Biodethatching Using Fungal Laccases: Process Optimization.

One major problem in management of turfgrass greens is the accumulation of high organic matter content in the form of thatch and mat layers causing various problems such as decreased movement of oxygen through the thatch or mat zone, decreased saturated hydraulic conductivity, and increased water retention in the thatch zone. Cultural practices like core aeration, vertical mowing, and top dressing that have been used to manage the thatch buildup are intensive in terms of cost, energy, and labor as well as have adverse effects on turfgrass quality. The rate of thatch degradation is limited by lignin, a plant cell wall constituent that is resistant to microbial degradation and limits the availability of easily degradable cellulose and hemi-cellulose to the microbes. Degradation of lignin in the environment in carried out by certain white-rot fungi which degrade lignin with the help of lignolytic enzymes. We developed a novel approach in which we used fungal laccase, a lignolytic enzyme, from Trametes versicolor, to facilitate lignin degradation and in turn manage thatch. In 2010, a split plot field study was conducted on a bentgrass green to optimize the rate and frequency of laccase application and to compare laccase application to core aeration followed by sand top dressing, a cultural management practice. Experiments with reduced number of treatments were also conducted on bermudagrass green and a zoysiagrass lawn. Plots to which laccase was applied at different levels and frequencies were monitored for parameters such as thatch layer thickness, total organic carbon, and saturated hydraulic conductivity as well as the turf quality. After six months of treatment with laccase, thatch layer thickness was significantly reduced and saturated hydraulic conductivity was improved on both bentgrass and bermudagrass greens. Total organic carbon content of bermudagrass was also significantly reduced by laccase treatments.