Production Of Laccase By A Locally Isolated Fungus For Biodegradation Of Selected Agrowastes

The present study was conducted to screen the significant laccase (ligninolytic enzyme) producers from locally isolated white-rot fungi using agitated and non-agitated culture conditions. The highest laccase producer, identified as Pycnoporus sp. (strain S16) was selected for the optimisation of laccase production with particular attention to the effect of physiological factors on laccase production using submerged culture technique. Laccase was characterised to assist in formulating the best condition for the bioconversion of agro-wastes. Significant laccase production was obtained under carbon-depleted condition and dependent on culture morphology. The culture with high laccase activity was observed with the presence of small mycelial pellets with 1−2 mm diameter. The pellet formation and optimum laccase production influenced by various physiological factors are investigated. The best culture condition obtained consisted of 5 g/L of glucose, 12 mM of nitrogen, inoculum concentration of 8 × 106 spores/mL, initial pH 5, incubation temperature of 37°C and agitation speed of 100 rpm. Under the above culture conditions, the time of fermentation was shortened from 16 days to 7 days with maximum laccase activity of 225 U/L. The characterisation study of concentrated laccase revealed the importance of an acidic condition for the highest laccase activity. The biodegradation study showed that some locally available agro-waste materials are suitable for soluble sugar production and that rice bran gave the best results with 1.90 g/L of soluble sugar produce

Growth performance and gonad development in Diploid and Triploid Clarias batrachus (Linnaeus)

Full siblings of diploid and triploid walking catfish, Clarias batrachus, were reared in rectangular fibreglass tanks starting at the age of three weeks. Growth performances of diploids and triploids were compared by feeding with a 30% protein diet. At the end of the study period growth rate was found to be insignificantly different (P>0.05) between the diploid and the triploid. However, triploid fish had poorly developed gonads. Triploid ovaries contained fewer primary oocytes with some abnormal maturing oocytes. Triploid testes contained fewer seminiferous tubules and a larger amount of connective tissue