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The quantum of marine fish wastes produced by fish processing industries has necessitated to search new methods for its disposal. Hence, this study is focused on production and purification of halophilic organic solvent tolerant protease (HOSP) from marine Alcaligenes faecalis APCMST-MKW6 using marine shell wastes as substrate. The candidate bacterium was isolated from the marine sediment of Manakudi coast and identified as A. faecalis APCMST-MKW6. The purified protease showed 16.39-fold purity, 70.34 U/mg specific activity with 21.67 % yield. The molecular weight of the purified alkaline protease was 49 kDa. This purified protease registered maximum activity at pH 9 and it was stable between pH 8–9 after 1.30 h of incubation. The optimum temperature registered was 60 °C and it was stable between 50 and 60 °C even after 1.30 h of incubation. This enzyme also showed maximum activity at 20 % NaCl concentration. Further, manganese chloride, magnesium chloride, calcium chloride and barium chloride influenced this enzyme activity remarkably and it was also found to be enhanced by many of the tested surfactants and solvents. The candidate bacterium effectively deproteinized the shrimp shell waste compared to the other tested crustaceans shell wastes and also attained maximum antioxidant activity.

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The present work aims at assessing Bakers’s yeast, Saccharomyces cerevisiae as an efficient and eco-friendly probiotic feed additives for ornamental fish, Carassias auratus. For this study an indoor culture experiment was carried out 300l plastic trough containing 200l water in triplicate. In each tank five fishes at fingerlings stage (1.58 ± 0.14g) were reared for a period of 30 days. An uniform water quality parameters such as temperature (28.0 ± 1.0 0C), pH (7.60 ± 0.12), dissolved oxygen (4.80 ± 0.82mg/l) and ammonia (< 0.08 mg/l) were maintained. The results inferred that, the percentage increase in the biochemical constituents in both skin and muscle tissue of C. auratus received 2% yeast added diet (EDY2) registered higher values when compared to control and other experimental diets fed fishes. The total carotenoid content in the acetone extracted skin tissues of C. auratus fed with 2% yeast supplemented diet varied from 0.748+  0.042 in 0 day to 0.944 + 0.014 µg/g wet tissue on 30th day of experiment. Likewise, in the muscle tissue of C. auratus extracted with acetone, the total carotenoid varied from 0.376+0.014 (0 day) to 0.541 + 0.008 µg/g wet tissue (30 day). The carotenoid content of both the tested tissues on methanol extract was low, when compared with acetone extract. The overall results inferred that S. cerevisiae supplementation @ 2g/ 100g diet distingly altered the carcass composition of C. auratus and also the accumulation of cartenoids in skin and muscle tissues. S. cerevisiae contains bioactive lead molecules, which accelerated the vital physical and metabolic activities in host fish species.