TYPES OF STAINING Figure 1. Simple stain of Bacillus subtilis and Staphylococcus aureus. Figure 2. Gram stain: Staphylococcus aureus and Pseudomonas aeruginosa. Figure 3. Acid-fast stain of Mycobacterium smegmatis and Staphylococcus aureus. Figure 4. Negative stain of Bacillus and Staphylococcus using nigrosin. Figure 5. Spore stain of Bacillus. Figure 6. Flagellar stain of a Salmonella Typhi. Salmonella are motile by means of peritrichous flagella.