10:45 AM - 12:15 PM
[BBG01-P09] Phylogenic and functional diversity of microbial ecosystems based on iron-oxidizing chemolithoautotroph
Keywords:Iron-oxidizing bacteria, Hot spring, Chloroflexi, Metagenome
Iron-oxidizing chemolithoautotroph is thought to be a key player in supplying organic matter to microbial ecosystems in the iron-rich oceans that prevailed for most of Earth's history. However, in modern oxygen-rich and neutral pH hydrosphere, iron oxidation mostly proceeds abiologically, and microbial ecosystems based on iron-oxidizing chemolithoautotroph are rarely established. Therefore, phylogenic and functional diversity is poorly understood.
In this study, we performed metagenomic analyses for iron oxides in three iron-rich hot springs (neutral pH and 38-51°C). We also compared the microbial compositions and functional genes in reported metagenomic data from three iron mats around submarine hydrothermal vents (35-62°C). Microbial ecosystem based on iron-oxidizing chemolithoautotroph was characterized using those metagenomic data.
First, the microbial compositions based on ribosomal protein genes show that the class Ignavibacteria (1.8-5.9% of the total) and the class Deltaproteobacteria (0.4-1.2%) are common in all samples. Furthermore, the class Anaerolinea (4.6-20.7%) is commonly abundant in iron-rich hot springs. Next, diverse iron-reducing bacteria with iron-reducing genes are also confirmed. The common lineages in all samples are the class Ignavibacteria and the class Deltaproteobacteria. In addition, the class Thermodesulfovibrionia (0.6-2.3%) and Ardenticatenia (0.4-9.7%) are also present in the iron-rich hot spring. Woesearchaeia (1.5-3.6%), belonging to DPANN, is also commonly found in the environments where Mariprofundus sp. is dominated. Draft genomes of Woesearchaeia in this study show the potential for iron reduction. Our study indicates that iron-reducing bacteria are certainly present in microbial ecosystems where iron-oxidizing chemolithoautotroph are dominated.
Metagenomic Assembled Genomes (MAGs) belonging to the class Anaerolinea, reconstructed from metagenomic data of iron-rich hot spring, reveals that several MAGs possess RuBisCO and genes for Wood-Ljungdahl (WL) pathway. Furthermore, in all samples, the relative abundance of those MAGs was highest in the MAGs belonging to the class Anaerolinea. The class Anaerolinea has been proposed the capability of carbon fixation by the Calvin-Benson-Bassham cycle. In addition, in deep-sea sediment, several Single Cell Genome (SAG) possessed genes for WL pathway. On the other hand, the class Anaerolinea that possesses both RuBisCO and genes for WL pathway has not been reported. This study indicates the unique metabolic potential of the class Anaerolinea in iron-rich environments, especially for carbon fixation.
We plan to characterize the microbial ecosystem based on iron-oxidizing chemolithoautotroph more specifically by network analysis methods to identify core bacterial and functional gene groups.
In this study, we performed metagenomic analyses for iron oxides in three iron-rich hot springs (neutral pH and 38-51°C). We also compared the microbial compositions and functional genes in reported metagenomic data from three iron mats around submarine hydrothermal vents (35-62°C). Microbial ecosystem based on iron-oxidizing chemolithoautotroph was characterized using those metagenomic data.
First, the microbial compositions based on ribosomal protein genes show that the class Ignavibacteria (1.8-5.9% of the total) and the class Deltaproteobacteria (0.4-1.2%) are common in all samples. Furthermore, the class Anaerolinea (4.6-20.7%) is commonly abundant in iron-rich hot springs. Next, diverse iron-reducing bacteria with iron-reducing genes are also confirmed. The common lineages in all samples are the class Ignavibacteria and the class Deltaproteobacteria. In addition, the class Thermodesulfovibrionia (0.6-2.3%) and Ardenticatenia (0.4-9.7%) are also present in the iron-rich hot spring. Woesearchaeia (1.5-3.6%), belonging to DPANN, is also commonly found in the environments where Mariprofundus sp. is dominated. Draft genomes of Woesearchaeia in this study show the potential for iron reduction. Our study indicates that iron-reducing bacteria are certainly present in microbial ecosystems where iron-oxidizing chemolithoautotroph are dominated.
Metagenomic Assembled Genomes (MAGs) belonging to the class Anaerolinea, reconstructed from metagenomic data of iron-rich hot spring, reveals that several MAGs possess RuBisCO and genes for Wood-Ljungdahl (WL) pathway. Furthermore, in all samples, the relative abundance of those MAGs was highest in the MAGs belonging to the class Anaerolinea. The class Anaerolinea has been proposed the capability of carbon fixation by the Calvin-Benson-Bassham cycle. In addition, in deep-sea sediment, several Single Cell Genome (SAG) possessed genes for WL pathway. On the other hand, the class Anaerolinea that possesses both RuBisCO and genes for WL pathway has not been reported. This study indicates the unique metabolic potential of the class Anaerolinea in iron-rich environments, especially for carbon fixation.
We plan to characterize the microbial ecosystem based on iron-oxidizing chemolithoautotroph more specifically by network analysis methods to identify core bacterial and functional gene groups.