategies, chemical modification is a simple and effective technique for generating stable enzyme. Horseradish peroxidase (HRP; EC 1.11.1.7) was chemically modified by conjugating with 10 different polysaccharides. All polysaccharides were found to increase the thermal and pH stability of HRP with starch being most promising. Further, different parameters were evaluated for effective conjugation and thus stability of HRP conjugate. The degradation kinetics and storage stability of HRP proved the conjugate to be 6.4 times more stable than free enzyme. The starch conjugated HRP and free HRP were further evaluated for its application in decolorization of bromophenol blue dye. Both the enzymes were able to efficiently (>90%) decolorize the dye within minutes.

Biotransformation of polyphenols for improved bioavailability and processing stability.

Research on the functions and effects of polyphenols has gained considerable momentum in recent times. This is attributed to their bioactivities, ranging from antioxidant to anticancer activities. But their potential is seldom fully realized since their solubility and stability is quite low and their bioavailability is hampered due to extensive metabolism in the body. Biotransformation of polyphenols using enzymes, whole cell microbes, or plant cell cultures may provide an effective solution by modifying their structure while maintaining their original bioactivity. Lipase, protease, cellulase, and transferases are commonly used enzymes, with lipase being the most popular for carrying out acylation reactions. Among the whole cell microbes, Aspergillus, Bacillus, and Streptomyces sp. are the most widely used, while Eucalyptus perriniana and Capsicum frutescens are the plant cell cultures used for the production of secondary metabolites. This chapter emphasizes the development of green solvents and identification of different sources/approaches to maximize polyphenol transformation for varied applications.

Wheat flour based propionic acid fermentation: an economic approach.

A process for the fermentative production of propionic acid from whole wheat flour using starch and gluten as nutrients is presented. Hydrolysis of wheat flour starch using amylases was optimized. A batch fermentation of hydrolysate supplemented with various nitrogen sources using Propionibacterium acidipropionici NRRL B 3569 was performed. The maximum production of 48.61, 9.40, and 11.06 g of propionic acid, acetic acid and succinic acid, respectively, was found with wheat flour hydrolysate equivalent to 90 g/l glucose and supplemented with 15 g/l yeast extract. Further, replacement of yeast extract with wheat gluten hydrolysate showed utilization of gluten hydrolysate without compromising the yields and also improving the economics of the process. The process so developed could be useful for production of animal feed from whole wheat with in situ production of preservatives, and also suggest utilization of sprouted or germinated wheat for the production of organic acids.

Cyclosporin A--a review on fermentative production, downstream processing and pharmacological applications.

In present times, the immunosuppressants have gained considerable importance in the world market. Cyclosporin A (CyA) is a cyclic undecapeptide with a variety of biological activities including immunosuppressive, anti-inflammatory, antifungal and antiparasitic properties. CyA is produced by various types of fermentation techniques using Tolypocladium inflatum. In the present review, we discuss the biosynthetic pathway, fermentative production, downstream processing and pharmacological activities of CyA.