An investigation on the seasonal variations of the biomarkers of oxidative stress response and their correlations to Polonium-210 in mussel (Mytilus galloprovincialis) and common sole (Solea solea) from Izmir Bay, Turkey.

It is well known that the marine organisms are used as biological indicators for environmental pollution studies. Among these studies, the research on oxidative stress has been increasing in recent years. In this study, mussels (Mytilus galloprovincialis) and fish (Solea solea) samples were collected seasonally from Inciralti, Izmir, Turkey. This station was in an area where fishing is carried out for human consumption. The relationship between 210Po and oxidative stress markers (lipid peroxidation (LPO), H2O2 and proline) was investigated in the mussel tissue (digestive gland, gills) and fish tissue (liver, gills) samples. The present study indicated that H2O2 accumulated with increasing 210Po concentration in mussel samples. Statistically significant correlation were found between H2O2 and 210Po and LPO and proline in mussel samples. This correlation between LPO and proline can be attributed to common environmental parameters (other than 210Po) affecting expression of both LPO and proline levels. There was not a significant correlation between 210Po and LPO levels. Similarly, a significant correlation was not found between 210Po and proline.

Comperative study of catalase immobilization on chitosan, magnetic chitosan and chitosan-clay composite beads.

Catalase was immobilized on chitosan and modified chitosan. Studies were carried out on free-immobilized catalase concerning the determination of optimum temperature, pH, thermal, storage stability, reusability, and kinetic parameters. Optimum temperature and pH for free catalase and catalase immobilized were found as 35°C and 7.0, respectively. After 100 times of repeated tests, the immobilized catalases on chitosan-clay and magnetic chitosan maintain over 50% and 60% of the original activity, respectively. The ease of catalase immobilization on low-cost matrices and good stability upon immobilization in the present study make it a suitable product for further use in the food industry.

Immobilization of tyrosinase on chitosan-clay composite beads.

Tyrosinase was immobilized on glutaraldehyde crosslinked chitosan-clay composite beads and used for phenol removal. Immobilization yield, loading efficiency and activity of tyrosinase immobilized beads were found as 67%, 25% and 1400 U/g beads respectively. Optimum pH of the free and immobilized enzyme was found as pH 7.0. Optimum temperature of the free and immobilized enzyme was determined as 25-30 °C and 25 °C respectively. The kinetic parameters of free and immobilized tyrosinase were calculated using l-catechol as a substrate and K(m) value for free and immobilized tyrosinase were found as 0.93 mM and 1.7 mM respectively. After seven times of repeated tests, each over 150 min, the efficiency of phenol removal using same immobilized tyrosinase beads were decreased to 43%.