Rhizospheric bacteria from the Atacama Desert hyper-arid core: cultured community dynamics and plant growth promotion

Abstract

The Atacama Desert is the oldest and driest desert on Earth, encompassing great temperature variations, high UV-radiation, drought, high salinity, making it ideal to study the limits of life and resistance strategies. It is also known for harboring great biodiversity of adapted life forms. While desertification is increasing as result of climate change and human activities, is necessary to optimize soil and water usage, where stress-resistant crops are possible solutions. As many studies have revealed the great impact of rhizobiome over plant growth efficiency and resistance to abiotic stress, we set up to explore the rhizospheric soils of Suaeda foliosa and Distichlis spicata desert plants. By culturing these soils and using 16S rRNA amplicon sequencing, we address the community taxonomy composition dynamics, the stability through time and the ability to promote lettuce plants growth. The rhizospheric soil communities were dominated by the families Pseudomonadaceae, Bacillaceae and Planococcaceae for S. foliosa and Porphyromonadaceae and Haloferacaceae for D. spicata. Nonetheless, the cultures were completely dominated by the Enterobacteriaceae family (up to 98%). Effectively, lettuce plants supplemented with the cultures showed greater size and biomass accumulation, we identify 12 candidates that could be responsible of these outcomes, of which 5 (Enterococcus, Pseudomonas, Klebsiella, Paenisporosarcina and Ammoniphilus) were part of the built co-occurrence network. We aim to contribute to the efforts to characterize the microbial communities as key for the plant's survival in extreme environments, and as a possible source of consortia with plant growth promotion traits aiming agricultural applications.