Optimization of chitinase production by serratia marcescens la

Abstract EN

Fifty bacterial isolates from nine samples of fresh shrimp shells exhibited chitinolytic activities.

Five isolates showed high chitinase activity with clear zones of 2.0, 1.6, 1.5, 1.3 and 1.3 cm in diameter and were identified (API 20E System) as : Serratia marcescens biogroup 1a, Serratia marcescens biogroup 1b, Klebsiella oxycota a, Klebsiella oxycota b and Bacillus sp., respectively.

Serratia marcescens biogroup 1a (the highest producer) is reported as a promising chitinase producer and therefore, optimization of fermentation conditions to maximize chitinase synthesis by this organism was conducted and factors such as carbon source, chitin concentration (up to 3.0 %, w / w), nitrogen source, yeast extract concentration (up to 2.0 %,w / w), medium pH (5.0 to 8.0) and cultivation temperature (30 to 45°C) were evaluated.

The highest chitinase activity (85 u.

ml-1) was obtained after three days of fermentation at 30°C in medium (pH 8.0) contained chitin (2 %), proteose peptone (2 %) and yeast extract (0.25 %) under shaking conditions (160 rpm).