Actinobiota of <i>Rhaponticum carthamoides</i> (Willd.) Iljin roots as potential source of microbiological preparations for cropping

Abstract

The paper determines the number and structure of actinomycete complexes associated with the roots of the medicinal plant – leuzea safflower (Rhaponticum carthamoides (Willd.) Iljin) during long-term cultivation on sod-podzolic soil. The total number of actinomycetes in the rhizosphere varied within (4.4-13.2)×105 CFU/g of soil, and in the rhizoplane ‒ within (7.6-24.1)×103 CFU/g of roots. The complex of mycelial prokaryotes is represented by the genera Streptomyces, Micromonospora, Streptosporangium, Streptoverticillium and oligospore forms. Streptomycetes dominated both in the rhizosphere and in the rhizoplane of leuzea safflower. From these microlocuses, 30 cultures of mycelial prokaryotes were isolated using selective techniques. The cultural-morphological and physiological-biochemical properties of the isolates were studied. High-performance screening conducted using a dual reporter system revealed among 19 isolates associated with leuzea roots the ability to produce protein synthesis inhibitors in four (21 %) streptomycetes cultures. PCR detection of type II polyketide synthetase genes did not reveal their carriers among streptomycetes associated with leuzea. A significant proportion (67 %) of streptomycetes isolates from the rhizosphere and rhizoplana of leuzea had moderate and high cellulase activity. It has been established that the majority (92 %) of streptomycetes in the rhizoplana complex produce indole compounds (IUC) in the amount of 40±16.1 mcl/ml, up to 61 % of isolates produce water-soluble metabolites of antifungal action. New strains of streptomyces antagonists of phytopathogenic fungi, cellulolytics and auxin producers promising for further study have been identified.