Some of the first organisms on Earth could be magnitostaticheskie scientists came to this conclusion, for the first time to find magnitostaticheskie the genome of bacteria in the phylum Elusimicrobia. Previously it was thought that magnitostaticheskie bacteria appeared about 3.2 billion years ago, but new data indicate that bacteria close to the last common bacterial ancestor that lived around 3.6 billion years ago, could already be magnitostaticheskie. Article published in the journal Scientific Data.
Magnitostaticheskie bacteria (MTB) are characterized by their ability to synthesize magnetosom special cellular organelles, which is a product of the biomineralization of iron. They are formed by crystals of magnetite or greigite covered with a lipoprotein membrane. Thanks to magnetosomes MTB able to navigate in space along the magnetic field lines of the Earth. The movement of such reference points is performed using a flagella and is called magnetotaxis. Synthesis magnetosom controlled magnetosome genomic cluster, which includes unique genes involved in all stages of biomineralization. The main genes present in the genomes of all MTB are called the mam (magnetosome membrane) genes. There are groupspecific genes: for example, man ‘s genes are present only in the MTB of the phylum Nitrospirae and probably responsible for the bullet shape magnetosom.
Magnitostaticheskie bacteria of importance to medicine: members of this group have already started to use in the treatment of cancer. Due to its magnetic properties and the presence of membrane magnetosome can be used to deliver drugs directly to the tumor. Scientists for over 50 years we are looking for representatives of this group in the environment. During this time they managed to find only 60 genomes, 45 of which belong to the phylum Proteobacteria.
Microbiologists continue to search for magnetotacticum in soil, water and sediments (they can live only in an environment with a significant amount of water), but this is a very difficult task in almost any microbiocenosis they make up no more than one percent of the total number of bacteria. In recent years, there are new opportunities for such studies due to the increased amount of genomic and metagenomic data in the public databases. Scientists from around the world into new metagenomic data, but most such sequences are not used in the metagenomes, the authors of the studies looking only for representatives of their interest groups.
scientists from the Institute of bioengineeringn Academy of Sciences under the leadership of Denis Gruzdev (Denis Grouzdev) conducted the world’s first large-scale search of magnitostaticheskikh genomes of bacteria, based on data bases NCBI and IMG. For this purpose they used all the genomes in both databases in April 2018 and 10587 metagenomes from IMG. In each genome or metagenome, the study authors conducted a search of mam genes. The metagenomes, sequences which included such genes, they are kept for further processing. Scientists have reconstructed the genome containing genes magnetosome genomic cluster, using programs BusyBee, MaxBin2 and MyCC and built consensus Assembly in DasTool.
All the authors of the study identified 38 genome with the desired genes. Determining their phylogenetic position, they first discovered the MTB in the phyla Elusimicrobia, Nitrospinae and Ca. Hydrogenedentes. Reconstruction magnetosome genomic gene cluster allowed us to hypothesize about the origin and evolution of magnetotaxis. In the study the authors first identified the presence of man genes in MTB of the class Deltaproteobacteria, which may indicate horizontal gene transfer between the phyla that were not previously observed among MTB. In addition, the method of principal components was predicted chemical composition of magnetosome have MTB of new phylogenetic groups. Probably MTB of the phyla Elusimicrobia and Ca. Hydrogenedentes synthesize magnetosome graycolor composition, and Nitrospinae — magnetite.