Abstract

The aim of this present work is to produce Paecilomyces marquandii crude extract and its in vitro larvicidal action. Saccharose, glucose, coffee residue, soluble starch, insoluble starch, soybean meal and wheat bran were the carbon sources tested. NaNO₃, NH₄Cl, soybean meal, (NH₄)₂SO₄, yeast extract, casein peptone, tryptone and NH₄NO₃ were the nitrogen sources tested. Central composite design was applied to determine the optimal concentration of the tested significant variables. The best carbon sources were glucose and soybean meal, while the best nitrogen source observed was tryptone. The greatest value for proteolytic activity was 246.58 U/ml due to the concentration of tryptone and pH value. Results showed that the optimum pH was 8.0, while the optimum temperature was 60°C. The optimized extract obtained from P. marquandii exhibited in vitro larvicidal activity with 60.1% reduction. Tryptone and pH optimized the production of proteases by fungus P. marquandii.

Key words: Nematophagous fungi, Paecilomyces marquandii, crude extract, larvicidal action, surface response.