Prenatal dietary supplements influence the infant airway microbiota in a randomized factorial clinical trial.

Maternal dietary interventions during pregnancy with fish oil and high dose vitamin D have been shown to reduce the incidence of asthma and wheeze in offspring, potentially through microbial effects in pregnancy or early childhood. Here we analyze the bacterial compositions in longitudinal samples from 695 pregnant women and their children according to intervention group in a nested, factorial, double-blind, placebo-controlled, randomized trial of n-3 long-chain fatty acids and vitamin D supplementation. The dietary interventions affect the infant airways, but not the infant fecal or maternal vaginal microbiota. Changes in overall beta diversity are observed, which in turn associates with a change in immune mediator profile. In addition, airway microbial maturation and the relative abundance of specific bacterial genera are altered. Furthermore, mediation analysis reveals the changed airway microbiota to be a minor and non-significant mediator of the protective effect of the dietary interventions on risk of asthma. Our results demonstrate the potential of prenatal dietary supplements as manipulators of the early airway bacterial colonization.

Bacterial potentials for uptake, solubilization and mineralization of extracellular phosphorus in agricultural soils are highly stable under different fertilization regimes.

Phosphorus is one of the most important macronutrient for plants. In agriculture, amending fertilizer with phosphorus (P) is common practice. However, natural phosphorus sources are finite, making research for more sustainable management practices necessary. We postulated that the addition of carbon (C) and nitrogen (N) would stimulate phosphorus mobilization by bacteria because of their desire to maintain a stable intracellular C:N:P stoichiometry. Therefore, we chose a metagenomic approach to investigate two agricultural soils, which only received mineral N fertilizer or mineral N and organic fertilizer for more than 20 years. The most abundant genes involved in the acquisition of external P sources in our study were those involved in solubilization and subsequent uptake of inorganic phosphorus. Independent of site and season, the relative abundance of genes involved in P turnover was not significantly affected by the addition of fertilizers. However, the type of fertilization had a significant impact on the diversity pattern of bacterial families harbouring genes coding for the different P transformation processes. This gives rise to the possibility that fertilizers can substantially change phosphorus turnover efficiency by favouring different families. Additionally, none of the families involved in phosphorus turnover covered all investigated processes. Therefore, promoting bacteria which play an essential role specifically in mobilization of hardly accessible phosphorus could help to secure the phosphorus supply of plants in soils with low P input.

Novel oligonucleotide primers reveal a high diversity of microbes which drive phosphorous turnover in soil.

Phosphorus (P) is of central importance for cellular life but likewise a limiting macronutrient in numerous environments. Certainly microorganisms have proven their ability to increase the phosphorus bioavailability by mineralization of organic-P and solubilization of inorganic-P. On the other hand they efficiently take up P and compete with other biota for phosphorus. However the actual microbial community that is associated to the turnover of this crucial macronutrient in different ecosystems remains largely anonymous especially taking effects of seasonality and spatial heterogeneity into account. In this study seven oligonucleotide primers are presented which target genes coding for microbial acid and alkaline phosphatases (phoN, phoD), phytases (appA), phosphonatases (phnX) as well as the quinoprotein glucose dehydrogenase (gcd) and different P transporters (pitA, pstS). Illumina amplicon sequencing of soil genomic DNA underlined the high rate of primer specificity towards the respective target gene which usually ranged between 98% and 100% (phoN: 87%). As expected the primers amplified genes from a broad diversity of distinct microorganisms. Using DNA from a beech dominated forest soil, the highest microbial diversity was detected for the alkaline phosphatase (phoD) gene which was amplified from 15 distinct phyla respectively 81 families. Noteworthy the primers also allowed amplification of phoD from 6 fungal orders. The genes coding for acid phosphatase (phoN) and the quinoprotein glucose dehydrogenase (gcd) were amplified from 20 respectively 17 different microbial orders. In comparison the phytase and phosphonatase (appA, phnX) primers covered 13 bacterial orders from 2 different phyla respectively. Although the amplified microbial diversity was apparently limited both primers reliably detected all orders that contributed to the P turnover in the investigated soil as revealed by a previous metagenomic approach. Genes that code for microbial P transporter (pitA, pstS) were amplified from 13 respectively 9 distinct microbial orders. Accordingly the introduced primers represent a valuable tool for further analysis of the microbial community involved in the turnover of phosphorus in soils but most likely also in other environments.