Glossary Term: Melzer’s Reagent

1. Iodine solution used to test amyloidy and dextrinoidy of spores and other structures.
2. Melzer’s reagent is an iodine solution producing a blue-black “amyloid” reaction in some spores and parts of fungi. However, Melzer’s reagent contains chloral hydrate, a medically controlled substance and therefore it has been hard to get. The history of iodine use for identifi cation of fungi dates back to the mid 1800s; its use for white spore identification was described by Melzer in 1924. The production of the positive amyloid reaction is due to an amylose-iodine complex. In some cases a reddish “dextrinoid” color may occur due presumably to a glycine-betaine complex. The spores of 35 species of fungi were tested with Melzer’s, Lugol’s, and iodine solutions. All 35 species reacted as predicted from authoritative sources with Melzer’s but results were inconsistent with Lugol’s and iodine. Fungal tissue that turns blue or black with Melzer’s reagent is an amyloid positive reaction, sometimes written as I+ or J+.

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Created: 2019-06-25 12:34:34 CDT (-0400)
Last modified: 2019-06-25 12:34:34 CDT (-0400)