ACTINOMYCETES AND BIOPREPARATIONS IN AGRICULTURE

Abstract

In recent decades, it has been confirmed that the application of biopreparations containing microorganisms in vegetative or resting (spore) form is a promising ecological alternative to the application of industrial fertilisers and pesticides. In addition to traditionally applied vegetative and spore forms of bacteria, with different physiological abilities, mycorrhizal fungi and algae, it is confirmed that actinomycetes can be used in biopreparations as a prospective. The advantage of actinomycetes is their presence in any, even dry, stressed environment, their easy isolation, especially in the case of species of the genus Streptomyces, and also the production of a wide variety of metabolites that promote plant growth by direct or indirect mechanisms. Their most effective direct mechanisms for plant growth include phosphate solubilization, production of phytohormones and siderophores, nitrogen fixation, ethylene regulation, and indirectly induced systemic resistance, production of chitinases, antibiotics, and antifungal agents. Actinomycetes grow more slowly than other bacteria, so the addition of biostimulants is advisable to improve their growth and metabolic activity in field conditions. Streptomycetes are key biocontrol agents in agriculture due to their ability to produce diverse secondary metabolites with strong antimicrobial effects. Species such as Streptomyces avermitilis, S. lydicus, S. griseus, S. kasugaensis and S. hygroscopicus suppress a wide range of plant pathogens by inhibiting protein or cell wall synthesis or by disrupting membrane integrity. These preparations are commonly applied as foliar sprays, seed treatments or soil drenches and represent a sustainable alternative to synthetic pesticides.

This review aimed to summarise the latest knowledge about the occurrence, mechanisms and effects of actinomycetes isolated from different environments on the growth of agriculturally important plants and their possible application, in the form of biopreparations, in crop production with an ecological approach.