<P> In many industrial wastewater treatment plants, EDTA elimination can be achieved at about 80% using microorganisms . Resulting byproducts are ED3A and iminodiacetic acid (IDA)--suggesting that both the backbone and acetyl groups were attacked . Some microorganisms have even been discovered to form nitrates out of EDTA but degrade optimally at moderately alkaline conditions of pH 9.0--9.5 . </P> <P> Several bacterial strains isolated from sewage treatment plants efficiently degrade EDTA . Specific strains include Agrobacterium radiobacter ATCC 55002 and the sub-branches of Proteobacteria like BNC1, BNC2, and strain DSM 9103 . The three strains share similar properties of aerobic respiration and are classified as gram - negative bacteria . Unlike photolysis, the chelated species is not exclusive to iron (III) in order to be degraded . Rather, each strain uniquely consumes varying metal--EDTA complexes through several enzymatic pathways . Agrobacterium radiobacter only degrades Fe (III) EDTA while BNC1 and DSM 9103 are not capable of degrading iron (III) EDTA and are more suited for calcium, barium, magnesium and manganese (II) complexes . EDTA complexes require dissociation before degradation . </P> <P> Interest in environmental safety has brought up concerns about biodegradability in aminopolycarboxylates such as EDTA . For example, under the 28 - day ISO 7827 test Austrian paper and pulp industries must use chelating agents that have biodegradation levels over 70% or 80% (after 28 days). An increased interest in safety has led to the development and research of alternative chelating ligands which can still bind strongly to metal ions but also have a higher biodegradability and a lower content of nitrogen . </P> <P> Commercially used since 1998, iminodisuccinic acid (IDS) biodegrades by about 80% after only 7 days . IDS binds to calcium exceptionally well and forms stable compounds with other heavy metal ions . In addition to having a lower toxicity after chelation, the production of IDS is environment - friendly . Specifically, IDS is degraded through the use of IDS epimerase and C − N lyase found in Agrobacterium tumefaciens (BY6), which can be harvested on a large scale . Additionally, the reactions catalyzed by both enzymes do not require any cofactors and can thus be applied directly . </P>

The most widely used method of hormone classification is by ph