Studies in the following areas will be continued: (a) Development and improvement of gene transmission systems in Erwinia amylovora, Erwinia chrysanthemi, and other phytopathogenic bacteria; (b) Mapping genetic loci for virulence in Erwinia amylovora and for pectolytic enzymes in Erwinia chrysanthemia; (c) Genetic and molecular properties of E-lac ion, a transmissible plasmid orifinating in human clinical strains of Erwinia herbicola; (d) Comparisons of pectolytic enzymes from Erwinia, Klebsiella, and Yersinia; (e) Distribution of Serratia on plants, with particular reference to the bacterial sorts that cause nosocomial infections in man; (f) Isolation and characterization of unusual, possibly plant-associated bacteria isolated from waters and soils; (g) Xanthomonadin pigments and demonstration (by their lack) that the alleged "Xanthomonas species" from human clinical sources are not members of the genus Xanthomonas; (h) Demonstration and characterization of a putative necrotoxin in Erwinia amylovora, and the possible ultrastructural basis of virulence.