CONICET | Buscador de Institutos y Recursos Humanos

Herbaspirillum hutiense isolated from algae as a wheat growth promoting bacteriumJoaquín Inchaurrondo, Mauro Do Nascimento, Andres Arruebarrena Di Palma, Leonardo CurattiInstituto de Investigaciones en Biodiversidad y Biotecnología (INBIOTEC-CONICET), Mar del Plata, Argentina. Fundación para Investigaciones Biológicas AplicadasIn present days, agriculture is associated with extensive use of fertilizers, pesticides and other chemical products, to improve crop productivity. However, extensive use of these agrochemicals is harmful to the environment, and often times, also to human?s health. Thus, there is increasing interest in developing and improving biological alternatives as partial or complete substitutes for agrochemicals for the production of most crops. Our group is interested in developing the concept of plant growth promoting bacteria (PGPB) for the culture of aquatic microalgae mostly for bioenergy purposes. After three years of enrichment by successive dilutions of algae cultures in growth medium for autotrophic algae (no carbon source other than CO2), some bacterial strains have been isolated. Most of them have been characterized for their algae growth promoting activities. The majority of the isolates belong to bacterial genera that are known for their PGPR activities, however most of them appear to correspond to different species of those genera.In this work we characterize in more detail several aspects of a strain of Herbaspirillum hutiense. This strain produces copious amounts of auxin?like substances and contrary to the most studied species of the genus, H. seropediacea, it appears not to be a N2-fixer. Inoculation of wheat seeds with H. hutiense strain 15III, improved the percentage of seeds germination by 37 %. When inoculated onto groups of seeds on top of vermiculite substrate watered with NO3-lacking INTA 13 fertilizer solution, it produced a noticeable effect at 28 days on length and chlorophyll content of third leave, total weight of leaves and length and total weight of roots per pot. A similar growth promotion effect was observed when young seedlings (equalized by size) were incubated in the presence of the bacterium for two hours and then individually transplanted onto vermiculite substrate and watered with different dilutions of the INTA 13 fertilizer. The effect was consistent under a wide range of fertilizer dilutions. Moreover, growth promotion under fertilizer deficiency was also confirmed in pots containing different mixtures of perlite and soil, watered with tap water, but fertilized lightly once after 30 days of seedlings emergence. These findings suggest that algae/microalgae might serve as an alternative source of PGPRs for sustainable agriculture.