Bacteria are microbes are unicellular organism. Bacteria are prokaryote cell. Naturally found in soil, water and air. There are several ways to identified bacteria. In this example, we will be the most popular way to do that is a gram stain. If cell wall is stain with methylene blue, its mean this bacteria is gram positive bacteria because cell wall contain with a big peptidoglycan layer. But if its stain with nigrosin, it’s mean that this bacteria is gram negative bacteria because cell wall contain with a thin peptidoglycan layer.