The diversity of bacteria in ectomycorrhizas and other tissues of trees
Diversity of bacteria inside the some ectomycorrhizas have been studied. To this end, isolation method using surface-sterilisation with chemical reagents was developed. The isolated bacteria from ectomycorrhizas of Suillus and Russula include Pseudomonas, Bacillus and Paenibacillus with other genera that have not been isolated from ectomycorrhizas. The isolated bacteria through cultivation include the genera of Pseudomonas, Bacillus and Acinetobacter while cultivation-independent methods detect significant amount of plant plastid-originated sequences. Cultivation-dependent and cultivation-independent methods including DNA and RNA based molecular methods were applied to investigate to study bacteria inside ectomycorrhizas colonised Corsican pine growing different nutrient status. These two methods gave rise to different bacterial species associated with ectomycorrhizas and, in particular, genus Pseudomonas was identified as metabolically active populations by RNA-based molecular methods. Possible functional roles of the bacteria associated with ectomycorrhizas were examined by detecting nitrogenase gene (nifH). While nif H DNA was detected in all the samples its expression was confirmed in only three samples collected from the nutrient deficient stand. NifH occurrence and their activity show that contribution of biological nitrogen fixation may not be significant in the field conditions studied here. The bacteria associated with ectomycorrhizas were studied in exotic environment by looking at pine plantations in south east Queensland, Australia. The study shows that there may be similar kind of bacteria in exotic pine plantations compared to pine forest in Scotland. Therefore it is possible that the bacteria may move around the globe by accompanying with the host plants although this is not fully appreciated yet.