Solid waste, especially electronic waste is increasingly considered as secondary sources of base, critical, precious, rare and heavy metals. Some microorganisms that possess specific metabolic pathways, adapted to the recycling of these materials, have been shown to be a cost-effective resource in the bioleaching of such secondary sources. Bioleaching not only provides an efficient alternative to extract and recuperate metals, but it also provides a green approach for tackling environmental challenges. As such, while environmental concerns have limited the use of chemical cyanidation, biocyanidation is a more sustainable approach that utilises cyanogenic organisms that are able to solubilise gold and other noble metals via cyanogenesis and through the production of specific metabolites and siderophores. To illustrate this process, this review describes cyanogenesis and explores its use and associated challenges through the cyanogenic metabolic pathways (i.e. enzymes and intracellular functions), biocyanidation and metal complexation. In addition, the following process of metal-cyanide complex formation is also summarised. Finally, recent biotechnological developments, which promote recovery and provide guidance for the improvement of downstream processes for recovery from pregnant solutions, will be described.

固体废物，尤其是电子废物，越来越多地被视为贱金属，关键，贵重，稀有和重金属的次要来源。一些具有特定代谢途径的微生物，适合于这些物质的循环利用，已被证明是这种次级来源生物浸出的一种经济有效的资源。生物浸出不仅为金属的提取和回收提供了一种有效的替代方法，而且还为应对环境挑战提供了一种绿色方法。因此，尽管环境问题限制了化学氰化的使用，但生物氰化是一种更具可持续性的方法，利用能够通过氰化作用以及通过生产特定代谢产物和铁载体来溶解金和其他贵金属的生氰生物。为了说明这个过程，这篇综述描述了生氰作用，并通过生氰代谢途径（即酶和细胞内功能），生物氰化作用和金属络合物探讨了其用途和相关挑战。另外，还总结了以下金属氰化物配合物的形成过程。最后，将描述最近的生物技术发展，其促进回收并为改进从怀孕溶液中回收的下游工艺提供指导。