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Kluyveromyces marxianus CCT 7735 shows potential for producing ethanol from lactose; however, its low ethanol tolerance is a drawback for its industrial application. The first aim of this study was to obtain four ethanol-tolerant K. marxianus CCT 7735 strains (ETS1, ETS2, ETS3, and ETS4) by adaptive laboratory evolution. The second aim was to select among them the strain that stood out and to evaluate metabolic changes associated with the improved ethanol tolerance in this strain. The ETS4 was selected for displaying a specific growth rate higher than the parental strain under ethanol stress (122%) and specific ethanol production rate (0.26 g/g/h) higher than those presented by the ETS1 (0.22 g/g/h), ETS2 (0.17 g/g/h), and ETS3 (0.17 g/g/h) under non-stress condition. Further analyses were performed with the ETS4 in comparison with its parental strain in order to characterize metabolic changes. Accumulation of valine and metabolites of the citric acid cycle (isocitric acid, citric acid, and cis-aconitic acid) was observed only in the ETS4 subjected to ethanol stress. Their accumulation in this strain may have been important to increase ethanol tolerance. Furthermore, the contents of fatty acid methyl esters and ergosterol were higher in the ETS4 than in the parental strain. These differences likely contributed to enhance ethanol tolerance in the ETS4. Key points: • K. marxianus ethanol-tolerant strains were selected by adaptive laboratory evolution. • Valine and metabolites of the TCA cycle were accumulated in the ETS4. • High contents of fatty acids and ergosterol contributed to enhance ethanol tolerance. [ABSTRACT FROM AUTHOR]

Gas chromatography mass spectroscopy was applied to characterize the metabolic profiles of hatchery-reared mussel ( Perna canaliculus) larvae before and after a prolonged handling and water exchange process, and to investigate the effect of culture conditions. A decrease in succinate and an increase in alanine were observed after the water exchange, which indicated alterations in energy production and osmotic balance. However, these variations were subtle and it is unlikely that the water exchange practice had any lasting negative effects on larval physiology and performance. Multivariate pattern recognition tools (hierarchical clustering, principal component analysis and projection to latent squares discriminant analysis) were used to assess metabolite variations in larvae reared in low-density static and high-density flow through systems and to construct a culture condition classification model. Twelve metabolites contributed most towards the model, which indicated differences in energy, protein and lipid metabolism. The clear group separations were not represented by observable variations in morphological traits. This suggests that growth performance is metabolically buffered through an adaptive physiological mechanism to provide similar developmental characteristics under these conditions. [ABSTRACT FROM AUTHOR]

Introduction: Maternal obesity is associated with a range of pregnancy complications, including fetal growth restriction (FGR), whereby a fetus fails to reach its genetically determined growth. Placental insufficiency and reduced nutrient transport play a role in the onset of FGR. Objectives: Metabolomic profiling was used to reveal altered maternal and fetal metabolic pathways in a model of diet induced obesity during pregnancy, leading to reduced fetal growth. Methods: We examined the metabolome of maternal and fetal livers, and placenta following a high fat and salt intake. Sprague-Dawley rats were assigned to (a) control diet (CD; 1 % salt, 10 % kcal from fat), (b) high salt diet (SD; 4 % salt, 10 % kcal from fat), (c) high fat diet (HF; 1 % salt, 45 % kcal from fat) or (d) high-fat high-salt diet (HFSD; 4 % salt, 45 % kcal from fat) 21 days prior to pregnancy and during gestation. Metabolites from maternal and fetal livers, and placenta were identified using gas and liquid chromatography combined with mass spectrometry. Results: Maternal HF intake resulted in reduced fetal weight. Altered metabolite profiles were observed in the HF maternal and fetal liver, and placenta. Polyunsaturated fatty acid metabolism was significantly altered in maternal and fetal liver by maternal fat intake. Conclusion: Excess of linoleic and α-linoleic acid (essential fatty acids) may be detrimental during placentation and associated with a reduction in fetal weight. Additionally, maternal, placental and fetal response to increased fat consumption seems likely to involve palmitoleic acid utilization as an adaptive response during maternal obesity. [ABSTRACT FROM AUTHOR]

Introduction: Technological advances in the area of analytical chemistry and the development of state-of-the-art analytical instrumentation have allowed for a shift in the focus from a previously strict targeted approach towards the approach adopted in metabolomics, the essence of which is non-targeted providing an unbiased analysis of metabolites in biological samples. Metabolite profiling methods have served their purpose in providing descriptive information about biological systems through qualitative and relative semi-quantitative data. However, quantitative characterization of a system cannot be fully accomplished without using absolute metabolite concentrations, an area which is lacking in most current metabolomics platforms. Objectives: The objective of this work was to develop a calibration-curve free method for quantitation of amino and non-amino organic acids in biological samples. Methods: We developed a novel calibration curve-free GC-MS method based on isotope-coded derivatization for absolute non-targeted quantification of polar metabolites. A new R-based package MetabQ was created for automated data processing of GC-MS data files performing data extraction and calculation of absolute metabolite values. The new method requires metabolite response factors which should be calculated only once for each equipment, and was validated for metabolite quantification of different biological matrices. Results: The method showed high reproducibility and accuracy, and does not require the use of calibration curves using standards to be analyzed in parallel with every sample batch. However, there is a small group of metabolites where their quantification required additional steps of correction due to their chemical instability. The introduced R package significantly increased the throughput in the data analysis process, extensively reducing the time required to perform the task manually. Conclusion: Our novel approach gives the potential to identify and quantify hundreds of metabolites, far exceeding the capabilities of any absolute quantitative targeted metabolite analysis, limited only by the size of the mass spectral library. [ABSTRACT FROM AUTHOR]

The article discusses the study which determines whether maternal hair was link with the development of gestational diabetes mellitus (GDM) through investigating the metabolome of maternal hair. The study analyzed hair samples from about 94 pregnant women from China whose hair were deconvulated through Automated Mass Spectral Deconvolution and Identification System (AMDIS). Result shows that a total of 30 metabolites were identified through a in-house mass spectral library.

Current early pregnancy screening tools to identify women at risk of developing gestational diabetes mellitus lack both specificity and sensitivity. As a result, the foetus and mother are often subjected to insult during disease progression, prior to diagnosis and treatment in later pregnancy. Metabolomics is an analytical approach, which allows for appraisal of small molecular mass compounds in a biofluid. The aim of this pilot study was to investigate the relationship between the early gestation serum metabolite profile and the subsequent development of gestational diabetes mellitus in the search for early pregnancy biomarkers and potential metabolic mechanisms. Our nested case-control study analysed maternal serum at 20 weeks' gestation, obtained from the New Zealand cohort of the Screening for Pregnancy Endpoints study. Metabolomic profiling was performed using gas chromatography coupled to mass spectrometry, and metabolites were identified using R software and an in-house mass spectral library. Statistical analysis was performed using SPSS version 21.0. Forty-eight metabolites were identified in the serum samples. Itaconic acid ( P = 0.0003), with a false discovery rate of 0.012, was found to be significantly more abundant in women who subsequently developed gestational diabetes mellitus, when compared to controls with uncomplicated pregnancies. The current pilot study found that itaconic acid may have potential as a novel biomarker in early pregnancy to predict the subsequent development of gestational diabetes mellitus. However, the findings from this pilot study require validation with a larger, diverse population before translation into the clinical setting. [ABSTRACT FROM AUTHOR]

Candida albicans is an opportunistic pathogen of humans with significant mortality in severely immunocompromised patients. The ability to switch from yeast to hyphal morphology and vice versa, in response to various environmental cues, is believed to be a critical virulence factor of this fungus. However, the mechanisms that recognize such environmental signals and trigger the morphological change at a system level are still not clearly understood. Therefore, we have compared the metabolite profiles of C. albicans cells growing under different hyphae-inducing conditions to the metabolite profiles of growing yeast cells. Surprisingly our results suggest an overall downregulation of cellular metabolism during the yeast to hyphal morphological transition. Among the metabolic pathways involved in the central carbon metabolism, we have found seventeen that were significantly downregulated in all three hyphae-inducing conditions. This indicates that these central carbon metabolic pathways are likely to be intrinsically involved in the downstream effects of the morphogenetic process. [ABSTRACT FROM AUTHOR]

It is undeniable that music and sounds can affect our emotions and mood, but so far the study of physical stimuli provoked by sound on living organisms has been mostly focused on brain and sensorimotor structures rather than cellular metabolism. Using metabolomics, we compared the physiology of yeast cells growing in defined liquid medium exposed to music, high and low frequency sonic vibration and silence. All sonic stimuli tested not only increased the growth rate of the yeast cells by 12% but they also reduced biomass production by 14%. The intra- and extracellular metabolite profiles differed significantly depending on the sonic stimulus applied showing that different metabolic pathways are affected differently by different sound frequency. Therefore, our results clearly demonstrate that sound does affect microbial cell metabolism when growing in liquid culture, opening an entirely new perspective for scientific investigation interfacing acoustics, biophysics and biochemistry. [ABSTRACT FROM AUTHOR]

The field of metabolomics is getting more and more popular and a wide range of different sample preparation procedures are in use by different laboratories. Chemical extraction methods using one or more organic solvents as the extraction agent are the most commonly used approach to extract intracellular metabolites and generate metabolite profiles. Metabolite profiles are the scaffold supporting the biological interpretation in metabolomics. Therefore, we aimed to address the following fundamental question: can we obtain similar metabolomic results and, consequently, reach the same biological interpretation by using different protocols for extraction of intracellular metabolites? We have used four different methods for extraction of intracellular metabolites using four different microbial cell types (Gram negative bacterium, Gram positive bacterium, yeast, and a filamentous fungus). All the quenched samples were pooled together before extraction, and, therefore, they were identical. After extraction and GC-MS analysis of metabolites, we did not only detect different numbers of compounds depending on the extraction method used and regardless of the cell type tested, but we also obtained distinct metabolite levels for the compounds commonly detected by all methods ( P-value < 0.001). These differences between methods resulted in contradictory biological interpretation regarding the activity of different metabolic pathways. Therefore, our results show that different solvent-based extraction methods can yield significantly different metabolite profiles, which impact substantially in the biological interpretation of metabolomics data. Thus, development of alternative extraction protocols and, most importantly, standardization of sample preparation methods for metabolomics should be seriously pursued by the scientific community. [ABSTRACT FROM AUTHOR]

The quantity and chemical composition of honeydew produced by scale insects may influence wider community structure, but little is known about the detailed chemical composition of the honeydew found in forest ecosystems. We used gas chromatography-mass spectrometry to examine the amino acid and carbohydrate composition of honeydew from three New Zealand communities. Low molecular weight carbohydrates (mono-, di-, and tri-saccharides) were derivatized using a modified trimethylsilyl (TMS) method, and amino and non-amino organic acids were derivatized using methylchloroformate (MCF). These recently developed derivatization methods allowed us to detect atypical compounds such as sugar alcohols, fatty acids, and non-amino organic acids, in addition to the more routinely studied compounds such as sugars and amino acids. Some compounds could not be identified and may be novel. Multivariate analysis showed that honeydew from each scale insect species had a distinctive amino acid and carbohydrate signature. We suggest these chemical signatures may influence the types of consumers that are attracted to different honeydews and may explain the characteristic communities associated with these honeydews. [ABSTRACT FROM AUTHOR]

Lignocellulolytic enzymes from conventional and non-conventional yeasts are not commonly studied, and they have never been described for Candida utilis species. After solid-substrate cultivation of C. utilis (CCT 3469) on apple pomace, degradation of cellulose, pectin and lignin fragments was observed. Production of the main lignocellulolytic enzymes by C. utilis was investigated and high activity for pectinase (239 U ml−1) as well as a significant manganese-dependent peroxidase (19.1 U ml−1) activity was found. Low cellulase (3.0 U ml−1) and xylanase (1.2 U ml−1) activities were also observed suggesting that C. utilis may have lignocellulose degradation ability. [ABSTRACT FROM AUTHOR]

Introduction: Saccharomyces cerevisiae has been widely used for fermenting food and beverages for over thousands years. Its metabolism together with the substrate composition play an important role in determining the characteristics of the final fermented products. We previously showed that the polyunsaturated fatty acid, linoleic acid, which is present in the grape juice at trace levels, significantly affected the development of aroma compounds of the wines. However, the effect of linoleic acid on the overall cell metabolism of S. cerevisiae is still not clear. Therefore, we aimed to unlock the metabolic response of S. cerevisiae to linoleic acid using metabolomics and isotope labelling experiments.Methods: We cultured the cells on a minimal mineral medium supplementing them with linoleic acid isomers and 13C-linoleic acid. Both intracellular and extracellular metabolite profiles were determined using gas chromatography coupled to mass spectrometry (GC-MS) to investigate which S. cerevisiae pathways were affected by linoleic acid supplementation.Results: The utilisation of linoleic acid by S. cerevisiae had a significant impact on the primary carbon metabolism increasing the glucose consumption and the ethanol production under anaerobic condition. The energetic state of the cell was, therefore, affected and the glycolytic pathway, the TCA cycle and the amino acid production were up-regulated. We also observed that linoleic acid was transported into the cell and converted into other fatty acids affecting their profile even under anaerobic condition.Conclusion: Our data clearly shows that linoleic acid supplementation in growth medium increased glucose consumption and ethanol production by S. cerevisiae under anaerobic condition. We also suggest that S. cerevisiae might be able to perform an alternative anaerobic pathway to β-oxidation, which has not been reported yet. [ABSTRACT FROM AUTHOR]