Depolymerisation of Kraft Lignin by Tailor-Made Alkaliphilic Fungal Laccases

Lignins released in the black liquors of kraft pulp mills are an underutilised source of aromatics. Due to their phenol oxidase activity, laccases from ligninolytic fungi are suitable biocatalysts to depolymerise kraft lignins, which are characterised by their elevated phenolic content. However, the alkaline conditions necessary to solubilise kraft lignins make it difficult to use fungal laccases whose activity is inherently acidic. We recently developed through enzyme-directed evolution high-redox potential laccases active and stable at pH 10. Here, the ability of these tailor-made alkaliphilic fungal laccases to oxidise, demethylate, and depolymerise eucalyptus kraft lignin at pH 10 is evidenced by the increment in the content of phenolic hydroxyl and carbonyl groups, the methanol released, and the appearance of lower molecular weight moieties after laccase treatment. Nonetheless, in a second assay carried out with higher enzyme and lignin concentrations, these changes were accompanied by a strong increase in the molecular weight and content of β-O-4 and β-5 linkages of the main lignin fraction, indicating that repolymerisation of the oxidised products prevails in one-pot reactions. To prevent it, we finally conducted the enzymatic reaction in a bench-scale reactor coupled to a membrane separation system and were able to prove the depolymerisation of kraft lignin by high-redox alkaliphilic laccase.

How storage time affects sensory, chemical, and physical characteristics of flavored olive oil

The objectives of this study were to evaluate sensory, chemical, and physical characteristics of olive oil prepared by three flavoring methods and analyze changes during storage (0, 3, and 6 months). Favored olive oil was prepared by three flavoring methods (fresh, dried, and essential oil). Selected sensory, chemical, and color parameters were monitored based on international standards. The color was determined by spectrophotometer. The results confirmed that storage time and flavoring method affect sensory characteristics of the oil. Fresh garlic oil had significantly lower (p < .05) fruity smell. The level of pungent taste significantly increased (p < .05) in the dried rosemary oil, rosemary essential oil, and fresh and dried garlic flavored oils. The intensity of rosemary smell in the sample flavored with essential oil significantly decreased (p < .05) during storage. Opposite effect was observed in the sample flavored with dried rosemary, where the smell significantly increased (p < .05) during storage. The intensity of taste significantly increased (p < .05) in samples flavored by dried rosemary during storage. The peroxide value of all flavored oils samples increased (p < .05) during storage compared to unflavored oil where peroxide value did not change. Color indicators L*, a*, and b* show that addition of fresh rosemary causes the greatest change in olive oil color. The color change, especially the turbidity, was not perceived positive by tasters.

Study on Extraction, Physicochemical Properties, and Bacterio-Static Activity of Polysaccharides from Phellinus linteus

We optimized an ultrasound-assisted extraction process of Phellinus linteus mycelium polysaccharides (PLPs) and studied their monosaccharide composition and bacteriostatic properties. Based on a single-factor experiment, a three-factor, three-level Box-Behnken design was used to optimize the ultrasound-assisted extraction process of PLP, using the yield of PLP as the index. The chemical composition and monosaccharide composition of PLP were determined by chemical analysis and HPLC analysis, respectively. Microscopic morphological analysis of the surface of PLP was performed via swept-surface electron microscopy. The bacteriostatic properties of PLP were determined using the spectrophotometric turbidimetric method. The results showed that the best extraction process of PLP with ultrasonic assistance achieved a result of 1:42 g/mL. In this method, the ultrasonic temperature was 60 °C, ultrasonic extraction was performed for 20 min, and the yield of PLP was 12.98%. The monosaccharide composition of PLP mainly contains glucose (Glc), mannose (Man), galactose (Gal), and glucuronic acid (GlcA). The intracellular polysaccharide of Phellinus igniarius Mycelia (PIP) is an irregular spherical accumulation, the surface is rough and not smooth, and the extracellular polysaccharide (PEP) is a crumbly accumulation. PIP has a stronger inhibitory ability for S. aureus and E. coli and a slightly weaker inhibitory effect for B. subtilis; the inhibitory effect of PEP on S. aureus, E. coli, and B. subtilis is slightly inferior to that of PIP.

Chemical Characterization and In Vitro Gas Production Kinetics of Alternative Feed Resources for Small Ruminants in the Maltese Islands

The ever-increasing human population, the problem associated with climate change and recent crises-COVID-19 disease and trade conflicts-all impacted on the availability and cost of animal feed raw materials. This is clearly visible in realities which heavily rely on importation such as islands and small states, where producers involved in the agricultural sector were strongly affected by the sharp increase in prices. To deal with these global issues, alternative resources are perceived to replace conventional ingredients. This work aimed at assessing the nutritive value of different resources (sheep feed, mature carob, Maltese bread, wild asparagus, prickly lettuce, and loquat) for small ruminants present in the Maltese Islands, analyzing their chemical composition, gas production kinetics and antioxidant properties. In general, the variation in chemical composition resulted in different rumen fermentation kinetics (p < 0.007). The ratio between GP-24 h and GP-48 h was higher in Maltese bread than other substrates; loquat, prickly lettuce and wild asparagus showed lower fermentation kinetics in accordance with their high NDF and ADF contents. The antioxidant activity may be partially related to the polyphenolic content that was higher in wild asparagus, prickly lettuce and loquat. All feed characteristic confirmed their potential to be included as ingredients in ruminant diets and as a source of fiber.

Addition of Spirulina to Craft Beer: Evaluation of the Effects on Volatile Flavor Profile and Cytoprotective Properties

SPME-GC-MS and PTR-ToF-MS techniques were applied to describe the content of volatile flavor compounds in a craft beer before and after adding spirulina. The obtained results showed that the volatile profile of the two beer samples differed. Furthermore, to chemically characterize biomass spirulina, a derivatization reaction followed by GC-MS analysis was performed, highlighting a high content of molecules belonging to different chemical classes, such as sugars, fatty acids and carboxylic acids. A spectrophotometric analysis of total polyphenols and tannins, investigation into the scavenging activity towards DPPH and ABTS radicals and confocal microscopy of brewer's yeast cells were carried out. Moreover, the cytoprotective and antioxidant properties towards the oxidative damage induced by tert-butyl hydroperoxide (tBOOH) in human H69 cholangiocytes were investigated. Finally, the modulation of Nrf2 signaling under oxidative stress conditions was also evaluated. Both samples of beer were shown to contain similar levels of total polyphenols and tannins, with slightly increased levels in that containing spirulina 0.25% w/v. Moreover, the beers were found to be endowed with radical scavenging properties towards both DPPH and ABTS radicals, albeit with a weak contribution of spirulina; however, a higher riboflavin content was detected in spirulina-treated yeast cells. Conversely, the addition of spirulina (0.25% w/v) appeared to improve the cytoprotective properties of beer towards tBOOH-induced oxidative damage in H69 cells and reduce intracellular oxidative stress. Accordingly, the cytosolic Nrf2 expression was found to be increased.

Nickel, cobalt, and chromium in nail sticker and tip products in Korea

BACKGROUND

Nail stickers and nail tips are increasingly used nail products in Korea, and the rest of the world. However, no studies have examined if these specific consumer products might contain nickel, cobalt, and/or chromium, that is, metals known to provoke contact allergy.

OBJECTIVE

We aimed to assess the release and content of nickel, cobalt, and chromium in nail stickers and tips by performing qualitative and quantitative analyses, respectively, of 50 convenience samples purchased in Korea.

METHODS

Eighty-six qualitative spot tests were performed to determine the release of nickel, cobalt, and chromium on 35 nail stickers and 15 nail tips across five brands. Subsequently, the metal contents were quantified using inductively coupled plasma-optical mass spectrometry (ICP-MS).

RESULTS

According to the spot tests, nickel was released in 7/86 (8.1%) tests before and 10/86 (11.6%) tests after exposure to artificial sweat. Cobalt and chromium (VI) spot test results were negative. However, ICP-MS detected nickel, cobalt, and chromium in 11%, 6.3%, and 16.7% of the samples, respectively. Detection rates were higher in nail tips than in stickers and were most common in rhinestones.

CONCLUSION

Nail stickers and tips may contain nickel, cobalt, and/or chromium.

Combination of Biochemical, Molecular, and Synchrotron-Radiation-Based Techniques to Study the Effects of Silicon in Tomato (Solanum Lycopersicum L.)

The work focused on the analysis of two cultivars of tomato (Solanum lycopersicum L.), Aragon and Gladis, under two different treatments of silicon, Low, 2 L of 0.1 mM CaSiO3, and High, 0.5 mM CaSiO3, weekly, for 8 weeks, under stress-free conditions. We subsequently analyzed the morphology, chemical composition, and elemental distribution using synchrotron-based µ-XRF techniques, physiological, and molecular aspects of the response of the two cultivars. The scope of the study was to highlight any significant response of the plants to the Si treatments, in comparison with any response to Si of plants under stress. The results demonstrated that the response was mainly cultivar-dependent, also at the level of mitochondrial-dependent oxidative stress, and that it did not differ from the two conditions of treatments. With Si deposited mainly in the cell walls of the cells of fruits, leaves, and roots, the treatments did not elicit many significant changes from the point of view of the total elemental content, the physiological parameters that measured the oxidative stress, and the transcriptomic analyses focalized on genes related to the response to Si. We observed a priming effect of the treatment on the most responsive cultivar, Aragon, in respect to future stress, while in Gladis the Si treatment did not significantly change the measured parameters.

Macrocyclic Lactones Act as a Queen Pheromone in a Primitively Eusocial Sweat Bee

Eusociality is characterized by the reproductive division of labor between two castes: fertile queens and largely sterile workers. Queen pheromones are known to influence worker behavior and reproductive physiology and are therefore key components in regulating complex eusocial behavior [1]. Recent studies indicate that cuticular hydrocarbons (CHCs) act as queen pheromones in various eusocial hymenopteran species [2-8]. However, almost all species investigated to date are highly eusocial and do not include extant transitory stages from solitary to eusocial behavior [9]. Indeed, primitively eusocial species, which largely lack morphologically distinct castes, are thought to control worker reproduction through the physical aggression of the queen rather than via pheromones [10-12]. Halictid or sweat bees exhibit a high variability of eusociality including solitary and facultatively eusocial species [9, 13-16]. However, the mechanisms controlling worker reproduction in these transitory species are unknown. The results of a recent correlative study based on caste-specific chemical profiles in various halictid bees of different social levels have revealed an overproduction of macrocyclic lactones in queens compared with workers [17]. Using chemical analyses and behavioral experiments in which we simulated below-ground nests of the primitively eusocial sweat bee Lasioglossum malachurum, we identified a queen pheromone and found that macrocyclic lactones, not CHCs, influence worker behavior and decrease ovarian activation in this species. Our data suggest that the evolution of queen pheromones is more complex than previously inferred from highly eusocial species and shed new light on the complexity of the evolution of queen pheromones.

Methyljasmonate Elicitation Increases Terpenoid Indole Alkaloid Accumulation in Rhazya stricta Hairy Root Cultures

Methyl jasmonate is capable of initiating or improving the biosynthesis of secondary metabolites in plants and therefore has opened up a concept for the biosynthesis of valuable constituents. In this study, the effect of different doses of methyl jasmonate (MeJA) elicitation on the accumulation of terpenoid indole alkaloids (TIAs) in the hairy root cultures of the medicinal plant, Rhazya stricta throughout a time course (one-seven days) was investigated. Gas chromatography-mass spectrometry (GC-MS) analyses were carried out for targeted ten major non-polar alkaloids. Furthermore, overall alterations in metabolite contents in elicited and control cultures were investigated applying proton nuclear magnetic resonance (1H NMR) spectroscopy. Methyl jasmonate caused dosage- and time course-dependent significant rise in the accumulation of TIAs as determined by GC-MS. The contents of seven alkaloids including eburenine, quebrachamine, fluorocarpamine, pleiocarpamine, tubotaiwine, tetrahydroalstonine, and ajmalicine increased compared to non-elicited cultures. However, MeJA-elicitation did not induce the accumulation of vincanine, yohimbine (isomer II), and vallesiachotamine. Furthermore, principal component analysis (PCA) of 1H NMR metabolic profiles revealed a discrimination between elicited hairy roots and control cultures with significant increase in total vindoline-type alkaloid content and elevated levels of organic and amino acids. In addition, elicited and control samples had different sugar and fatty acid profiles, suggesting that MeJA also influences the primary metabolism of R. stricta hairy roots. It is evident that methyl jasmonate is applicable for elevating alkaloid accumulation in "hairy root" organ cultures of R. strica.

Sensory evaluation and chemical analysis of exhaled and dermally emitted bioeffluents

Conditions in which exhaled and dermally emitted bioeffluents could be sampled separately or together (whole-body emission) were created. Five lightly dressed males exhaled the air through a mask to another, identical chamber or without a mask to the chamber in which they were sitting; the outdoor air supply rate was the same in both chambers. The carbon dioxide concentration in the chamber with exhaled air was 2000 ppm. Chamber temperatures were 23°C or 28°C, and ozone was present or absent in the supply airflow. When dermally emitted bioeffluents were present, the perceived air quality (PAQ) was less acceptable, and the odor intensity was higher than when only exhaled bioeffluents were present. The presence or absence of exhaled bioeffluents in the unoccupied chamber made no significant difference to sensory assessments. At 28°C and with ozone present, the odor intensity increased and the PAQ was less acceptable in the chambers with whole-body bioeffluents. The concentrations of nonanal, decanal, geranylacetone, and 6-MHO were higher when dermally emitted bioeffluents were present; they increased further when ozone was present. The concentration of squalene then decreased and increased again at 28°C. Dermally emitted bioeffluents seem to play a major role in the sensory nuisance experienced when occupied volumes are inadequately ventilated.

Landfill mining: Resource potential of Austrian landfills--Evaluation and quality assessment of recovered municipal solid waste by chemical analyses

Since the need for raw materials in countries undergoing industrialisation (like China) is rising, the availability of metal and fossil fuel energy resources (like ores or coal) has changed in recent years. Landfill sites can contain considerable amounts of recyclables and energy-recoverable materials, therefore, landfill mining is an option for exploiting dumped secondary raw materials, saving primary sources. For the purposes of this article, two sanitary landfill sites have been chosen for obtaining actual data to determine the resource potential of Austrian landfills. To evaluate how pretreating waste before disposal affects the resource potential of landfills, the first landfill site has been selected because it has received untreated waste, whereas mechanically-biologically treated waste was dumped in the second. The scope of this investigation comprised: (1) waste characterisation by sorting analyses of recovered waste; and (2) chemical analyses of specific waste fractions for quality assessment regarding potential energy recovery by using it as solid recovered fuels. The content of eight heavy metals and the net calorific values were determined for the chemical characterisation tests.