Cultured population
Genomic DNA samples were prepared following the standard phenol-chloroform DNA isolation method . The DNA quality and concentration was assessed by agarose gel electrophoresis and Nanodrop spectrophotometer. The DNA samples were interrupted with a length of 350 bp using a Covaris ultrasonic crusher. Then, the sequence library for each sample was constructed by a NEB Next Ultra II DNA Library Prep Kit, following the manufactures protocol. Finally, all the libraries were subjected to 150 bp paired-end sequencing on the Illumina Novaseq 6084 platform.