Huge Micro Problem
As you know, bacteria are everywhere, invisible to the naked eye, yet influencing every environment on Earth. What happens when you need to know how many individual bacterial cells are contaminating a food, living in an environmental sample, or growing in a culture tube? You need some method for counting the bacteria accurately. But, it is not uncommon for a liquid culture of bacteria to have a billion cells in every milliliter of media. Think about that for one second. In your kitchen, you probably have a teaspoon. Every teaspoon has about 5 milliliters. That means that every teaspoon of liquid could potentially have 5 billion bacteria in it. Even if you counted one bacteria every second, it would take you over 150 years to get to 5 billion! Obviously, this is not a viable option. So what can you do? You need fewer bacteria to count. Ideally, you want to only have to count between 30 and 300 bacteria, a range of numbers that takes only at most a few minutes to count. But, how do we get there?