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ABSTRACT Pseudomonas aeruginosais considered one of the most challenging, drug-resistant, opportunistic pathogens partly due to its ability to synthesize robust biofilms. Biofilm is a mixture of extracellular polymeric substances (EPS) that encapsulates microbial cells, leading to immune evasion, antibiotic resistance, and thus higher risk of infection. In the cystic fibrosis lung environment,P. aeruginosaundergoes a mucoid transition, defined by overproduction of the exopolysaccharide alginate. Alginate encapsulation results in bacterial resistance to antibiotics and the host immune system. Given its role in airway inflammation and chronic infection, alginate is an obvious target to improve treatment forP. aeruginosainfection. Previously, we demonstrated polysaccharide lyase Smlt1473 fromStenotrophomonas maltophiliastrain k279a can catalyze the degradation of multiple polyuronidesin vitro, including D-mannuronic acid (poly-ManA). Poly-ManA is a major constituent ofP. aeruginosaalginate, suggesting that Smlt1473 could have potential application against multidrug-resistantP. aeruginosaand perhaps other microbes with related biofilm composition. In this study, we demonstrate that Smlt1473 can inhibit and degrade alginate fromP. aeruginosa. Additionally, we show that testedP. aeruginosastrains are dominant in acetylated alginate and that all but one have similar M-to-G ratios. These results indicate that variation in enzyme efficacy among the isolates is not primarily due to differences in total EPS or alginate chemical composition. Overall, these results demonstrate Smlt1473 can inhibit and degradeP. aeruginosaalginate and suggest that other factors including rate of EPS production, alginate sequence/chain length, or non-EPS components may explain differences in enzyme efficacy. IMPORTANCEPseudomonas aeruginosais a major opportunistic human pathogen in part due to its ability to synthesize biofilms that confer antibiotic resistance. Biofilm is a mixture of polysaccharides, DNA, and proteins that encapsulate cells, protecting them from antibiotics, disinfectants, and other cleaning agents. Due to its ability to increase antibiotic and immune resistance, the exopolysaccharide alginate plays a large role in airway inflammation and chronicP. aeruginosainfection. As a result, colonization withP. aeruginosais the leading cause of morbidity and mortality in CF patients. Thus, it is an obvious target to improve the treatment regimen forP. aeruginosainfection. In this study, we demonstrate that polysaccharide lyase, Smlt1473, inhibits alginate secretion and degrades established alginate from a variety of mucoidP. aeruginosaclinical isolates. Additionally, Smlt1473 differs from other alginate lyases in that it is active against acetylated alginate, which is secreted during chronic lung infection. These results suggest that Smlt1473 may be useful in treating infections associated with alginate-producingP. aeruginosa, as well as have the potential to reduceP. aeruginosaEPS in non-clinical settings. 

Abstract Berries from the European Mistletoe (Viscum album) possess a sticky tissue called viscin that facilitates adhesion and germination onto host trees. Recent studies of viscin have demonstrated its adhesive capacity on a range of natural and synthetic surfaces including wood, skin, metals, and plastic. Yet, the underlying mechanisms remain poorly understood. Here, an investigation of the adhesive performance of mistletoe viscin is performed, demonstrating its hygroscopic nature and ability to self‐heal following adhesive failure. It is identified that adhesion originates from a water‐soluble adhesive component that can be extracted, isolated, and characterized independently. Lap shear mechanical testing indicates that the mistletoe adhesive extract (MAE) outperforms native viscin tissue, as well as gum arabic and arabinogalactan—common plant‐based adhesives. Furthermore, humidity uptake experiments reveal that MAE can reversibly absorb nearly 100% of its mass in water from the atmosphere. In‐depth spectroscopic and mass spectrometry investigations reveal a composition consisting primarily of an atypical arabinogalactan, with additional sugar alcohols. Finally, several proof‐of‐concept applications are demonstrated using MAE for hygro‐responsive reversible adhesion between various surfaces including skin, plastic, PDMS, and paper, revealing that MAE holds potential as a biorenewable and reusable adhesive for applications in cosmetics, packaging, and potentially, tissue engineering.