Microbial metabolism of phthalic acid esters by bakers' yeast Saccharomyces cerevisiae

The microbial metabolism behavior of two phthalic acid esters (PAEs), namely, diethyl phthalate (DEP) and butylbenzyl phthalate (BBP), from aqueous solution by bakers' yeast Saccharomyces cerevisiae was quantitatively characterized by high performance liquid chromatography (HPLC). The optimal culture temperature, amount of yeast, yeast growth time, and ammonium dihydrogen phosphate (ADP) amount, that can influence on biodegradation of PAEs were 30 C, 2.0 mg mL(-1), 30 min, and 0.5 mg mL(-1), respectively. Under the optimal conditions, the degradation percentage of DEP and BBP were 19% and 43%, respectively after 24 h of cultivation. The metabolites of DEP degradation as identified by gas chromatography-mass spectrometry (GC/MS) appeared to be ethyl methyl phthalate (EMP), dimethyl phthalate (DMP) and phthalic acid (PA), whereas monobutyl phthalate (MBP), diethyl phthalate (DEP) and phthalic acid (PA) were identified as metabolites of BBP. Therefore, it can be considered that one of the degradation pathways involves sequential cleavage of the ester bond to yield PA.