Page 229 - Advances in Textile Biotechnology

210 Advances in textile biotechnology

Tyr generates l-dopa. Similarly to other neurotransmitters, the latter
product stimulates the formation of gold nanoparticles, which are detected
by optical methods. The sensitivity of the detection of tyrosinase activity

was as low as 10 units. Since tyrosinase is specifically expressed in melano-

cytes and melanoma cells and is viewed as a specific marker of these cells,
this analytical protocol may have positive outcomes in clinical diagnostics.
Increasingly strict environmental regulations require the development of

more efficient analytical techniques for monitoring wastewater and air
pollutants such as the phenolic derivatives generated by textile, coal, chem-
ical, petrochemical, and mining industries. To achieve this, biosensors based
on immobilised mushroom tyrosinase are currently being developed
(Abdullah et al., 2006; Gu et al., 2009; Perez Lopez and Merkoci, 2009).
Various measuring principles, such as detection of oxygen consumption,
direct reduction of liberated o-quinones, or reduction of the o-quinones by
a redox mediator, can be utilised in these biosensors. However, the previ-
ously outlined relatively poor stability of mushroom tyrosinase under
storage and measuring conditions still represents a limitation for the
commercial exploitation of these devices.
Bioremediation, i.e. removal of phenolic compounds from wastewater, is
another forefront application for which an enzymatic process could provide
advantages compared with the traditional chemical and physical methods.
Mushroom tyrosinase has been used as a biocatalyst confined in a fl at

membrane bioreactor to oxidise polyphenols present in agro-food waste-
waters, and the results reported confirmed the validity of the membrane

bioreactor system (Calabro et al., 2009). Wu et al. (2001) studied the ability
of volatile phenols to react with tyrosinase and to couple by chemisorption
onto a chitosan support. The p-cresol could be removed from vapours if

contacted with tyrosinase-coated chitosan films. Mushroom tyrosinase
immobilised onto chitosan provided optimum performance in terms of
phenol removal efficiency, even at low phenol concentration, and for the

segregation of oxidation products.

Food processing

Texture plays a major role in food product quality. Besides a number of
hydrophobic, hydrogen bonding, and electrostatic bonds present in a food
matrix, the covalent linkages in and between the food biopolymers, i.e.
proteins, carbohydrates and lipids, make a major contribution to the tex-
tural characteristics of food. Enzymes are interesting tools for altering the
number of covalent bonds and tailoring the properties of the end-product
(Buchert et al., 2007). As previously discussed for TGases, other crosslinking
enzymes such as tyrosinases can be exploited for improving various food
properties. The effects of T. reesei tyrosinase-catalysed crosslinking on the

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