fqtrimは、アダプター、polyA tail、未知塩基（Ns）および低クオリティな3 '領域をトリミングできる多目的トリミングツール。アダプターとポリA配列の不正確なマッチングにも対応している。 このユーティリティは、複雑さの低い配列（ダスト）のフィルターを適用したり、重複リードをカウントすることもできる。例えばこの論文（リンク）では、low complexilityなONTリードの除去に使用されている。
公式サイト
https://ccb.jhu.edu/software/fqtrim/
インストール
https://github.com/gpertea/fqtrim
公式よりダウンロードするか、Githubからcloneしてビルドする。
git clone https://github.com/gpertea/fqtrim.git
cd fqtrim/
make release
> ./fqtrim
$ ./fqtrim
fqtrim v0.9.7. Usage:
fqtrim [{-5 <5adapter> -3 <3adapter>|-f <adapters_file>}] [-a <min_match>]\
[-R] [-q <minq> [-t <trim_max_len>]] [-p <numcpus>] [-P {64|33}] \
[-m <max_percN>] [--ntrimdist=<max_Ntrim_dist>] [-l <minlen>] [-C]\
[-o <outsuffix> [--outdir <outdir>]] [-D][-Q][-O] [-n <rename_prefix>]\
[-r <trim_report.txt>] [-y <min_poly>] [-A|-B] <input.fq>[,<input_mates.fq>\
Trim low quality bases at the 3' end and can trim adapter sequence(s), filter
for low complexity and collapse duplicate reads.
If read pairs should be trimmed and kept together (i.e. never discarding
only one read in a pair), the two file names should be given delimited by a comma
or a colon character.
Options:
-n rename the reads using the <prefix> followed by a read counter;
if -C option was also provided, the suffix "_x<N>" is appended
(where <N> is the read duplication count)
-o write the trimmed/filtered reads to file(s) named <input>.<outsuffix>
which will be created in the current (working) directory (unless --outdir
is used); this suffix should include the file extension; if this extension
is .gz, .gzip or .bz2 then the output will be compressed accordingly.
NOTE: if the input file is '-' (stdin) then this is the full name of the
output file, not just the suffix.
--outdir for -o option, write the output file(s) to <outdir> directory instead
-f file with adapter sequences to trim, each line having this format:
[<5_adapter_sequence>][ <3_adapter_sequence>]
-5 trim the given adapter or primer sequence at the 5' end of each read
(e.g. -5 CGACAGGTTCAGAGTTCTACAGTCCGACGATC)
-3 trim the given adapter sequence at the 3' end of each read
(e.g. -3 TCGTATGCCGTCTTCTGCTTG)
-A disable polyA/T trimming (enabled by default)
-B trim polyA/T at both ends (default: only poly-A at 3' end, poly-T at 5')
-O output only reads affected by trimming (discard clean reads!)
-y minimum length of poly-A/T run to remove (6)
-q trim read ends where the quality value drops below <minq>
-w for -q, sliding window size for calculating avg. quality (default 6)
-t for -q, limit maximum trimming at either end to <trim_max_len>
-m maximum percentage of Ns allowed in a read after trimming (default 5)
-l minimum read length after trimming (if the remaining sequence is shorter
than this, the read will be discarded (trashed)(default: 16)
-r write a "trimming report" file listing the affected reads with a list
of trimming operations
-s1/-s2: for paired reads, one of the reads (1 or 2) is not being processed
(no attempt to trim it) but the pair is discarded if the other read is
trashed by the trimming process
--aidx option can only be given with -r and -f options and it makes all the
vector/adapter trimming operations encoded as a,b,c,.. instead of V,
corresponding to the order of adapter sequences in the -f file
-T write the number of bases trimmed at 5' and 3' ends after the read names
in the FASTA/FASTQ output file(s)
-D pass reads through a low-complexity (dust) filter and discard any read
that has over 501506411212f its length masked as low complexity
--dmask option is the same with -D but fqtrim will actually mask the low
complexity regions with Ns in the output sequence
-C collapse duplicate reads and append a _x<N>count suffix to the read
name (where <N> is the duplication count)
-p use <numcpus> CPUs (threads) on the local machine
-P input is phred64/phred33 (use -P64 or -P33)
-Q convert quality values to the other Phred qv type
-M disable read name consistency check for paired reads
-V show verbose trimming summary
Advanced adapter/primer match options (for -f or -5 , -3 options):
-a minimum length of exact suffix-prefix match with adapter sequence that
can be trimmed at either end of the read (default: 6)
--pid5 minimum percent identity for adapter match at 5' end (default 96.0)
--pid3 minimum percent identity for adapter match at 3' end (default 94.0)
--mism mismatch penalty for scoring the adapter alignment (default 3)
--match match reward for scoring the adapter alignment (default 1)
-R also look for terminal alignments with the reverse complement
of the adapter sequence(s)
ラン
クオリティ30以下の部位をトリミングし、25bp以下になったリードは除去する。
fqtrim -q 30 -l 25 -o filtered.fq input.fq
- -P input is phred64/phred33 (use -P64 or -P33)
- -q trim read ends where the quality value drops below <minq>
- -l minimum read length after trimming (if the remaining sequence is shorter than this, the read will be discarded (trashed)(default: 16)
- -o write the trimmed/filtered reads to file(s) named <input>.<outsuffix> which will be created in the current (working) directory (unless --outdir is used); this suffix should include the file extension; if this extension is .gz, .gzip or .bz2 then the output will be compressed accordingly. NOTE: if the input file is '-' (stdin) then this is the full name of the output file, not just the suffix.
- -p use <numcpus> CPUs (threads) on the local machine
- -P input is phred64/phred33 (use -P64 or -P33)
input. filtered.fqが出力される。
low complexilityフィルターをかける。低複雑度の配列が除去される。
fqtrim -D -o filtered.fq input.fq
- -D pass reads through a low-complexity (dust) filter and discard any read that has over 501577251212f its length masked as low complexity
- --dmask option is the same with -D but fqtrim will actually mask the low
引用
https://ccb.jhu.edu/software/fqtrim/
https://zenodo.org/record/1185412#.WsmDTSPAORc
