A protocol combining breath testing and ex vivo fermentations to study the human gut microbiome.

This protocol describes the application of breath testing and ex vivo fermentations to study the association between breath methane and the composition and functionality of the gut microbiome. The protocol provides a useful systems biology approach for studying the gut microbiome in humans, which combines standardized methods in human breath testing and fecal sampling. The model described is accessible and easy to repeat, but its relative simplicity means that it can deviate from human physiological conditions.

Authenticating bioplastics using carbon and hydrogen stable isotopes - An alternative analytical approach.

RATIONALE: A combination of stable carbon (δ13 C) and hydrogen (δ2 H) isotope ratios and carbon content (% C) was evaluated as a rapid, low-cost analytical approach to authenticate bioplastics, complementing existing radiocarbon (14 C) and Fourier transform infrared (FTIR) analytical methods. METHODS: Petroleum- and bio-based precursor materials and in-market plastics were analysed and their δ13 C, δ2 H and % C values were used to establish isotope criteria to evaluate plastic claims, and the source and biocontent of the samples. 14 C was used to confirm the findings of the isotope approach and FTIR analysis was used to vertify the plastic type of the in-market plastics. RESULTS: Distinctive carbon and hydrogen stable isotope ratios were found for authentic bio-based and petroleum-based precursor plastics, and it was possible to classify in-market plastics according to their source materials (petroleum, C3, C4, and mixed sources). An estimation of C4 biocontent was possible from a C4-petroleum isotope mixing model using δ13 C which was well correlated (R2 = 0.98) to 14 C. It was not possible to establish a C3-petroleum isotope mixing model due to δ13 C isotopic overlap with petroleum plastics; however, the addition of δ2 H and % C was useful to evaluate if petroleum-bioplastic mixes contained C3 bioplastics, and PLS-DA modelling reliably clustered each plastic type. CONCLUSIONS: A combined dual stable isotope and carbon content approach was found to rapidly and accurately identify C3 and C4 bio-based products from their petroleum counterparts, and identify instances of petroleum and bio-based mixes frequently found in mislabelled bioplastics. Out of 37 in-market products labelled as bioplastic, 19 were found to contain varying amounts of petroleum-based plastic and did not meet their bio-based claims.

The Effect of Formulation, Dose, and Adjuvants on Uptake of Phosphite Into Pine Foliage.

The aim of this investigation was to determine the effect of dose and adjuvant on uptake of two phosphite products (Phos-A and Phos-B) into Pinus radiata needles. In experiment 1, uptake of 6 kg ha-1 phosphite, applied as Phos-A, in 100 liters of water, together with an organosilicone superspreader (0.2%), was high (>60%). Uptake at doses greater than 6 kg ha-1 (12, 15, 18, and 24 kg ha-1) and applied in volumes less than 100 liters of water (75 and 50 liters) was poor (1 to 30%). Using stability tests and NMR spectroscopy in experiment 2, this appeared to be linked to a concentration dependent reaction resulting in the degradation of the organosilicone adjuvant that facilitated uptake of Phos-A. In experiment 3, uptake of phosphite applied as Phos-B, between 6 and 24 kg ha-1 in 100 liters of water, was tested alone and with four adjuvants (an organosilicone, alcohol ethoxylate, lecithin, and esterified seed oil). Uptake of Phos-B without any adjuvant was high (>50%) across all doses, indicating the formulation was optimized for P. radiata needles. Uptake of Phos-B increased with concentration up to 72% at 24 kg ha-1 in 100 liters of water. Symptoms of phytotoxicity were observed at rates of ≥12 kg ha-1. This study highlighted the effect of formulation, dose, concentration, and adjuvant on the uptake of phosphite into P. radiata needles.