Abstract
This study investigated the binding abilities of extracellular polymers produced by an environmentally isolated strain of Enterococcus hirae towards phytoestrogen endocrine disruptors-biochanin A, formonetin, genistein and daidzein. The extracellular biopolymer exhibited notable binding and removal for all four phytoestrogens, with a maximum removal of daidzein (87%) followed by genistein (72%) at a 1-1.5 mg/mL concentration. Adsorption proceeded rapidly at ambient temperature. The adsorption data fitted well with the Langmuir isotherm. Based on the adsorption energy, the biopolymer binding of phytoestrogens was inferred as daidzein > genistein > biochanin A > formononetin. Toxicity of the biopolymer (5-250 µg/mL) evaluated using RAW 264.7 cell lines indicated no significant (p < 0.05) changes in viability. In biopolymer-challenged Caenorhabditis elegans previously exposed to daidzein, complete protection to developmental toxicity, such as reduced egg-laying capacity, egg viability and progeny counts of the worm, was observed. The results of this study offer valuable insights into understanding the potential role of microbial extracellular biopolymers in binding and removal of phytoestrogens with sustainable technological implications in modulating the toxic effect of high levels of endocrine disruptors in the environment.