Poly-beta-hydroxyalkanoates consumption during degradation of 2,4,6-trichlorophenol by Sphingopyxis chilensis S37

AIMS: To analyse the possible effect of poly-beta-hydroxyalkanoate (PHA) consumption on 2,4,6-trichlorophenol (2,4,6-TCP) degradation during starvation by Sphingopyxis chilensis S37 strain, which stores PHAs and degrades 2,4,6-TCP. METHODS AND RESULTS: The strain was inoculated in saline solution supplemented with 2,4,6-TCP (25-400 microm). Chlorophenol degradation was followed both spectrophotometrically and by chlorine released; viable bacterial counts were also determined. Cells starved for 24, 48 or 72 h were incubated with 25 microm of 2,4,6-TCP and PHA in cells investigated by spectrofluorimetric and flow cytometry. Results demonstrated that starvation decreased the ability to degrade 2,4,6-TCP. After 72 h of starvation, degradation of 2,4,6-TCP decreased to less than 10% and the relative PHA content diminished to ca 50% during the first 24 h. CONCLUSION: Utilization of PHA may be an important factor for the degradation of toxic compounds, such as 2,4,6-TCP, in bacterial strains unable to use this toxic compound as carbon and energy source. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study describing a relationship between intracellular PHA consumption and 2,4,6-TCP degradation. Therefore, PHAs provides an endogenous carbon and energy source under starvation and can play a significant role in the degradation of toxic compounds.