bbduk flags ‘tossbrokenreads’ and ‘nullifybrokenquality’

bbduk flags ‘tossbrokenreads’ and ‘nullifybrokenquality’

2

I seek help understanding these 2 flags for BBDUK of BBMAP = ‘tossbrokenreads‘ and ‘nullifybrokenquality

I see these flags mentioned in the STDERR of my bbduk.sh step using BBMap version 38-60 while
decontaminating Illumina SE 100nt raw reads via “Adapter and Quality Trimming” – please see a relevant block of the STDERR copy-pasted below

[E::bgzf_read] Read block operation failed with error 2 after 58624 of 65536 bytes
Error 3 in block starting at offset 1321362048(4EC26280)
java.lang.Exception: 
Mismatch between length of bases and qualities for read 17377414 (id=HWI-ST797:117:D091UACXX:4:1303:5955:45869 1:).
# qualities=27, # bases=101

CCCFFFFFHHHHHJJIIJJJIJIEIHJ
TTCCCGATCATCCCGAGAAGGAACGTCTGCCATAATCTTCTCCTGACCGCGCCAAAGAATTTTGTCAATGACCCCAAATTCCTTAGCCAATAATGCGTCCA

This can be bypassed with the flag 'tossbrokenreads' or 'nullifybrokenquality'
    at shared.KillSwitch.kill(KillSwitch.java:96)
    at stream.Read.validateQualityLength(Read.java:214)
    at stream.Read.validate(Read.java:104)
    at jgi.BBDuk$ProcessThread.run(BBDuk.java:2418)

However, the bbduk.sh help menu does not have these exact flags (too long to fully copy / paste here), the closest flag I see is tossjunk=f . Therefore, I’m

A. confused about these messages,

B. curious when and why I would call these flags, and

C. why I receive these error messages – do they imply corrupted reads in my FASTQ input?

Could forum members please help? Thanks!


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