Biochemistry and Molecular Biology - Belyasova, N.A. 2002

Metabolism: Energy-requiring processes
Biological role and principles of antibiotic biosynthesis

Antibiotics are defined as specific metabolic products of organisms and their chemical modifications that exhibit high physiological activity (biostatic or biocidal) against specific groups of microorganisms or malignant tumors.

The vast majority of known antibiotics are produced by mycelial Fungi and actinomycetes, although antibiotics of PLANT AND ANIMAL origin have also been discovered. An important distinguishing feature of antibiotics is their high potency against susceptible Cells (Viruses), allowing them to act even at very low concentrations, most commonly 1—100 mcg/ml. Exposure to an antibiotic can either inhibit the growth of susceptible cells (biostatic activity) or cause their death (biocidal activity). While the most common antibiotics target Bacteria—exerting a bacteriostatic or bactericidal effect—there are numerous antibiotics effective against fungi, Protozoa, viruses, and Cancer cells as well.

A characteristic feature of antibiotics that sets them apart from other antimicrobial agents is their selective toxicity. This means that each antibiotic affects strictly defined organisms without harming others. Furthermore, cells contain specific “targets” that are disrupted in accordance with the specific MECHANISM OF ACTION unique to each antibiotic.

Antibiotics are classified according to various criteria: chemical Structure, type of effect (biostatic, biocidal), target Organism groups (antibacterial, antiviral, antitumor, etc.), cellular targets (Cell wall, Plasma Membrane, METABOLISM/36.html">DNA Replication, Transcription and Translation machinery, Enzymes, etc.), and the type of producer organism (actinomycetes, mycelial fungi, plants, protozoa, etc.).

Based on their chemical structure, antibiotics can be divided into the following groups: Peptides and Amino Acid Derivatives, polyene compounds, carbohydrate-derived substances, aliphatic, polycyclic, and Aromatic Compounds, as well as oxygen- and nitrogen-containing heterocycles. This list alone demonstrates the remarkable diversity of antibiotics, mirroring the variety of their biological Functions.

Currently, more than 6,000 different antibiotics are known, and the search for new forms, alongside the chemical modification of existing ones, continues unabated. This is due, on the one hand, to the broad functionality of antibiotics: they are used in human and veterinary therapy, for prophylactic purposes, as plant protection agents, growth promoters in livestock and poultry farming, and food preservatives. On the other hand, microorganisms targeted by antibiotics eventually develop resistance through various mechanisms, including the genetic exchange of drug-resistance factors (see below). Finally, antibiotics are widely used in research to elucidate the mechanisms of various cellular processes.

Since a comprehensive review of the Structure and properties of all known antibiotics is beyond The Scope of this publication, it is logical to focus on their Mechanisms of action against cellular targets, which will provide another opportunity to examine and better understand the interconnectedness of metabolic processes.