Initial Glucose Concentration Research Articles

Melanoidin Content Determines the Primary Pathways in Glucose Dark Fermentation: A Preliminary Assessment of Kinetic and Microbial Aspects

Melanoidins are heterogeneous polymers with a high molecular weight and brown color formed during the Maillard reaction by the combination of sugars and amino acids at high temperatures with the potential to inhibit the microbial activity in bioprocesses. This study assessed the impacts of melanoidins on the kinetic of substrate conversion and production of organic acids via dark fermentation using microbial consortia as inoculum. The investigations were carried out in fed-batch reactors using synthetic melanoidins following glucose-to-melanoidin ratios (G/M; g-glucose g−1 melanoidins) of 0.50, 1.50, 1.62, 1.67, and 5.00, also considering a melanoidin-free control reactor. The results showed that melanoidins negatively impacted the kinetics of glucose fermentation by decreasing the first-order decay constant (k1): when dosing equivalent initial concentrations of glucose (ca. 3 g L−1), the absence of melanoidins led to a k1 of 0.62 d−1, whilst dosing 2 g L−1 (G/M = 1.5) and 6.0 g L−1 (G/M = 0.5) of melanoidins produced k1 values of 0.37 d−1 and 0.27 d−1, respectively. The production of butyric and acetic acids was also negatively impacted by melanoidins, whilst the lactic activity was not impaired by the presence of these compounds. Lactate production reached ca. 1000 mg L−1 in G/M = 1.67, whilst no lactate was detected in the control reactor. The presence of melanoidins was demonstrated to be a selective metabolic driver, decreasing the microbial diversity compared to the control reactor and favoring the growth of Lactobacillus. These results highlight the importance of further understanding the impacts of melanoidins on melanoidin-rich organic wastewater bioconversion, such as sugarcane vinasse, which are abundantly available in biorefineries.

Isolation, screening, and characterization of the newly isolated osmotolerant yeast Wickerhamomyces anomalus BKK11-4 for the coproduction of glycerol and arabitol.

This study explored the isolation and screening of an osmotolerant yeast, Wickerhamomyces anomalus BKK11-4, which is proficient in utilizing renewable feedstocks for sugar alcohol production. In batch fermentation with high initial glucose concentrations, W. anomalus BKK11-4 exhibited notable production of glycerol and arabitol. The results of the medium optimization experiments revealed that trace elements, such as H3BO3, CuSO4, FeCl3, MnSO4, KI, H4MoNa2O4, and ZnSO4, did not increase glucose consumption or sugar alcohol production but substantially increased cell biomass. Osmotic stress, which was manipulated by varying initial glucose concentrations, influenced metabolic outcomes. Elevated glucose levels promoted glycerol and arabitol production while decreasing citric acid production. Agitation rates significantly impacted the kinetics, enhancing glucose utilization and metabolite production rates, particularly for glycerol, arabitol, and citric acid. The operational pH dictated the distribution of the end metabolites, with glycerol production slightly reduced at pH 6, while arabitol production remained unaffected. Citric acid production was observed at pH 6 and 7, and acetic acid production was observed at pH 7. Metabolomic analysis using GC/MS identified 29 metabolites, emphasizing the abundance of sugar/sugar alcohols. Heatmaps were generated to depict the variations in metabolite levels under different osmotic stress conditions, highlighting the intricate metabolic dynamics occurring post-glucose uptake, affecting pathways such as the pentose phosphate pathway and glycerolipid metabolism. These insights contribute to the optimization of W. anomalus BKK11-4 as a whole-cell factory for desirable products, demonstrating its potential applicability in sustainable sugar alcohol production from renewable feedstocks.

Enhanced Production of Erythritol from Glucose by the Newly Obtained UV Mutant Yarrowia lipolytica K1UV15.

Erythritol is a polyol with a sweet taste but low energy value. Thanks to its valuable properties, as well as growing social awareness and nutritional trends, its popularity is growing rapidly. The aim of this study was to increase the effectiveness of erythritol production from glucose using new UV mutants of the yeast Yarrowia lipolytica obtained in the Wratislavia K1 strain. The ability of the new strains to biosynthesize erythritol and utilize this polyol was examined in shake-flask cultures and fed-batch processes conducted in a stirred tank reactor with a total glucose concentration of 300 and 400 g/L. The Wratislavia K1 strain produced erythritol most efficiently (97.5 g/L; 192 h) at an initial glucose concentration of 250 g/L (total: 300 g/L). New strains were assessed under such conditions, and it was noted that the highest erythritol concentration (145 g/L; 183 h) was produced by the K1UV15 strain. A significant improvement in the erythritol biosynthesis efficiency (148 g/L; 150 h) was achieved upon the increase in (NH4)2SO4 to 3.6 g/L. Further, in the culture with such a concentration of the nitrogen source and increased total glucose level (400 g/L), the K1UV15 strain produced 226 g/L of erythritol within 281 h.

Selective glucose electro-oxidation catalyzed by TEMPO on graphite felt.

Long-term electrolyses of glucose in a potassium carbonate (K2CO3) aqueous electrolyte have been performed on graphite felt electrodes with TEMPO as a homogeneous catalyst. The influences of the operating conditions (initial concentrations of glucose, TEMPO, and K2CO3 along with applied anode potential) on the conversion, selectivity toward gluconate/glucarate, and faradaic efficiency were assessed first. Then, optimizations of the conversion, selectivity, and faradaic efficiency were performed using design of experiments based on the L9 (34) Taguchi table, which resulted in 84% selectivity toward gluconate with 71% faradaic efficiency for up to 79% glucose conversion. Side products such as glucaric acid were also obtained when the applied potential exceeded 1.5V vs. reversible hydrogen electrode.

Culture Shock! Investigating the Importance of Physiological Tumour-Like Conditions on Cultured Cancer Cells

The tumour microenvironment (TME) is complex and dynamic, characterized by poor vascularization, limited nutrient availability, hypoxia, and an acidic pH. This environment plays a critical role in cancer progression, driving hallmark changes in cancer cell metabolism, morphology, proliferation, and motility. Although mammalian cell culture is a foundational tool for investigating cancer cell biology in vitro, standard cell culture practices fall short of replicating the in vivo conditions of tumours. Recently, ‘physiologic’ cell culture media that closely resemble human plasma (e.g., Plasmax, HPLM) have been developed, along with more frequent adoption of physiological oxygen conditions (2-8% O2) rather than standard atmosphere (~18% O2). Although an improvement, these conditions are not representative of all in vivo cellular environments, particularly that of the TME. Considering the tight regulatory capacity of cancer cells to sense and respond to changes in metabolic availability, we hypothesized that alterations in nutrient and oxygen availability, even if within the physiological range, may subtly rewire the metabolism in cultured cancer cells. This may necessitate further refinement of cell-specific physiologic culture conditions to better maintain the in vivo biology of cells. In this study, we directly address this hypothesis by describing the development of a tumour microenvironment-like medium (TMEM) based on metabolomic profiling of murine pancreatic ductal adenocarcinoma tumour interstitial fluid from relevant literature. We found that murine pancreatic ductal adenocarcinoma (KPCY) cells cultured under TME-like conditions (TMEM, pH 7.0, 1.5% O2) exhibited increased glucose uptake and lactate production rates compared to those cultured under healthy plasma-like conditions (Mouse Plasma-like Medium, pH 7.4, 5% O2), despite lower initial glucose concentrations in TMEM (2.3 mM vs. 4.4 mM in Mouse Plasma-like Medium). Moreover, cell proliferation rates were lower in TMEM, suggesting an overall reduction in ATP consumption fueling cell division. Seahorse Extracellular Flux Analysis is being performed to determine effects on cellular bioenergetics. Metabolomic amino acid uptake using LCMS is also being performed to further assess the effect of TMEM on nutrient utilization. Using RNA-sequencing, we showed that culture in TMEM increased expression of genes associated with angiogenesis, amino acids biosynthesis, cell migration, and endothelial-to-mesenchymal transition. Migration assays confirmed increased motility in KPCY cells cultured in TMEM. Taken together, these results demonstrate that growth in a medium designed to simulate the TME alters KPCY cell biology in ways that are relevant to their pathology, which highlights the significance of maintaining TME-like conditions in culture. This research was funded by a Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant from JAS and a NSERC Canadian Graduate Student (Masters) Grant awarded to GLG. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Improving dietary citric acid production by the wild‐type Aspergillus niger ASP26 strain isolated from date by‐product

AbstractThis research investigates citric acid (CA) synthesis using the indigenous strain Aspergillus niger ASP26, which was isolated from date by‐products. The study initially involved isolating fungi capable of CA production and identifying the most potent strain based on its characteristic enzymatic activity. A. niger ASP26 was acknowledged in a previous study for its remarkable ability to produce extracellular enzymes, such as cellulase and amylase, which enable it to degrade organic materials effectively. After the identification phase, these isolates were screened for CA production using a modified Czapek‐Dox medium. The research identified significant factors affecting CA production in submerged fermentation, including pH, carbon source, inoculum size, and fermentation time. Optimal conditions were determined for A. niger ASP26, resulting in a maximum CA yield of 16.89 g/L. These conditions included a 2.5% spore suspension at 2 × 107 spores/mL, an initial glucose concentration of 125 g/L, and incubation at 30°C for 144 h. Notably, A. niger ASP26 demonstrated the ability to produce CA under stress conditions as well. Citric acid is essential for various biological processes, such as cellular respiration, and is naturally present in citrus fruits. It also serves as a preservative and flavor enhancer in processed foods and beverages. The ability of A. niger ASP26 to produce CA from agricultural residues positions it as a viable candidate for sustainable CA production, harnessing the value from organic waste materials.

Optimization of the fermentative production of L-methionine by engineered Escherichia coli

As the only essential amino acid containing elemental sulphur, L-methionine has important physiological and biochemical functions in living organisms. However, the fermentative production of L-methionine has not met the requirements of industrial production because of its low production level. In this paper, the fermentation process of an efficient L-methionine producing strain E. coli W3110ΔIJAHFEBC trc-fliY trc-malY/PAM glyA-22 metF constructed previously was systematically optimized. Based on the optimal initial glucose concentration, the effects of different fed-batch fermentation processes, including DO-Stat, pH-Stat, controlling residual sugar control at different level and feeding glucose with constant rate, on L-methionine fermentation were studied. It was found that the control of glucose concentration greatly affected the fermentation process. Subsequently, an optimal fed-batch fermentation process was developed, where the L-methionine titer was increased to 31.71 g/L, the highest yield reported to date, while the fermentation time was shortened to 68 h. Meanwhile, a fermentation kinetics model under the optimal fed-batch fermentation conditions was established, which fitted well with the biosynthesis process of L-methionine. This study may facilitate further development of the fermentative production of L-methionine.

Exploring the untapped practices in bacterial-fungal mixed-based cultures for acidic treatment of metal-enriched printed circuit board waste

This study explores the extraction of metals from spent mobile phone printed circuit boards (SMPhPCBs) to address environmental and resource depletion concerns. The challenges in metal recovery from SMPhPCBs arise due to their complex composition and high metal content. While previous research has primarily focused on using bio-cyanide, bio-sulfate, and bio-ferric compounds from acidophilic bacteria, the potential of bio-oxalic acid for SMPhPCBs treatment and the alteration of their complex structure has not yet been explored. Additionally, this study suggests evaluating the untapped potential of Aspergillus niger in oxalic acid production through mixed cultures with bacteria, marking a pioneering approach. A unique culture of Bacillus megaterium and A. niger was created, inducing bio-stress by bacterial metabolites, including gluconic acid (2683 mg/l) and live/dead bacterial cells in a medium with glucose deficiency. Results demonstrated reducing sugar consumption and oxalic acid over-production in mixed cultures compared to pure cultures, ranging from 1350 to 4951 mg/l at an initial glucose concentration (IGC) of 10 g/l and 4276 to 7460 mg/l at IGC 20 g/l. This over-production is attributed to proposed fungal signaling mechanisms to bacteria. Metal extraction using organic acids and siderophores at 10 g/l pulp density, 24 h, and 60 °C yielded Mn (100 %), Pt (100 %), Pd (70.7 %), Fe (50.8 %), Co (48.3 %), Al (21.8 %), among others. The final valuable residue containing copper, gold, and silver holds potential for future recycling. The study concludes with XRD and FTIR analyses to assess the bioleaching effect on the bio-leached powder.

Brewer’s spent grain as a self-sufficient feedstock for homofermentative production of optically pure L-lactic acid using Lactobacillus rhamnosus

Brewer’s spent grain (BSG), accounting for 85% of the total by-product from breweries, was used as a feedstock for L-lactic acid production in the present study. BSG was enzymatically hydrolysed and promoted to be a self-sufficient feedstock for L-lactic acid production by using it as a sole source of carbon, protein and minerals. Process parameters like glucose concentration (10–20 g/L), glucose-to-protein source ratio (1:1 – 5:1), source of protein and inoculum concentration (3 – 10% v/v) were selected to divert the carbon source and enhance L-lactic acid concentration, which would otherwise result in bacterial biomass production. Yeast extract and whey permeate resulted in high bacterial growth, whereas self-sustained protein (SSP) in BSG resulted in higher L-lactic acid production. Further, the glucose-to-protein source ratio was maintained at its lowest level for better glucose conversion to L-lactic acid. Glucose concentration strongly influenced L-lactic acid production. Therefore glucose concentration in the batch fermentation process was further increased from 60 to 120 g/L. A maximum L-lactic acid concentration of 114.4 g/L and productivity of 5.14 g/L·h was achieved with an initial glucose concentration of 120 g/L, and the rest of the process parameters such as glucose to protein source ratio of 1:1, inoculum concentration of 10% v/v and SSP in BSG were maintained at its optimum level. Finally, L-lactic acid in the fermentation broth was purified and analysed for its similarity with commercially available L-lactic acid using proton-NMR and FTIR spectroscopy. Thus, the present study valorised BSG by producing L-lactic acid under a biorefinery approach.

Enhanced sporulation of B. licheniformis BF-002 through automatic co-feeding of carbon and nitrogen sources.

Bacillus licheniformis formulations are effective for environmental remediation, gut microbiota modulation, and soil improvement. An adequate spore quantity is crucial for the activity of B. licheniformis formulations. This study investigated the synergistic effects of carbon/nitrogen source consumption and concentration on B. licheniformis BF-002 cultivation, with the aim of developing an automatic co-feeding strategy to enhance spore production. Initial glucose (10 g/L) and amino nitrogen (1.5 g/L) concentrations promote cell growth, followed by reduced glucose (2.0 g/L) and amino nitrogen (0.5 g/L) concentrations for sustained spore generation. The spore quantity reached 2.59 × 1010 CFU/mL. An automatic co-feeding strategy was developed and implemented in 5 and 50 L cultivations, resulting in spore quantities of 2.35 × 1010 and 2.86 × 1010 CFU/mL, respectively, improving by 6.81% and 30.00% compared to that with a fixed glucose concentration (10.0 g/L). The culture broth obtained at both the 5 and 50 L scales was spray-dried, resulting in bacterial powder with cell viability rates of 85.94% and 82.68%, respectively. Even after exposure to harsh conditions involving high temperature and humidity, cell viability remained at 72.80% and 69.89%, respectively. Employing the automatic co-feeding strategy increased the transcription levels of the spore formation-related genes spo0A, spoIIGA, bofA, and spoIV by 7.42%, 8.46%, 8.87%, and 9.79%, respectively. The proposed strategy effectively promoted Bacillus growth and spore formation, thereby enhancing the quality of B. licheniformis formulations.

Influence of initial glucose and lactic acid concentration on hyaluronic acid production by Streptococcus zooepidemicus: Kinetic and modeling

Hyaluronic acid (HA) is a molecule of significant commercial value with applications in the pharmaceutical, cosmetic, and medical industries. It is typically produced through microbial fermentation. However, the efficiency of this type of process can be affected by inhibition phenomena due to the substrate or the product. In this sense, the effect of different initial concentrations of glucose (9.3–59.9 g/L) and lactic acid (10.7–56.0 g/L) was studied in the present investigation to determine their effect on the growth of Streptococcus zooepidemicus and HA production in batch fermentation. The maximum HA concentration obtained was 3.3 g/L from 59.9 g/L glucose, while productivity, yield, and specific rate of HA formation were higher at 31.9 g/L glucose. The biomass produced followed a stepwise pattern with increasing glucose, although the specific growth rate decreased after reaching 39.1 g/L glucose. The initial presence of lactic acid (LA) hurt fermentation, decreasing the amount of biomass and HA produced; the inhibitory effect of LA was more pronounced at 19.4 g/L and above, decreasing productivities, yields, and specific rates. Compared to experimental data, the proposed mathematical model described satisfactorily (R2 > 0.9) the dynamics of the fermentation process at different culture conditions.

Efficient visible light photocatalytic performance of bismuth trioxide/titanium dioxide composite for selective conversion of glucose to arabinose and formic acid

The photocatalytic valorization of glucose has attracted more and more attention for producing value-added chemicals. Herein, value-added chemicals like arabinose and formic acid were obtained by selective photocatalytic oxidation of glucose irradiated with visible light, which was realized using Bi2O3/TiO2 composite as the photocatalyst and atmospheric O2 as the oxidant in water. It was found that the photocatalytic performance of Bi2O3/TiO2 composite in the glucose oxidation was obviously superior to that of pure Bi2O3 and pure TiO2, the significantly enhanced photocatalytic efficiency was mainly attributed to the promotion of photogenerated charge separation and adsorption capacity towards glucose. The influences of mass ratio of Bi2O3 to TiO2 and initial concentration of glucose on the glucose oxidation were further investigated with many details. Additionally, recycling experiments showed that the Bi2O3/TiO2 composite exhibited a favorable stability in the photocatalytic process, and the roles of various active species for glucose oxidation were also determined by the active species trapping experiments. This work could provide some valuable viewpoints for producing value-added chemicals from biomass by photocatalysis.

Enhancing β-farnesene production in engineered Yarrowia lipolytica: A new process control strategy

β-Farnesene, a sesquiterpene with diverse applications, is applied in fields ranging from bioenergy and agriculture to medicine. In this study, a series of fermentation conditions and process control strategies were employed to enhance the accumulation of β-farnesene. Through the optimization of medium components, a suitable environment was created for β-farnesene biosynthesis in Yarrowia lipolytica, using only three inorganic salts as the initial medium. On this basis, cell growth and citrate supply were enhanced by adjusting the feeding time point, which begins when dissolved oxygen level below 40%. Additionally, initial cell density and glucose concentration during fermentation were separately optimized. Ultimately, nitrogen-limited conditions were applied to maximize carbon flux towards β-farnesene synthesis and the ideal condition was found to be C/N ratio of 100. Under the optimal condition, the titer of β-farnesene was increased by 227%, reaching 22.04 g/L in a 2 L bioreactor. This study optimizes terpenoid biosynthesis fermentation control and establishes a platform for the potential utilizing of waste biomass in Y. lipolytica.

Modeling and simulation of astaxanthin production from Chlorella zofingiensis

Chlorella zofingiensis microalgae are highly regarded for their astaxanthin production, but understanding its kinetics is currently constrained. This study utilized yeast-based kinetics models (Monod and Contois) to scrutinize astaxanthin biosynthesis in C. zofingiensis. This research explored diverse light conditions, including low-high, cyclic, and continuous light assessments. In this investigation, MATLAB R2021a simulations were employed to systematically evaluate the impact of varying initial substrate concentrations and light treatments on biomass and astaxanthin production. Using the Contois-based modified model denoted as Model 2, optimal yields occurred with initial glucose concentrations at 30 g∙L−1 and 15 g∙L−1 under continuous light, resulting in the attainment of final biomass and astaxanthin concentrations of 8.37 g∙L−1 and 19.19 g∙L−1, respectively. Increasing the initial glucose concentration from 5 g∙L−1 to 25 g∙L−1 led to a remarkable 236.8 % enhancement in astaxanthin production.

Bacterial cellulose produced by Medusomyces gisevii on glucose and sucrose: biosynthesis and structural properties

In this work, the effects of carbon sources and culture media on the production and structural properties of bacterial cellulose (BC) synthesized by Medusomyces gisevii have been studied. The culture medium was composed of different initial concentrations of glucose or sucrose dissolved in 0.4% extract of plain green tea. Parameters of the culture media (titratable acidity, substrate conversion degree etc.) were monitored daily for 20 days of cultivation. The BC pellicles produced on different carbon sources were characterized in terms of biomass yield, crystallinity and morphology by field emission scanning electron microscopy (FE-SEM), atomic force microscopy and X-ray diffraction. Our results showed that Medusomyces gisevii had higher BC yields in media with sugar concentrations close to 10 g L−1 after a 18–20 days incubation period. Glucose in general lead to a higher BC yield (173 g L−1) compared to sucrose (163.5 g L−1). The BC crystallinity degree and surface roughness were higher in the samples synthetized from sucrose. Obtained FE-SEM micrographs show that the BC pellicles synthesized in the sucrose media contained densely packed tangles of cellulose fibrils whereas the BC produced in the glucose media displayed rather linear geometry of the BC fibrils without noticeable aggregates.

Mathematical modeling for operative improvement of the decoloration of Acid Red 27 by a novel microbial consortium of Trametes versicolor and Pseudomonas putida: A multivariate sensitivity analysis

In this work, it is presented a first approach of a mathematical and kinetic analysis for improving the decoloration and further degradation process of an azo dye named acid red 27 (AR27), by means of a novel microbial consortium formed by the fungus Trametes versicolor and the bacterium Pseudomonas putida. A multivariate analysis was carried out by simulating scenarios with different operating conditions and developing a specific mathematical model based on kinetic equations describing all stages of the biological process, from microbial growth and substrate consuming to decoloration and degradation of intermediate compounds. Additionally, a sensitivity analysis was performed by using a factorial design and the Response Surface Method (RSM), for determining individual and interactive effects of variables like, initial glucose concentration, initial dye concentration and the moment in time for bacterial inoculation, on response variables assessed in terms of the minimum time for: full decoloration of AR27 (R1 = 2.375 days); maximum production of aromatic metabolites (R2 = 1.575 days); and full depletion of aromatic metabolites (R3 = 12.9 days). Using RSM the following conditions improved the biological process, being: an initial glucose concentration of 20 g l-1, an initial AR27 concentration of 0.2 g l-1 and an inoculation moment in time of P. putida at day 1. The mathematical model is a feasible tool for describing AR27 decoloration and its further degradation by the microbial consortium of T. versicolor and P. putida, this model will also work as a mathematical basis for designing novel bio-reaction systems than can operate with the same principle of the described consortium.

Serum Oxidative Status in People with Obesity: Relation to Tissue Losses, Glucose Levels, and Weight Reduction.

This work aims to study the effect of reductions in various body mass components on the oxidative, glycemic, and lipid parameters of people with obesity (PWO). A total of 53 PWO underwent a six-month individualized low-calorie diet combined with moderate exercise, during which anthropometric, biochemical, and oxidative parameters were measured. Probands were divided into groups based on weight, visceral fat area (VFA), total body water (TBW), and skeletal muscle mass (SMM) losses. Weight reduction normalizes glycemia, but VFA reduction is less pronounced, while SMM and TBW reductions are more pronounced in patients with higher initial concentrations of glucose and fructosamine. Moreover, changes in oxidative parameters correlate with changes in glucose. Weight loss, regardless of the reduced tissue, decreases cardiovascular risk. We observed a significant change in almost all parameters related to the redox state. In general, parameters responsible for antioxidant action improved, and markers of oxidative damage decreased. Malondialdehyde, lipid peroxides, and total oxidative status levels can be considered biomarkers reflecting only the current severity of reactive oxygen species genesis processes. When considering the glycemic state, the results are not as clear due to the substantial differences between normoglycemic and hyperglycemic patients. Glycemic status is a factor playing a crucial role in weight reduction.

Risk of endothelial dysfunction in streptozotocin-induced diabetic Sprague-Dawley rats: Nitric oxide in focus

Endothelial dysfunction in diabetes manifests in part as reduction of nitric oxide (NO) bioavailability, which leads to inadequate relaxation of the vascular smooth muscle and a disparity between the vasoconstrictive and vasorelaxant intracellular pathways which favours a rise in vasoconstriction. In this current work, we evaluated serum Nitric oxide (NO) concentration and the activity of Nitric oxide synthase (NOS) in streptozotocin-induced diabetic male and female rats' serum. Our results showed initial and final fasting blood glucose concentration 5.30±0.16mmol/l and 5.24±.015mmol/l versus 5.68±0.18mmol/l and 5.43±0.15mmol/l in male and female controls. Among the diabetic rats, the initial and final fasting blood glucose concentration was 17.50±1.91mmol/l and 15.68±2.84mmol/l versus 20.50±4.76mmol/l and 19.40±4.13mmol/l in male and female rats respectively. NO concentration was 106.12±7.23μmol/l and 131.81±12.54 μmol/l in male and female control rats compared to 52.38±3.01μmol/l and 65.29±16.19 μmol/l in male and female diabetic rats respectively. Serum activity of NOS were 133.72±10.92μIU/l and 156.06±18.22 μIU/l in control male and female rats compared to 98.01±1.48 μIU/l, 78.89±8.39μIU/l in diabetic male and female rats respectively. The difference in both NO concentration and NOS activity was significant between diabetics and non-diabetic rats as well as between male and female diabetics rats (p< 0.05). The endothelial dysfunction in diabetic animals regardless of gender may be an initial pointer to upcoming pathogenesis and we recommend routine evaluation of NO concentration and NOS activities among diabetics.

Factors Associated with Need for Intravenous Glucose Infusion for the Treatment of Early Neonatal Hypoglycemia in Late Preterm and Term Neonates.

To determine which late-preterm (35-36wk gestational age [GA]) and term neonates with early-onset hypoglycemia in the first 72 hours postnatal required a continuous glucose infusion in order to achieve and successfully maintain euglycemia. Retrospective cohort study of late preterm and term neonates born in 2010-2014 and admitted to the Mother-Baby Unit at Parkland Hospital who had laboratory-proven blood glucose concentration <40 mg/dL (2.2 mmol/L) during the first 72h of life. Among the subgroup needing iv glucose infusion, we analyzed which factors predicted a maximum glucose infusion rate (GIR) ≥10 mg · kg-1 · min-1. The entire cohort was randomly divided into a derivation cohort (n=1288) and a validation cohort (n=1298). In multivariate analysis, the need for intravenous glucose infusion was associated with small size for GA, low initial glucose concentration, early-onset infection and other perinatal variables in both cohorts. A GIR ≥10 mg · kg-1 · min-1 was required in 14% neonates with blood glucose value <20 mg/dL during the first 3h of observation. The likelihood of a GIR ≥10 mg · kg-1 · min-1 was associated with lower initial blood glucose value and lower umbilical arterial pH. Need for intravenous glucose infusion was associated with small size for GA, low initial glucose concentration, early-onset infection and variables associated with perinatal hypoxia-asphyxia. The likelihood of a maximum GIR ≥10 mg · kg-1 · min-1 was greater in neonates with lower blood glucose value during the first 3 hours of observation and lower umbilical arterial pH.

Growth Response of Non-Conventional Yeasts on Sugar-Rich Media: Part 1: High Production of Lipid by Lipomyces starkeyi and Citric Acid by Yarrowia lipolytica.

Sugar-rich waste streams, generated in very high quantities worldwide, constitute an important source of environmental pollution. Their eco-friendly conversions into a plethora of added-value compounds through the use of microbial fermentations is currently a very "hot" scientific topic. The aim of this study, was to assess the potential of single cell oil (SCO), microbial mass and citric acid (CA) production by non-conventional yeast strains growing on expired ("waste") glucose. Six yeast strains (viz. Rhodosporidium toruloides DSM 4444, Rhodotorula glutinis NRRL YB-252, R. toruloides NRRL Y-27012, Yarrowia lipolytica LFMB Y-20, Y. lipolytica ACA-DC 50109 and Lipomyces starkeyi DSM 70296) were initially grown in shake flasks with expired glucose used as substrate under nitrogen limitation, in order to "boost" the cellular metabolism towards the synthesis of SCO and CA, and their growth response was quantitatively evaluated. Initial glucose concentration (Glc0) was adjusted at c. 50 g/L. Besides Y. lipolytica, all other yeast strains produced noticeable SCO quantities [lipid in dry cell weight (DCW) ranging from 25.3% w/w to 55.1% w/w]. Lipids of all yeasts contained significant quantities of oleic acid, being perfect candidates for the synthesis of 2nd generation biodiesel. The highest DCW production (=13.6 g/L) was obtained by L. starkeyi DSM 70296, while both Y. lipolytica strains did not accumulate noticeable lipid quantities, but produced non-negligible CA amounts. The most promising CA-producing strain, namely Y. lipolytica ACA-DC 50109 was further studied in stirred-tank bioreactor systems, while the very promising DCW- and SCO-producing L. starkeyi DSM 70296 was further studied in shake flasks. Both strains were grown on media presenting higher Glc0 concentrations and the same initial nitrogen quantity as previously. Indeed, L. starkeyi grown at Glc0 = 85 g/L, produced DCWmax = 34.0 g/L, that contained lipid =34.1% w/w (thus SCO was =11.6 g/L). The strain ACA-DC 50109 in stirred tank bioreactor with Glc0 ≈ 105 g/L produced CA up to 46 g/L (yield of CA produced on glucose consumed; YCA/Glc ≈ 0.45 g/g). Finally, in fed-batch bioreactor experiment, the significant CA quantity of 82.0 g/L (YCA/Glc = 0.50 g/g) was recorded. Concluding, "waste" glucose proved to be a suitable substrate for a number of non-conventional yeast strains. Y. lipolytica ACA-DC 50109 produced significant quantities of CA while L. starkeyi DSM 70296 was a very interesting DCW- and SCO-producing candidate. These strains can be used as potential cell factories amenable to convert glucose-based residues into the mentioned metabolic compounds, that present high importance for food, chemical and biofuel facilities.