【求助】求助翻译：colony purify是什么意思啊

Shocked cells were added to 1-ml SOC, incubated 1 h at 37°C, and then one-half was spread onto agar to select CmR or KmR transformants. If none grew within 24 h, the remainder was spread after standing overnight at room temperature. After primary selection, mutants were maintained on medium without an antibiotic. They were colony-purified once nonselectively at 37°C and then tested for ampicillin
sensitivity to test for loss of the helper plasmid. If it was not
lost, then a few were colony-purified once at 43°C and similarly tested.

colony purify是指丢失helper plasmid吗？“tested for ampicillin sensitivity to test for loss of the helper plasmid”具体应该怎么做呢？？

1\colony purify是指丢失helper plasmid吗
===背景不清晰，不好回答。从字面意思理解，colony purify是指挑取来自primary selection的单个克隆，进一步扩增。

2\tested for ampicillin sensitivity to test for loss of the helper plasmid
没有语境，不好判断。可以写信给作者询问。

wrote:
2\tested for ampicillin sensitivity to test for loss of the helper plasmid
没有语境，不好判断。可以写信给作者询问。