The wheat (Triticum aestivum) microbiome is essential to its growth and adaptation under the current climatic crisis. Wheat breeding programs are often mainly focused on obtaining more resistant cultivars; thus, plant genotype-by-microbiome interactions have gained attention. In this sense, local wheat cultivars represent a unique opportunity to examine how bacterial communities are recruited and support plant growth under field conditions. In this study, we explored the diversity, community structure, and potential functions of root-associated bacterial communities of four Chilean wheat (Triticum aestivum) cultivars under field conditions through Illumina MiSeq. Analyses showed that Proteobacteria was the most abundant phylum in root endosphere (51.1 to 74.4%) and rhizosphere samples (39.3 to 44.9%) across wheat cultivars. Significant differences (p ≤ 0.05) in alpha and beta diversity were observed in root endosphere and rhizosphere samples, independently of wheat genotypes. Potassium was identified as the main factor driving the rhizosphere microbiomes of wheat. A higher proportion of shared operational taxonomic units (OTUs) were found in rhizosphere (mainly Pseudomonas, Flavobacterium, and Janthinobacterium) compared with root endosphere (dominated by Delftia, Acinetobacter, Stenotrophomonas, Kaistobacter) samples across all cultivars. Analyses of larger predicted functional activities revealed that chemoheterotrophy and aerobic chemoheterotrophy were more observed in the root endosphere environment, whereas among the minor functions, nitrogen cycling was the more predicted trait, related to rhizosphere samples. A co-occurrence analysis revealed complex bacterial interactions in wheat cultivars’ niche microbiomes identifying three (Comamonadaceae, Enterobacteraceae, Micrococcaceae) and four (Corynebacteraceae, Dermabacteraceae, Xanthomonadaceae, Staphylococcaceae) families as keystone taxa for the root endosphere and rhizosphere, respectively. It is suggested that such findings on the differences in root microbiomes associated with wheat cultivars under field conditions would help to develop new cultivars with abilities to recruit specific bacterial communities.

Microbiota associated with bivalves have drawn considerable attention because studies have suggested their relevance to the fitness and growth of marine bivalves. Although the mussel Choromytilus chorus is a valuable resource for Chilean aquaculture and fisheries, its microbiota is still unknown. In this study, the composition and predicted functions of the bacterial community in tissues of C. chorus specimens grown in an estuary (Nehuentue) and a bay (Hueihue) were investigated. Using 16S rRNA genes as targets, the bacterial abundance in tissues was estimated by quantitative PCR and sequenced via Illumina MiSeq. The abundances of bacteria ranged from 10³ to 10⁵ copies of 16S rRNA genes g⁻¹ tissue. In the Nehuentue estuary, the bacterial communities in the tissues were dominated by the Tenericutes phylum, whereas the Tenericutes and Proteobacteria phyla dominated in mussels from Hueihue Bay. Higher numbers of operational taxonomic units (OTUs) were observed in tissues from the Nehuentue Estuary than in those from Hueihue Bay. Differences in bacterial community compositions in tissues between both locations were confirmed by nonmetric multidimensional scaling (nMDS) and Venn diagram analysis. In addition, linear discriminant analysis effect size (LEfSe) revealed that the Mollicutes class and Actynomycetales order were key phylotypes in tissues from the Nehuentue Estuary and Hueihue Bay, respectively. Our analysis also predicted a high abundance of sequences assigned to heterotrophy; however, relatively high functional diversity was also found in tissues from Hueihue Bay. This work represents our first attempt to elucidate the C. chorus microbiota in contrasting Chilean aquatic environments.

Plant microbiota that associate with pioneer plants are essential to their growth and adaptation to harsh conditions found in the Central Volcanic Zone of the Andes. In this sense, the rhizosphere of pioneer species represents a unique opportunity to examine how bacterial communities are recruited and support the growth of plants under abiotic stress conditions, such low nutrient availability, high solar irradiation, water scarcity, soil salinity, etc. In this study, we explored the community composition and potential functions of rhizobacteria obtained from specimens of Parastrephia quadrangularis (Meyen) Cabrera, commonly called Tola, grown on the slopes of the Guallatiri, Isluga, and Lascar volcanoes in the Atacama Desert of Chile by using 16S rRNA amplicon sequencing. Sequence analysis showed that the Actinobacteria, Proteobacteria, Acidobacteria, and Bacteroidetes were the most abundant phyla of the rhizobacterial communities examined. A similar diversity, richness, and abundance of OTUs were also observed in rhizosphere samples obtained from different plants. However, most of OTUs were not shared, suggesting that each plant recruits a specific rhizobacterial communities independently of volcanoes slope. Analyses of predicted functional activity indicated that the functions were mostly attributed to chemoheterotrophy and aerobic chemoheterotrophy, followed by nitrogen cycling (nitrate reduction and denitrification), and animal parasites or symbionts. In addition, co-occurrence analysis revealed that complex rhizobacterial interactions occur in P. quadrangularis rhizosphere and that members of the Patulibacteraceae comprise a keystone taxon. This study extends our understanding on the composition and functions of the rhizobiome, which is pivotal for the adaptability and colonization of pioneer plant to harsh conditions of the Atacama Desert, widely recognized as the driest place on planet Earth.

Thraustochytrids are aquatic unicellular protists organisms that represent an important reservoir of a wide range of bioactive compounds, such as essential polyunsaturated fatty acids (PUFAs) such as arachidonic acid (ARA), docosahexaenoic acid (DHA), eicosapentaenoic acid (EPA), which are involved in the regulation of the immune system. In this study, we explore the use of co-cultures of Aurantiochytrium sp. and bacteria as a biotechnological tool capable of stimulating PUFA bioaccumulation. In particular, the co-culture of lactic acid bacteria and the protist Aurantiochytrium sp. T66 induce PUFA bioaccumulation, and the lipid profile was evaluated in cultures at different inoculation times, with two different strains of lactic acid bacteria capable of producing the tryptophan dependent auxins, and one strain of Azospirillum sp., as a reference for auxin production. Our results showed that the Lentilactobacillus kefiri K6.10 strain inoculated at 72 h gives the best PUFA content (30.89 mg g⁻¹ biomass) measured at 144 h of culture, three times higher than the control (8.87 mg g⁻¹ biomass). Co-culture can lead to the generation of complex biomasses with higher added value for developing aquafeed supplements.