Coenzyme Q production by metabolic engineered Escherichia coli strains

Coenzyme Q (CoQ) plays an important role as an electron transporter in the respiratory chain. It is formed from a benzoquinone ring and an isoprenoid chain of a specific length depending on the organism. CoQ10 has been used in the treatment of different diseases including Parkinsons, Alzheimer and cardiovascular diseases. In addition, it is used as a dietary supplement and in cosmetic applications due to its important antioxidant property. Escherichia coli produces CoQ8 naturally but it is able to produce CoQ10 when an heterologous decaprenyl synthase is expressed. E. coli is easy to culture and relatively easy to modify genetically which makes it suitable for the development of an industrial-scale process. In a previous work, we constructed strains unable to produce demethylmenaquinone (DMK) and menaquinone (MK), compounds that compete for both chorismate, precursor of the benzoquinone ring, and the isoprenoid chain. In addition, mutant strains unable to produce enterobactin, high affinity siderophore, synthesized from chorismate, were also constructed. These strains where designed as platforms for the generation of novel CoQ-producing strains. In the present work, the production of CoQ was assessed in the mentioned strains at several culture conditions including the use of different carbon sources (glucose, glycerol and succinate) and different culture strategies (batch and continuous) in a Lab-Scale Bioreactor

Contemporary practices of physical trainers in professional soccer: A qualitative study

Introduction: Physical trainers (PTs) are integral for managing load, reducing injury and optimizing performance in professional soccer. However, little is known about how this practitioners operate in the applied setting and how some of the nuances experienced influence practice. Methods: This study explored the contemporary practices of PTs in professional soccer. Semi-structured interviews were undertaken with eight PTs from different professional teams in European and South American leagues. Interview questions were designed to extract information on the evaluation of physical abilities, monitoring and control of training and injury prevention. Subsequently, the interviews were video-recorded, transcribed, translated and analyzed using a content analysis approach. Results: The results suggest that the evaluation of physical capacities is carried out by PTs at the beginning of the preseason. It also appears that it is attempted that this process of regular testing is applied during the competitive period, with most participants conducting partial physiological and physical evaluations at different stages throughout the competitive season. In relation to the monitoring and control of training, subjective feedback scales are used to estimate the internal load, and the use of GPS devices is common to quantify external loads. Injury prevention programmes were implemented by all participants and were generally in a multi-component format focused on preventing or optimizing physical capabilities. Discussion: These insights can be used as a scientific reference point to inform applied practice in professional soccer, especially for practitioners that are inexperienced and aspiring to enhance how they operate in the field. Future investigations should explore the practices of PTs in detail and across a wider network in order to gain deeper and comprehensive insights into the applied soccer environment

Contemporary practices of physical trainers in professional soccer: A qualitative study

IntroductionPhysical trainers (PTs) are integral for managing load, reducing injury and optimizing performance in professional soccer. However, little is known about how this practitioners operate in the applied setting and how some of the nuances experienced influence practice.MethodsThis study explored the contemporary practices of PTs in professional soccer. Semi-structured interviews were undertaken with eight PTs from different professional teams in European and South American leagues. Interview questions were designed to extract information on the evaluation of physical abilities, monitoring and control of training and injury prevention. Subsequently, the interviews were video-recorded, transcribed, translated and analyzed using a content analysis approach.ResultsThe results suggest that the evaluation of physical capacities is carried out by PTs at the beginning of the preseason. It also appears that it is attempted that this process of regular testing is applied during the competitive period, with most participants conducting partial physiological and physical evaluations at different stages throughout the competitive season. In relation to the monitoring and control of training, subjective feedback scales are used to estimate the internal load, and the use of GPS devices is common to quantify external loads. Injury prevention programmes were implemented by all participants and were generally in a multi-component format focused on preventing or optimizing physical capabilities.DiscussionThese insights can be used as a scientific reference point to inform applied practice in professional soccer, especially for practitioners that are inexperienced and aspiring to enhance how they operate in the field. Future investigations should explore the practices of PTs in detail and across a wider network in order to gain deeper and comprehensive insights into the applied soccer environment

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality

Alginate Biosynthesis in Azotobacter vinelandii

The Gram-negative bacterium Azotobacter vinelandii can synthetize the biopolymer alginate that has material properties appropriate for plenty of applications in industry as well as in medicine. In order to settle the foundation for improving alginate production without compromising its quality, a better understanding of the polymer biosynthesis and the mechanism of regulation during fermentation processes is necessary. This knowledge is crucial for the development of novel production strategies. Here, we highlight the key aspects of alginate biosynthesis that can lead to producing an alginate with specific material properties with particular focus on the role of oxygen availability linked with the molecular mechanisms involved in the alginate production

Evaluation of gene expression and alginate production in response to oxygen transfer in continuous culture of Azotobacter vinelandii.

Alginates are polysaccharides used as food additives and encapsulation agents in biotechnology, and their functional properties depend on its molecular weight. In this study, different steady-states in continuous cultures of A. vinelandii were established to determine the effect of the dilution rate (D) and the agitation rate on alginate production and expression of genes involved in alginate polymerization and depolymerization. Both, the agitation and dilution rates, determined the partitioning of the carbon utilization from sucrose into alginate and CO2 under oxygen-limiting conditions. A low D (0.07 h(-1)) and 500 rpm resulted in the highest carbon utilization into alginate (25%). Quantitative real-time polymerase chain reaction was used to determine the transcription level of six genes involved in alginate polymerization and depolymerization. In chemostat cultures at 0.07 h(-1), the gene expression was affected by changes in the agitation rate. By increasing the agitation rate from 400 to 600 rpm, the algE7 gene expression decreased tenfold, whereas alyA1, algL and alyA2 gene expression increased between 1.5 and 2.8 times under similar conditions evaluated. Chemostat at 0.07 h(-1) showed a highest alginate molecular weight (580 kDa) at 500 rpm whereas similar molecular weights (480 kDa) were obtained at 400 and 600 rpm. The highest molecular weight was not explained by changes in the expression of alg8 and alg44 (genes involved in alginate polymerization). Nonetheless, a different expression pattern observed for lyases could explain the highest alginate molecular weight obtained. Overall, the results suggest that the control of alginate molecular weight in A. vinelandii cells growing in continuous mode is determined by a balance between the gene expression of intracellular and extracellular lyases in response to oxygen availability. These findings better our understanding of the biosynthesis of bacterial alginate and help us progress toward obtain tailor-made alginates

Increases in alginate production and transcription levels of alginate lyase (alyA1) by control of the oxygen transfer rate in Azotobacter vinelandii cultures under diazotrophic conditions

Background: Alginates are polysaccharides used in a wide range of industrial applications, with their functional properties depending on their molecular weight. In this study, alginate production and the expression of genes involved in polymerization and depolymerization in batch cultures of Azotobacter vinelandii were evaluated under controlled and noncontrolled oxygen transfer rate (OTR) conditions. Results: Using an oxygen transfer rate (OTR) control system, a constant OTR (20.3 ± 1.3 mmol L−1h−1) was maintained during cell growth and stationary phases. In cultures subjected to a controlled OTR, alginate concentrations were higher (5.5 ± 0.2 g L−1) than in cultures under noncontrolled OTR. The molecular weight of alginate decreased from 475 to 325 kDa at the beginning of the growth phase and remained constant until the end of the cultivation period. The expression level of alyA1, which encodes an alginate lyase, was more affected by OTR control than those of other genes involved in alginate biosynthesis. The decrease in alginate molecular weight can be explained by a higher relative expression level of alyA1 under the controlled OTR condition. Conclusions: This report describes the first time that alginate production and alginate lyase (alyA1) expression levels have been evaluated in A. vinelandii cultures subjected to a controlled OTR. The results show that automatic control of OTR may be a suitable strategy for improving alginate production while maintaining a constant molecular weight.How to cite: Ponce B, Urtuvia V, Maturana N, et al. Increases in alginate production and transcription levels of alginate lyase (alyA1) by control of the oxygen transfer rate in Azotobacter vinelandii cultures under diazotrophic conditions. Electron J Biotechnol 2021;51. https://doi.org/10.1016/j.ejbt.2021.04.00

Bacterial Alginate-Based Hydrogel Reduces Hydro-Mechanical Soil-Related Problems in Agriculture Facing Climate Change

Agricultural systems are facing the negative impacts of erosion and water scarcity, directly impacting the hydro-mechanical behavior of soil aggregation. Several technologies have been proposed to reduce hydro-mechanical soil-related problems in agriculture. Biopolymer-based hydrogels have been reported to be a great tool to tackle these problems in soils. In this study, we investigated the hydro-mechanical behavior of different soils media treated with Ca-bacterial alginate hydrogel. We used an unconfined uniaxial compression test, aggregate stability test and hydraulic conductivity measurements to investigate the mechanical and hydraulic behavior of treated soils media. Our results from unconfined uniaxial compression test showed that yield stress (i.e., strength) increased in treated soils with higher kaolinite and water content (i.e., HCM3), compared with untreated coarse quartz sand (i.e., CM1). Furthermore, we found that temperature is an important factor in the gelation capacity of our hydrogel. At room temperature, HCM3 displayed the higher aggregate stability, almost 5.5-fold compared with treated coarse quartz sand (HCM1), while this differential response was not sustained at warm temperature. In general, the addition of different quantities of kaolinite decreased the saturated hydraulic conductivity for all treatments. Finally, bright field microscopy imaging represents the soil media matrix between sand and clay particles with Ca-bacterial alginate hydrogel that modify the hydro-mechanical behavior of different soils media. The results of this study could be helpful for the soil-related problems in agriculture facing the negative effects of climate change

Maximization of poly(3-hydroxybutyrate) production in fed-batch cultures of A. vinelandii based on the variation of the agitation rate

1. Introduction The poly-hydroxybutyrate (PHB) is a polyethylene-like bioplastic naturally synthetized by several classes of microorganisms, as a source of energy and carbon unit [1]. This material, which is a promising candidate for the replacement of fossil-based plastic, is already present at an industrial scale. However, the maximization of its production process is the goal to achieve in order to reduce production costs. Azotobacter vinelandii is strictly aerobic gram-negative soil bacteria, able to produce PHB in a carbon substrate-rich environment and under oxygen-limitation conditions [2]. The production of this polymer is particularly interesting in this species, because it can accumulate up to 85% of its dried biomass as PHB [3]. It is known that agitation rate affects the PHB production by A. vinelandii [2]. In this work, the PHB productivity under fed-batch cultivation was evaluated to different volumetric oxygen transfer coefficient (kLa). Thus, it was possible to determine an adequate kLa range for scale-up the production of PHB. 2. Methods Batch cultures of Azotobacter vinelandii OP were performed in a 3 L bioreactor (30 g L-1 sucrose as carbon source) at 600 rpm during 30 h. After of this time, the cultures were fed by a single medium feeding pulse of the carbon source and the agitation speed was varied between 400 and 1000 rpm. The biomass evolution and the PHB production were evaluated. The kLa was estimated at different agitation rate using dynamic method. 3. Results and discussion The maximal accumulation of biomass was 13.3 g L-1, obtained at an agitation speed of 800 rpm (Table 1). The highest agitation speed increased the specific growth rate, reaching a value of 0.069 h-1 to 1000 rpm. During fed-batch cultivation, a change in the agitation speed affected the PHB accumulation, obtaining the highest value (79.1 % w w-1) to 600 rpm