Title : Environmental temperature fluctuations induced response mechanism of bio-degrader Acinetobacter pittii C3 to fluorocorticosteroids degradation: Bioactivity, gene expression and metabolic pathways
Abstract:
Environmental temperature determined the microbial activity and metabolic function, which synchronous impact on the biodegradation efficiency to micro-polluted fluorocorticosteroids (FGCs) in natural surface water. While the influence degree of temperature fluctuations and the internal molecular biological response mechanisms have gained little attention. This research indicated that the optimal temperature range were 15-25 °C for the functional dehalogenated stain Acinetobacter pittii C3, of which 20 °C is the threshold temperature with the highest degradation rate and removal efficiency of 0.0377 h-1 and 99.76% to triamcinolone acetonide (TA). This high removal was attributed to the rapid proliferation of cells and the stable energy release for defluorination and biodegradation. Meanwhile, the highest TA removal at 20 °C was positively correlated with the optimal microbial activity, the maximum biomass reproduction and the highest expression for dehalogenase genes. However, the degradation efficiency decreased approximately 1% with per temperature variation when the temperature was higher than 25 °C or lower than 15 °C because of the copy number reduction of dehalogenation genes with deficient transcription energy, inhibition of microbial growth and ATP activity. Furthermore, temperature affects the metabolic mechanism by controlling the expression of hydrolysis, oxidation, and reduction defluorination genes. However, temperature variation does not change the major defluorination pathways, which only affect the defluorination rate by controlling the expression of defluorination genes. This study provided an insight about environmental temperature fluctuations induced response mechanism of bio-degrader to fluorocorticosteroids biodegradation in natural water environment.
