Identification of three metallothioneins in the black soldier fly and their functions in Cd accumulation and detoxification

The black soldier fly (BSF) Hermetia illucens has a strong tolerance to cadmium stress. This helps to use BSF in entomoremediation of heavy metal pollution. Rich metallothionein (MT) proteins were thought to be important for some insects to endure the toxicity of heavy metal. We identified and characterized three MTs genes in BSF (BSFMTs), including BSFMTI, BSFMT2A, and BSFMT2B. Molecular modeling was used to predict metal binding sites. Phylogenetic analysis was used to identify gene families. Over-expression of the recombinant black soldier fly metallothioneins was found to confer Cd tolerance in Escherichia coli. Finally, functions of BSFMTs in BSF were explored through RNA interference (RNAi). RNAi results of BSFMT2B showed that the larval fresh weight decreased significantly, and the larvae mortality increased significantly. This study suggests that BSFMTs have important properties in Cd detoxification and tolerance in BSF. Further characterization analyses of physiological function about metallothioneins are necessary in BSF and other insects. (C) 2021 Published by Elsevier Ltd.

Automated summary

The black soldier fly (BSF) has a strong tolerance to cadmium stress, with metallothioneins playing a crucial role in detoxification and tolerance. RNA interference experiments confirmed the importance of metallothioneins in BSF's ability to withstand cadmium toxicity. Further studies on the physiological functions of metallothioneins in BSF and other insects are needed.