When we think of the word marker, the first thing that comes to our minds is something that is used to indicate a place. For example, it can be your current location on Google Maps or it can be the place where you planted some seeds in your garden. Similarly, in genomics studies, we can find marker genes in bacterial genomes. In this article, I will introduce you to marker genes used in metagenomics analysis, how they are used and walk you through an example of a commonly used gene prediction tool.
We know that there are trillions of microbes in the environment surrounding us, even in our bodies. These microscopic communities have very diverse ecosystems and by studying their composition and behaviour we can learn a lot about them. If you have come across my previous article Metagenomics — Who is there and what are they doing? then you know that binning is an important step in metagenomics analysis.
Did you know that your body houses about 100 trillion bacteria? Estimates show that a human has approximately a pound or two of bacteria living in his/her gut (stomach)  (Now don’t go and drink all the antibiotics you know, to kill those bacteria. In fact, these bacteria play an important role in our metabolism and immune system). The same goes for the backyard of your house. There can be many species of bacteria living in the soil and they help to enrich the soil (e.g.: nitrifying bacteria produce nitrates which are essential for plants). These microscopic communities have very diverse ecosystems and studying their composition and behaviour can provide us with valuable insights. In this article, I will provide a basic introduction to metagenomics, which is the study of genetic material obtained from microbial communities.