Degradation of lindane by a novel embedded bio-nano hybrid system in aqueous environment

Abstract

The objective of this study was to evaluate the effect of an embedded bio-nano hybrid system using nanoscale zinc oxide (n-ZnO) and lindane-degrading yeast Candida VITJzN04 for lindane degradation. Nano-embedding of the yeast was done with chemically synthesized n-ZnO particles (50 mg/mL) and was visualized by atomic force microscope (AFM) and scanning electron microscope (SEM). Nanoparticles were embedded substantially on the surfaces of the yeast cells and translocated into the cell cytoplasm without causing any lethal effect to the cell until 50 mg/mL. Lindane (600 mg/L) degradation was studied both in the individual and hybrid system. Rapid reductive-dechlorination of lindane was attained with n-ZnO under illuminated conditions, with the generation of chlorobenzene and benzene as dechlorination products. The bio-nano hybrid was found to be more effective compared to the native yeasts for lindane degradation and resulted in complete removal within 3 days. The kinetic data analysis implied that the half-life of lindane was 9 h for bio-nano hybrid and 28 h for Candida VITJzN04. The enhanced lindane degradation by bio-nano hybrid might be due to increased porosity and permeability of the yeast cell membrane, facilitating the easy entry of lindane into cell cytoplasm and n-ZnO-mediated dechlorination. To the best of our knowledge, this report, for the first time, suggests the use of n-ZnO-mediated dechlorination of lindane and the novel bio-nano hybrid system that reduces the half-life to one third of the time taken by the yeast alone. The embedded bio-nano hybrid system may be exploited as an effective remediation tool for the treatment of lindane-contaminated wastewaters.

Metabolic synergies in the biotransformation of organic and metallic toxic compounds by a saprotrophic soil fungus

“…Intermediates of HCH reductive dechlorination and hydroxylation have been observed in other studies on biotransformation of lindane by bacteria and saprotrophic fungi (Phillips et al 2005;Salam and Das 2015).…”

Insights Into the Biodegradation of Lindane (γ-Hexachlorocyclohexane) Using a Microbial System

“…These studies proposed reductive dechlorination of lindane by nanoparticles followed by oxidative degradation of metabolites by the microbial cells. Salam and Das (2015) evaluated the effect of an embedded bio-nano hybrid system using nanoscale zinc oxide (n-ZnO) and the lindane-degrading yeast Candida VITJzN04 for lindane degradation. The bio-nano hybrid degraded lindane more effectively than the native yeasts and completely removed lindane within 3 days.…”

A review on water pollution by γHCH (lindane) and its removal using nanomaterials

“…It is slowly metabolized through four possible routes. (i) Dehydrogenation results in gamma-hexachlorocyclohexane; (ii) dehydrochlorination in gamma-pentachlorocyclohexene; (iii) dechlorination to gamma-tetrachlorohexene; and (iv) hydroxylation results in hexachlorocyclohexanol [1][2][3][4] . Its use has been banned since 2009 under the Stockholm Convention on persistent organochlorine pesticides [5,6] .…”