COMPOST AS A RESERVOIR OF BACTERIA WITH BIOCONTROL POTENTIAL AGAINST PHYTOPATHOGENIC FUNGI

Abstract

Plant diseases caused by phytopathogenic fungi lead to significant economic losses in agriculture. Bacteria isolated from compost have been shown to exhibit suppressive activity against these pathogens. The aim of this study was to isolate bacteria from five compost samples differing in origin and physicochemical properties and to evaluate their biocontrol potential. A total of 38 bacterial isolates were obtained, of which 12 were selected for further characterization. These isolates were subjected to morphological and biochemical analyses, identified using MALDI-TOF MS, and tested for their ability to produce siderophores and inhibit selected phytopathogenic fungi (Botrytis cinerea, Penicillium olsonii, Fusarium oxysporum, and Alternaria alternata). Eight isolates demonstrated the ability to produce siderophores. The highest production was observed in isolate 68A-4 (H/G = 44.98 ± 9.66) and Brevundimonas diminuta 512B-6 (H/G = 23.36  ± 2.34). Antifungal assays revealed variable inhibitory effects on mycelial growth. The isolate Serratia sp. 19A-5 exhibited the strongest antifungal activity and showed no statistically significant difference compared to the reference strain Bacillus subtilis QST 713 in inhibiting Penicillium olsonii and Fusarium oxysporum. These results suggest that Serratia sp. 19A-5 represents a promising candidate for compost fortification with enhanced antifungal properties. The use of such beneficial bacteria as biological control agents represents a sustainable alternative to chemical pesticides, contributing to reduced environmental impact.