Isolation of thatch-degrading bacteria and their physiological characters

Abstract

Bacteira which were able to decompose the turf thatch layer were surveyed from various sources including turf residues in the thatch layer, soil of turf rhizosphere and decayed turf. At first, 47 bacterial isolates which released cellulase were selected by the cellulose-medium-plate assay. Three of them successfully decomposed turf leaves into fibrous residues in test tubes during one month incubation. All of the three isolates were identified as Bacillus pumilus, having variations in some physiological characters. The xylan-medium-plate assay revealed that these three isolates also released xylanase. They did not show any inappropriate effects on turf seedlings and rather accelerated their growth. They reduced dry weight of turf leaves and stems by 300o during one month incubation in vitro. Furthermore, all of them showed antifungal activity to a wide range of pathogenic fungi including Rhizoctonia, Sclerotinia, Microdochium, Curvularia, Gaeumannomyces. This activity was expressed on the medium suitable for bacterial growth prominently. One isolate, CA-39, which showed the strongest turf-decomposing and antifungal activities was considered as the best candidate to be applied to the actual turf field. A further careful study is required to analyze colonization of this candidate and its influence to microflora in the field.