بررسی مکانیسم‌های بیوکنترلی و ویژگی‌های محرک رشدی سودوموناس، باسیلوس، ازتوباکتر و آزوسپیریلیوم

The increasing demand for sustainable agriculture requires alternative methods to chemical pesticides for controlling plant pathogens and reducing economic losses. Biological control using natural antagonists like bacteria is a promising alternative. These bacteria improve plant growth and pathogen control through mechanisms such as antibiosis, competition, and induction of systemic resistance. The genera Pseudomonas, Bacillus, Azospirillum, and Azotobacter are among the best-studied PGPBs and are widely used in agriculture, as they can increase plant growth directly and indirectly. In summary, the main differences of these bacteria are in their oxygen needs, environmental preferences, and specific mechanisms to promote plant growth. Although all four genera of bacteria can be beneficial for plant growth and health, each of them uses specific mechanisms in this regard. The aim of this study was to examine the biocontrol mechanisms and growth improvement of 26 isolates from the genera Pseudomonas, Bacillus, Azotobacter, and Azospirillum. Protease enzyme production, hydrogen cyanide, siderophore, and phosphate solubilization, which are biological control factors and growth-stimulating characteristics, were evaluated. UJB13 and UJB30 isolates from the Bacillus genus were recognized as the superior isolates with the highest amount of protease enzyme production. The isolates UJB23, UJB18, and UJB29, which belonged to Bacillus, Azotobacter, and Azospirillum genera, had the maximum amount of hydrogen cyanide production. Fifteen isolates were able to produce siderophore, and isolates UJB33, UJB22 from the Bacillus genus and isolates UJB31 and UJB32 from the Pseudomonas and Azotobacter genera showed the highest amount of production. The highest amount of phosphate solubility was related to isolates UJB32, UJB11, UJB24, and UJB33, which belonged to the Azotobacter, Bacillus, and Pseudomonas genera, respectively.The production of a wide range of microorganisms for biological control and the use of biotechnology in improving mechanisms are among the important solutions in the biological control of plant diseases. Therefore, choosing an effective strain among hundreds of strains belonging to a species of biological control agents is the first step toward their commercialization and widespread use. Using appropriate screening methods based on detailed research is one of the requirements that researchers should pay attention to.