Abstract
Aims: Epiphytic bacteria, isolated from Deschampsia antarctica, were screened for their potential to inhibit the plant pathogen Botrytis cinerea, the causal agent of gray mold disease of strawberry pseudofruits. This phytopathogenic fungus is more active and the disease is more serious in temperate climate where the temperatures are lower. Methodology: The approach involved the isolation and characterization of bacteria from the phyllosphere of D. antarctica and the evaluation of their antifungal activity. Results: A total of 56 bacterial strains were isolated and only one of them, identified by the sequencing of 16S rDNA gene, as Pseudomonas frederiksbergensis CMAA 1323, inhibited the mycelial growth and the conidial germination of the fungus. Its ethyl acetate extract also inhibited Original Research Article Melo et al.; BMRJ, 14(3): 1-11, 2016; Article no.BMRJ.25314 2 the mycelial growth. Analysis of the bioactive fraction by using liquid chromatography coupled to a mass spectrometry (LC-MS) revealed the presence of cyclo(Pro-Val), a compound belonging to the class of diketopiperazines (DKPs). Conclusion: These findings support the potential use of the psychrophilic bacterium P. frederiksbergensis as promising antifungal agent, and highlight the need for more studies with this bacterium in the biological control of plant pathogenic fungi.
Highlights
INTRODUCTIONIn this extremely cold environment, bacteria have colonized various habitats and have evolved a number of strategies for coping with the extreme physico-chemical fluctuations to which they are exposed
Analysis of the bioactive fraction by using liquid chromatography coupled to a mass spectrometry (LC-MS) revealed the presence of cyclo(Pro-Val), a compound belonging to the class of diketopiperazines (DKPs). These findings support the potential use of the psychrophilic bacterium P. frederiksbergensis as promising antifungal agent, and highlight the need for more studies with this bacterium in the biological control of plant pathogenic fungi
A total of 56 bacterial isolates were obtained from the leaf surface of D. antarctica; all of them grew more densely at 4°C and 18°C than at 25°C; this putatively suggests a psychrophilic classification [23]
Summary
In this extremely cold environment, bacteria have colonized various habitats and have evolved a number of strategies for coping with the extreme physico-chemical fluctuations to which they are exposed They play key roles in ecology and have potential uses in low-temperature biotechnological processes. Some microbial agents have reduced the amount of decay caused by Botrytis cinerea in strawberries were reported [11,12,13,14,15] as effective BCAs against diseases of different fruits and produce various antibiotics with antifungal activity including phenazine-1-carboxilic acid, pyoluteorin, pyrrolnitrin, and 2,4diacetylphloroglucinol [16]. Biological control in the postharvest environment has significant advantages over that under field conditions because the two most important factors affecting biocontrol, temperature and relative humidity, are constant and under strict control This strategy may constitute an important alternative for control. The plant, with its adaptation to the cold environments of Antarctica, has attracted the interest of many researchers for genes associated with freezing tolerance
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