Advances in microbial protoplasts (Bacillus licheniformis beta-lactamase and the protoplast surface).

The changing nature of the research reported at these Symposia over the past two decades is noted, especially the current emphasis on plant protoplasts. Improvements in procedures for the preparation and regeneration of microbial protoplasts are summarized and the definition of optimal conditions for fusion and genetic transfer. The efficiency of fusion now attainable has led to considerable advances in the genetics of yeasts and mycelial fungi and of bacteria. In addition, the synthesis and secretion of beta-lactamase (penicillinase) in Bacillus licheniformis is described in order to illustrate how protoplasts can be utilized to investigate 1) the form in which the new enzyme emerges from the membrane surface, 2) the importance of accessibility in processing of the emerging chain and 3) the role of cell wall structure in the induction of beta-lactamase synthesis.