L-Asparaginase production by Bipolaris sp. BR438 isolated from brown rice in Thailand

Abstract

Thirty-six filamentous fungal isolates obtained from brown rice in Thailand were screened for their ability to produce L-asparaginase. Using modified Czapek Dox (mCD) agar containing L-asparagine and phenol red as indicator, 24 L-asparaginase producing fungal isolates could be preliminary identified by observing pink colour formation. It was found that isolate BR438 exhibited highest activity (6.3 ±0.65 U/ml) when cultured in the mCD medium containing 1% L-asparagine and 0.4% glucose at 30°C for 72 h. Its asparaginase was also proved to be non-cytotoxic when tested against Vero cell lines. The identification based on internal transcribed spacer (ITS) regions of ribosomal DNA and morphological study showed that isolate BR438 was Bipolaris sp. and was closely related to Bipolaris australiensis and B. ovariicola.