Protoplast Fusion - Protoplasts of bacteria, Actinomycetes and fungi are isolated by treatment with a variety of lytic enzymes. An osmoticum is necessary for protoplast stability, and fusion is usually induced by PEG (polyethylene glycol) treatment.

Usually, recombinants are recovered from protoplast fusion products, and some of them may possess desirable features. Protoplast fusion has been used to produce Cephalosporium acremonium strains, which yield significantly higher cephalosporin C; this was done by fusing auxotrophic mutants.

It may be noted that this organism had not responded well to mutant selection programmes.