Bioprospecting dietary antimicrobial proteins and peptides from donax cuneatus and pitar erycina

Abstract

Two marine bivalves, Donax cuneatus and Pitar erycina were collected from the shores of Tiruchendur, Tamil Nadu and were determined for their proximate compositions including total protein, total carbohydrate, total fat, moisture and ash content. The highest protein content (12.49g/100g),total carbohydrate (2.8g/100g), fat (4.2g/100g) and ash (2.6g/100g) were observed in Pitar erycina, whereas, moisture content (79.5g/100g) was relatively higher in D. cuneatus. A total of 28 fatty acids of different types newlineand 17 amino acids including eight essential amino acids and nine nonessential amino acids were recorded from the two bivalves. Among the four extraction methods, the acetic extraction protein showed high concentration and maximum antibacterial activities. Response surface methodology revealed that the predicted protein concentration from the polynomial model was 17.32 mg/mL, based on optimum conditions of variables: 13.36 g/mL solid/liquid ratio, 26.63ºC temperature and 18.36 min of homogenization time.The crude protein was extracted from the two bivalves by the acidicmethod, and the protein was precipitated with ammonium sulphate. The precipitated protein was subjected to purification by column chromatographic techniques. Fraction 3a from D. cuneatus and fraction 5b from P.erycina showed highest antibacterial activity against P. aeruginosa and S. aureus and exhibited good antibacterial activities against Proteus vulgaris (20 and#956;g/ml), Klebsiella pneumoniae (10 and#956;g/ml) and Streptococcus pyogenes (10and#956;g/ml) when compared to that of chloramphenicol 40 and#956;g/ml, 20 and#956;g/ml and 20 and#956;g/ml, respectively. newline newline