Catalyzed degradation of disperse dyes by calcium alginate-pectin entrapped bitter gourd （Momordica charantia） peroxidase

Calcium-alginate pectin entrapped bitter gourd peroxidase (BGP) has been employed for the treatment of disperse dyes: Disperse Brown 1 (DB 1) and Disperse Red 17 (DR 17). Peroxidase alone was unable to decolorize DR 17 and DB 1. However, the investigated dyes were decolorized maximally by BGP in the presence of 0.2 mmol/L redox mediator, violuric acid (VA). A slow decrease in percent decolorization was observed when VA concentration was higher than 0.2 mmol/L which could likely be due to the high reactivity of its aminoxyl radical (> N–O.) intermediate, that might undergo chemical reactions with aromatic amino acid side chains of the enzyme thereby inactivating it. Maximum decolorization of the dyes was observed at pH 3.0 and 40°C within 2 hr of incubation. Immobilized peroxidase decolorized 98% DR 17 and 71% DB 1 using 35 U of BGP in batch process in 90 min. Immobilized enzyme decolorized 85% DR 17 and 51% DB 1 whereas soluble enzyme decolorized DR 17 to 48% and DB 1 to 30% at 60°C. UV-visible spectral analysis was used to evaluate the degradation of these dyes and their toxicity was tested by Allium cepa test. The generally observed higher stability of the bioaffinity bound enzymes against various forms of inactivation may be related to the specific and strong binding of enzyme with bioaffinity support which prevents the unfolding/denaturation of enzyme. Thus entrapped peroxidase was found to be effective in the decolorization of the investigated dyes.     

The effect of vitamin E supplementation on ovary and testis histopathology in Oreochromis niloticus exposed to deltamethrin

The effects of deltamethrin on the histology of Oreochromis niloticus testis and ovary and the protective effect of vitamin E supplementation were investigated. The fish were divided into four groups, i.e. a control group, a vitamin-E-treated group, a deltamethrin-treated group and a vitamin E+deltamethrin-treated group. In the control and vitamin-E-treated groups, the ovaries and testes were normal at the end of 7, 14, and 21 days. In the deltamethrin-treated group, deformed oocytes, atretic oocytes, melanomacrophage centers, and focal necrotic areas were noted in the ovaries. Deltamethrin also caused cell necrosis, nuclear pycnosis, decreasing number of spermatogenic cells, decreasing spermatozoa within the lumen of tubule, decreasing number of spermatocyte cells, hypertrophy and degeneration of spermatogonia cells, and increasing number of macrophages in testis. Vitamin E decreased some histopathological changes induced by deltamethrin, but did not confer complete protection.