scholarly journals Silk-based antimicrobial peptide mixed with recombinant spidroin creates functionalized spider silk

2021 ◽  
Author(s):  
Frank Y.C. Liu
Keyword(s):  
Antimicrobial Peptide ◽  
Spider Silk ◽  
Antimicrobial Properties ◽  
Beta Sheets ◽  
Silk Fibers ◽  
E Coli ◽  
Log Reduction ◽  
Spider Silk Protein ◽  
Spinning Process ◽  
Recombinant Spidroin

Surgical site infection (SSI) from sutures is a global health emergency because of the antibiotic crisis. Methicillin-resistant S. aureus and other emerging strains are difficult to treat with antibiotics, so drug-free sutures with antimicrobial properties are a solution. Functionalized spider silk protein (spidroin) is a candidate for its extraordinary strength because it has a large repetitive region (150Rep) that forms crosslinked beta-sheets. The antimicrobial peptide HNP-1 can be connected to recombinant spidroin to create antimicrobial silk. Ni-NTA purified 2Rep-HNP1 fusion protein was mixed with recombinant NT2RepCT spidroin at 1:25, 1:20, 1:10 ratios, and spun into silk fibers by syringe-pumping protein into a 100% isopropanol bath. Beta-sheet crosslinking of the identical 2Rep regions tagged the 2Rep-HNP1 permanently onto the resultant silk. Silk showed no sign of degradation in an autoclave, PBS, or EtOH. The tagged 2Rep-HNP1 retained broad-spectrum antimicrobial activity >90% against S. aureus and E. coli as measured by log reduction and radial diffusion assay. Furthermore, a modified expression protocol increased protein yield of NT2RepCT 2.8-fold, and variable testing of the spinning process demonstrated the industrial viability of silk production. We present a promising suture alternative in antimicrobial recombinant spider silk.

scholarly journals Viability of lactic acid bacteria in different components of Ogi with anti diarrhoeagenic E. coli activities

2019 ◽  
Vol 3 (6) ◽  
pp. 206-213
Author(s):  
Roseline Eleojo Kwasi ◽  
Iyanuoluwa Gladys Aremu ◽  
Qudus Olamide Dosunmu ◽  
Funmilola A. Ayeni
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Antimicrobial Properties ◽  
Culture Method ◽  
Antimicrobial Activities ◽  
Drying Methods ◽  
Bacterial Strains ◽  
E Coli ◽  
Log Reduction ◽  
Freeze Dried

Background: Ogi constitutes a rich source of lactic acid bacteria (LAB) with associated health benefits to humans through antimicrobial activities. However, the high viability of LAB in Ogi and its supernatant (Omidun) is essential. Aims: This study was carried out to assess the viability of LAB in various forms of modified and natural Ogi and the antimicrobial properties of Omidun against diarrhoeagenic E coli. Methods and Material: The viability of LAB was assessed in fermented Ogi slurry and Omidun for one month and also freeze-dried Ogi with and without added bacterial strains for two months. A further 10 days viability study of modified Omidun, refrigerated Omidun, and normal Ogi was performed. The antimicrobial effects of modified Omidun against five selected strains of diarrhoeagenic E. coli (DEC) were evaluated by the co-culture method. Results: Both drying methods significantly affected carotenoids and phenolic compounds. The Ogi slurry had viable LAB only for 10 days after which, there was a succession of fungi and yeast. Omidun showed 2 log10cfu/ml reduction of LAB count each week and the freeze-dried Ogi showed progressive reduction in viability. Refrigerated Omidun has little viable LAB, while higher viability was seen in modified Omidun (≥2 log cfu/ml) than normal Omidun. Modified Omidun intervention led to 2-4 log reduction in diarrhoeagenic E. coli strains and total inactivation of shigella-toxin producing E. coli H66D strain in co-culture. Conclusions: The consumption of Ogi should be within 10 days of milling using modified Omidun. There are practical potentials of consumption of Omidun in destroying E. coli strains implicated in diarrhea. Keywords: Ogi, Omidun, lactic acid bacteria, diarrhoeagenic Escherichia coli strains, Viability.

Tough synthetic spider-silk fibers obtained by titanium dioxide incorporation and formaldehyde cross-linking in a simple wet-spinning process

Biochimie ◽  
2020 ◽  
Vol 175 ◽  
pp. 77-84
Author(s):  
Hongnian Zhu ◽  
Yuan Sun ◽  
Tuo Yi ◽  
Suyang Wang ◽  
Junpeng Mi ◽  
...  
Keyword(s):  
Titanium Dioxide ◽  
Spider Silk ◽  
Wet Spinning ◽  
Cross Linking ◽  
Silk Fibers ◽  
Spinning Process

Inactivation of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella in Cranberry, Lemon, and Lime Juice Concentrates

2003 ◽  
Vol 66 (9) ◽  
pp. 1637-1641 ◽  
Author(s):  
MARA C. L. NOGUEIRA ◽  
OMAR A. OYARZÁBAL ◽  
DAVID E. GOMBAS
Keyword(s):  
Escherichia Coli ◽  
Listeria Monocytogenes ◽  
Pathogenic Bacteria ◽  
Antimicrobial Properties ◽  
Escherichia Coli O157 ◽  
Bacterial Inactivation ◽  
Lime Juice ◽  
E Coli ◽  
Log Reduction ◽  
C 32

The production of thermally concentrated fruit juices uses temperatures high enough to achieve at least a 5-log reduction of pathogenic bacteria that can occur in raw juice. However, the transportation and storage of concentrates at low temperatures prior to final packaging is a common practice in the juice industry and introduces a potential risk for postconcentration contamination with pathogenic bacteria. The present study was undertaken to evaluate the likelihood of Escherichia coli O157: H7, Listeria monocytogenes and Salmonella surviving in cranberry, lemon, and lime juice concentrates at or above temperatures commonly used for transportation or storage of these concentrates. This study demonstrates that cranberry, lemon, and lime juice concentrates possess intrinsic antimicrobial properties that will eliminate these bacterial pathogens in the event of postconcentration recontamination. Bacterial inactivation was demonstrated under all conditions; at least 5-log Salmonella inactivation was consistently demonstrated at −23°C (−10°F), at least 5-log E. coli O157:H7 inactivation was consistently demonstrated at −11°C (12°F), and at least 5-log L. monocytogenes inactivation was consistently demonstrated at 0°C (32°F).

scholarly journals Critical Synergistic Concentration of Lecithin Phospholipids Improves the Antimicrobial Activity of Eugenol against Escherichia coli

2017 ◽  
Vol 83 (21) ◽  
Author(s):  
Haoshu Zhang ◽  
Edward G. Dudley ◽  
Federico Harte
Keyword(s):  
Escherichia Coli ◽  
Foodborne Pathogens ◽  
Rational Design ◽  
Microbial Population ◽  
Critical Concentration ◽  
Antimicrobial Properties ◽  
Content Type ◽  
E Coli ◽  
Log Reduction ◽  
Naturally Occurring

ABSTRACT In this study, the effect of individual lecithin phospholipids on the antimicrobial properties of eugenol against Escherichia coli C600 was investigated. We tested five major phospholipids common in soy or egg lecithin (1,2-dihexadecanoyl-sn-glycero-3-phosphocholine [DPPC], 1,2-dioctadecanoyl-sn-glycero-3-phosphocholine [DSPC], 1,2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine [DPPE], 1,2-dihexadecanoyl-sn-glycero-3-phosphate [sodium salt] [DPPA], and 1,2-dihexadecanoyl-sn-glycero-3-phospho-l-serine [DPPS]) and one synthetic cationic phospholipid (1,2-dioctadecanoyl-sn-glycero-3-ethylphosphocholine [18:0 EPC]). Among the six phospholipids, DPPC, DSPC, DPPE, DPPA, and the cationic 18:0 EPC showed critical synergistic concentrations that significantly improved the inactivation effect of eugenol against E. coli after 30 min of exposure. At the critical synergistic concentration, an additional ca. 0.4 to 1.9 log reduction (ca. 0.66 to 2.17 log CFU/ml reduction) in the microbial population was observed compared to eugenol-only (control) treatments (ca. 0.25 log reduction). In all cases, increasing the phospholipid amount above the critical synergistic concentration (which was different for each phospholipid) resulted in antimicrobial properties similar to those seen with the eugenol-only (control) treatments. DPPS did not affect the antimicrobial properties of eugenol at the tested concentrations. The critical synergistic concentration of phospholipids was correlated with their critical micelle concentrations (CMC). IMPORTANCE Essential oils (EOs) are naturally occurring antimicrobials, with limited use in food due to their hydrophobicity and strong aroma. Lecithin is used as a natural emulsifier to stabilize EOs in aqueous systems. We previously demonstrated that, within a narrow critical-concentration window, lecithin can synergistically enhance the antimicrobial properties of eugenol. Since lecithin is a mixture of different phospholipids, we aimed to identify which phospholipids are crucial for the observed synergistic effect. This research studied the bioactivity of lecithin phospholipids, contributing to a rational design in using lecithin to effectively control foodborne pathogens in foods.

An antimicrobial polycationic sand filter for water disinfection

2011 ◽  
Vol 63 (9) ◽  
pp. 1997-2003 ◽  
Author(s):  
Annalisa Onnis-Hayden ◽  
Bryan B. Hsu ◽  
Alexander M. Klibanov ◽  
April Z. Gu
Keyword(s):  
Treatment Plant ◽  
Antimicrobial Properties ◽  
Bacterial Count ◽  
Water Disinfection ◽  
Aqueous Sample ◽  
Secondary Effluent ◽  
E Coli ◽  
Log Reduction ◽  
Disinfection Process ◽  
Aqueous Effluent

A new sand filtration water disinfection technology is developed which relies on the antimicrobial properties of hydrophobic polycations (N-hexylated polyethylenimine) covalently attached to the sand's surface. The efficacy of the filter disinfection process was evaluated both with water spiked with E. coli and with real aqueous effluent from a wastewater treatment plant. For the former, over 7-log reduction in bacterial count was achieved. With real environmental wastewater secondary effluent samples, the E. coli concentration reduction declined to under 2 logs. This reduced inactivation efficiency compared to the model aqueous sample is likely due to the particulate or colloidal matter present that diminishes the contact between the immobilized polycation and the suspended bacteria. Preliminary sand washing methods were tested to assess potential ‘regeneration’ approaches. Potential advantages of the proposed approach over conventional disinfection in terms of eliminating harmful by-products and reducing energy consumption are discussed.

Progress in the application of spider silk protein in medicine

2021 ◽  
pp. 088532822110038
Author(s):  
Yi Liu ◽  
Wei Huang ◽  
Minsi Meng ◽  
Minhui Chen ◽  
Chengjian Cao
Keyword(s):  
Spider Silk ◽  
Silk Protein ◽  
Large Molecular Weight ◽  
Alternative Materials ◽  
Spider Silk Protein ◽  
Surgical Sutures ◽  
Main Protein ◽  
Biomaterial Application ◽  
Derivatives Of ◽  
Recombinant Spidroin

Spider silk protein has attracted much attention on account of its excellent mechanical properties, biodegradability, and biocompatibility. As the main protein component of spider silk, spidroin plays important role in spider spinning under natural circumstances and biomaterial application in medicine as well. Compare to the native spidroin which has a large molecular weight (>300 kDa) with highly repeat glycine and polyalanine regions, the recombinant spidroin was maintained the core amino motifs and much easier to collect. Here, we reviewed the application of recombinant spider silk protein eADF4(C16), major ampullate spidroin (MaSp), minor ampullate spidroin (MiSp), and the derivatives of recombinant spider silk protein in drug delivery system. Moreover, we also reviewed the application of spider silk protein in the field of alternative materials, repairing materials, wound dressing, surgical sutures along with advances in recombinant spider silk protein.

Mechanical Properties of Spider Silk for Use As a Biomaterial: Molecular Dynamics Investigations

2020 ◽  
Author(s):  
Atul Rawal ◽  
Kristen L. Rhinehardt ◽  
Ram V. Mohan
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
Spider Silk ◽  
Complete Separation ◽  
Silk Protein ◽  
Silk Proteins ◽  
Silk Fibers ◽  
Spider Silk Protein ◽  
Β Chain ◽  
Smd Simulations

Abstract Even though silkworm are the most dominant type of silk fibers used for commercial applications, spider silk has a definitive role in biomedical applications due to its biocompatibility and excellent mechanical properties as biomaterials. In recent years, recombinant production of the silk proteins at a larger scale has found new interest. Spider silk composites with a combination of a variety of other biomaterials have also been used to improve properties such as bio-compatibility, mechanical strength and controlled degradation. [1] A major constituent of spider silk fibers, are spidroin proteins. These are made up of repetitive segments flanked by conserved non-repetitive domains. The fiber proteins consist of a light chain and a heavy chain that are connected via a single disulfide bond. [2] Present paper employed steered molecular dynamics (SMD) as the principal method of investigating the mechanical properties of these nanoscale spider silk protein 3LR2, with a residual count of 134 amino acids. [3]. SMD simulations were performed by pulling on β-chain of the protein in the x-direction, while holding the other fixed. The focus of this paper is to investigate the mechanical properties of the nanoscale spider silk proteins with lengths of about 4.5nm in a folded state, leading to understanding of their feasibility in bio-printing of a composite spider silk biomaterial with a blend of various other biomaterials such as collagen. An in-depth insight into the fraying and tensile deformation and structural properties of the spider silk proteins are of innovative significance for a multitude of biomedical engineering applications. A calculated Gibbs free energy value of 18.59 kCal/mol via umbrella sampling corresponds with a complete separation of a single chain from a spider silk protein in case of fraying. Force needed for complete separation of the chain from the spider silk protein is analyzed, and discussed in this paper. It is found that the protein molecule undergoes a tensile stretch at strain rates of ≅ 11.65. An elastic modulus of 20.136 GPa, calculated via simple SMD simulations by subjecting the silk β-chain to a tensile stretch is also presented.

scholarly journals A New Evidence of Lubrication Hypothesis on Nephila pilipes Spider Silk Spinning

2017 ◽  
Author(s):  
Hsuan-Chen Wu ◽  
Shang-Ru Wu ◽  
Jen-Chang Yang
Keyword(s):  
Spider Silk ◽  
Fiber Diameter ◽  
Underlying Mechanism ◽  
Silk Fibers ◽  
Novel Approach ◽  
Lubrication Layer ◽  
Spinning Process ◽  
Spun Fiber ◽  
Material Fabrication ◽  
New Evidence

In spite of all the efforts on deciphering such spinning process of spiders, the underlying mechanism currently is yet to be fully revealed. In this research, we designed a novel approach to quantitatively estimate the overall concentration change of spider silk along the progression of liquid-to-solid silk transition from the gland silk. As a prior characterization, we first studied the influence of silking-rate, ranged from 1.5 to 8.0 m/min, on spun fiber diameters as well as fiber strengths. Furthermore, the liquid contents of silk in the sac and the silk fibers leaving the spinneret were investigated by thermogravimetric analysis (TGA) and by estimating the ratio of collected dried silk to the weight loss of spider, respectively. The strength of spun silk fiber showed in the range of 7.5 - 8.5 g/denier; while, the fiber diameter of 0.7 - 1.1 deniers for spun silk first increased then decreased with take-up speed of winder. The results showed that the percentage liquid content of silk stored in the major ampullate sac (50.0 wt%) was lower than that of silk leaving the spinnerets (80.9 - 96.1 wt%), indicating a liquid supplying mechanism might be involved during the spinning process. Thus, a hypothesis of liquid coating on the outer surface of the silk thread served as a lubrication layer to reduce the silking resistance in spinning spigot of spider was proposed. In addition, we speculated the spigot serves as a valve-like regulator that controls not only the fiber diameter but also the lubrication layer. These findings provide understanding in physiological function of the spider spinning process and could further shed some light on future biomimetic development of silk material fabrication.

Disinfection of Fruits with Activated Water

2019 ◽  
Vol 10 ◽  
pp. 1864-1872
Author(s):  
Prof. Teodora P. Popova
Keyword(s):  
Antimicrobial Activity ◽  
Aqueous Solutions ◽  
Antimicrobial Properties ◽  
The Other ◽  
Gram Negative Bacteria ◽  
High Antimicrobial Activity ◽  
Gram Negative ◽  
E Coli ◽  
Number Of Microorganisms ◽  
Lower Effect

The effect of ionized aqueous solutions (anolytes and catholyte) in the processing of fruits (cherries, morellos, and strawberries) for decontamination has been tested. Freshly prepared analytes and catholyte without the addition of salts were used, as well as stored for 7 months anolytes, prepared with 0.5% NaCl and a combination of 0.5% NaCl and 0.5% Na2CO3. The anolyte prepared with a combination of 0.5% NaCl and 0.5% Na2CO3, as well as the anolyte obtained with 0.5% NaCl, exhibit high antimicrobial activity against the surface microflora of strawberries, cherries, and sour cherries. They inactivate E. coli for 15 minutes. The other species of the fam. Enterobacteriaceae were also affected to the maximum extent, as is the total number of microorganisms, especially in cherries and sour cherries. Even stored for 7 months, they largely retain their antimicrobial properties. Anolyte and catholyte, obtained without the addition of salts, showed a lower effect on the total number of microorganisms, but had a significant effect on Gram-negative bacteria, and especially with regard to the sanitary indicative E. coli.

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