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16S vs 18S vs ITS

16S vs 18S vs ITS

CapitalBio, a leader in microbiome research, delves into the fascinating world of microbial identification through 16S, 18S, and ITS sequencing technologies. This article explores these techniques to understand the intricacies of the microbiome RNA sequencing and their distinct roles in unraveling the mysteries of the microbiome.

What are 16S and 18S Sequencing?

16S and 18S ribosomal RNA (rRNA) genes are highly conserved regions present in the DNA of all living organisms, making them valuable tools for identifying and classifying various life forms.

  • 16S rRNA sequencing: This technique specifically targets the 16S rRNA gene in bacteria and archaea. By analyzing the sequence variations within this gene, scientists can identify the types of bacteria present in a sample and even estimate their relative abundance. This information provides valuable insights into the composition and diversity of bacterial communities, making it an essential tool in various fields like environmental studies, human health research, and food safety analysis.

  • 18S rRNA sequencing: Primarily used for eukaryotic diversity studies, 18S rRNA sequencing targets the 18S rRNA gene found in the small ribosomal subunit of eukaryotes (organisms with complex cells, like plants, animals, and fungi). Analyzing the variations in this gene sequence allows researchers to identify and classify diverse eukaryotic species within a sample.

16s 18s its

What Is 16s And ITS Amplicon Sequencing?

16S amplicon sequencing refers to a specific technique used within the broader field of 16S rRNA sequencing. This method amplifies, or replicates, a specific region within the 16S rRNA gene, focusing on the highly variable regions that differ significantly between bacterial species. By focusing on these variable regions, scientists can achieve higher resolution and accuracy in identifying and differentiating various bacterial species present in a sample.

What Is 16s rRNA Species Identification?

Once a sample has undergone 16S rRNA sequencing, the resulting data needs to be analyzed to identify the specific bacterial species present. This process involves comparing the obtained sequences with reference databases containing known sequences of various bacterial species. By identifying the closest matches in the database, scientists can confidently assign species-level identifications to the bacteria found in the sample.

What is 18S rRNA Sequencing for Bacterial Identification?

While 16S rRNA sequencing is the preferred method for bacterial identification, 18S rRNA sequencing can be used in specific scenarios. However, due to lower sequence variability within the 18S rRNA gene compared to 16S, differentiating closely related bacterial species using 18S is often more challenging. Therefore, 18S typically finds application in broader eukaryotic diversity studies, including fungal and protist identification.

What is the Difference Between 16S and ITS?

While both 16S and ITS (Internal Transcribed Spacer) sequencing techniques play roles in microbial identification, they target different regions and have distinct applications.

  • 16S rRNA sequencing: Primarily focuses on identifying and classifying bacteria and archaea based on variations within the 16S rRNA gene.

  • ITS sequencing: Targets the Internal Transcribed Spacer region located between the small and large ribosomal subunit genes in various organisms, including bacteria, fungi, and archaea. This region exhibits higher variability compared to the 16S rRNA gene, making it valuable for differentiating closely related species within these groups.

What is the Difference Between 18S ITS Sequencing?

Although both ITS and 18S sequencing target non-coding regions within the rDNA molecule, they offer distinct advantages for different applications:

  • ITS sequencing: Offers higher discriminatory power compared to 18S sequencing, making it ideal for differentiating closely related fungal and bacterial species.

  • 18S sequencing: More suitable for broad identification of eukaryotic organisms across various groups, including plants, animals, and fungi, due to its wider coverage of eukaryotic diversity.


CapitalBio, at the forefront of microbiome analysis, utilizes advanced sequencing technologies like 16S 18S ITS to unlock the secrets of the microbial world. By understanding the differences and specific applications of each technique, scientists gain valuable tools to delve deeper into the diverse communities of microbes present in various environments. From exploring the human gut microbiome to analyzing the complex ecosystems in the soil, these sequencing methods pave the way for a deeper understanding of the microbial world and its impact on various aspects of life.

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