Volume 2, Number 3-4, January - June 2014

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About the Cover

Clams have high nutritive value and are important in the economy of coastal fishing villages. Due to the development of export market for the frozen clam meat, research had been undertaken for culturing the clams along the estuaries and creeks. Clams such as Paphia malbarica (False clam), Meretrix casta (Backwater clam), Katelysia opima (Inflated clam), Villorita cyprinoids (Black clam), Meretrix meretrix (Great clam), Donax cuneatus (Wedge clam) and other bivalves belonging to the family Veneridae form vast beds in estuaries and backwaters of the Ratnagiri coast. Though practice of clam culture has not become widespread as oyster and mussel culture, some of the clam species are being cultured traditionally along the Ratnagiri coast. Study of the culture sites along the Kalbadevi and Kajali estuaries was done during the present work. Stocking density of the transplanted clams at randomly selected pits, environmental and soil parameters were recorded. The largest pit was 2.25 m3 while the smallest pit was of 0.50 m3, where the stocking density was 1700 and 350 respectively. The clams are kept in the pits for a period of 15 days to 3 months, after which they are harvested for sale. During the study, dead clams with blackening of sand due to formation of hydrogen sulphide were recorded in the pits with higher stocking density (Ref: Mohite SA, Sawant PP. Traditional bivalve culture practices along the Ratnagiri coast of Maharashtra, India. Discovery Agriculture, 2014, 2(3), 3-8), (Image: th00.deviantart.net).

RESEARCH

Traditional bivalve culture practices along the Ratnagiri coast of Maharashtra, India

Mohite SA, Sawant PP

Clams have high nutritive value and are important in the economy of coastal fishing villages. Due to the development of export market for the frozen clam meat, research had been undertaken for culturing the clams along the estuaries and creeks. Clams such as Paphia malbarica (False clam), Meretrix casta (Backwater clam), Katelysia opima (Inflated clam), Villorita cyprinoids (Black clam), Meretrix meretrix (Great clam), Donax cuneatus (Wedge clam) and other bivalves belonging to the family Veneridae form vast beds in estuaries and backwaters of the Ratnagiri coast. Though practice of clam culture has not become widespread as oyster and mussel culture, some of the clam species are being cultured traditionally along the Ratnagiri coast. Study of the culture sites along the Kalbadevi and Kajali estuaries was done during the present work. Stocking density of the transplanted clams at randomly selected pits, environmental and soil parameters were recorded. The largest pit was 2.25 m3 while the smallest pit was of 0.50 m3, where the stocking density was 1700 and 350 respectively. The clams are kept in the pits for a period of 15 days to 3 months, after which they are harvested for sale. During the study, dead clams with blackening of sand due to formation of hydrogen sulphide were recorded in the pits with higher stocking density.

Discovery Agriculture, 2014, 2(3), 3-8

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RESEARCH

Optimization of xylanase production by Alternaria alternata isolated from apple (pyrus malus l.)

Mary Sushma T, Supriya Sarkar

The objective of the present investigation was to isolate the fruit spoilage fungi from Apple (Pyrus malus L.) sold in twin cities of Hyderabad and to identify the strains that secrete maximum amount of xylanase under submerged conditions. Recently xylanases have been explained for their use in many processing industries such as paper, pulp, food and textile industries. In all 12 fruit spoilage fungi were isolated. Alternaria alternata was selected for further studies based on the pathogenicity test and initial screening by xylan - agar diffusion method for its ability to produce extracellular xylanase during its growth on enriched malt extract agar medium containing xylan as the sole source of carbon. The influence of various culture conditions including incubation period, synthetic media, initial pH, temperature, carbon sources and nitrogen sources on xylanase production by A. alternata was studied. Apart from birch wood xylan, xylose (174.0 U/ml) was the best inducer for the xylanase production. Xylanase production was maximum in medium B (medium A supplemented with 1 % fruit peel extract) with an enzyme activity of 102.0 U/ml. Alternaria alternata was more active in the production of xylanase when grown in Asthana and Hawker’s medium at pH 7 (149.0 U/ml). Optimum xylanase activity was shown at temperature at 35°C (137.8 U/ml). On the 6th day of incubation period xylanase production was maximum with an enzyme activity of 203.8 U/ml. Among the nine different nitrogen sources selected to study their effect on xylanase production, Glycine was found to be the best nitrogen source for enzyme production as it showed maximum enzyme activity (185.0 U/ml).

Discovery Agriculture, 2014, 2(4), 11-21

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