pku-embl/metagenomics-skills/bbmap

BBMap

Upstream: BBMap

Citation

Bushnell, B. BBMap: a fast, accurate, splice-aware aligner. LBNL Report (2014). https://escholarship.org/uc/item/1h3515gn

See also docs/references.md.

Analytical thinking

Useful Swiss-army mapper/utilities; for standard metagenome coverage prefer Bowtie2/strobealign unless BBMap is already standardized in the lab.

How to run

set -Eeuo pipefail
id="${1:?usage: map-one.sh SAMPLE_ID REF R1 R2 OUTPUT_DIR}"
ref="${2:?usage: map-one.sh SAMPLE_ID REF R1 R2 OUTPUT_DIR}"
r1="${3:?usage: map-one.sh SAMPLE_ID REF R1 R2 OUTPUT_DIR}"
r2="${4:?usage: map-one.sh SAMPLE_ID REF R1 R2 OUTPUT_DIR}"
out="${5:?usage: map-one.sh SAMPLE_ID REF R1 R2 OUTPUT_DIR}"
threads="${THREADS:-16}"
[[ "$id" =~ ^[A-Za-z0-9][A-Za-z0-9._-]*$ ]] || exit 2
for input in "$ref" "$r1" "$r2"; do test -s "$input" || exit 2; done
test ! -e "$out" || { echo "use a new output directory: $out" >&2; exit 2; }
mkdir -p "$out"
 
bbmap.sh ref="$ref" in1="$r1" in2="$r2" \
  out="$out/${id}.unsorted.bam" threads="$threads" \
  >"$out/${id}.bbmap.stdout.log" 2>"$out/${id}.bbmap.stderr.log"
samtools sort -@ "$threads" -o "$out/${id}.bam" "$out/${id}.unsorted.bam"
samtools index "$out/${id}.bam"
samtools quickcheck -v "$out/${id}.bam"
rm "$out/${id}.unsorted.bam"

Key parameters

Decision notes

• Stage: mapping / utilities (BBTools suite)
• Prefer for specialized BBMerge/BBDuk tasks; for Illumina→contigs coverage prefer strobealign / bowtie2

Validation, recovery, and provenance

Require a coordinate-sorted/indexed BAM and inspect BBMap statistics plus samtools flagstat/idxstats. Confirm that paired inputs remained paired and that the reference is the intended assembly. BBMap covers many utilities; do not silently substitute BBDuk/BBMerge preprocessing for the study's declared QC route.

Record BBMap/Java/Samtools versions, memory settings, reference/read checksums, commands, logs, BAM checksum, and mapping summaries. Failed or changed runs should use a fresh directory because index and temporary files may persist.

Related skills

bowtie2 · samtools · coverm · tool-selection · metagenomics-workflow