An environmentally benign antimicrobial nanoparticle based on a silver-infused lignin core

Silver nanoparticles have antibacterial properties, but their use has been a cause for concern because they persist in the environment. Here, we show that lignin nanoparticles infused with silver ions and coated with a cationic polyelectrolyte layer form a biodegradable and green alternative to silver nanoparticles. The polyelectrolyte layer promotes the adhesion of the particles to bacterial cell membranes and, together with silver ions, can kill a broad spectrum of bacteria, including Escherichia coli, Pseudomonas aeruginosa and quaternary-amine-resistant Ralstonia sp. Ion depletion studies have shown that the bioactivity of these nanoparticles is time-limited because of the desorption of silver ions. High-throughput bioactivity screening did not reveal increased toxicity of the particles when compared to an equivalent mass of metallic silver nanoparticles or silver nitrate solution. Our results demonstrate that the application of green chemistry principles may allow the synthesis of nanoparticles with biodegradable cores that have higher antimicrobial activity and smaller environmental impact than metallic silver nanoparticles

Discovering collectively informative descriptors from high-throughput experiments

<p>Abstract</p> <p>Background</p> <p>Improvements in high-throughput technology and its increasing use have led to the generation of many highly complex datasets that often address similar biological questions. Combining information from these studies can increase the reliability and generalizability of results and also yield new insights that guide future research.</p> <p>Results</p> <p>This paper describes a novel algorithm called BLANKET for symmetric analysis of two experiments that assess informativeness of descriptors. The experiments are required to be related only in that their descriptor sets intersect substantially and their definitions of case and control are consistent. From resulting lists of n descriptors ranked by informativeness, BLANKET determines <b>shortlists </b>of descriptors from each experiment, generally of different lengths p and q. For any pair of shortlists, four numbers are evident: the number of descriptors appearing in both shortlists, in exactly one shortlist, or in neither shortlist. From the associated contingency table, BLANKET computes Right Fisher Exact Test (RFET) values used as scores over a plane of possible pairs of shortlist lengths <abbrgrp><abbr bid="B1">1</abbr><abbr bid="B2">2</abbr></abbrgrp>. BLANKET then chooses a pair or pairs with RFET score less than a threshold; the threshold depends upon n and shortlist length limits and represents a quality of intersection achieved by less than 5% of random lists.</p> <p>Conclusions</p> <p>Researchers seek within a universe of descriptors some minimal subset that collectively and efficiently predicts experimental outcomes. Ideally, any smaller subset should be insufficient for reliable prediction and any larger subset should have little additional accuracy. As a method, BLANKET is easy to conceptualize and presents only moderate computational complexity. Many existing databases could be mined using BLANKET to suggest optimal sets of predictive descriptors.</p

A Temporal -omic Study of Propionibacterium freudenreichii CIRM-BIA1T Adaptation Strategies in Conditions Mimicking Cheese Ripening in the Cold

Propionibacterium freudenreichii is used as a ripening culture in Swiss cheese manufacture. It grows when cheeses are ripened in a warm room (about 24°C). Cheeses with an acceptable eye formation level are transferred to a cold room (about 4°C), inducing a marked slowdown of propionic fermentation, but P. freudenreichii remains active in the cold. To investigate the P. freudenreichii strategies of adaptation and survival in the cold, we performed the first global gene expression profile for this species. The time-course transcriptomic response of P. freudenreichii CIRM-BIA1T strain was analyzed at five times of incubation, during growth at 30°C then for 9 days at 4°C, under conditions preventing nutrient starvation. Gene expression was also confirmed by RT-qPCR for 28 genes. In addition, proteomic experiments were carried out and the main metabolites were quantified. Microarray analysis revealed that 565 genes (25% of the protein-coding sequences of P. freudenreichii genome) were differentially expressed during transition from 30°C to 4°C (P<0.05 and |fold change|>1). At 4°C, a general slowing down was observed for genes implicated in the cell machinery. On the contrary, P. freudenreichii CIRM-BIA1T strain over-expressed genes involved in lactate, alanine and serine conversion to pyruvate, in gluconeogenesis, and in glycogen synthesis. Interestingly, the expression of different genes involved in the formation of important cheese flavor compounds, remained unchanged at 4°C. This could explain the contribution of P. freudenreichii to cheese ripening even in the cold. In conclusion, P. freudenreichii remains metabolically active at 4°C and induces pathways to maintain its long-term survival

Potential therapeutic applications of microbial surface-activecompounds

Numerous investigations of microbial surface-active compounds or biosurfactants over the past two decades have led to the discovery of many interesting physicochemical and biological properties including antimicrobial, anti-biofilm and therapeutic among many other pharmaceutical and medical applications. Microbial control and inhibition strategies involving the use of antibiotics are becoming continually challenged due to the emergence of resistant strains mostly embedded within biofilm formations that are difficult to eradicate. Different aspects of antimicrobial and anti-biofilm control are becoming issues of increasing importance in clinical, hygiene, therapeutic and other applications. Biosurfactants research has resulted in increasing interest into their ability to inhibit microbial activity and disperse microbial biofilms in addition to being mostly nontoxic and stable at extremes conditions. Some biosurfactants are now in use in clinical, food and environmental fields, whilst others remain under investigation and development. The dispersal properties of biosurfactants have been shown to rival that of conventional inhibitory agents against bacterial, fungal and yeast biofilms as well as viral membrane structures. This presents them as potential candidates for future uses in new generations of antimicrobial agents or as adjuvants to other antibiotics and use as preservatives for microbial suppression and eradication strategies

Carbon Monoxide as a Colorant in Cooked or Fermented Sausages

The study aimed at substituting nitrite with carbon monoxide (CO) in cooked or fermented meat batter products by investigating color and color stability in myoglobin solutions, model meat systems, and full-scale hotdog and salami sausages of pork and beef. For cooked model meat systems and hotdogs at 75 to 80 °C core temperatures, direct flushing with a 1% CO gas mixture during the last stage of the batter chopping produced an initial red color equal to nitrite or more intense than with nitrite. For fermented model meat systems and salami sausages with a final pH of 4.7, pretreatment and storage of ground raw meat in a 1% CO mixture, and later use of the pretreated meat in batters, also formed an initial red color in the final products. The color stability during air and light display of cooked and fermented meat products with CO was inadequate compared to products with nitrite, although the red color of CO products was largely maintained by anaerobic packaging and storage. Spectra of carboxy- and nitrosomyoglobin at pH 4.7 demonstrated higher absorbance for carboxymyoglobin

Factors affecting survival of Shigatoxin-producing Escherichia coli on abiotic surfaces

Shigatoxin-producing Escherichia coli (STEC) causes severe infections, and has been the cause of a number of foodborne outbreaks. Knowledge on the survival of STEC is crucial in order to limit the risk of cross contamination and transfer of STEC to food during processing. In this study survival of STEC and non-STEC on surfaces under various humidities, temperatures and in the presence of different types of soil was investigated. A model system with controlled relative humidity and temperature was established by using saturated salt solutions. All the 12 STEC strains had a reduction in viable count during incubation at 70% RH at 12 °C. The reduction was 2-3.5 log and 4.5-5.5 log after 1 and 7 days of incubation, respectively. Surviving cells were observed after 19 days of incubation. The STEC strains were more resistant to desiccation than non-STEC strains. STEC survived better at 12 °C, compared to 20 °C. The survival of STEC was much lower than the survival of a Staphylococcus simulans strain tested, which showed less than 1 log reduction until day 7 at 70% RH at 12 °C, while several STEC strains had comparable survival to a Salmonella Agona strain. The survival of two STEC strains tested was highest at 98% RH. The lowest survival was observed at 85% RH, with better survival at drier conditions. Presence of proteins and glucose protected the cells at dry conditions. Two commercial disinfectants tested at in-use concentration had limited effect (0.8-2.5 log reduction) against STEC on stainless steel, especially for cells incubated at high relative humidity (98% RH). STEC surviving on surfaces in the food industry may impose a risk for cross contamination. Cleaning and use of suitable disinfectants will reduce the survival of STEC, but surfaces should be allowed to dry completely since humid conditions will promote the survival and growth of STEC. © 2010 Elsevier B.V. All rights reserved.Link_to_subscribed_fulltex

Stroke

Background and Purpose— Evidence links antidepressant use with cerebral small vessel disease; however, it remains unclear whether people with depression face comparable risk. This study aims to determine the association between antidepressant drug use and depression with markers of cerebral small vessel disease. Methods— One thousand nine hundred five participants (mean age, 72.5 years; 60% women) without stroke or dementia history underwent brain magnetic resonance imaging at baseline, and 1402 individuals underwent a second magnetic resonance imaging at 4 years. Outcomes were lacunes 3 to 15 mm and white matter hyperintensity volume (cm3) at baseline and follow-up. Exposure to antidepressants was grouped as (1) selective serotonin reuptake inhibitors (n=68), (2) tricyclics (n=40), (3) atypicals (n=24), (4) depressed nonusers (n=303), and (5) nondepressed/nonuser group (reference group, n=1470). Statistical analyses adjusted for propensity scores due to the nonrandomized exposure to antidepressant drugs. Results— There was an association between use of atypical antidepressants with lacunes at baseline (adjusted rate ratio, 2.59 [95% CI, 1.14–5.88]; P=0.023) and follow-up (adjusted rate ratio, 3.05 [95% CI, 1.25–7.43]; P=0.014). Lacunes at baseline were also associated with depressed nonusers (adjusted rate ratio, 1.53 [95% CI, 1.06–2.21]; P=0.023). Selective serotonin reuptake inhibitor users and depressed nonusers displayed higher total, periventricular, and deep white matter hyperintensity volumes at baseline. Selective serotonin reuptake inhibitor users had higher deep white matter hyperintensity volumes at follow-up. Conclusions— Users of atypical antidepressants, selective serotonin reuptake inhibitors, and depressed people without any antidepressant exposure all displayed markers of cerebral small vessel disease higher than the nondepressed/nonuser group. The findings suggest that cerebral small vessel disease is associated with depression and exposure to antidepressants