Isolation, Screening and Characterization of Effective Microbes with Potential for Biological Control of Fusarium wilt of Rock Melon

Abstract

Effective microbes are a group of microorganisms that can be found in the rhizosphere, in association with plant roots which can suppress soil-borne plant pathogens directly or indirectly. A large number of bacteria including species of Alcaligenes, Arthrobacter, Bacillus, Pseudomonas, Rhizobium and Serratia have been reported to suppress the soil borne plant pathogens. In this study, Fusarium wilt symptomless Rock melon rhizospheric soil samples were collected from three locations (Malaysia). A total of seventy two effective bacteria were isolated by the dilution method. These isolates were firstly dually cultured in vitro on PDA medium with F. oxysporum f.s. melonis, the causal agent of Fusarium wilt of Rock melon. Isolates with inhibitory characteristics against the test fungus were selected for further screening by means of extracellular metabolite test. Seven isolates which showed >60% inhibition of the fungal growth was further identified on the basis of colony morphology, biochemical tests and Biolog® System. These isolates were identified as Pseudomonas sp., Bacillus sp., Serratia sp., only one isolate could not be identified. MKB04 and MKB10 gave the best suppression of Fom mycelial growth. Further molecular identification of these two isolates identified them as Bacillus amyloliquefaciens, and Alcaligenes faecalis respectively. Effective microbes are environmental friendly and in vitro antagonistic activities they manifested against F. oxysporium f. s. melonis in this study suggest that they can be used as an effective biological control agent.