High-efficiency glufosinate ammonium degradation by Dunaliella salina: Discovery and preliminary mechanistic insights

Abstract

Glufosinate ammonium (GA), a widely used organophosphorus herbicide, poses significant environmental risks due to its high solubility and chemical stability. Once introduced into aquatic ecosystems via surface runoff, GA can accumulate and persist, particularly in hypersaline environments. This study explores the biodegradation efficiency and underlying mechanisms of GA degradation by Dunaliella salina under hypersaline conditions. The findings revealed that D. salina exhibited a maximum GA tolerance of 0.8 mg/mL and effectively reduced GA concentrations from 0.194 mg/mL to 0.016 mg/mL within three days, achieving a degradation efficiency of 91.74 %. Notably, the GA degradation efficiency of D. salina displayed a broad salinity tolerance, with degradation rates being influenced by cell density and light intensity. Exposure to GA induced acetyltransferase-related, phosphinothricin acetyltransferase (PAT)-immunoreactive signals in D. salina, suggesting the involvement of GA-responsive acetyltransferase-associated processes. In addition, physiological assays, nutrient utilization experiments, transcriptomic analyses, and phosphate-dynamics measurements indicate that D. salina can utilize GA as a phosphorus source, potentially involving carbon–phosphorus bond cleavage. Transcriptomic profiling further identified coordinated regulation of genes related to glutamine metabolism, antioxidant defense, polyamine biosynthesis, and carbohydrate metabolism, reflecting adaptive metabolic responses to GA-induced stress. Collectively, this study provides the first evidence that D. salina can reduce GA toxicity in hypersaline environments. Multiple biological responses, including GA-derived phosphorus utilization and acetyltransferase-related stress responses, play an important role in GA degradation. These findings advance our understanding of the adaptive metabolic network of D. salina and offer foundational insights for developing bioremediation strategies for herbicide-contaminated saline water bodies.