Cobalamin (Vitamin B₁₂) is a cofactor for many enzymes, including those in bacteria, archaea, algae, and mammals. In humans, cobalamin deficiency can lead to pernicious anaemia as well as gastrointestinal and neurological disorders. In contrast to marine ecosystems, there is a great paucity of information on the role of soils and terrestrial plants in the supply of cobalt and cobalamin to microorganisms and animals. The content of cobalt cations in most soils is usually sufficient to maintain growth, and the density of cobalamin-producing soil prokaryotes is high in comparison to water bodies. The cobalt content of most soils is usually sufficient in comparison with water, and the density of cobalamin-producing soil prokaryotes is high. Therefore, terrestrial plants are an important cobalt source for cobalamin-producing rumen and gut prokaryotes. The major source of cobalamin for most other animals is the meat of ruminants as well as other animal-derived products, bacteria in insects, and coprophagy, e.g., by rodents. In addition, faecal deposits, and fertilizers as well as soil bacteria add to the cobalamin supply. However, those archaea and bacteria that do not produce cobalamin obtain this coenzyme or its analogues from the environment. Therefore, presence or absence of cobalamin-producing species in soil affects the whole soil microbiome. However, our knowledge concerning microbial producers and consumers of cobalamin in soils is still limited, despite some recent advances. The main reasons are a low cobalamin content in soils and challenging methods of determination. In this regard, advanced analytical knowledge and technical equipment are required, which are usually unavailable in soil laboratories. This review provides relevant methodological information on sample homogenization, extraction, concentration, and purification as well as analysis of cobalamin.

钴胺素（维生素 B ₁₂）是许多酶的辅助因子，包括细菌、古细菌、藻类和哺乳动物中的酶。在人类中，钴胺素缺乏会导致恶性贫血以及胃肠道和神经系统疾病。与海洋生态系统相比，关于土壤和陆地植物在向微生物和动物供应钴和钴胺素方面的作用的信息非常缺乏。大多数土壤中钴阳离子的含量通常足以维持生长，并且与水体相比，产生钴胺素的土壤原核生物的密度较高。与水相比，大多数土壤的钴含量通常是足够的，并且产生钴胺素的土壤原核生物的密度很高。因此，陆生植物是产生钴胺素的瘤胃和肠道原核生物的重要钴来源。对于大多数其他动物来说，钴胺素的主要来源是反刍动物的肉以及其他动物衍生产品、昆虫中的细菌以及啮齿动物等的食粪行为。此外，粪便沉积物、肥料以及土壤细菌也会增加钴胺素的供应。然而，那些不产生钴胺素的古细菌和细菌从环境中获取这种辅酶或其类似物。因此，土壤中是否存在产生钴胺素的物种会影响整个土壤微生物组。然而，尽管最近取得了一些进展，但我们对土壤中钴胺素微生物生产者和消费者的了解仍然有限。主要原因是土壤中钴胺素含量低且测定方法具有挑战性。在这方面，需要先进的分析知识和技术设备，而这些通常是土壤实验室所不具备的。本综述提供了样品均质、提取、浓缩和纯化以及钴胺素分析的相关方法学信息。