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Pectobacterium wasabiae is a dreadful causal agent of potato soft rot. It relied mainly on the production a wide range of plant cell wall-degrading enzymes to cause disease. Of the different enzymes, the endo-b-1,4-glucanase may be important in pathogenesis, being responsible for hydrolyzing the cellulose. In the process of pathogen infection, cellulase secreted by the pathogen is major determinant of pathogenicity, which played an important role in softening and decomposition of cell wall. But so far, the related research very rarely. However, most characteristic of the cellulase in the soft rot bacteria was not clear so far. Here, a putative endo-b-1,4-glucanase gene from P. wasabiae SCC3193 was previously synthesized according the bias codon of yeast, heteroexpressed in Pichia pastoris, and further investigated for its characteristic. Pectobacterium wasabiae SCC3193 is a genetically well characterized model in soft rot research. SDS-PAGE analysis showed that the recombinant endo-b-1,4-glucanase (PcegAI) produced in P. pastoris has a molecular mass of approximately 30kDa. When CMC was used as substrate, it exhibited maximal activity at pH 4.0 with an optimum temperature of 40°C, and stable at pH 5-8. The Km and specific activity values for CMC are 64.5 mM and 7 ×103 U mg-1 respectively. Most metallic ions had no influence on the activity of endo-b-1,4-glucanase at a concentration of 1 mM except for Cu2+ and Mn2+. These characteristics suggested that PcegAI may play a major role in degrading of cellulose polymers. The high activity of this enzyme also has potential in biomass opening, such as the bioconversion of lignocellulosic materials and bioethanol production.

Pectobacterium parmentieri is a Gram-negative plant-pathogenic bacterium able to infect potato (Solanum tuberosum L.). Little is known about lytic bacteriophages infecting P. parmentieri and how phage-resistance influences the environmental fitness and virulence of this species. A lytic phage vB_Ppp_A38 (ϕA38) has been previously isolated and characterized as a potential biological control agent for the management of P. parmentieri. In this study, seven P. parmentieri SCC 3193 Tn5 mutants were identified that exhibited resistance to infection caused by vB_Ppp_A38 (ϕA38). The genes disrupted in these seven mutants encoded proteins involved in the assembly of O-antigen, sugar metabolism, and the production of bacterial capsule exopolysaccharides. The potential of A38-resistant P. parmentieri mutants for plant colonization and pathogenicity as well as other phenotypes expected to contribute to the ecological fitness of P. parmentieri, including growth rate, use of carbon and nitrogen sources, production of pectinolytic enzymes, proteases, cellulases, and siderophores, swimming and swarming motility, presence of capsule and flagella as well as the ability to form biofilm were assessed. Compared to the wild-type P. parmentieri strain, all phage-resistant mutants exhibited a reduced ability to colonize and to cause symptoms in growing potato (S. tuberosum L.) plants. The implications of bacteriophage resistance on the ecological fitness of P. parmentieri are discussed.