http://cutadapt.readthedocs.io/en/stable/guide.html

Question：我们要不要在mapping前对fastq file进行triming？

1) directly using `bwa mem` without the trimming process, and they told me the mapping quality is good enough. 

2) we should firstly run the fastqc to determine whether the reads quality is good or not, then use fastx or cutadapt tool to trim the reads for better alignment.