Iminoglutamic succinic acid: assessment of the degree of biodegradation and toxicity of half-decomposition products.

Abstract

Chelating agents used in agriculture and land reclamation practices must exhibit the capacity to firmly bind metal ions while also rapidly decomposing into non-toxic compounds due to their introduction into the environment in substantial quantities. It is therefore crucial to identify an alternative to EDTA, a prevalent chelating agent known for its low biodegradability and relatively high toxicity. This study focuses on assessing the degree of biodegradation of iminoglutamic succinic acid (IGSA) and the toxicity of its half-decomposition products. For this purpose, two bacterial and fungal isolates capable of decomposing IGSA were isolated and characterized, identified as Ralstonia pickettii and Fusarium foetens, respectively. The results of a 28-day experiment demonstrated that Ralstonia pickettii was capable of decomposing IGSA by 18.0% according to the manometric test and by 24.5% based on the analysis of decomposition products via HPLC. In comparison, Fusarium foetens exhibited a more effective biodegradation capacity, with rates of 20.3% and 32.5%, respectively. The half-decomposition products of IGSA were characterized by low ecotoxicity levels (LID10) concerning Paramecium caudatum (11.2-13.2 g/l) and Ceriodaphnia affinis (3.6-8.9 g/l). However, a stimulating effect was observed on microalgae, with growth stimulation ranging from 63.65-96.60%.