17:15 〜 19:15
[BCG05-P06] Heterogenous distribution of methanogenic archaeal communities in the trunk of trees in mountain forest
キーワード：メタン、メタン生成古細菌、森林
Recent studies have revealed that various trees in upland forests harbor anaerobic methanogenic archaea and emit significant amounts of methane through the trunk. However, knowledge about the composition, abundance, and distribution of methanogenic archaeal communities in tree trunks has been limited. This study investigates the community structure of methanogenic archaea at different heights on the trunk of trees in a mountain forest, using culture-independent techniques targeting methanogenic archaeal mcrA genes, to gain more insights into their ecology in tree trunks.
Wood core segments were obtained with an increment borer at different heights (about 1-11 m) on the trunk of three tree species, Aesculus turbinata (At, Tochinoki), Cryptomeria japonica (Cj, Sugi), and Fagus crenata (Fc, Buna) in the Ashiu Experimental Forest of Kyoto University in October 2023. DNA was extracted from the heartwood part of the core samples. The abundance of group-specific methanogenic archaea was quantified by digital PCR technique to reveal the distribution of methanogenic archaeal community. Clone library analysis of methanogenic archaeal mcrA genes was also carried out on the samples that showed the highest copy number in each tree species to reveal the phylogenetic composition of methanogenic archaeal community.
Digital PCR analysis showed that mcrA genes were detected from all the heights of the three trees, but the abundance and distribution varied greatly among the trees. In At, 106 copies g-1 dry wood of mcrA gene were detected at the lower positions of the trunk (1.6 and 3.5 m), and Methanobacterium spp., Methanobrevibacter spp., and Methanomassiliicoccus spp. predominated at those heights. Meanwhile, the copy numbers decreased by 104 copies g-1 dry wood at the height of 4.6–10.8 m and the mcrA genes of various groups of methanogenic archaea were detected. In Cj and Fc, 104–105 copies g-1 dry wood of mcrA gene were detected irrespective of the height (Cj:2.1–10.7 m, Fc:1-10.9 m), and the members of Methanomicrobiales were the predominant group at all heights. Clone library analysis revealed that methanogenic archaea related to Methanobacterium formicicum, Methanosarcina vacuolata, Methanosarcina thermophila, and Methanomassiliicoccus luminyensis inhabited the heartwood of At, while Cj and Fc were predominated by an unknown group in Methanomicrobiales. These results suggest that anoxic and methanogenic environments were widely developed within trees, but that environmental conditions must have been highly variable across heights and individuals (or tree species), which would explain why distinct methanogenic archaeal communities were heterogeneously distributed within and among trees.
Wood core segments were obtained with an increment borer at different heights (about 1-11 m) on the trunk of three tree species, Aesculus turbinata (At, Tochinoki), Cryptomeria japonica (Cj, Sugi), and Fagus crenata (Fc, Buna) in the Ashiu Experimental Forest of Kyoto University in October 2023. DNA was extracted from the heartwood part of the core samples. The abundance of group-specific methanogenic archaea was quantified by digital PCR technique to reveal the distribution of methanogenic archaeal community. Clone library analysis of methanogenic archaeal mcrA genes was also carried out on the samples that showed the highest copy number in each tree species to reveal the phylogenetic composition of methanogenic archaeal community.
Digital PCR analysis showed that mcrA genes were detected from all the heights of the three trees, but the abundance and distribution varied greatly among the trees. In At, 106 copies g-1 dry wood of mcrA gene were detected at the lower positions of the trunk (1.6 and 3.5 m), and Methanobacterium spp., Methanobrevibacter spp., and Methanomassiliicoccus spp. predominated at those heights. Meanwhile, the copy numbers decreased by 104 copies g-1 dry wood at the height of 4.6–10.8 m and the mcrA genes of various groups of methanogenic archaea were detected. In Cj and Fc, 104–105 copies g-1 dry wood of mcrA gene were detected irrespective of the height (Cj:2.1–10.7 m, Fc:1-10.9 m), and the members of Methanomicrobiales were the predominant group at all heights. Clone library analysis revealed that methanogenic archaea related to Methanobacterium formicicum, Methanosarcina vacuolata, Methanosarcina thermophila, and Methanomassiliicoccus luminyensis inhabited the heartwood of At, while Cj and Fc were predominated by an unknown group in Methanomicrobiales. These results suggest that anoxic and methanogenic environments were widely developed within trees, but that environmental conditions must have been highly variable across heights and individuals (or tree species), which would explain why distinct methanogenic archaeal communities were heterogeneously distributed within and among trees.