DNA analysis as tool for identification of bacteria in archaeological waterlogged wood

Abstract In this work molecular techniques were applied in order to integrete the results obtained by Optical (OM) and Scanning Electron (SEM) Microscopy, to understanding and assessing the changes in the anatomical structure of archaeological waterlogged wood (Pinus sp.) induced by bacteria colonization. Observation of wooden thin sections revealed by OM showed the presence of black and dark -brown areas (must probably due to sulphur compounds) and mineral concretions. The SEM micrographs revealed a specific cell wall alteration attributable to bacterial activity and abundant pyrite framboids (as single structure or clustered). The presence of sulfur compounds in archaeological waterlogged wood, indicate both long-term burial in anoxic environment and colonization by sulfate-reducing bacteria. Molecular biology investigation was performed through ad hoc protocols by direct DNA extraction from wood samples and in vitro amplification of bacteria DNA target sequence (16S, ITS regions-r RNA). The results reveal and identify bacterial genus as Pseudomonas, Cellulomonas, Xanthomonas and Bacillus that, as reported in the related scientific literature, are the most common cellulosolytic and ligninolytic bacteria. Moreover were also revealed the presence of Marinobacter sp. and Desulforudis audaxviator, respectively iron- oxidizing and sulfate- reducing bacteria. The investigation protocol set up in this work can be applied to a range of wooden artifacts of archaeological findings for both identification of bacteria colonization shed some light on the degradation phenomena, indispensable for correct conservation and restoration strategies.