Understanding the Intersection of Climate/Environmental Change, Health, Agriculture, and Improved Nutrition: A Case Study on Micronutrient Nutrition and Animal Source Foods.

With a growing global population, the demand for high-quality food to meet nutritional needs continues to increase. Our ability to meet those needs is challenged by a changing environment that includes constraints on land and water resources and growing concerns about the impact of human activity including agricultural practices on the changing climate. Adaptations that meet food/nutritional demands while avoiding unintended consequences including negatively affecting the environment are needed. This article covers a specific case study, the role of animal source foods (ASFs) in meeting micronutrient needs in a changing environment. The article covers our understanding of the role of ASFs in meeting micronutrient needs, evidence-based approaches to the development of nutrition guidance, the current issues associated with the relation between animal production practices and greenhouse gas emissions, and examples of how we might model the myriad sources of relevant data to better understand these complex interrelations.

Separation and purification of xylose oligomers using centrifugal partition chromatography.

Xylose oligomers, which have a prebiotic effect, have been used as additives to human and animal food. These oligomers are also the primary intermediate in hemicellulose degradation during the pretreatment of biomass. Centrifugal partition chromatography (CPC) was used in this study to separate and purify xylan-derived oligomers from birchwood xylan. The xylan was partially hydrolyzed to achieve varying degrees of polymerization at 130°C using 0.98% aqueous sulfuric acid for 20 min with a 2.5% solid loading. The CPC solvent system consisting of dimethyl sulfoxide (DMSO), tetrahydrofuran (THF), and water in a 1:6:3 volumetric ratio was used because of its ability to dissolve xylose oligomers of different degrees of polymerization. The CPC was operated in the ascending mode with the water- and DMSO-rich bottom phase acting as the stationary phase, while the THF-rich top phase was the eluent. This paper delineates a method for the production and purification of xylose monomer and xylose oligomers (up to xylopentaose) using CPC. The amount and purity of compounds collected from the CPC fractionation based on 1 g of birchwood xylan were 25.26 mg of xylose at 91.86% purity, 10.71 mg of xylobiose at 85.07% purity, 4.15 mg of xylotriose at 54.71% purity, 5.03 mg of xylotetraose at 38.33% purity and 3.31 mg of xylopentaose at 30.43% purity.

A simple substrate feeding strategy using a pH control trigger in fed-batch fermentation.

A simple automated glucose feeding strategy based on pH control was developed to produce high-cell-density fed-batch fermentation. In this strategy, the pH control scheme utilized an acidified concentrated glucose solution to lower the pH. The frequency of glucose addition to the fermentor is determined by the culture's growth kinetics. To demonstrate the effectiveness of the coupled pH and glucose control strategy in biomass and/or secondary metabolite production, several fed-batch fermentations of indigenous Escherichia coli and recombinant E. coli were carried out. Both strains produced biomass with optical density of greater than 40 at 600 nm. We also tested the glucose control strategy using two types of pH controller: a less sophisticated portable pH controller and a more sophisticated online proportional-integral-derivative (PID) controller. Our control strategy was successfully applied with both controllers, although better control was observed using the PID controller. We have successfully demonstrated that a glucose feeding strategy based on a simple pH control scheme to indirectly control the glucose concentration can be easily achieved and adapted to conventional bioreactors in the absence of online glucose measurement and control.

Gas-lift digester configuration effects on mixing effectiveness.

Computational fluid dynamics simulations were used to study the effect of bottom configuration and a hanging baffle on the mixing inside a gas-lift digester filled with non-Newtonian sludge. The Navier-Stokes and continuity equations were solved numerically using commercially available finite element method-based solver. The results from this simulation were found to be in good agreement with previously reported experimental findings. At a gas recirculation rate of 84.96l/h, the poorly mixed zones inside a flat bottom digester were about 33.6% of the digester volume, while in the case of digesters with 25 degrees and 45 degrees conical bottoms poorly mixed zones were about 31.9% and 29.6%, respectively. The power law viscosity index, n, did not have a significant effect on the mixing pattern under the conditions studied. Introduction of a hanging baffle in combination with a 45 degrees hopper bottom resulted in reduction of the poorly mixed zone by a factor of three compared to a flat bottom without baffle configuration. Although the introduction of a hanging baffle was able to significantly reduce the size of the poorly mixed zones inside a gas-lift digester, further optimization of the digester geometry may lead to additional improvements.