Taiwanese scientists have bred a strain of Escherichia coli (Escherichia coli), able to use methanol as the sole source of food, reported in Cell. The speed of propagation of such bacteria were not significantly different from the speed of propagation of the species, which was originally methylotrophy: the number of feeding methanol E. coli has doubled every 8.5 hours. The researchers also found a problem that occurs due to the metabolism of methanol (chemical linkage of DNA with certain proteins), which microorganisms partially solved by increasing the number of copies of certain genes.
To support various biochemical processes in the body and renew the structure in its structure, all living things must eat to obtain energy, carbon and electrons. Depending on what food sources used by the species, it belongs to different categories “-tropov” (“eating” in Greek). For example, among the bacteria there are methylotrophy — those who receive carbon and electrons from methane derivatives CH4, but not from him. However, they are not very much.
Meanwhile, the methanol (CH3OH) is a compound that can serve as a good source of electrons for microorganisms. In addition, it is easy to get from greenhouse gases — CO2 and methane. If you could create easily breed bacteria, which can metabolize methanol, have been able to reduce the emissions of these gases in the atmosphere.
Attempts to bring methylotrophs have been made with E. coli (Escherichia coli), the most popular model object prokaryotes. Different teams of microbiologists have identifiedwhich enzymes allow the bacteria to metabolize CH3OH and what genes these enzymes are encoded. Also identifythe methods of cultivation it is better to use to effectively grow the right bacteria. However, strains of E. coli, which were able to utilize methanol as a sole source of nutrition, has not yet been established.
Now the staff of the Institute of biological chemistry at academia Sinica (Taiwan) under the direction of James Liao (James C. Liao) managed to ensure that E. coli survived and with acceptable speed multiply only one methanol. To do this, they gradually, not in one generation, replaced bacteria the genes of the enzymes involved in pentozofosfatnogo cycle, such that can handle methanol (new genes “took” from methylotrophs). Previously, the authors have modeled what genes and in what sequence will need to change, but, of course, took into account data of real experiments as they conduct.
The first modified bacteria could grow on medium containing methanol and sugar xylose. They still could not eat one of only methanol, but was not able to live on only one xylose. This has created evolutionary pressure in the course of which the population consisted of fixed genes, allowing us to process methanol. Then E. coli were replaced with other stretches of DNA, due to which they found the optimal expression level of genes needed for metabolism of CH3OH. The fact that when processing formed toxic formaldehyde, which need to have time to neutralize. Nutrient medium is also changed so that ultimately there remained only the methanol.