The Use of Sudan Black B as a Bacterial Fat Stain

Sudan black B was introduced as a specific fat stain for the detection of lipids in tissue sections by L. Lison in 1934. Saturated solutions of Sudan black B in 70% alcohol or in ethylene glycol stain the fat bodies of bacteria a deep blue-black color, and this dye is recommended as superior to the other Sudans.The method used in staining the bacteria was to suspend a loopful of the cells in a drop of the stain solution and to prepare flat wet mounts. The organisms giving positive fat tests with Sudan black B included Bacillus cereus, Bacillus mycoides, Azotobacter beijerinckii, Rhizobium leguminosarum, Mycobacterium avium, Mycobacterium leprae, Oospora lactis, Bacillus tumescens, water spirilla, and fungi.