This paper is a brief introduction to the different methods used to quantify the enteric methane emission from ruminants. A thorough knowledge of the advantages and disadvantages of these methods is very important in order to plan experiments, understand and interpret experimental results, and compare them with other studies. The aim of the paper is to describe the principles, advantages and disadvantages of different methods used to quantify the enteric methane emission from ruminants. The best-known methods: Chambers/respiration chambers, SF₆ technique and in vitro gas production technique and the newer CO₂ methods are described. Model estimations, which are used to calculate national budget and single cow enteric emission from intake and diet composition, are also discussed. Other methods under development such as the micrometeorological technique, combined feeder and CH₄ analyzer and proxy methods are briefly mentioned. Methods of choice for estimating enteric methane emission depend on aim, equipment, knowledge, time and money available, but interpretation of results obtained with a given method can be improved if knowledge about the disadvantages and advantages are used in the planning of experiments.

The claimed low production of CH₄ by kangaroos and marsupials in general has been questioned because of a lack of data. The extent of their CH₄ production is of interest both from the point of view of discussing meat production of marsupials and as a basis for developing methods to reduce CH₄ production from ruminants. In the present experiment, the CH₄ production of 8 red-necked wallabies (Macropus rufogriseus) was measured of which 4 were fed 2 different diets in an open-circuit respiration chamber. These results were compared with a newly developed, inexpensive, and simple method that does not influence the behavior of the animal, and where the ratio between CH₄ and CO₂ is measured and used together with the calculated CO₂ to quantify the CH₄ production. The experiment demonstrated that the wallabies produce CH₄. However, the amount of CH₄ produced by these wallabies was between 1.6 and 2.5 L/d equivalent to 1.6 and 2.5% of GE or 2.2% and 3.5% of DE intake and 0.22 L/BW, kg^0.75. This is between 25 and 33% of what can be expected from ruminants fed the same diet. Based on the uneven release of CH₄ with time, it is most likely that the CH₄ is excreted through flatulence and not through breathing as is seen in ruminants. The experiments also showed that a reasonably accurate determination of the CH₄ production of a group of animals can be obtained by simply measuring the CH₄/CO₂ ratio over a limited time span. This may represent the situation in a natural setting better than measurements in a respiration chamber. It was found that the CH₄/CO₂ ratio in itself represents a reasonable prediction of the proportion of feed GE that is lost as CH₄, and that this method offers new opportunities for CH₄ measurements on a large number of animals. Copyright © 2012. American Society of Animal Science .

In vitro transaminase catalyzed asymmetric synthesis is not a new phenomenon in the biocatalytic toolbox. Our group published a review on process consideration for these reactions in 2011, in which process metrics and the unfavorable reaction equilibrium was deduced to be the main bottlenecks at the time. Now, a decade later, this has been solved by different process methods presented in this review, with the development of enzymatic cascades one of the main solutions. Today, the new bottleneck is the downstream processing, due to the complexity of transaminase reactions, in which a ketone and an amine as substrates and a new ketone and a new amine as products. How to recover the produced amine from the resulting product mixture is considered and will be the key challenge for scale‐up of such systems in the near future.

Raman spectroscopy has been used to measure the concentration of a pharmaceutically relevant model amine intermediate for positive allosteric modulators of nicotinic acetylcholine receptor in a ω‐transaminase‐catalyzed conversion. A model based on a one‐dimensional convolutional neural network was developed to translate raw data augmented Raman spectra directly into substrate concentrations, with which the conversion from ketone to amine by ω‐transaminase could be determined over time. The model showed very good predictive capabilities, with R ² values higher than 0.99 for the spectra included in the modeling and 0.964 for an independent dataset. However, the model could not extrapolate outside the concentrations specified by the model. The presented work shows the potential of Raman spectroscopy as a real‐time monitoring tool for biocatalytic reactions.

Mutants of the amine oxidase from Aspergillus niger were tested to ascertain the need for molecular oxygen across the family of mutant enzymes. Two of the variants were selected, namely D5 and D11, which had 5 and 10 mutations, respectively, versus the wild type. Experimental observations showed a difference in oxygen requirements between variants. Molecular dynamics simulations were then used to give a potential explanation for this difference in observed activity at a molecular level.