Toxicity and biodegradation of diamines

Area of Science:

• Environmental Science
• Toxicology
• Microbiology

Background:

• 2,4-diaminotoluene (2,4-D), 4,4'-methylenedianiline (4,4-D), and 1,6-hexanediamine (1,6-D) are industrial chemicals with potential environmental impact.
• Understanding their phytotoxicity, cytotoxicity, and biodegradability is crucial for risk assessment.

Purpose of the Study:

• To evaluate the phytotoxicity and cytotoxicity of 2,4-D, 4,4-D, and 1,6-D.
• To investigate the biodegradation potential of activated sludge and isolated microorganisms for these diamines.
• To compare the degradation efficiency of bacteria and fungi.

Main Methods:

• Phytotoxicity was assessed using radish seed germination.
• Cytotoxicity was determined using HeLa cell viability assays.
• Biodegradation was studied using a modified Sturm test and isolation of microbial consortia.

Main Results:

• Cytotoxicity order: 2,4-D > 4,4-D > 1,6-D. Phytotoxicity order: 4,4-D > 2,4-D > 1,6-D.
• Activated sludge degraded all three diamines without pre-acclimation.
• Ochrobacterium antropi and Pseudomonas citronellolis were isolated for bacterial degradation, while Thielevia sp. and Aspergillus sp. were identified as fungal degraders.
• Fungi exhibited faster degradation rates compared to bacteria.

Conclusions:

• The study provides insights into the differential toxicity profiles of 2,4-D, 4,4-D, and 1,6-D.
• These diamines are biodegradable by unacclimated activated sludge.
• Specific bacterial and fungal strains capable of degrading these compounds were identified, with fungi showing higher efficiency.