Question: Which is the easiest characteristic to detect a bacteria through a microscope?

Natasha Myhill answered on 6 Nov 2017:

Most bacteria have two obvious shapes – rods or spheres. By staining the bacteria with a Gram stain, you can tell if the bacteria is Gram-positive (stains purple) or Gram-negative (stains red). Gram-positive bacteria have a thick cell wall and no cell membrane. Gram-negative bacteria have a thin cell wall and a cell membrane. With just these two characteristics, you can identify a lot of bacteria!