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Fast metabolite quantification methods are required for high throughput screening of microbial strains obtained by combinatorial or evolutionary engineering approaches. In this study, a rapid RIP-LC-MS/MS (RapidRIP) method for high-throughput quantitative metabolomics was developed and validated that was capable of quantifying 102 metabolites from central, amino acid, energy, nucleotide, and cofactor metabolism in less than 5 minutes. The method was shown to have comparable sensitivity and resolving capability as compared to a full length RIP-LC-MS/MS method (FullRIP). The RapidRIP method was used to quantify the metabolome of seven industrial strains of E. coli revealing significant differences in glycolytic, pentose phosphate, TCA cycle, amino acid, and energy and cofactor metabolites were found. These differences translated to statistically and biologically significant differences in thermodynamics of biochemical reactions between strains that could have implications when choosing a host for bioprocessing.

L-serine is a promising building block biochemical with a high theoretical production yield from glucose. Toxicity of L-serine is however prohibitive for high-titer production in E. coli. Here, E. coli lacking L-serine degradation pathways was evolved for improved tolerance by gradually increasing L-serine concentration from 3 to 100g/L using adaptive laboratory evolution (ALE). Genome sequencing of isolated clones revealed multiplication of genetic regions, as well as mutations in thrA, thereby showing a potential mechanism of serine inhibition. Additional mutations were evaluated by MAGE combined with amplicon sequencing, revealing role of rho, lrp, pykF, eno, and rpoB on tolerance and fitness in minimal medium. Production using the tolerant strains resulted in 37g/L of L-serine with a 24% mass yield. The resulting titer is similar to the highest production reported for any organism thereby highlighting the potential of ALE for industrial biotechnology.

In this study, field trials on fine and coarse spray quality application of pesticides on apples were performed. The main objectives were to study the variation of pesticide residue levels in individual fruits versus composite samples, and the effect of standard fine spray quality application versus coarse spray quality application on residue levels. The applications included boscalid, bupirimate, captan, fenoxycarb, indoxacarb, pirimicarb, pyraclostrobin and thiophanate-methyl. Apples were collected from four zones in the tree and pesticide residues were detected in the individual apples. None of the results for the pesticides residues measured in individual apples exceeded the EU Maximum Residue Levels (MRLs). However, there was a large variation in the residues levels in the apples, with levels from 0.01 to 1.4 mg kg −1 for captan, the pesticide with the highest variation, and from 0.01 to 0.2 mg kg −1 for pyraclostrobin, the pesticide with the lowest variation. Residues of fenoxycarb and indoxacarb were only found in a few apples, probably due to the early application time of these two compounds. The evaluation of the effect of spray quality did not show any major difference between fine and coarse spray quality, except for carbendazim, the degradation product of thiophanate-methyl, where fine spray quality resulted in higher carbendazim residue levels than coarse spray quality. To examine the relationship between individual results and average results from ten apples, 20 composite samples were statistically constructed from sets of ten of the individual results. The variability factors for the individual samples ( n = 80) at the 97.5 percentile were calculated for both standard and air induction nozzle application and were in the range of 0.9–9.4. The variability factor of seven used when EU member states calculate possible exceeding of Acute Reference Dose (ARfD) was adequate to encompass almost all the average results from the analyses of ten individual apples. However, for captan up to 9% of the results were not covered depending on which of the mathematically constructed composite concentrations was chosen. The variability factor of three, recommend by Codex, seems to be too low, because up to 30% of the apple samples for captan were not covered if the worst case scenario was chosen. The factor of three seems was also too low for thiophanate-methyl.

The aim of this study was to investigate the amount of pesticide residues in fruits and vegetables from South America. A total of 724 samples of 46 different fruits and vegetables from eight South American countries were collected in 2007. In 19% of the samples no residues were found, 72% of samples contained pesticide residues at or below MRL, and 8.4% of samples contained pesticide residues above MRL. Thiabendazole, imazalil and chlorpyrifos were the pesticide most frequently found. Thirty-seven pesticides were found with frequencies higher that 1% in the samples. The results emphasize the need for continuous monitoring of pesticide residues, especially in imported fruits and vegetables.

A method for analysing carbamates and other relatively polar pesticides by LC–MS–MS with electrospray ionisation has been developed. The method is based on extraction by ultrasonication using a methanolic ammonium acetate–acetic acid buffer. After centrifugation the samples are filtered in Miniprep filter HPLC vials and detected by LC–MS–MS. To compensate for variations in the MS response [ 13 C 6 ]-carbaryl was used as internal standard and matrix-matched pesticide solutions were used as external standards for the quantification. The method has been validated for the matrices apple, avocado, carrot, lettuce, orange, potato and wheat at the spiking levels—0.02; 0.04 and 0.20 mg kg−1. Recoveries were generally in the range 70–120%. Results from participation in three intercomparisons proved the accuracy of the method. As the analytical procedure does not include any concentration or cleanup steps, it is easy and fast to perform, making it applicable for routine analysis in large pesticide monitoring programmes.