Protoplast fusion and gene recombination in the uncommon actinomycete Planobispora rosea producing GE2270

An efficient method for protoplast generation for the uncommon actinomycete Planobispora rosea, the producer of the thiazolylpeptide antibiotic GE2270, was developed using a combination of hen egg white lysozyme and Streptomyces globisporus mutanolysin. This method converted more than 70% of vegetative mycelium to protoplasts, which were then regenerated with 50% efficiency in an optimized medium. When P rosea protoplasts were efficiently fused, recombination between different antibiotic (streptomycin and gentamicin) resistance markers originated sensitive strains (str(s)gen(s)) at frequencies as high as 18% and double resistant fusants (strr(r)gen(r)) at frequencies as high as 29%. Double resistant fusants showed GE2270 productivity intermediate between the productivity of the parental strains. Protoplast generation and fusion in P rosea makes whole genome shuffling feasible as an approach to be used alternately with classical random mutagenesis in industrial strain improvement programs.