Production of pectinases and cellulase by six Pythium species isolated from necrotic strawberry roots
Polygalacturonase and polymethylgalacturonase activity was detected in filtrates ofPythium irregulare, P. perniciosum, P. sylvaticum, andP. dissotocum but not in filtrates ofP. rostratum andP. acanthicum. OnlyP. irregulare, P. perniciosum andP. dissotocum elaborated pectin methyl esterase and in trace amounts. None of the species produced detectable pectintrans-eliminase and “macerating enzyme” activity.P. sylvaticum was the only species of four tested which produced cellulase.
PECTIC ENZYME SYNTHESIS IN RELATION TO VIRULENCE IN FUSARIUM OXYSPORUM F. LYCOPERSICI (SACC.) SNYDER AND HANSEN
The pectic enzymes produced by Fusarium oxysporum f. lycopersici appear to be causally related to the virulence of the pathogen. The effects of various cultural conditions on the synthesis of pectin methylesterase by two strains of the pathogen were investigated. The virulent strain grew better and produced more pectic enzymes than the avirulent one, and this difference became even more pronounced in media with high pectin content and when the temperature of incubation was raised from 15° to 28 °C. The correlation between the virulence of the pathogen and the production of the pectic enzymes is discussed.
Serological Studies of the Genus Xanthomonas
It was demonstrated in a previous paper (Elrod and Braun, 1947) that the genus Xanthomonas could be divided into five immunologically distinct groups plus several apparently unrelated species. Of the six organisms which did not fall into any group, three were doubtful Xanthonwnas cultures. The group with the greatest membership was called the Xanthomonas translucens group. It is the purpose of.this paper to report on the serological relationship of each member of the latter group, to demonstrate the immunological homogeneity of certain members, and to elucidate specific entities within this large group.