Do you know that your plasmid replicates in your algal cell or has a mechanism for chromosomal insertion if not?

You need a protocol for transformation or electroporation of your cells as well.

Nobody can make any suggestions since you did not provide any details such as what algae and what plasmid etc.

Dear sir, thank you for your response. I have gene cloned in pET28a vector and i wish to transform into Chlorella sorokiniana cells.

Let me know your progress.

So that is not going to work. pET28 will not replicate in algal cells nor will it provide a promoter for any gene expression. The pET28 plasmid is strictly designed for use with E. coli.