Production of tyrosinase by Auricularia auricula using low cost fermentation medium
Low cost fermentation media using agricultural by-products (wheat bran extract, rice bran extract and soybean meal extract) as a major nutrient source, were evaluated for the production of tyrosinase from the fungus Auricularia auricula in submerged culture. In single-factor experiments, three components (wheat bran extract, casein and CuSO4) were chosen to further optimize medium composition using response surface methodology (RSM). The central composite experimental results showed the following optimum medium composition: wheat bran extract 36.0 %, casein 1.1 g/l and CuSO4 0.13 g/l. Under these conditions, the highest tyrosinase activity was 17.22 U/ml, which was 2.1 fold higher than that obtained using the non-optimized medium. The present study is the first to report the statistical optimization of medium composition for production of tyrosinase by A. auricula using cheaper wheat bran extract as a major nutrient source. These results might provide a reference for the development of a cost-effective medium for commercial production of tyrosinase.
Plant enzymes in metabolism of organic pollutants
Abstract Anthropogenic activities and natural processes pollute soil and aquatic environments with high quantity of organic pollutants or substances such as pesticides, solvents, halogenated compounds, petroleum hydrocarbons, and phthalate esters. The use of traditional or conventional approaches like physical and chemical methods for remediation of these organic pollutants is economically challenging process. In this regard, remediation with biological agents poses promising alternative. Enzyme-based technologies are crucial for metabolism and degradation of organic substances. They can be used in metabolism of simple and complex organic pollutants. This chapter provides an overview on different plant enzymatic alternatives for decontamination of soils and their role in transformation and metabolism of organic pollutants.
Thermal inactivation of lectins (PHA) isolated from Phaseolus vulgaris
The influence of the thermal process on the loss of ability to bind a carbohydrate target was studied on lectins (PHA) purified from Phaseolus vulgaris seeds. Thermal inactivation of aqueous solutions of pure PHA occurred according to a biphasic first-order mechanism, the thermodynamic parameters, at pH 7·3, being as follows: ΔH∗1 = ΔH∗2 = 86·2 kcal mole−1, ΔS∗1 = − 54·04 cal deg−1 and ΔS∗2 = − 56·71 cal deg−1. The first-order rate constants appeared to be dependent on pH (minimal around 7) and divalent cations. All different subunits constituting the whole PHA were inactivated at the same rate. The biphasic nature of this process is independent of the presence of 10 mm Ca++ or Mg++ and appeared to indicate a discrete aggregation of PHA molecules.