MOSCOW, March 5. /TASS/. Researchers from the Irkutsk State University (Russia) and University of North Florida (United States) have discovered that Lake Baikal’s large bacteria do not produce antibiotics, as similar organisms do, but fight microbes using other compounds that were never researched before, Russian Science Foundation said Thursday.

"Irkutsk University biologists, together with their Florida counterparts, have examined metabolism of Baikal actinobacteria — large micro-organisms capable of synthesizing biologically active substances. It turned out that these bacteria lack genes that code enzymes, required for antibiotic production. This means these bacteria fight microbes using other proteins and, possibly, chemical compounds unknown to the science," the message says.

Actinobacteria is a class of bacteria of large size and complex shape, capable of breaking down toxic chemicals that pollute the environment. They produce secondary metabolism products, which they do not need for growth and development, but which fulfill other roles. These chemicals include compounds used in medicine to suppress growth of pathogen bacteria and fungi.

Under the new study, Russian and American researchers examined secondary metabolism products in 24 strains of actinobacteria, discovered in Lake Baikal sediments. They have isolated their DNA and examined the genes that code biologically active compounds. It turned out that these strains lacked genes for flavin adenine dinucleotide (FAD)-dependent halogenases.

FAD is an enzyme, used in many biochemical processes. This enzyme is responsible for combination of halogen atoms, such as bromine and iodine, with various molecules. This leads to creation of antibiotics, such as tetracycline, chloramphenicol, and others.

In the meantime, although Baikal actinobacteria lacked those genes, biological activity was observed in 75% of the examined strains, so the researchers have concluded that it happens due to some other enzymes.

"Normal actinobacteria might include halogen atoms into chemical molecules they synthesize. The lack of such ability in Baikal bacteria is their unique feature, which suggests long evolution in ultra-fresh environment. Special features of Baikal actinobacteria indicate their significant potential for production of yet unknown antibiotics and natural compounds," says lead researcher Maxim Timofeyev.