Chapter 21, Problem 2Q

Summary Introduction

To analyze:

If natural biofilm is a pure culture.

Introduction:

A biofilm is a 3D consortium in which many microorganisms live together. They work together to provide nutrition, eradicate waste and utilize resources. They also secrete Extracellular Polymeric Substances (EPS) which protects the biofilm from outside environment and makes sharing of nutrients easier. A biofilm can be formed by bacteria, protista, fungi and algae.

Explanation of Solution

Naturally it is difficult to find a biofilm containing a pure culture. A biofilm grows by attracting more microorganisms and making them a part of it. Even if the biofilm was started by a single species, in the growth phase it will attract the microbes from surrounding environment. These microbes may or may not be of same species. Hence, slowly many types of microbes will become a part of biofilm. For example, eukaryotic biofilms are usually initiated by eukaryotes but they slowly include bacteria too. A biofilm containing a pure culture is very rare. For example, biofilm in stomach containing Helicobacter pylori is a pure culture biofilm.

Conclusion

Thus, in nature biofilm usually consists of a mix of species. Some biofilms like the one formed by Helicobacter pylori in stomach is a pure culture but it is less frequent than mixed culture biofilms.