Great successes in full-genomic sequencing opened the ways to decode complete genomic sequence of living organisms. This extremely difficult scientific problem was solved gradually from the mid-90s of 20 century and finally reached its node point with the deciphering of human genome in 2000-2001. This outstanding result has been achieved only due to the primary experiments that identified more simple genetic sequences of bacteria and viruses.
Tens of thousands of bacterial and viral genomes have been sequenced up to the present date. The characteristics of some investigated microbial genomes are shown below.
Also it was proven that the closest relationships exist between microbial and human genomes. Human genome was found to contain a great number of prokaryotic genes. For instance, many genes, which are very similar in humans and bacteria, control essential metabolic pathways. Nevertheless, vast representation of viral genes within human genome remains unclear. Maybe, it gives human beings some selective advantages in evolutionary process.Knowledge of microbial genome clarified a great number of unclear circumstances in infection pathogenesis and treatment, including bacterial capacity to produce toxins, adhesins and other virulence factors, mechanisms of bacterial invasion and persistency, spread of multidrug microbial resistance, etc. Determination of unique genetic clusters in microbial genomes ensures rapid precise diagnostics of infectious diseases.
And finally, the next task of ultimate importance is to conceive the basic mechanisms of genotype realization towards corresponding phenotype. This is the subject of functional genomics, transcriptomics, epigenetics, proteomics, and metabolomics.
For instance, the new scientific direction of proteomics investigates the proteome. In this vein, proteome means the continiously changing array of cellular proteins and a complex of their interactions at the certain stage of cell development.
Similarly, transcriptome is the complete number of messenger RNAs in microbial cells. And metabolome is the total array of microbial chemical metabolites taken at a certain time point and resulted from all cellular metabolic pathways.
While the genome is rather stable, the transcriptome, proteome and metabolome states are dynamic.
Of the extreme importance for the genome proper function is the influence of epigenetics and epigenetic factors.
Epigenetics investigates the heritable changes in the genome that are not related with the changes of primary sequence of microbial DNA. Epigenetic alterations ensue from various environmental impacts on the microbial cell that affect the expression of microbial genes. Epigenetic changes become fixed, being demonstrated in the next several generations of microbial offspring cells.
Overall, the elucidation of bacterial cell response to the different types of internal and external signalling, the discovery of the mechanisms of microbial reactivity and adaptation should result in design of new methods of infectious disease control and treatment.