(Topic v-(6) States)---16S Amplicon Sequencing Quiz

Which of the following is NOT a typical application of 16S amplicon sequencing?

• Identifying pathogenic microorganisms in clinical samples

• Studying microbial ecology in environmental samples

• Monitoring freshwater quality

• Determining the complete genome sequence of a single bacterial species

Answer explanation

16S amplicon sequencing is used for identifying microorganisms and studying microbial ecology, but it does not provide complete genome sequences, making 'Determining the complete genome sequence of a single bacterial species' the correct choice.

What is a major limitation of 16S amplicon sequencing compared to whole-genome sequencing?

• It cannot identify bacteria at all

• It has lower taxonomic resolution, especially at the species and strain level

• It is more expensive and time-consuming

• It requires culturing of all bacteria in the sample

Answer explanation

16S amplicon sequencing targets a specific gene, limiting its ability to resolve bacterial taxa at the species and strain levels compared to whole-genome sequencing, which provides a more comprehensive view of genetic diversity.

Which region of the 16S rRNA gene is commonly targeted for amplicon sequencing on Illumina platforms?

• V1-V2

• V3-V4

• V5-V6

• V8-V9

Answer explanation

The V3-V4 region of the 16S rRNA gene is commonly targeted for amplicon sequencing on Illumina platforms due to its optimal length and variability, making it suitable for distinguishing between different microbial taxa.

What does alpha diversity in 16S amplicon sequencing data represent?

• Differences between microbial communities

• Richness and evenness within a single microbial community

• Functional capabilities of the microbiome

• Evolutionary relationships between bacterial species

Answer explanation

Alpha diversity refers to the richness and evenness of species within a single microbial community, indicating how diverse that community is in terms of the number of different species and their relative abundances.

Which of the following factors does NOT typically affect the outcome of 16S amplicon sequencing experiments?

• DNA extraction method

• PCR amplification bias

• Choice of variable regions sequenced

• The phase of the moon during sample collection

Answer explanation

The phase of the moon during sample collection does not influence 16S amplicon sequencing outcomes. In contrast, DNA extraction method, PCR amplification bias, and choice of variable regions are critical factors affecting results.

The 16S rRNA gene is approximately (a)   base pairs in length.

Answer explanation

The 16S rRNA gene is approximately 1550 base pairs in length, making this the correct answer. It plays a crucial role in the identification and classification of bacteria.

In 16S amplicon sequencing, (a)   diversity measures the differences between microbial communities.

Answer explanation

In 16S amplicon sequencing, beta diversity measures the differences between microbial communities, contrasting with alpha diversity, which focuses on diversity within a single community.

The (a)   index is a commonly used alpha diversity metric that accounts for both richness and evenness of a microbial community.

Answer explanation

The Shannon index is a widely used metric for assessing alpha diversity in microbial communities, as it incorporates both species richness and evenness, making it a comprehensive measure.

16S amplicon sequencing cannot reliably identify _______ and _______, which are two major groups of microorganisms besides bacteria and archaea.

(a)  

Answer explanation

16S amplicon sequencing primarily targets bacterial and archaeal ribosomal RNA genes, making it ineffective for identifying fungi and viruses, which belong to different biological domains.

The (a)   pipeline is a popular bioinformatics tool for analyzing 16S amplicon sequencing data, which uses amplicon sequence variants instead of OTUs.

Answer explanation

The QIIME2 pipeline is widely used for analyzing 16S amplicon sequencing data, focusing on amplicon sequence variants (ASVs) rather than operational taxonomic units (OTUs), making it a preferred tool in microbiome studies.