N-173. Effects of Chlorothalonil and BHT on Bacterial Communities Involved in the Deterioration of Wood Using Terminal Restriction Fragment Length (T-RFLP) Analysis

G. T. Kirker, S. V. Diehl, M. L. Prewitt, L. C. Mangum;
Mississippi State Univ., Mississippi State, MS.

Introduction The effects of chlorothalonil (CTN) and butylated hydroxytoluene (BHT) on the bacterial community in southern yellow pine field stakes were assessed using terminal restriction fragment length polymorphism (T-RFLP) analysis. Materials and Methods Field stakes were treated using a full cell method with 0.25 and 0.37% ammoniacal copper quat (ACQ-C), 0.1 and 0.25% CTN, 0.1 and 0.25% CTN combined with 2.0% BHT and installed in field test sites representing two decay hazard zones in Mississippi as designated by the American Wood Preserver’s Association (AWPA). Stakes were sampled at 90 day intervals at each site and visually rated for damage due to decay. Bacterial DNA was amplified using general 16S rDNA primers. Community data were analyzed to determine the effects of site, exposure (above or below ground), treatment, and time on the bacterial communities inhabiting the field stakes. Non-Metric multidimensional Scaling (NMDS) was also used to visually depict changes in community compositions for treatments over time. Results Results indicate that all of the wood preservatives altered the initial colonization of field stakes by bacteria resulting in higher species richness, evenness, and diversity that gradually decrease over time to levels more similar to the untreated samples by 15 months exposure. The beta diversity of bacterial populations was less similar in the early stages of exposure (3-9 months) for preservative treated wood, and became more similar as the preservatives depleted, which was supported by the NMDS analysis. Visual decay ratings and preservative depletions were also correlated with diversity data and negative correlations were found between bacterial species richness and diversity associated with low retentions (0.1%) of chlorothalonil. Summary Samples treated with either ACQ-C or CTN exhibited higher bacterial species richness and diversity initially, but eventually decreased to levels consistent with untreated samples. Significant depletion of all preservatives was noted, but only the low retention of CTN was directly correlated with bacterial richness and diversity.