Polysaccharolytic activities of bacterial enzymes that degrade the cell walls of Pythium porphyrae, a causative fungus of red rot disease in Porphyra yezoensis

Abstract

Four bacteria with degrading activity against the cell walls of Pythium porphyrae were successfully isolated from Porphyra-culturing environments. The crude enzymes from these bacterial isolates, Bacillus sp. BE1, Bacillus sp. FE1, Pseudomonas sp. PE1, and Pseudomonas sp. PE2, degraded the mycelial cell walls of Pythium sp. N-Acetylglucosamine and glucose were detected in the supernatants of Pythium cell walls treated with the enzymes from Bacillus sp. BE1, Bacillus sp. FE1, and Pseudomonas sp. PE2 as the final degrading products by high-performance liquid chromatography, whereas only glucose was detected in the supernatant of the cell walls treated with the enzyme from Pseudomonas sp. PE1. Moreover, the activities of β-1, 3-glucanase, β-1, 3-1, 4-glucanase, and chitinase were observed by polysaccharolytic analysis using the enzymes from Bacillus sp. BE1, Bacillus sp. FE1, and Pseudomonas sp. PE2, whereas only the activities of β-1, 3-glucanase and β-1, 3-1, 4-glucanase were found during analysis using Pseudomonas sp. PE1. β-1, 4-Glucanase, β-1, 6-glucanase, and mannanase activities were not detected in any of the crude enzymes obtained from these isolates. From the four isolates, the molecular weights (MW) of β-1, 3-glucanase and chitinase were estimated to be approximately 50000-100000 by the ultrafiltration method. Two Pseudomonas spp. were also suggested to have β-1, 3-1, 4-glucanases with MW of 50000-100000. However, the MW of β-1, 3-1, 4-glucanases from the two Bacillus spp. might be close to 50000 or they produce at least two β-1, 3-1, 4-glucanases with MW of 30000-50000 and 50000-100000, respectively.