Conjugation, mobilization, and retromobilization are three related mechanisms of horizontal gene transfer in bacteria. They have been extensively studied in gram-negative species, where retromobilization, the capture of DNA from a recipient by a donor cell, was shown to result from two successive steps: the transfer of the conjugative plasmid from the donor to the recipient followed by the retrotransfer of the mobilizable plasmid to the donor. This successive model was established for gram-negative bacteria but was lacking experimental data from the gram-positive counterparts. In the present work, the mobilization and retromobilization abilities of the conjugative plasmid pXO16 from Bacillus thuringiensis subsp. israelensis were studied using the mobilizable plasmids pUB110 and pE194 and the "nonmobilizable" element pC194 lacking the mob and oriT features (all from Staphylococcus aureus). Experimental data suggested a successive model, since different retromobilization frequencies were observed between the small plasmids. More importantly, retromobilization was shown to be delayed by 50 and 150 min for pUB110 and pE194, respectively, compared to pXO16 conjugation. Natural liquid foods (cow milk, soy milk, and rice milk) were used to evaluate the putative ecological impact of these transfers. In cow and soy milk, conjugation, mobilization, and retromobilization were shown to occur at frequencies of 8.0 ؋ 10 ؊1 , 1.0 ؋ 10 ؊2 , and 1.2 ؋ 10 ؊4 transconjugants per recipient, respectively. These data are comparable to those obtained with LB medium and about 10-fold lower than in the case of rice milk. Taken together, these results emphasize the potential role of plasmid capture played by B. thuringiensis in natural environments.

There have been a number of recent developments in NIR technology which may prove to be significant in the near future. The overall objective of this work is to compare the performance of different NIR devices (i.e. bench-top, hyperspectral imaging and pocket NIR spectrometers) for the determination of a classical quality parameter, the protein content. In order to achieve this goal, several studies have been carried out with the different instrumentation on wheat flours (selected as a "homogeneous" product). These studies should determine if NIR hyperspectral imaging and NIR pocket instruments are as efficient as classical NIR bench-top instruments for predicting protein content.

The purpose of this study was to evaluate two different locally based regression methods (LOCAL and Local Calibration by Customized Radii Selection) and compare their performance to the classical global PLS for large NIR data. The data used in this study came from two inter-laboratory studies for wheat grain analysis organized in 2016 in the framework of the REQUASUD network. The results showed that improved predictions in terms of prediction errors can be obtained using local approaches compared to the classical global PLS. Moreover, the study highlighted clear differences between inter-laboratory studies and participating laboratories, which were even more evident when working with local procedures.

The nitrogen nutrition index (NNI) is recognized as a reliable plant-based method for diagnosing the crop nitrogen status (CNS). The NNI is based on the concept of critical nitrogen (Nc) dilution curve describing the Nc concentration in the whole plant as a function of the total crop biomass (W). The objectives of this study were (i) to establish the specific potato Nc dilution curve for cv. Bintje under Belgian growing conditions; (ii) to assess if the established curve for cv. Bintje could be used for cv. Charlotte; (iii) to compare the established curve with the existing Nc potato curves; and (iv) to assess the possibility of using the obtained Nc curve to evaluate the potato CNS and to predict the final yield. Field experiments studying increasing nitrogen (N) rates were conducted at different locations in Belgium for several years. Biomass N concentration and W production were determined at different sampling dates, and the final tuber yield was determined at harvest. At a sampling date, the Nc was determined by selecting the data point from the treatment presenting the highest W. The NNI was calculated as the ratio between the measured N concentration in W and the predicted Nc according to the Nc dilution curve. The Nc curve (Nc (%) = 5.37 W −0.45) was developed for potato for cv. Bintje under Belgian conditions matching also for cv. Charlotte. The Belgian Nc curve presented similar values as the curves developed previously in Scotland and the Netherlands. NNI was related to relative tuber yield (ratio between the tuber yield obtained for a given N rate and the highest tuber yield obtained among all N application rates). The Nc curve and the NNI adequately identified situations of limiting and non-limiting N nutrition and could be used to establish the potato CNS and to predict the final yield.

Description of the subject. Feed is the main variable cost in dairy farming. More efficient use of forage resources is one way to reduce production costs. Improving forage resource efficiency can start with a better assessment of the dry matter content and nutritional value of forages. Currently, analytical process time is often long and analyses are not repeatable while the quality of the fodder changes over time. Being able to analyze forages directly on-farm would make it possible to adapt the animal diet according to forage variability, in order to improve the profitability of the farm. Objectives. To propose in situ rapid analysis solutions to better characterize dry matter content and the chemical composition of fodder for assessing its feeding value. Method. The performance of three recently developed spectroscopic handheld devices, namely the Viavi’s MicroNIR 1700, the Ocean Insight’s FlameNIR and the Malvern Panalytical’s ASD FieldSpec 4, are evaluated to predict dry matter content and the chemical composition of fresh and unground grass silage in the framework of precision feeding and compared to the reference benchtop Foss’s XDS instrument. The conventional global PLS and local PLS are used as multivariate calibration methods. Results. The assessed handheld devices allow the dairy farmer to obtain a relatively precise quantitative prediction of the dry matter and crude fiber content (2.5% and 1.8% respectively on average, in terms of ratios between the local PLS error on fresh forage and the reference method error) in order to adapt the livestock diet. Crude protein, even if the prediction accuracy is lower (6.4%), is still well predicted. Higher errors are obtained for ash (9.2%), crude neutral (6.8%) and acid detergent fiber (6.9%). Conclusions. The studied devices should allow the dairy farmer to obtain a relatively precise quantitative prediction of those quality parameters in order to directly adapt the quantity of forage distributed to the animals. Performances could probably be improved by including more samples/spectra into the databases.