Metabolite secretion in microorganisms: the theory of metabolic overflow put to the test

Introduction Microbial cells secrete many metabolites during growth, including important intermediates of the central carbon metabolism. This has not been taken into account by researchers when modeling microbial metabolism for metabolic engineering and systems biology studies. Materials and Methods The uptake of metabolites by microorganisms is well studied, but our knowledge of how and why they secrete different intracellular compounds is poor. The secretion of metabolites by microbial cells has traditionally been regarded as a consequence of intracellular metabolic overflow. Conclusions Here, we provide evidence based on time-series metabolomics data that microbial cells eliminate some metabolites in response to environmental cues, independent of metabolic overflow. Moreover, we review the different mechanisms of metabolite secretion and explore how this knowledge can benefit metabolic modeling and engineering.The authors are thankful to Mia Jullig for assistance with Fig. 2. Callaghan Innovation and Bioresource Processing Alliance provided PhD stipends for James Daniell and Ninna Granucci respectively.info:eu-repo/semantics/publishedVersio

Assessment of Various Mandibular Divergence Pattern or Vertical Cephalometric Pattern in Bangladeshi Adult Patients

Introduction : Orthodontic diagnosis as well as the treatment planning of the patients are affected by vertical dimension of face. Lateral cephalometric radiographs are used by orthodontists to find out the norms of different skeletal, dental and soft tissue variables. Present study was undertaken with the aim to assess the various mandibular divergence pattern or vertical cephalometric pattern in Bangladeshi adult orthodontic patients. Materials and methods : This cross sectional study was conducted with 120 pretreatment lateral cephalograms of Bangladeshi adult orthodontic patients who visited Dhaka Dental College Hospital (DDCH) for orthodontic treatment for the duration of six months. The angular measurement used in this study to assess the vertical divergence pattern or vertical cephalometric pattern was mandibular plane to anterior cranial base (MP-SN). Collected data were analyzed by SPSS software version 26 and statistical significance was set as p=0.05. Results : The study result showed that out of 120 orthodontic patients hypodivergent vertical cephalometric pattern found in 26.6% patients having ˂270 MP-SN angle and normodivergent, hyperdivergent pattern found in (45.8%), (27.5%) patients having 270 to ˂ 370 MP-SN angle and > 370 MP-SN angle respectively. Sex of the patient was not significantly associated with the vertical cephalometric pattern (as p >0.05). It was also observed that age was not statistically significantly different between male and female patients within each mandibular divergence pattern and across the three mandibular divergence patterns. Conclusion : Present study concluded that age and sex of Bangladeshi adult orthodontic patients were not significantly associated with different mandibular divergence pattern or vertical cephalometric pattern. In all the three vertical cephalometric pattern the MP-SN angle were greater in Bangladeshi female than Bangladeshi male patients

Analysis of Intracellular Metabolites from Microorganisms: Quenching and Extraction Protocols

Sample preparation is one of the most important steps in metabolome analysis. The challenges of determining microbial metabolome have been well discussed within the research community and many improvements have already been achieved in last decade. The analysis of intracellular metabolites is particularly challenging. Environmental perturbations may considerably affect microbial metabolism, which results in intracellular metabolites being rapidly degraded or metabolized by enzymatic reactions. Therefore, quenching or the complete stop of cell metabolism is a pre-requisite for accurate intracellular metabolite analysis. After quenching, metabolites need to be extracted from the intracellular compartment. The choice of the most suitable metabolite extraction method/s is another crucial step. The literature indicates that specific classes of metabolites are better extracted by different extraction protocols. In this review, we discuss the technical aspects and advancements of quenching and extraction of intracellular metabolite analysis from microbial cells

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Rapid Quantification of Major Volatile Metabolites in Fermented Food and Beverages Using Gas Chromatography-Mass Spectrometry

Here we present a method for the accurate quantification of major volatile metabolites found in different food and beverages, including ethanol, acetic acid and other aroma compounds, using gas chromatography coupled to mass spectrometry (GC-MS). The method is combined with a simple sample preparation procedure using sodium chloride and anhydrous ethyl acetate. The GC-MS analysis was accomplished within 4.75 min, and over 80 features were detected, of which 40 were positively identified using an in-house and a commercialmass spectrometry (MS) library. We determined different analytical parameters of these metabolites including the limit of detection (LOD), limit of quantitation (LOQ) and range of quantification. In order to validate the method, we also determined detailed analytical characteristics of five major fermentation end products including ethanol, acetic acid, isoamyl alcohol, ethyl-L-lactate and, acetoin. The method showed very low technical variability for the measurements of these metabolites in different matrices (<3%) with an excellent accuracy (100% ± 5%), recovery (100% ± 10%), reproducibility and repeatability [Coefficient of variation (CV) 1–10%)]. To demonstrate the applicability of the method, we analysed different fermented products including balsamic vinegars, sourdough, distilled (whisky) and non-distilled beverages (wine and beer)

Translational Metabolomics: Current Challenges and Future Opportunities

Metabolomics is one of the latest omics technologies that has been applied successfully in many areas of life sciences. Despite being relatively new, a plethora of publications over the years have exploited the opportunities provided through this data and question driven approach. Most importantly, metabolomics studies have produced great breakthroughs in biomarker discovery, identification of novel metabolites and more detailed characterisation of biological pathways in many organisms. However, translation of the research outcomes into clinical tests and user-friendly interfaces has been hindered due to many factors, some of which have been outlined hereafter. This position paper is the summary of discussion on translational metabolomics undertaken during a peer session of the Australian and New Zealand Metabolomics Conference (ANZMET 2018) held in Auckland, New Zealand. Here, we discuss some of the key areas in translational metabolomics including existing challenges and suggested solutions, as well as how to expand the clinical and industrial application of metabolomics. In addition, we share our perspective on how full translational capability of metabolomics research can be explored