NEUTRAL RED 95 % excellent quality manufacturer, exporter and supplier. Neutral red is a eurhodin dye used for staining in histology. It stains lysosomes red. It is used as a general stain in histology, as a counterstain in combination with other dyes, and for many staining methods. In microbiology, it is used in the MacConkey agar and broth media to differentiate bacteria for lactose fermentation. Neutral red is added to some growth media for bacterial and cell cultures. Neutral red acts as a pH indicator, changing from red to yellow between pH 6.8 and 8.0.