problem with competent cells

[ms]

hi all,

i want to share one problem regarding DH5 alpha ultra com cells
preparation using inoue method. i am getting contamination as i am not
sure whether it is contamination exactly i donot know but i am getting
good efficiency. everything i am doing in sterile environment. all
buffers i prepared in hood and filtered through .22 micron filter but
i donot know what is the problem. so,  please suggest me what is the
problem.

ms