ANTIFUNGAL ACTIVITY AGAINST PATHOGENS OF CEREALS AND CHARACTERIZATION OF ANTIBIOTICS OF Streptomyces sp. STRAIN K-541 ISOLATED FROM EXTREME ECOSYSTEMS IN KAZAKHSTAN

Abstract

A b s t r a c tThe general requirement for biologicals is that they must be insensitive to climate change and soil conditions, including soil physicochemical composition, fertility levels, and pH values. Actinomycetes isolated from extreme habitats are able to produce biologically active substances not only under neutral conditions but also in saline, alkaline and acidic environments, which determines their importance in the biopreparations, being developed for plant protection. This study is the first to report the Streptomyces sp. strain K-541 antibiosis against the causative agents of several cereal fungal infections under various environmental conditions and the identification of the antibiotic produced. Streptomyces sp. strain K-541 isolated from extreme ecosystems of Kazakhstan was cultured under neutral (pH 7.0) and alternative growth conditions at 25.0 g/l NaCl (pH 7.2) or 2.5 g/l Na 2 CO 3 (pH 8.0). Antifungal activity was determined in agar block diffusion experiments and under paired coincubation with phytopathogenic fungi Fusarium solani (Mart.) Sacc., F. oxysporum Schlecht., F. heterosporum Nees, F. sporotrichiella Sherb., Piricularia oryzae Cavara, Alternaria triticina Prasada & Prabhu, A. alternate (Fr.) Keissl., Bipolaris sorokiniana (Sacc.) Shoemaker, and Aspergillus niger van Tieghem. For antibiotic A-541 production, the strain was cultured on an orbital shaker (180-200 rpm) for 120 hours at 28 С. The antibiotic was extracted with organic solvents and analyzed using thin layer chromatography and spectrophotometry. The studies have shown high antifungal activity of K-541 against all the phytopathogens examined. After 72 hour incubation at 25 С the growth inhibition zones were 20-56 mm in diameter depending on growth conditions which simulated different ecological niches. In co-culturing the strain K-541 and the phytopathogenic fungi, the fungal colonies decreased 1.8-2.7 times in diameter indicating the possibility of K-541 introduction into soil biocenoses for biocontrol of cereal fungal pathogens. High inhibition of growth was also observed under saline (2 % NaCl) and alkaline (0.2 % Na 2 CO 3 ) conditions. The antibiotic produced by strain K-541 was classified as a member of polyene group, a subgroup of the hexaenes. So strain K-541 is recognized as promising for the development of a new biopreparation with fungicidal activity against causal agents of cereal fungal infections under different environmental conditions.

The effect of bacterial preparations on the growth, development and quality indicators of sugar beet yield

“…Bacillus sp. Strains produce substances acting against pathogens, Pseudomonas putida can secrete growth stimulants, contributing to the plant growth, and Trichoderma viride can be used to produce antibiotics, stimulate growth and weight of the root system which increases the crop yield [6][7][8][9][10].…”

The biopotential of extremophilic microorganisms isolated from Kuzbass for protection and growth stimulation of oat (Avena sativa L.)

“…Biological preparations are widely used to protect various crops, especially cereals, which are increasingly threatened by toxinogenic fungi. Every year, phytopathogenic fungi of the genus Fusarium, Alternaria, Pyriclelia, and Aspergillus cause significant production losses (more than 40% of the cereal yield) [3]. In this context, the primary focus in the development of biopesticides should be devoted to the exploration of promising microbe-plant interactions that enhance the resistance of cereal crops to fungal illnesses.…”

CELLULOLYTIC BACTERIA AND ASSOCIATION OF EFFECTIVE MICROORGANISMS FOR BIOCONTROL OF ROOT ROT INFECTIONS IN SUGAR BEET (Beta vulgaris L.)

“…В качестве альтернативы выступают биологические методы защиты растений. Актуален поиск микроорганизмов и разработка на их основе биопрепаратов для борьбы с фитопатогенами растений (21)(22)(23)(24).…”

“…В наших опытах при лабораторной оценке антифунгальной активности штамма С-82/3 диаметр зоны подавления роста тест-культур составил 28,9±0,2 мм для F. oxysporum, 38,2±0,3 мм для F. solani и 46,6±0,9 мм для A. alternata. Такая видовая специфичность влияния бактерий на фитопатогенные грибы согласуется с результатами, полученными другими авторами (22,24).…”