ИСТИНА

Целью настоящего проекта является поиск и изучение новых механизмов автотрофной фиксации СО2 у термофильных прокариот, выявление модификаций уже известных путей автотрофной ассимиляции СО2 (в том числе новых), и исследование эволюции процессов первичной продукции органического вещества, играющих важнейшую роль в развитии и существовании жизни на нашей планете. В основные задачи проекта входит: (1) скрининг имеющейся коллекции термофильных прокариот на наличие в ней микроорганизмов, использующих модифицированные или неизвестные ранее пути автотрофной ассимиляции неорганического углерода; (2) выделение автотрофных термофильных прокариот из образцов природных термальных местообитаний в условиях, благоприятствующих развитию микроорганизмов с новыми путями ассимиляции СО2; (3) анализ полных геномов новых автотрофных изолятов с целью определения возможных путей ассимиляции ими неорганического углерода; 4) биохимическое подтверждение функционирования новых путей ассимиляции СО2 в выявленных микроорганизмах с предположительно новыми типами автотрофного метаболизма; (5) выявление генетических детерминант новых процессов, способных служить их маркерами и анализ баз данных для получения представления о распространенности новых механизмов; (6) радиоизотопный, метагеномный и при необходимости метатранскриптомный/метапротеомный анализ микробных сообществ термальных источников Камчатки, Курил и/или Байкальской рифтовой зоны с целью определения вклада новых механизмов ассимиляции СО2 в продукцию органического вещества.

Autotrophic CO2 fixation is one of the most important biosynthetic processes in nature. To date, six autotrophic CO2 fixation mechanisms are known, which reflects the diversity of the physicochemical parameters of the habitats and of the autotrophic organisms living in them. In this project, special attention is paid to thermophilic microorganisms that develop at high temperatures in natural thermal habitats and are represented by various (including the most ancient) phylogenetic groups in the Archaea and Bacteria domains. Thermophilic microorganisms are characterized by an extraordinary variety of biochemical processes, both of catabolic reactions, allowing the use of an unusually wide range of electron donors and acceptors, and of pathways of inorganic carbon assimilation into organic matter. For example, two of six mentioned above CO2 fixation pathways are known exclusively among thermphiles. The applicants team has at its disposal a large collection of phylogenetically and metabolically diverse autotrophic thermophilic prokaryotes, isolated from terrestrial and marine thermal habitats(collection of the Department of Biology of Extremophilic Microorganisms, FRC Biotechnology, RAS). Preliminary studies, including the analysis of the complete genomes, have revealed the presence of some genes, encoding proteins of various autotrophic CO2 fixation pathways in the collection strains, including both long known and recently discovered pathway variants. At the same time, the genomes of some of the autotrophic isolates lacked key genes of the known pathways of CO2 assimilation or harbored key genes of several pathways. The main goal of the project is the search for and study of new (alternative) pathways for autotrophic CO2 fixation and of possible variants of the already known pathways in thermophilic bacteria (and archaea). To achieve this goal it is supposed to perform: (1) screening of the available collection of thermophilic prokaryotes for the presence in it of microorganisms carrying out new modifications or new pathways of autotrophic assimilation of inorganic carbon; (2) isolation of thermophilic autotrophic prokaryotes from samples of natural thermal habitats under conditions favorable for microorganisms possessing new variations of the pathways of CO2 assimilation; (3) analysis of complete genomes of new autotrophic isolates in order to determine the pathways used by them to assimilate inorganic carbon; (4) biochemical confirmation of the functioning of new CO2 assimilation pathways in microorganisms with supposedly new types of autotrophic metabolism; (5) identification of genomic determinants of the new pathways that can serve as their markers and analysis of databases to get an idea of the occurrence and distribution of the new mechanisms; (6) radioisotopic, metagenomic and, if needed, metatranscriptomic/metaprotomic analyses of the microbial communities of hot springs of Kamchatka, Kuriles and/or the Baikal rift zone in order to determine the contribution of new CO2 assimilation mechanisms to organic matter production in these ecosystems. As a result of the project, knowledge about the mechanisms of autotrophic CO2 assimilation and about their ecological roles and evolutionary histories will be expanded.