A complete bacterial genome assembled de novo using only nanopore sequencing data

Area of Science:

• Genomics
• Bioinformatics
• Microbial Genetics

Background:

• De novo genome assembly is crucial for understanding microbial genetics.
• Nanopore sequencing offers long reads but presents assembly challenges.
• Accurate genome reconstruction is essential for bacterial research.

Purpose of the Study:

• To develop and validate a method for de novo genome assembly using only nanopore data.
• To achieve a complete, single contig assembly of the Escherichia coli K-12 MG1655 chromosome.
• To assess the accuracy and integrity of the assembled genome.

Main Methods:

• Read overlap detection and correction using multiple-alignment.
• Genome assembly utilizing the Celera Assembler software.
• Post-assembly polishing with a probabilistic signal-level data model.

Main Results:

• Successful de novo assembly of the Escherichia coli K-12 MG1655 chromosome into a single 4.6-Mb contig.
• The assembly accurately reconstructs gene order.
• Achieved 99.5% nucleotide identity compared to the reference genome.

Conclusions:

• Nanopore sequencing data, when processed with this method, is sufficient for complete bacterial genome assembly.
• The developed three-stage approach (detection, assembly, polishing) is effective for high-accuracy genome reconstruction.
• This work provides a robust method for assembling microbial genomes from long-read sequencing data.