Low-cost agro-industrial sources as a substrate for the production of l-asparaginase using filamentous fungi

Abstract

In this paper, Aspergillus caespitosus CCDCA 11593 was first described as a producer of the enzyme l-asparaginase. A new fiber substrate of the Pereskia aculeata Miller was used in solid-state fermentation (SSF) for the production of l-asparaginase. In the submerged fermentation (SbmF), the substrate applied was whey. A total of six filamentous fungi were tested in semi-quantitative tests using the plate method assay to select potential enzyme producers. The most productive ones were Penicillium solitum with sucrose, pH 7.0 and 96 h of culture (0.0410 U.mL−1), Aspergillus caespitosus with glucose, pH 6.0, and 96 h of culture (0.0960 U.mL−1), and Aspergillus oryzae with sucrose, pH 7.0, and 24 h of culture (0.0388 U.mL−1). From these results, A. caespitosus and A. oryzae were selected as the producers of l-asparaginase using the fibrous residue of Pereskia aculeata Miller as the substrate in SSF and whey as the substrate in SbmF. Three moistening agents were investigated in SSF, namely, tap water, deionized water, and Khanna salts. In the production of l-asparaginase in SbmF with whey, A. caespitosus presented 0.0249 U.mL−1 and A. oryzae 0.0139 U.mL−1 of enzyme activities. l-asparaginase produced by A. caespitosus in SSF using P. aculeata's Miller leaf fiber displayed two bands of proteins obtained from SDS-PAGE, 57 kDa and 45 kDa. As substrates, the leaf fiber of P. aculeata Miller and whey were found to be efficient and low-cost for the production of l-asparaginase.