PAENIBACILLUS POLYMYXA КВ — PRODUCER OF BIOLOGICALLY ACTIVE SUBSTANCES

Abstract

Objective. To investigate the ability of Paenibacillus polymyxa KB to produce biologically active substances that stimulate the growth and development of plants. Methods. Qualitative and quantitative determination of auxins, abscisic acid (ABA) and cytokinins in the culture fluid (CF) of P. polymyxa KB was carried out by high-performance liquid chromatography (HPLC) using Agilent 1200 liquid chromatograph; gibberellins were measured by high-performance liquid chromatography (HPLC/MS) using Agilent 1200 liquid chromatograph (Agilent Technologies, USA) and Agilent G1956B mass spectral detector. The content of vitamins in P. polymyxa KB was determined using Waters liquid chromatograph with a tqs-micro mass-selective detector. The content of amino acids in CF was studied by ion exchange chromatography on a Sycam amino acid analyser. The ability of P. polymyxa KB to synthesize exopolysaccharides and enzymes was determined using classical microbiological and biochemical research methods. Antifungal properties of the bacterium were studied by the dual culture method. Statistical calculations were carried out using analysis-of-variance method. Results. P. polymyxa KB synthesises phytohormonal compounds: auxins — up to 81.15 μg/g of dry biomass, abscisic acid — up to 9.84 μg/g; gibberellic acids (GA3 — within 2.48 μg/g and GA4 — 1.96 μg/g of dry biomass); cytokinins (zeatin — up to 16.42 μg/g, kinetin — up to 6.78 μg/g, isopentenyl-adenine — up to 9.03 μg/g of dry biomass), as well as vitamins: thiamine (B1) — within 0.93 mg/dm3 CF, riboflavin (B2) — 0.48 mg/dm3, pyridoxine (B6) — 0.27 mg/dm3, folic acid (B9) — 0.18 mg/dm3 CF. P. polymyxa KB shows phosphatase, amylolytic, proteolytic, pectolytic activity, produces amino acids: histidine — within 300.4 mg/dm3, alanine — 236.3 mg/dm3, proline — 164.2 mg/dm3, valine — 157.8 mg/dm3, isoleucine — 148.4 mg/dm3, threonine — 126.2 mg/dm3, cystine — 124.0 mg/dm3 CF and others. The bacterium synthesizes exopolysaccharides amylopectin and levan. P. polymyxa KB shows antagonistic activity against phytopathogenic micromycetes from the genera Fusarium, Alternaria, Nigrospora — pathogens of agricultural crops. Conclusion. P. polymyxa KB synthesizes a significant amount of physiologically active substances that can play an important role in the processes of plant organogenesis.