Antibiotic activity of bacterial isolates associated with entomopathogenic nematodes

Abstract

In the present study, we isolated 23 strains of symbiotic bacteria from 23 entomopathogenic nematodes strains gathered in different vegetation from different regions of China. The antibiotic activities of all these bacteria strains isolated were evaluated in the laboratory. All the bacteria effectively inhibited seven kinds of plant pathogenic fungi (Bipolaris sorokinianum, Fusarium graminearum, Fusarium moniliforme,Cordana musae (zimm.) Hohn, Colletotrichum gloeosporiodies, Alternaria solani andAlternaria alternata (Fries) Keissler) cultured on agar plates. Among these strains, strain SY5 was the most effective symbiotic bacteria strain, which was further selected as the highly virulent bacteria for the adversity resistance study. The adversity resistance showed that the stability of the antibiotic activity against different plant pathogenic fungi was different. The antibiotic activity against A. solani was the most stable and the inhibiting rate was not affected by treatment in a 50°C water bath for 60 min and in 100°Cfor 10 min, ultraviolet light exposure for 120 min and storing at room temperature for 90 days. Key words: Entomopathogenic nematode symbiotic bacteria, Inhabiting rate, temperature, ultraviolet light exposure and duration of maintenance.