Iam trying to clone 100-200 bp fragment in PBI121. After ligation i am getting lots of white color colonies and some of translucent colonies. these white colonies results in less or no plasmid when i proceed them for plasmid isolation. I had also parallelly transform empty vector which doesnot have that problem. the problem is only when i transform the ligated vector. though I have changed my comp cell , the problem still sustain.

can anyone suggest me the best probable reason for the same.

Vector is PBI121 and cloning sites is BAMH1 and SAC1

strain is DH5a