Aerobic Production Research Articles

Lactic acid bacterial diversity in Brie cheese focusing on salt concentration and pH of isolation medium and characterisation of halophilic and alkaliphilic lactic acid bacterial isolates

Latently existing non-starter lactic acid bacteria (NSLAB) were isolated from the French Brie de Meaux cheese using 12 isolation media with different NaCl concentrations and pH. Lactobacilli were frequently isolated using lactobacilli MRS agar, generally used for LAB isolation. Halophilic NSLAB (Tetragenococcus halophilus and Tetragenococcus koreensis) and slightly alkaliphilic NSLAB (Vagococcus lutrae), not detected using lactobacilli MRS agar or PCR-DGGE, were isolated using saline or alkaline media at log 6 to 8 cfu g−1 in the cheese rind. Their NaCl and pH optima were close to those of their isolation conditions. Phylogenetic independence of the T. halophilus isolate and genome characteristics and growth behaviour that allow T. koreensis and V. lutrae to survive in cheese rind via aerobic production of acetate from lactose were revealed. Thus, general laboratory isolation procedures should include various NaCl concentrations and pH conditions to capture a diversity of NSLAB in a living state from cheese.

Effects of Gas Supplying Patterns on Aerobic Anaerobic Biogas Production of Rice Straw

Background: Rice straw as a plant photosynthesis product, is a valuable renewable resource and it contains protein, fat, cellulose, hemicellulose, lignin and ash. It has received wide attention for biogas can solve both the energy and environment problems. Objective: To improve the degradation rate of rice straw in aerobic and anaerobic bi-phase fermentation process. Methods: Different aerobic methods were adopted to improve the degradation rate of aerobic acid producing cellulose. Results: The results showed that in different ways of gas supply test experiments the total enzyme activity of aeration mode was higher than that of the stirring air supply mode, which indicated that the aeration mode was more favorable to the growth of mixed strains of Trichoderma and Aspergillus. The gas production of TS was 438.69 mL•g-1, which was higher than both the stirring group and control group. Conclusion: The degradation utilization rate of rice straw solid organic matter can be significantly improved using method of aeration mode, and the conversion of straw biomass into biogas was promoted.

Effect of daily supplementation with ubiquinol on muscle coenzyme Q10 concentrations in Thoroughbred racehorses

Coenzyme Q10 (CoQ10) is essential for mitochondrial aerobic production of ATP via oxidative phosphorylation, but has had little study in horses. Its biologically active form is ubiquinol. We evaluated the effects of daily supplementation with ubiquinol on gluteal muscle CoQ10 concentrations and an indicator of phosphorylation status, citrate synthase (CS), in fit Thoroughbreds. Six horses received either 1 g ubiquinol daily for 3 weeks followed by 21 days without supplement, or had a 3 week unsupplemented period followed by 3 weeks of supplementation. A seventh horse received the same diet as the other horses, but no supplement, and served as a negative control. Middle gluteal muscle biopsies were obtained before feeding at day 0 (baseline), and after 10 and 21 days of each period. Muscle CoQ10 concentration was determined by HPLC with UV detection at 275 nm. CS was measured spectrophotometrically at 37 °C and related to mitochondrial CoQ10 concentration. Results (mean ± standard deviation) were analysed by 2-way RM ANOVA for effects of supplementation and time (P<0.05). Muscle baseline and non-supplemented CoQ10 concentrations prior to beginning supplementation were not different (458±156 pmol/mg protein). Values increased from 413±276 (baseline) to 977±227 pmol/mg after 10 days supplementation (P=0.03), but not thereafter (21 days: 867±194 pmol/mg; P=0.31). CS activity increased in concert with CoQ10 concentration (P=0.02; baseline: 67±18, 10 days: 155±68, 21 days: 163±78 nmol/(min.mg)). Muscle CoQ10 concentration was strongly correlated with CS activity (P=0.002; r2=0.53). Discontinued supplementation decreased muscle CoQ10 concentration and tended towards significance (P=0.06). Daily dietary supplementation with 1 g ubiquinol increased gluteal muscle [CoQ10] from day 0 to day 10, but not from days 10 to 21, possibly indicating saturation of mitochondria with ubiquinol. Associated increases in CS activity suggested aerobic metabolic capacity was enhanced with supplementation. Discontinuing supplementation decreased CoQ10 concentration.

Exploiting Hydrogenophaga pseudoflava for aerobic syngas-based production of chemicals

Gasification is a suitable technology to generate energy-rich synthesis gas (syngas) from biomass or waste streams, which can be utilized in bacterial fermentation processes for the production of chemicals and fuels. Established microbial processes currently rely on acetogenic bacteria which perform an energetically inefficient anaerobic CO oxidation and acetogenesis potentially hampering the biosynthesis of complex and ATP-intensive products. Since aerobic oxidation of CO is energetically more favorable, we exploit in this study the Gram-negative β-proteobacterium Hydrogenophaga pseudoflava DSM1084 as novel host for the production of chemicals from syngas. We sequenced and annotated the genome of H. pseudoflava and established a genetic engineering toolbox, which allows markerless chromosomal modification via the pk19mobsacB system and heterologous gene expression on pBBRMCS2-based plasmids. The toolbox was extended by identifying strong endogenous promotors such as PgapA2 which proved to yield high expression under heterotrophic and autotrophic conditions. H. pseudoflava showed relatively fast heterotrophic growth in complex and minimal medium with sugars and organic acids which allows convenient handling in lab routines. In autotrophic bioreactor cultivations with syngas, H. pseudoflava exhibited a growth rate of 0.06 h−1 and biomass specific uptakes rates of 14.2 ± 0.3 mmol H2 gCDW−1 h−1, 73.9 ± 1.8 mmol CO gCDW−1 h−1, and 31.4 ± 0.3 mmol O2 gCDW−1 h−1. As proof of concept, we engineered the carboxydotrophic bacterium for the aerobic production of the C15 sesquiterpene (E)-α-bisabolene from the C1 carbon source syngas by heterologous expression of the (E)-α-bisabolene synthase gene agBIS. The resulting strain H. pseudoflava (pOCEx1:agBIS) produced 59 ± 8 μg (E)-α-bisabolene L−1 with a volumetric productivity Qp of 1.2 ± 0.2 μg L−1 h−1 and a biomass-specific productivity qp of 13.1 ± 0.6 μg gCDW−1 h−1. The intrinsic properties and the genetic repertoire of H. pseudoflava make this carboxydotrophic bacterium a promising candidate for future aerobic production processes to synthesize more complex or ATP-intensive chemicals from syngas.

Abstract 2063A: Glucolipotoxicity and altered oxidative stress responses in cancer cells

Abstract Alterations in energy metabolism, such as aerobic glycolysis and lactic acid production, and mitochondrial bioenergetics are the key metabolic changes associated with increased glucose uptake in cancer cells (Warburg effect). Metabolic adaptation, inflammatory responses and oxidative stress have been implicated in cancer etiology and pathology. Both experimental and epidemiological studies have suggested that caloric restriction is beneficial in reducing the complications of cancer cells. Studies have also suggested that increased availability of energy metabolites, such as glucose and fatty acids, as also seen in obesity and diabetes, which induces inflammatory and oxidative stress responses, may also be key factors in cancer development. In the present study, we have used human hepatoma, HepG2 and rodent pancreatic cancer derived Rin-5F cells to investigate the effects of high glucose (25mM) and high palmitic acid (up to 0.3mM) on cell survival and cell death along with the metabolic, inflammatory and oxidative stress associated alterations in these cells. Our results have shown that both increased glucose and fatty acids induce DNA damage and caspase-dependent apoptosis and mitochondrial respiratory dysfunction. Glucolipotoxicity in these cells, due to increased ROS production and oxidative stress has been suggested to be involved in altering the mitochondrial membrane potential and bioenergetics. Altered Nrf-2/NFk-B/AMPK/mTOR-dependent cell signaling and inflammatory (IL6/PGE2) responses have also been observed when cells were treated with high glucose and palmitic acid. Interestingly, pretreatment with N-acetyl cysteine (NAC, 10mM), a GSH precursor, resulted in partial recovery from the oxidative stress-induced glucolipotoxicity. Our results suggest that the presence of high energy metabolites enhance inflammatory and oxidative stress responses that may be responsible for alterations in cancer cell signaling and metabolism. Citation Format: Arwa MT Al-Nahdi, Annie John, Haider Raza. Glucolipotoxicity and altered oxidative stress responses in cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2063A.

Effects of Glucose Concentration on Ethanol Fermentation of White-Rot Fungus Phanerochaete sordida YK-624 Under Aerobic Conditions.

White-rot fungi are microorganisms capable of ethanol fermentation; however, the specific conditions activating ethanol fermentation are unclear in contrast to fermentation by yeasts. In this study, we investigated the conditions favoring ethanol fermentation by the white-rot fungus Phanerochaete sordida YK-624, which is able to produce ethanol from woody material. In aerobic stationary cultivation with various concentrations of glucose (0.8-33g/l), the fungus produced ethanol in media containing an initial glucose concentration of 2.8g/l or higher. The amount of glucose consumption, mycelial weight, and ethanol production on the second day of culture increased in a concentration-dependent manner at low glucose concentrations; however, these were saturated at high concentrations. Biomass yields (growth/glucose consumption) were decreased until the initial glucose concentration increased to 6.0g/l, after which the biomass yields showed constant values at higher concentrations (12-33g/l). On the other hand, ethanol yields increased with decreasing biomass yields. In short shaking cultivation using mycelial suspension, trace amounts of instantaneous aerobic ethanol production were observed with 1.1 and 2.1g/l glucose, but the relative gene expression levels of key enzymes at the pyruvate branch point showed no significant differences between ethanol production and non-production conditions. From these experimental results, it appears that the white-rot fungus P. sordida YK-624 produces ethanol due to overflow in sugar metabolism under aerobic conditions, although P. sordida YK-624 prioritizes glucose utilization for respiratory growth.

Особенности мощностных и массообменных характеристик биореактора с дисковыми перфорированными мешалками

In the implementation of aerobic biosynthesis processes, the productivity of a bioreactor depends on the intensity of oxygen mass transfer. Disk mixers with a perforated surface, providing an increase in the contact surface of the gas and liquid phases, were studied. The power characteristics of disk mixers with bent segments and sectors was experimentally established to depend on the slope of the working surfaces. For multi-tier mixers, the exponent regarding the number of tiers in the expression of total power was determined to be proportional to the value of the distance between tiers in the range of specified distance equal to 0–1.4 of the diameter of the mixer. At a distance between tiers exceeding the diameter of the mixer by 1.5 or more times, the total power is equal to the sum of the powers of single mixers. The energy efficiency of the process of oxygen mass transfer decreases sharply with decreasing distance between tiers. The eff iciency indicator of the oxygen mass transfer depends on the ratio of aeration and power of the mixer, demonstrated in the form of a saturation curve. An analysis of the obtained experimental dependences supports a conclusion concerning the intensive and energy-efficient process of oxygen mass transfer obtained by ensuring a small ratio of the diameter of the unit to its height, use of multi-tier mixers with a distance between tiers greater than the diameter of the mixer and specific aeration of at least 3 min -1 . Perforated disk mixers can be recommended for use in bioreactor designs with the optimal implementation in the processes of aerobic microorganism production, including the cultivation of high-density seed crops. At oxygen mass transfer rates exceeding 10 kgO 2 /m 3 ·h, modes ensuring the achievement of a high population density of aerobic microorganisms are characterised by relatively low energy efficiency (1–1.2 kg O 2 /kWh). The authors declare no conflict of interests regarding the publication of this article.

O2-inducible H2O2-forming NADPH oxidase is responsible for the hyper O2 sensitivity of Bifidobacterium longum subsp. infantis

Bifidobacteria are beneficial anaerobes, and their O2 sensitivity levels differ among species as a function of unknown molecular mechanisms. Bifidobacterium longum subspecies infantis (B. infantis), a predominant colonizer of the gastrointestinal tract of infants, showed a hyper O2-sensitive growth profile with accompanying a production of H2O2. In this study, we characterized an NADPH oxidase as a key enzyme responsible for this microbe’s hyper O2 sensitivity. A dominant active elution peak of H2O2-forming NADPH oxidase activity was detected in the first step of column chromatography, and the purified NADPH oxidase (NPOX) was identified as a homolog of nitroreductase family proteins. The introduction of the gene encoding B. infantis NPOX (npoxA) into O2-tolerant Bifidobacterium minimum made the strain O2 sensitive and allowed it to produce H2O2. Knockout of the npoxA gene in B. infantis decreased the production of H2O2 and mitigated its B. infantis hyper O2 sensitivity. A transcript of B. infantis npoxA is induced by O2, suggesting that the aerobic production of toxic H2O2 is functionally conserved in B. infantis.

Metabolic pairing of aerobic and anaerobic production in a one-pot batch cultivation

BackgroundThe versatility of microbial metabolic pathways enables their utilization in vast number of applications. However, the electron and carbon recovery rates, essentially constrained by limitations of cell energetics, are often too low in terms of process feasibility. Cocultivation of divergent microbial species in a single process broadens the metabolic landscape, and thus, the possibilities for more complete carbon and energy utilization.ResultsIn this study, we integrated the metabolisms of two bacteria, an obligate anaerobe Clostridium butyricum and an obligate aerobe Acinetobacter baylyi ADP1. In the process, a glucose-negative mutant of A. baylyi ADP1 first deoxidized the culture allowing C. butyricum to grow and produce hydrogen from glucose. In the next phase, ADP1 produced long chain alkyl esters (wax esters) utilizing the by-products of C. butyricum, namely acetate and butyrate. The coculture produced 24.5 ± 0.8 mmol/l hydrogen (1.7 ± 0.1 mol/mol glucose) and 28 mg/l wax esters (10.8 mg/g glucose).ConclusionsThe cocultivation of strictly anaerobic and aerobic bacteria allowed the production of both hydrogen gas and long-chain alkyl esters in a simple one-pot batch process. The study demonstrates the potential of ‘metabolic pairing’ using designed microbial consortia for more optimal electron and carbon recovery.

A metabolic core model elucidates how enhanced utilization of glucose and glutamine, with enhanced glutamine-dependent lactate production, promotes cancer cell growth: The WarburQ effect.

Cancer cells share several metabolic traits, including aerobic production of lactate from glucose (Warburg effect), extensive glutamine utilization and impaired mitochondrial electron flow. It is still unclear how these metabolic rearrangements, which may involve different molecular events in different cells, contribute to a selective advantage for cancer cell proliferation. To ascertain which metabolic pathways are used to convert glucose and glutamine to balanced energy and biomass production, we performed systematic constraint-based simulations of a model of human central metabolism. Sampling of the feasible flux space allowed us to obtain a large number of randomly mutated cells simulated at different glutamine and glucose uptake rates. We observed that, in the limited subset of proliferating cells, most displayed fermentation of glucose to lactate in the presence of oxygen. At high utilization rates of glutamine, oxidative utilization of glucose was decreased, while the production of lactate from glutamine was enhanced. This emergent phenotype was observed only when the available carbon exceeded the amount that could be fully oxidized by the available oxygen. Under the latter conditions, standard Flux Balance Analysis indicated that: this metabolic pattern is optimal to maximize biomass and ATP production; it requires the activity of a branched TCA cycle, in which glutamine-dependent reductive carboxylation cooperates to the production of lipids and proteins; it is sustained by a variety of redox-controlled metabolic reactions. In a K-ras transformed cell line we experimentally assessed glutamine-induced metabolic changes. We validated computational results through an extension of Flux Balance Analysis that allows prediction of metabolite variations. Taken together these findings offer new understanding of the logic of the metabolic reprogramming that underlies cancer cell growth.

Nonheme Iron-Oxo-Catalyzed Methane Formation from Methyl Thioethers: Scope, Mechanism, and Relevance for Natural Systems.

A range of nonheme oxo-iron(IV) model systems with tetra- or pentadentate ligands is shown to produce methane from methionine and other thioethers. This model reaction for the natural aerobic production of methane is shown to proceed via two sulfoxidation steps involving the oxo-iron(IV) complexes, with a bifurcation in the second step that either produces the sulfone or leads to demethylation with similar probabilities. In the presence of O2 , the resulting methyl radicals produce methanol and formate or, in an O2 -depleted environment, lead to formation of methane.

Mechanisms That Modulate Peripheral Oxygen Delivery during Exercise in Heart Failure.

Oxygen uptake ([Formula: see text]o2) measured at the mouth, which is equal to the cardiac output (CO) times the arterial-venous oxygen content difference [C(a-v)O2], increases more than 10- to 20-fold in normal subjects during exercise. To achieve this substantial increase in oxygen uptake [[Formula: see text]o2 = CO × C(a-v)O2] both CO and the arterial-venous difference must simultaneously increase. Although this occurs in normal subjects, patients with heart failure cannot achieve significant increases in cardiac output and must rely primarily on changes in the arterial-venous difference to increase [Formula: see text]o2 during exercise. Inadequate oxygen delivery to the tissue during exercise in heart failure results in tissue anaerobiosis, lactic acid accumulation, and reduction in exercise tolerance. H+ is an important regulatory and feedback mechanism to facilitate additional oxygen delivery to the tissue (Bohr effect) and further aerobic production of ATP when tissue anaerobic metabolism increases the production of lactate (anaerobic threshold). This H+ production in the muscle capillary promotes the continued unloading of oxygen (oxyhemoglobin desaturation) while maintaining the muscle capillary Po2 (Fick principle) at a sufficient level to facilitate aerobic metabolism and overcome the diffusion barriers from capillary to mitochondria ("critical capillary Po2," 15-20 mm Hg). This mechanism is especially important during exercise in heart failure where cardiac output increase is severely constrained. Several compensatory mechanisms facilitate peripheral oxygen delivery during exercise in both normal persons and patients with heart failure.

Effect of temperature and soil organic matter quality on greenhouse-gas production from temperate poor and rich fen soils

Production of carbon dioxide (CO2) and methane (CH4) from peatland soil is controlled by rates of organic matter decomposition; soil organic matter (SOM) decomposition is influenced by the quality of the SOM and the soil temperature. This study determined the effect of increasing temperature and SOM quality on rates of greenhouse-gas production in lab incubations from peat soils formed under different plant functional types found in temperate rich and poor fens of southern Ontario, Canada. Peat derived from different plant functional type (sedge, shrub, and non-vascular vegetation) between the fens was composed of different amounts of SOM, lignin, and cellulose. Rates of CO2 and CH4 production from the lab slurries increased with increasing temperature; however, the relative increases were specific to the vegetation type overlying the soils. Anaerobic to aerobic production ratios ranged from 7% (Chamaedaphne soils) to >30% (Sphagnum soils). Ratios of potential anaerobic production (CO2 to CH4) generally decreased with increasing temperature. The interaction between temperature and SOM quality was demonstrated through the range of Q10 values (1.09–2.38 for CO2; 2.98–21.40 for CH4). These measures were correlated to lignin and cellulose content and the lingo-cellulose index. Results of this study indicate the variability of greenhouse-gas fluxes from peatland soils is influenced by the SOM quality derived from the overlying vegetation. As the climate warms soil temperatures will increase rates of decomposition, and this study will improve models of temperate peatland carbon cycling and can inform land management planning by providing options for minimizing carbon loss.

Correlation and phenotypic path coefficient studies in rice under system of aerobic rice production

Correlation and phenotypic path coefficient studies in rice under system of aerobic rice production

Potash use in aerobic production system for basmati rice may expand its adaptability as an alternative to flooded rice production system

Potash use in aerobic production system for basmati rice may expand its adaptability as an alternative to flooded rice production system

Effects of overexpression of carboxylation pathway genes and inactivation of malic enzymes on malic acid production in Escherichia coli

Malic acid is a dicarboxylic acid that is widely used in food, pharmaceutical and chemical industries. We studied the effects of overexpression of carboxylation pathway genes and inactivation of malic enzymes on the aerobic production of malic acid. Over expression of phosphoenolpyruvate (PEP) carboxylase (ppc) generated strain E21, which increased malic acid production from 0.57 g/L to 3.83 g/L. Then pyc gene from Coryenbacterium glutamicus and pck gene from Actinobacillus succinogenes were overexpressed in E21 separately. The resulting strains E21 (pTrcpyc) and E21 (pTrc-A-pck) produced 6.04 and 5.01 g/L malate with a yield of 0.79 and 0.65 mol/mol glucose, respectively. Deleting two malic enzymes (encoded by maeA and maeB) also led to an increase of 36% in malic acid production with a production of 5.21 g/L. However, the combination of malic enzymes deletion and pyc overexpression could not further increase the yield of malic acid. After optimization of fermentation conditions, strain E21 (pTrcpyc) produced 12.45 g/L malic acid with a yield of 0.84 mol/mol which is 63.2% of the theoretical yield.

Anaerobic and sequential aerobic production of high-titer ethanol and single cell protein from NaOH-pretreated corn stover by a genome shuffling-modified Saccharomyces cerevisiae strain

In this study, a Saccharomyces cerevisiae recombinant strain 14 was constructed through genome shuffling method by transferring the whole genomic DNA of Candida intermedia strain 23 into a thermo-tolerant S. cerevisiae strain. The recombinant strain 14 combined the good natures of both parent strains that efficiently produced ethanol from glucose and single cell protein from xylose with 54.6% crude protein and all essential amino acids except cysteine at 35°C. Importantly, the recombinant strain 14 produced 64.07g/L ethanol from 25%(w/v) NaOH-pretreated and washed corn stover with the ethanol yield of 0.26g/g total stover by fed-batch simultaneous saccharification and fermentation and produced 66.50g/L dry cell mass subsequently from the residual hydrolysate and ethanol. Therefore, this study represents a feasible method to comprehensively utilize hexose and pentose in lignocellulosic materials.

Medium factors on anaerobic production of rhamnolipids by Pseudomonas aeruginosa SG and a simplifying medium for in situ microbial enhanced oil recovery applications.

Aerobic production of rhamnolipid by Pseudomonas aeruginosa was extensively studied. But effect of medium composition on anaerobic production of rhamnolipid by P. aeruginosa was unknown. A simplifying medium facilitating anaerobic production of rhamnolipid is urgently needed for in situ microbial enhanced oil recovery (MEOR). Medium factors affecting anaerobic production of rhamnolipid were investigated using P. aeruginosa SG (Genbank accession number KJ995745). Medium composition for anaerobic production of rhamnolipid by P. aeruginosa is different from that for aerobic production of rhamnolipid. Both hydrophobic substrate and organic nitrogen inhibited rhamnolipid production under anaerobic conditions. Glycerol and nitrate were the best carbon and nitrogen source. The commonly used N limitation under aerobic conditions was not conducive to rhamnolipid production under anaerobic conditions because the initial cell growth demanded enough nitrate for anaerobic respiration. But rhamnolipid was also fast accumulated under nitrogen starvation conditions. Sufficient phosphate was needed for anaerobic production of rhamnolipid. SO4(2-) and Mg(2+) are required for anaerobic production of rhamnolipid. Results will contribute to isolation bacteria strains which can anaerobically produce rhamnolipid and medium optimization for anaerobic production of rhamnolipid. Based on medium optimization by response surface methodology and ions composition of reservoir formation water, a simplifying medium containing 70.3 g/l glycerol, 5.25 g/l NaNO3, 5.49 g/l KH2PO4, 6.9 g/l K2HPO4·3H2O and 0.40 g/l MgSO4 was designed. Using the simplifying medium, 630 mg/l of rhamnolipid was produced by SG, and the anaerobic culture emulsified crude oil to EI24 = 82.5 %. The simplifying medium was promising for in situ MEOR applications.

The bright side of reactive oxygen species: lifespan extension without cellular demise.

Oxidative stress and the generation of reactive oxygen species (ROS) can lead to mitochondrial dysfunction, DNA damage, protein misfolding, programmed cell death with apoptosis and autophagy, and the promotion of aging –dependent processes. Mitochondria control the processing of redox energy that yields adenosine triphosphate (ATP) through the oxidation of glucose, pyruvate, and nicotinamide adenine dinucleotide. Ultimately, the generation of ROS occurs with the aerobic production of ATP. Although reduced levels of ROS may lead to tolerance against metabolic, mechanical, and oxidative stressors and the generation of brief periods of ROS during ischemia-reperfusion models may limit cellular injury, under most circumstances ROS and mitochondrial dysfunction can lead to apoptotic caspase activation and autophagy induction that can result in cellular demise. Yet, new work suggests that ROS generation may have a positive impact through respiratory complex I reverse electron transport that can extend lifespan. Such mechanisms may bring new insight into clinically relevant disorders that are linked to cellular senescence and aging of the body’s system. Further investigation of the potential “bright side” of ROS and mitochondrial respiration is necessary to target specific pathways, such as the mechanistic target of rapamycin, nicotinamidases, sirtuins, mRNA decoupling and protein expression, and Wnt signaling, that can impact oxidative stress-ROS mechanisms to extend lifespan and eliminate disease onset.

The Effects of Varied Terrain and Bicycle Fitting on Aerobic Power Production: Test methodology

Background : Elite cycling occurs over varied terrain and distances, within all of these events the need to maximise performance is of paramount importance. This can be in the form of specific training, nutrition plan or optimal bicycle fit (Faria et al., 2005: Sports Medicine, 35(4), 313-- ‐ 337). Currently there are recommend setups published for maximising anaerobic power, aerobic economy and injury prevention (Silberman et al., 2005: Clinical Journal of Sport Medicine, 15, 271-- ‐ 276; Bini et al., 2011: Sports Medicine, 41(6), 463-- ‐ 476). However, none take into account the effects of varied terrain and no recommendation exists for aerobic power. Purpose : The aim of this study was to develop a process to identify an optimal bicycle fit for aerobic power production for varied terrain. Methods : The testing protocol involved 4 separate trials conducted on a custom-- ‐ made ergometer within the Sports Technology Institute at Loughborough University (Lugo et al., 2014: Journal of Science and Cycling, 3(2), 27). During the first trial the subjects performed a 20-- ‐ minute time trial from which their Functional Threshold Power) and Functional Threshold Heart Rate (FTHR) are obtained. Current bicycle fit (i.e. saddle height, handlebar reach) and anthropometric (i.e. 25o knee flexion, inseam) measurements were also recorded during the first trial. The FTP and FTHR magnitudes were used on subsequent trials to set the intensity and torque values. On the remaining 3 trials the subject pedalled against a load chosen to simulate a specific terrain (see Table 1). Within each trial the subject performed a 5-- ‐ minute effort at 80% FTHR for each of 9 possible bicycle setups (see Table 2). Electromyography (EMG) surface electrodes were placed on both the left and right legs for the Vastus Lateralis (VL), Biceps Femoris Long Head (BF) and Medial Head of the Gastronemius (G). Power and muscle activity were measured for the whole 5-- ‐ minute effort however, the analysis was focused on the last minute of the effort. Results : Paired t-- ‐ tests comparing the net power output for the original setup and all the other 8 alternative positions were carried out, a significant difference was found for positions 2, 3, and 8 (see Table 3). The most significant difference was found for position 8 (p-- ‐ value = 0.011). Using the average power observed for each setup, the time difference for a simulated 10 -- ‐ mile time trial when compared to the original setup was calculated following the mechanistic model presented by Dahmen et al., 2-- ‐ 11 (see Figure 1). For the positions with significant differences (i.e. 2, 3, 8) the largest improvement was seen for position 8 while the largest deterioration occurred for position 3. The power across the pedal cycle shows that for the right leg the difference between the 8th position and the original position is small (mean difference = 0.20 W) however for the left leg the difference is considerable (mean difference = 4.49 W), starting at 200o and reaching a maximum at 300o (see Figure 2). The increase in net power observed during the second phase of the upstroke occurs due to an increased right leg Vastus Lateralis (VL) activity (see Figure 3). Discussion : The used ergometer allows automated alteration of the setup while the rider is cycling, therefore several positions can be tested in a single trial. This capability also reduces the errors associated with EMG electrode placement between trials and longitudinal effects due to subject variability observed when current ergometers are used (Hug F. and Dorel S. Journal of Electromyography and Kinesiology: 2009 19, 182 -- ‐ 198). Comparison between the original and alternate setups from mechanical (i.e. power) and biomechanical (i.e. EMG) points of view allow identifying the effect of bike setup changes and the mechanisms behind them for different terrains. Currently only 2 subjects have completed all trials however, a larger number of subjects are being recruited and results will be reported in the future. Conclusion : The proposed methodology together with the ergometer capabilities can be used to identify optimal bicycle setups for different terrains based on maximal aerobic power production. The corresponding muscle activation patterns allow a greater understanding of pedalling mechanics and the how terrain and bicycle set up affects them.