Co-Metabolic Growth and Microbial Diversity: Keys for the depletion of the α, δ, β and γ-HCH isomers

Abstract

The objective of this study was to select and enhance microbiomes capable of degrading the α, δ, β and γ-HCH isomers. These microbiomes were isolated and enriched from an HCH-contaminated dumpsite in Italy, both in the presence of HCH isomers (1:1:1:1) as the sole carbon sources and under co-metabolic growth conditions in presence of glucose (0.1%). Four microbiomes were assessed for their relevant metabolic capabilities. A quantitative metabarcoding approach was employed to analyze the compositional evolution of the four microbiomes during the enrichment phase and the phase of tsting of the HCH isomers degradation kinetics. The use of a co-metabolic substrate during enrichment process was essential for selecting microbiomes with higher biodiversity. All microbiomes efficiently degraded the α, δ, and γ-HCH isomers. The highest efficiency in the β-HCH degradation capacity was associated to the highest biodiversity of the microbiome, and the involvement ofChryseobacteriumandAsinibacteriumsps. has been proposed for a recorded increment in bacterial load during the HCH degradation process.Statement of environmental implicationsSoil contaminated with hexachlorocyclohexane (HCH), including all four isomers, poses a significant risk to environmental and public health. This study isolates and selects microbiomes capable of degrading HCH, demonstrating their degradation efficiency using GC-MS analysis, and studies the microbial communities through metabarcoding of both the initial soils and the selected microbiomes. The contaminated soil originates from the historically polluted area of Italy known as SIN-Valle del Sacco. Developing and optimizing microbiome selection techniques for application on contaminated sites can significantly enhance soil bioremediation, thereby reducing contamination and protecting the environment.