Influența compușilor coordinativi ai bariului și stronțiului asupra biosintezei amilazelor extracelulare la micromiceta Aspergillus niger CNMN FD 06

Abstract

The aim of this study was to establish the optimal conditions for the application of barium and strontium heterometallic coordinating compounds in the technology of Aspergillus niger CNMN FD 06 micromycete cultivation as a strategy of exocellular amylase biosynthesis enhancing. Heterometallic [Ba(L)3-μ2-(NCS)2-Co(NCS)2], [Sr(L)3][Co(NCS)4] complexes obtained from pyridine-2,6-dicarbonyl dichloride and Sr(II), Ba(II) and Co(II) salts have been found to exhibit biostimulating and enhancing properties on amylase biosynthesis. The compounds, applied in optimal selected concentrations - 1 mg /L - for [Ba(L)3-μ2-(NCS)2-Co(NCS)2] and 5 mg /L - for [Sr(L)3][Co(NCS)4], ensure both the increase of the enzymatic activity (by 39.2 and, respectively 42.9%), as well as the modification of the term of manifestation of the maximum of biosynthesis. The peak of enzymatic activity was recorded at the initial pH of the culture medium 5.0, previously established as optimal for the synthesis of exocellular amylases in classical conditions of cultivation.