Engineering microbes to sense and eradicate Pseudomonas aeruginosa, a human pathogen

A synthetic genetic system is designed and characterized that allows Escherichia coli to sense and eradicate Pseudomonas aeruginosa, providing a novel antimicrobial strategy that could potentially be applied to fighting infectious pathogens

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Correction to: Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

The original version of this article unfortunately contained a mistake

Prevalence, associated factors and outcomes of pressure injuries in adult intensive care unit patients: the DecubICUs study

Funder: European Society of Intensive Care Medicine; doi: http://dx.doi.org/10.13039/501100013347Funder: Flemish Society for Critical Care NursesAbstract: Purpose: Intensive care unit (ICU) patients are particularly susceptible to developing pressure injuries. Epidemiologic data is however unavailable. We aimed to provide an international picture of the extent of pressure injuries and factors associated with ICU-acquired pressure injuries in adult ICU patients. Methods: International 1-day point-prevalence study; follow-up for outcome assessment until hospital discharge (maximum 12 weeks). Factors associated with ICU-acquired pressure injury and hospital mortality were assessed by generalised linear mixed-effects regression analysis. Results: Data from 13,254 patients in 1117 ICUs (90 countries) revealed 6747 pressure injuries; 3997 (59.2%) were ICU-acquired. Overall prevalence was 26.6% (95% confidence interval [CI] 25.9–27.3). ICU-acquired prevalence was 16.2% (95% CI 15.6–16.8). Sacrum (37%) and heels (19.5%) were most affected. Factors independently associated with ICU-acquired pressure injuries were older age, male sex, being underweight, emergency surgery, higher Simplified Acute Physiology Score II, Braden score 3 days, comorbidities (chronic obstructive pulmonary disease, immunodeficiency), organ support (renal replacement, mechanical ventilation on ICU admission), and being in a low or lower-middle income-economy. Gradually increasing associations with mortality were identified for increasing severity of pressure injury: stage I (odds ratio [OR] 1.5; 95% CI 1.2–1.8), stage II (OR 1.6; 95% CI 1.4–1.9), and stage III or worse (OR 2.8; 95% CI 2.3–3.3). Conclusion: Pressure injuries are common in adult ICU patients. ICU-acquired pressure injuries are associated with mainly intrinsic factors and mortality. Optimal care standards, increased awareness, appropriate resource allocation, and further research into optimal prevention are pivotal to tackle this important patient safety threat

Using smart tags for simplified processing of proteins and peptides

The main objectives of this work were to study and exploit the use of stimuli-responsive tags for purification, refolding and process intensification applications at an early stage of downstream processing. Results from this work have opened the way to overcome low purification efficiency and recoveries in bioprocessing flowsheets by elucidation of the means of polymer-biomolecule interaction for selective purification of cellular-derived contaminants, and protein refolding enhancement. Polyethyleneimine (PEI) and poly(methyl methacrylate) (Eudragit) were investigated for protein purification applications. PEI was superior to Eudragit for selective purification of cellular-derived nucleic acids, due to higher cationic properties compared to Eudragit. Polyethylene glycol (PEG) was investigated for its ‘refolding enhancing’ ability for lysozyme and bovine serum albumin model proteins. The effectiveness of PEG in improving refolding yields was dependent on PEG molecular weights and polymer to protein load ratios, where below the critical polymer to protein load, preferential binding of the polymer to the protein was dominant over self-association of the polymer molecules, thus minimising hydrophobic protein aggregation. Investigations of Eudragit as a refolding enhancer are currently ongoing. Preliminary results show that Eudragit can significantly enhance lysozyme refolding yield at optimum polymer and urea concentrations. It is envisaged that the ability of the pH-responsive polymer to first preferentially bind refolding intermediates to minimize hydrophobic-driven aggregation and then selectively extract the refolded protein into a purified phase upon a switch in pH conditions, will significantly advance current bioprocessing practices in both laboratory and industry settings.RG 126/0

High productivity chromatography refolding process for Hepatitis B Virus X (HBx) protein guided by statistical design of experiment studies

The Hepatitis B Virus X (HBx) protein is a potential therapeutic target for the treatment of hepatocellular carcinoma. However, consistent expression of the protein as insoluble inclusion bodies in bacteria host systems has largely hindered HBx manufacturing via economical biosynthesis routes, thereby impeding the development of anti-HBx therapeutic strategies. To eliminate this roadblock, this work reports the development of the first ‘chromatography refolding’-based bioprocess for HBx using immobilised metal affinity chromatography (IMAC). This process enabled production of HBx at quantities and purity that facilitate their direct use in structural and molecular characterization studies. In line with the principles of quality by design (QbD), we used a statistical design of experiments (DoE) methodology to design the optimum process which delivered bioactive HBx at a productivity of 0.21 mg/ml/h at a refolding yield of 54% (at 10 mg/ml refolding concentration), which was 4.4-fold higher than that achieved in dilution refolding. The systematic DoE methodology adopted for this study enabled us to obtain important insights into the effect of different bioprocess parameters like the effect of buffer exchange gradients on HBx productivity and quality. Such a bioprocess design approach can play a pivotal role in developing intensified processes for other novel proteins, and hence helping to resolve validation and speed-to-market challenges faced by the biopharmaceutical industry today

Production of fatty acid-derived valuable chemicals in synthetic microbes

Fatty acid derivatives, such as hydroxy fatty acids, fatty alcohols, fatty acid methyl/ethyl esters and fatty alka(e)nes, have a wide range of industrial applications including plastics, lubricants and fuels. Currently, these chemicals are obtained mainly through chemical synthesis, which is complex and costly, and their availability from natural biological sources is extremely limited. Metabolic engineering of microorganisms has provided a platform for effective production of these valuable biochemicals. Notably, synthetic biology-based metabolic engineering strategies have been extensively applied to refactor microorganisms for improved biochemical production. Here, we reviewed (i) the current status of metabolic engineering of microbes that produce fatty acid-derived valuable chemicals, and (ii) the recent progress of synthetic biology approaches that assist metabolic engineering, such as mRNA secondary structure engineering, sensor-regulator system, regulatable expression system, ultrasensitive input/output control system, and computer science-based design of complex gene circuits. Furthermore, key challenges and strategies were discussed. Finally, we concluded that synthetic biology provides useful metabolic engineering strategies for economically viable production of fatty acid-derived valuable chemicals in engineered microbes

Biomolecular engineering of a human beta defensin model for increased salt resistance

Human beta defensins (hBDs) are natural antimicrobial peptides (AMPs) with broad spectrum antimicrobial activity. However, hBDs, like many AMPs, are easily inactivated by salt, which limits their extracellular applications as antimicrobial coating agents. In this study, a salt-resistant hBD28 peptide was designed by increasing C-terminus cationicity of the wild type peptide via rational amino acid substitution. The mutant hBD28 exhibited salt-tolerance behaviour and improved antimicrobial potency compared to wild type hBD28. Zeta potential analysis confirmed that increased cationicity was crucial to overcome salt-induced charge-shielding effects, which enhanced peptide-membrane interaction compared to the wild type peptide. The mutant hBD28 did not exhibit obvious differences with respect to hydrophobicity, oligomerization ability, and secondary structure compared to the wild type peptide. A simple design strategy to overcome salt-inactivation in hBD28 is demonstrated through this study, which will guide the design of other salt-resistant AMPs to accelerate their development as anti-infective agents in ionic environments.close

Dimers of human -defensins and their interactions with the POPG membrane

The stable dimeric structures of human ??-defensin (HBD)-3 and-28 have been first computationally identified via a protein docking approach in conjunction with all atom molecular dynamic simulation. We found that both HBD dimers contain an extended ??-sheet platform stabilised mainly by the interaction of second ??-sheets and further investigated interaction mechanisms of these dimers including HBD-2 against 1-palmitoyl-2-oleoyl-sn- phosphatidylglycerol membrane bilayer by using coarse-grained model combined with the ElNeDyn network. The extended ??-sheet platform of the HBD dimer stayed over the bilayer due to the attachment of the amphipathic region located on one side of the ??-sheet platform. The hydrophobic residues of HBDs on the surface interact with the hydrophobic tails of the lipids, whereas the positively charged residues interact with the lipid polar head groups. Finally, antimicrobial nature of HBD-2, HBD-3 and HBD-28 dimers is found to be kept because they are not detached in interacting with the membrane.close0

The imminent role of protein engineering in synthetic biology

Protein engineering has for decades been a powerful tool in biotechnology for generating vast numbers of useful enzymes for industrial applications. Today, protein engineering has a crucial role in advancing the emerging field of synthetic biology, where metabolic engineering efforts alone are insufficient to maximize the full potential of synthetic biology. This article reviews the advancements in protein engineering techniques for improving biocatalytic properties to optimize engineered pathways in host systems, which are instrumental to achieve high titer production of target molecules. We also discuss the specific means by which protein engineering has improved metabolic engineering efforts and provide our assessment on its potential to continue to advance biology engineering as a whole