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Synergism between Pseudomonas caryophylli and a Species of Corynebacterium. Chelston W. D. Brathwaite, Graduate Assistant, Department of Plant Pathology, Cornell University, Ithaca, New York 14850; Robert S. Dickey, Professor, Department of Plant Pathology, Cornell University, Ithaca, New York 14850. Phytopathology 60:1046-1051. Accepted for publication 4 February 1970. DOI: 10.1094/Phyto-60-1046.

Corynebacterium sp. and Pseudomonas caryophylli were grown separately or together in various synthetic and semisynthetic media. When grown alone in media containing free sugars, Corynebacterium sp. produced acids which apparently restricted its growth. Growth of Corynebacterium sp. was greater when associated with P. caryophylli than when grown alone in these media, and acid accumulation was not detected. Growth of P. caryophylli was enhanced when associated with Corynebacterium sp., except in media where glucose or sodium polypectate served as the sole carbon source. Corynebacterium sp. produced extracellular pectic and cellulolytic enzymes, but these enzymes were not detected in supernatants of fragmented cells of P. caryophylli or in culture filtrates of this pathogen. Cellulase synthesis was repressed in media containing glucose or sucrose. Cellulolytic activity could not be detected in a carnation extract medium inoculated with Corynebacterium sp. alone, but was detected when the same medium was inoculated with both bacteria simultaneously. Synthesis of cellulase in media inoculated with both bacteria was due to a rapid depletion of the reducing sugar content and derepression of cellulase biosynthesis by Corynebacterium sp. The pectic enzyme produced by Corynebacterium sp. was characterized as an endo-polygalacturonate trans-eliminase.