Extracellular enzyme production

Novotny C, Svobodova K, Erbanova P, Cajthamal T, Kasinath A, Lang E (2004) Lignolytic fungi in bioremediation extracellular enzyme production and degradation rate. Soil Biol Biochem 36 1545-1551... 

Sinsabaugh, R. L., and D. L. Moorhead. 1994. Resource allocation to extracellular enzyme production A model for nitrogen and phosphorus control of litter decomposition. Soil Biology and Biochemistry 26 1305-1311. 

Rowe, M.T., Johnston, D.E., Kilpatrick, D.J., Dunstall, G., Murphy, R.J. 1990. Growth and extracellular enzyme production by psychrotrophic bacteria in raw milk stored at a low temperature. Milchwissenschaft 45, 495 199. 

They act as antipathogenic agents and thus affect the process of pathogenesis. They may act on the host through the Induction of plant resistance mechanisms such as stimulation of lignification or enhancement of phytoalexin production. (Please refer to the chapter by Salt and Kuc in this volume for further discussion of this type of compound.) They may act on the pathogen to accentuate elicitor release or to prevent infection (host penetration), colonization (inhibition of phytotoxin synthesis, extracellular enzyme production and action, or phytoalexin degradation) or reproduction. 

Strain NRRL B-512(F) produces large proportions of the extracellular enzyme dextransucrase,339 which is responsible for the synthesis of linear sequences ofa-D-(l —> 6)-linked D-glucosyl residues. The enzyme transfers the D-glucosyl group from a sucrose molecule to an enlarging dextran chain and liberates the D-fructose portion. As dextransucrase is an extracellular enzyme, production of dextran by cell-free, culture filtrates can result in enhanced yield and quality, and ease of purification of the product. By suitable adjustment of the conditions, products in a chosen molecular-weight range can be obtained. Formation of branches is not yet well understood, but the enzymes responsible will certainly be found. 

C Rtittimann-Johnson, L Salas, R Vicuna, TK Kirk. Extracellular enzyme production and synthetic lignin mineralization by Ceriporiopsis subvermispora. Appl Environ Micmbiol 59 1192-1191, 1993. 

Greenmail J, Holland KT and Cunliffe WJ (1981) Effects of glucose concentration on biomass, maximum specific growth rate and extracellular enzyme production by three species of cutaneous propionibacteria grown in continuous culture. J Gen Microbiol 127 371-376... 

More detailed studies on B. amyloliquefaciens showed that, in this system, extracellular protein accounted for a large proportion of the organism s total protein output (Stormonth and Coleman, 1974). Under favorable conditions the maximum rate of extracellular protein formation was equal to the maximum rate of cell protein synthesis. This observation drew attention to the fact that if exoprotein formation was regulated by catabolite repression then, during exponential growth, if the repressing catabolites were removed, it would not be possible to achieve the maximum rate of extracellular enzyme production without considerable reduction in the growth rate. 

Fermentation broths are complex, aqueous mixtures of cells, comprising soluble extracellular, intracellular products and any unconverted substrate or unconvertible components. Recovery and extraction of product is important in bioprocess engineering. In particular separation is a useful technique it depends on product, its solubility, size of the process, and product value. Purification of high-value pharmaceutical products using chromatography such as hormones, antibody and enzymes is expensive and difficult to scale up.1 Tire necessary steps to follow a specific process depend on the nature of the product and the characteristics of the fermentation broth. There are a few steps for product recovery the following processes are discussed, which are considered as an alternative for product recovery from fermentation broth. 

Digestion of PGA by the PelL enzyme yielded a mixture of unsaturated ohgogalacturonides, giving evidence that PelL is an endo-deaving lyase (17). An exo-enz3mie, such as the EC 16 PelX, would generate a single product (15). The PelL protein differs from the major E. chrysanthemi pectate lyases in its ability to cleave both PGA and methylated pectin (17). The PelL activity has a basic optimum pH and an absolute requirement for Ca + ions. Analysis of culture supernatants demonstrated that PelL is an extracellular enzyme, such as the other secondary pectate lyases (17). 

An extracellular enzyme from Xanthomonas sp. is able to degrade poly(c -l,4-isoprene) with the production of 12-keto-4,8-dimethyltrideca-4,8-diene-l-al (Braaz et al. 2004), and functions as a heme-dependent oxygenase (Braaz et al. 2005). 

Buckley KF, Dobson ADW (1998) Extracellular ligninolytic enzyme production and polymeric dye decolourization in immobilized cultures of Chrysosporium lignorum CL1. Biotechnol Lett 20 301-306... 

X particulate substrate (hydrolyzable substrate) available as substrate for the microorganisms after hydrolysis by extracellular enzymes and diffusion of the products into the cell... 

---