Xia, J.-M., Hu, X.-M., Huang, C.-H., Yu, L.-B., Xu, R.-F., Tang, X.-X., Lin, D.-H., 2020. Metabolic profiling of Microbacterium sediminis cold adaptation of a deep-sea psychrotolerant to prolonged low temperature under high hydrostatic pressure. Applied Microbiology and Biotechnology 104, 277-289.

https://doi.org/10.1007/s00253-019-10134-4 The most wide- spread 'hostile' environmental factor for marine microorganisms is low temperature, which is usually accompanied by high hydrostatic pressure (HHP). Metabolic mechanisms of marine microorganisms adapting to prolonged low temperature under HHP remain to be clarified. To reveal the underlying metabolic mechanisms, we performed NMR-based metabolomic analysis of aqueous extracts derived from a Microbacterium sediminis psychrotolerant YLB-01, which was isolated from deep-sea sediment and possess great biotechnology potentials. The YLB-01 cells were firstly cultivated at the optimal condition (28 °C, 0.1 MPa) for either 18 h (logarithmic phase) or 24 h (stationary phase), then continually cultivated at either 28 °C or 4 °C under HHP (30 MPa) for 7 days. The cells cultivated at low temperature, which experienced cold stress, were distinctly distinguished from those at normal temperature. Cold stress primarily induced metabolic changes in amino acid metabolism and carbohydrate metabolism. Furthermore, the logarithmic and stationary phase cells cultivated at low temperature exhibited distinct metabolic discrimination, which was mostly reflected in the significantly disturbed carbohydrate metabolism. The logarithmic phase cells displayed suppressed TCA cycle, while the stationary phase cells showed decreased pyruvate and increased lactate. In addition, we performed transcriptome analysis for the stationary phase cells to support the metabolomic analysis. Our results suggest that the cold adaptation of the psychrotroph YLB-01 is closely associated with profoundly altered amino acid metabolism and carbohydrate metabolism. Our work provides a mechanistic understanding of the metabolic adaptation of marine psychrotrophs to prolonged low temperature under HHP.

Xia, L., Yang, J., Su, R., Zhou, W., Zhang, Y., Zhong, Y., Huang, S., Chen, Y., Li, G., 2020. Recent progress in fast sample preparation techniques. Analytical Chemistry 92, 34-48.

https://doi.org/10.1021/acs.analchem.9b04735 Sample preparation prior to instrument analysis plays a significant role in whole analytical process. In modern analytical chemistry, samples with wide varieties and high complexity are receiving increasing attention, which probably contain multiple target analytes and a complex matrix. Moreover, these target analytes may be extremely similar to each other but present a trace amount in the sample matrix. Thus, to eliminate matrix interference, extraction and separation of target analytes as well as concentration of trace level compounds must be accomplished before instrument analysis. Theoretically, sample preparation is the procedure of transferring analytes from a sample matrix to qualitative and quantitative evaluation with better applicability by their differences in the physical, chemical, and biological properties. From chaos to order, this mass transfer procedure cannot occur automatically. Essentially, sample preparation is dealing with how to maximize the spontaneous process of the second law of thermodynamics in the opposite direction. In other words, to achieve enough or even better efficiency of sample preparation, including separation and enrichment processes, additional energy or reduced entropy have to be applied into the mass transfer system. Beyond producing work, changing the distribution of chemical potential in the system, which is caused by the introduction of phase, membrane, and field, turns out to be an alternative approach to reduce system entropy and improve the sample preparation efficiency. Therefore, sample preparation is an important but probably the most time-consuming and labor-intensive part of sample analysis. However, with the development of rapid and sensitive detection systems, accelerating the sample preparation becomes the bottleneck of rapid sample analysis. For example, in point-of-care tests, novel sample pretreatment methods and devices are highly desired to obtain results in a very short of period with acceptable accuracy.(1,2) Practically, four approaches can be used to cut down the time consumed in sample preparation. First, introduction of additional energy into the preparation process can help to accelerate mass transfer and heat exchange. By employing an assisting field, including acoustic wave, microwave, and electrical field, the speed and efficiency of sample preparation can be improved. Second, speeding up mass transfer in the sample preparation process can be realized by adding materials. Four classical materials-based acceleration methods might be used for fast sample preparation; they are phase adsorption or partition, chemical transformation, sized-based recognition, and mass transfer acceleration. Third, size reduction of the sample is a direct way to