Endophytic microorganisms isolated from coffee leaves, roots and branches as plant growth promoters and biocontrol agents of coffee leaf rust

Suppression of plant diseases and growth promotion due to the action of endophytic microorganisms has been demonstrated in several pathosystems. Experiments under controlled conditions involving 234 endophytic bacteria and fungi isolated from coffee leaves, roots and branches were conducted with the objective of evaluating the germination inhibition of Hemileia vastatrix urediniospores, the control of coffee leaf rust development in tests with leaf discs and on plastic bags seedling, and to promote growth of coffee seedlings. None of the fungal isolates induced plant growth or reduced disease severity. The bacterial isolates (identified by the fatty acids profile analysis) 85G (Escherichia fergusonii), 161G, 163G, 160G, 150G (Acinetobacter calcoaceticus) and 109G (Salmonella enterica) increased plant growth, the maximum being induced by 85G. This isolate produced in vitro phosphatase and indol acetic acid. In assay to control rust on coffee leaf disc, nine bacterial isolates, 64R, 137G, 3F (Brevibacillus choshinensis), 14F (Salmonella enterica), 36F (Pectobacterium carotovorum), 109G (Bacillus megaterium), 115G (Microbacterium testaceum), 116G and 119G (Cedecea davisae) significantly reduced disease severity, when applied 72 or 24h before challenging with the pathogen. In seedling tests most disease severity reduction was achieved by the isolates 109G and 119G. There was no correspondence between the organisms that promoted seedling growth and those that reduced rust severity on seedlings or leaf discs.

Biological control of root rot caused by Pythium aphanidermatum and growth promotion in hydroponic cucumber with microorganisms from mangrove

The prospection of biological control agents in similar environments to the microbe application improves the chances of microorganisms establishment added to the environment. The low survival of these beneficial microorganisms added to hydroponic environment is a problem for the growth promotion and root rot biological control success in hydroponic crops. Because of the environmental similarity between hydroponic systems and mangrove ecosystems, the aim of this work was to evaluate the ability of mangrove microbes to control root rot caused by Pythium aphanidermatum and to improve plant growth in hydroponic cucumbers. Among the 28 strains evaluated for disease control in small-hydroponic system using cucumber seedlings, Gordonia rubripertincta SO-3B-2 alone or in combination with Pseudomonas stutzeri (MB-P3A- 49, MB-P3-C68 and SO-3L-3), and Bacillus cereus AVIC-3-6 increased the seedlings survival and were subsequently evaluated in hydroponic cucumbers in a greenhouse. Bacillus cereus AVIC-3-6 protected the plants from stunting caused by the pathogen and Gordonia rubripertincta SO-3B-2 and Pseudomonas stutzeri MB-P3A-49 increased the plant growth. We concluded that microorganisms from mangroves are useful as biocontrol agents and for improving plant growth in hydroponic crops.