Bacillus sp. alone or combined with salicylic acid inhibited Trichoderma spp. infection on harvested white Hypsizygus marmoreus.

Introduction: White Hypsizygus marmoreus is a popular edible mushroom. It is rich in nutrition and flavor but vulnerable to fungal disease, resulting in nutrient loss and aging. Methods: In this study, the pathogenic fungus Trichoderma spp. BBP-6 and its antagonist Bacillus sp. 1-23 were isolated and identified. The negative effects caused by this pathogen were judged by detecting a series of changes in the infected white H. marmoreus. The effects of Bacillus sp. 1-23 on Trichoderma spp. BBP-6 and the infected white H. marmoreus were detected. The effect of Bacillus sp. 1-23 treatment combined with salicylic acid (SA) was also considered. Results: The results showed that Trichoderma spp. BBP-6 could affect the activities of antioxidant enzymes PAL, POD, CAT, SOD, GR, PPO, and APX to interfere with the stability of the white H. marmoreus antioxidant enzyme system and cause the mushroom severe browning and nutrition loss, as well as general quality deterioration. Bacillus sp. 1-23 could produce chitinase and chitosanase enzymes to inhibit Trichoderma spp. BBP-6 directly. SA reinforced this inhibitory. Bacillus sp. 1-23 alone or combined with SA could help white H. marmoreus from the Trichoderma spp. BBP-6 infection to effectively maintain nutrients, restore and stabilize the antioxidant system, and reduce the production of malondialdehyde, superoxide anion and hydrogen peroxide. Discussion: Thus, such treatments could be considered potential methods to alleviate damage from disease and extend the shelf life of white H. marmoreus.

l-Cysteine Treatment Delayed the Quality Deterioration of Fresh-Cut Button Mushrooms by Regulating Oxygen Metabolism, Inhibiting Water Loss, and Stimulating Endogenous H2S Production.

Although fresh-cut button mushrooms are popular with consumers, quality deterioration presents a significant shelf-life challenge. In this study, fresh-cut button mushrooms were treated with 0.25 g/L l-cysteine (l-Cys) and evaluated in terms of quality, physiology, and transcriptome sequencing. The results indicated that l-Cys application significantly delayed the browning degree of fresh-cut button mushrooms and reduced weight loss. l-Cys treatment reduced the malondialdehyde content, lipoxygenase activity, and reducing sugar levels while enhancing the soluble protein and total phenolic content. Furthermore, l-Cys treatment reduced the O2- generation rate and H2O2 accumulation while enhancing the catalase activity. Moreover, l-Cys improved the superoxide dismutase, glutathione reductase, and phenylalanine ammonia-lyase activities while reducing those of polyphenol oxidase and peroxidase. Additionally, l-Cys treatment increased endogenous H2S production and AbCBS enzyme activity while decreasing AbCSE enzyme activity. Notably, additional treatment with 1 mM propargylglycine significantly reduced the effect of l-Cys. Moreover, transcriptome sequencing analysis indicated that the differentially expressed genes in the l-Cys group were primarily related to the reactive oxygen species metabolism, oxidoreductase process, membrane integrality, and sulfur metabolism. These findings suggested that l-Cys treatment delayed the aging and extended the shelf life of fresh-cut button mushrooms by regulating the active oxygen species metabolism and water loss and stimulating endogenous H2S production.

Gibberellic acid maintains postharvest quality of Agaricus bisporus mushroom by enhancing antioxidative system and hydrogen sulfide synthesis.

The application of gibberellic acid (GA3 ) treatment to the postharvest quality maintenance of white button mushroom (Agaricus bisporus) was investigated. The optimum concentration of exogenous GA3 was 100 mg/L. At this concentration, the color change was inhibited, the firmness was maintained, and the weight loss and respiratory rates were reduced. The GA3 group had significantly lower malonaldehyde (MDA) content and membrane permeability. Reactive oxygen species accumulation was reduced due to the regulation of polyphenol oxidase (PPO), peroxidase (POD), and superoxide dismutase (SOD) enzyme activities. Moreover, the production of endogenous gaseous signaling molecule hydrogen sulfide (H2 S) was triggered by GA3 treatment, which enhanced cystathionine γ-lyase (AbCSE) and cystathionine ß-synthase (AbCBS) activities alongside the corresponding gene expressions. The preservation of button mushroom postharvest storage quality by GA3 was most likely due to the regulation of reactive oxygen species metabolism and hydrogen sulfide biosynthesis. PRACTICAL APPLICATIONS: Mushroom is rich in nutrients and functional substances. However, due to the lack of cuticle, high respiration rate, and moisture content, mushroom's postharvest quality deteriorates rapidly. A safe and effective reagent that prevents the senescence and quality deterioration of harvested mushroom is urgently needed. The effects of plant hormone GA3 on the postharvest quality of edible fungi remain unclear. The present study provided convincing evidence that 100 mg L-1 of GA3 effectively maintained postharvest button mushroom quality by regulating reactive oxygen species metabolism and hydrogen sulfide biosynthesis.

H2S is synthesized via CBS/CSE pathway and triggered by cold conditions during Agaricus bisporus storage

BACKGROUND: H2S is proved to be functioning as a signaling molecule in an array of physiological processes in the plant and animal kingdom. However, the H2S synthesis pathway and the responses to cold conditions remain unclear in postharvest mushroom. RESULTS: The biosynthesis of H2S in the Agaricus bisporus mushroom tissues exhibited an increasing tendency during postharvest storage and was significantly triggered by cold treatment. The cystathionine clyase (AbCSE) and cystathionine b-synthase (AbCBS) genes were cloned and proved responsible for H2S biosynthesis. Furthermore, transcriptional and posttranscriptional regulation of AbCSE and AbCBS were crucial for the enzyme activities and subsequent H2S levels. However, the AbMST was not involved in this process. Moreover, the AbCSE and AbCBS genes displayed low identity to the characterized genes, but typical catalytic domains, activity sites, subunit interface sites, and cofactor binding sites were conserved in the respective protein sequences, as revealed by molecular modeling and docking study. The potential transcription factors responsible for the H2S biosynthesis in cold conditions were also provided. CONCLUSIONS: The H2S biosynthetic pathway in postharvest mushroom was unique and distinct to that of other horticultural products.

A composite chitosan derivative nanoparticle to stabilize a W1/O/W2 emulsion: Preparation and characterization.

For preparing stable water-in-oil-in-water emulsion, the role of nanoparticles in stabilizing the interface is very important. In this study, chitosan hydrochloride-carboxymethyl chitosan (CHC-CMC) nanoparticles were prepared considering electrostatic interactions; then the emulsion was prepared and the stability characteristics in presence of NaCl (0-200 mmol/L) and 30 d storage were studied. CHC-CMC nanoparticles (261 nm) were obtained when the CHC: CMC ratio was 1:2. CHC-CMC formation was verified by FT-IR when a new peak appeared at 1580 cm-1; W2 contained 2 wt % CHC-CMC and W1 contained 1 wt % sodium alginate, the creaming index (81.6 %) was higher for the emulsions than Tween 80 (67.4 %) after 30 d. Confocal laser scanning microscopy confirmed the double microstructures, in contrast to the collapse with Tween 80, because the CHC-CMC nanoparticles were densely adsorbing on the oil-water interface. This indicates that CHC-CMC has a stronger ability to stabilize W1/O/W2 emulsion than Tween 80.

Double enzymatic hydrolysis preparation of heme from goose blood and microencapsulation to promote its stability and absorption.

Iron deficiency anemia (IDA) is the most common nutritional deficiency worldwide. This deficiency could be solved by preparing stable, edible, and absorbable iron food ingredients using environmentally friendly methods. This study investigated enzymatic hydrolysis and microencapsulation process of goose blood. The physicochemical properties, stabilities of the microencapsulated goose blood hydrolysate (MGBH) and a supplement for rats with IDA were also evaluated. The results showed that the synergetic hydrolytic action of neutrase and alkaline protease significantly increased the heme-releasing efficiency. The heme was then microencapsulated using sodium caseinate, maltodextrin and carboxymethyl cellulose (CMC) as the edible wall material, and the encapsulation efficiency of the product reached 98.64%. Meanwhile, favorable thermal, storage and light stabilities were observed for the microencapsulation. It was found that MGBH can significantly improve the body weight and hematological parameters of IDA Wistar rat.

SERS optrode as a "fishing rod" to direct pre-concentrate analytes from superhydrophobic surfaces.

SERS optrodes were used to "fish" aqueous drops from superhydrophobic surfaces. The technique led to an improvement of 2-3 orders of magnitude in the lowest detectable amount of the Raman probe nile blue A, reaching 25 fg (34 attomoles). Further tests run on samples containing pesticide revealed that 20 pg of triazophos could be clearly detected from a single drop.

Fabrication of SERS swab for direct detection of trace explosives in fingerprints.

Swab sampling is of great importance in surface contamination analysis. A cotton swab (cotton Q-tip) was successfully transformed into surface-enhanced Raman scattering (SERS) substrate (SERS Q-tip) through a bottom-up strategy, where Ag NPs were first self-assembled onto the Q-tip followed by in situ growing. The capability for direct swab detection of Raman probe Nile Blue A (NBA) and a primary explosive marker 2,4-dinitrotoluene (2,4-DNT) using the SERS Q-tip was explored. It was found that at optimum conditions, a femotogram of NBA on glass surface could be swab-detected. The lowest detectable amount for 2,4-DNT is only ∼1.2 ng/cm(2) (total amount of 5 ng) on glass surface, 2 orders of magnitude more sensitive than similar surface analysis achieved with infrared technique, and comparable even with that obtained by ion mobility spectrometry-mass spectrometry. Finally, 2,4-DNT left on fingerprints was also analyzed. It was found that SERS signal of 2,4-DNT from 27th fingerprint after touching 2,4-DNT powder can still be clearly identified by swabbing with the SERS Q-tip. We believe this is the first direct SERS swabbing test of explosives on fingerprint on glass. Considering its relative long shelf life (>30 d), the SERS Q-tip may find great potential in future homeland security applications when combined with portable Raman spectrometers.

A silver nanoparticle embedded hydrogel as a substrate for surface contamination analysis by surface-enhanced Raman scattering.

A surface enhanced Raman scattering (SERS) substrate, capable of extracting small amounts of organic species from surfaces of different types of materials with variable roughness, has been fabricated. The substrate consists of Ag NPs encapsulated in poly(vinyl alcohol) (PVA) hydrogels, commonly known as PVA "slime". Unlike traditional SERS substrates, such as colloidal suspensions, the resulting PVA slime SERS substrate presents good viscoelasticity, allowing it to conform to the surface of various materials of arbitrary roughness. Surfaces of different materials, including sandpapers, cotton, metal, and wood, previously contaminated with nile blue A (NBA) were analyzed with the PVA slime SERS substrate. Limits of detection (LOD) as low as 100 ppb (0.79 ng in a total amount on an area of ∼3 cm(2)) were achieved for all surfaces tested. Pesticides and Sudan red III on the glass surface have also been detected, with a LOD of 1.6 ng per ∼3 cm(2).

Development of multicolor carbon nanoparticles for cell imaging.

Multicolor carbon nanoparticles (CNPs) were prepared, characterized and developed as fluorescent probes for cell imaging. The fluorescent CNPs were prepared with a facile hydrothermal oxidation route by using linear polysaccharide cellulose and cyclic oligosaccharide cyclodextrin as carbon sources. The characterizations by transmission electron microscopy show that the prepared cellulose-CNPs and cyclodextrin-CNPs are spherical, well-dispersed in water with average diameters of 100 nm and 76 nm, respectively. Under the excitation of UV light, the CNPs are strongly luminescent with an excitation-dependent emission behavior and bathochromic emission properties. The fluorometric methods show that the cellulose-CNPs and cyclodextrin-CNPs are strongly fluorescent with fluorescence quantum yield of 7.47% and 4.49%, respectively. The multicolor CNPs have excellent photostability toward photobleaching. Strong near-infrared fluorescence of the carbon nanoparticles was observed with a 632.8 nm excitation wavelength laser. The oxidative metal ions like Hg(II), Cu(II) and Fe(III) show an quench effect on the fluorescence intensity of the CNPs. The multicolor CNPs were successfully used as fluorescent probes for mouse melanoma cells imaging. The results indicate that the multicolor CNPs derived from cellulose and cyclodextrin may have a great potential for the applications in bioimaging.

Novel xylanase from a holstein cattle rumen metagenomic library and its application in xylooligosaccharide and ferulic Acid production from wheat straw.

A novel gene fragment containing a xylanase was identified from a Holstein cattle rumen metagenomic library. The novel xylanase (Xyln-SH1) belonged to the glycoside hydrolase family 10 (GH10) and exhibited a maximum of 44% identity to the glycoside hydrolase from Clostridium thermocellum ATCC 27405. Xyln-SH1 was heterologously expressed, purified, and characterized. A high level of activity was obtained under the optimum conditions of pH 6.5 and 40 °C. A substrate utilization study indicated that Xyln-SH1 was cellulase-free and strictly specific to xylan from softwood. The synergistic effects of Xyln-SH1 and feruloyl esterase (FAE-SH1) were observed for the release of xylooligosaccharides (XOS) and ferulic acid (FA) from wheat straw. In addition, a high dose of Xyln-SH1 alone was observed to improve the release of FA from wheat straw. These features suggest that this enzyme has substantial potential to improve biomass degradation and industrial applications.

A protease-insensitive feruloyl esterase from China Holstein cow rumen metagenomic library: expression, characterization, and utilization in ferulic acid release from wheat straw.

A metagenomic library of China Holstein cow rumen microbes was constructed and screened for novel gene cluster. A novel feruloyl esterase (FAE) gene was identified with a length of 789 bp and encoded a protein displaying 56% identity to known esterase sequences. The gene was functionally expressed in Escherichia coli BL21 (DE3), and the total molecular weight of the recombined protein was 32.4 kDa. The purified enzyme showed a broad specificity against the four methyl esters of hydroxycinnamic acids and high activity (259.5 U/mg) to methyl ferulate at optimum conditions (pH 8.0, 40 °C). High thermal and pH stability were also observed. Moreover, the enzyme showed broad resistance to proteases. FAE-SH1 can enhance the release of ferulic acid from wheat straw with cellulase, ß-1,4-endoxylanase, ß-1,3-glucanase, and pectase. These features suggest FAE-SH1 as a good candidate to enhance biomass degradation and improve the health effects of food and forage.

[Quantitative structure-gas chromatographic retention relationship of polycyclic aromatic sulfur heterocycles using molecular electronegativity-distance vector].

The chemical structures of 114 polycyclic aromatic sulfur heterocycles (PASHs) have been studied by molecular electronegativity-distance vector (MEDV). The linear relationships between gas chromatographic retention index and the MEDV have been established by a multiple linear regression (MLR) model. The results of variable selection by stepwise multiple regression (SMR) and the powerful predictive abilities of the optimization model appraised by leave-one-out cross-validation showed that the optimization model with the correlation coefficient (R) of 0.994 7 and the cross-validated correlation coefficient (Rcv) of 0.994 0 possessed the best statistical quality. Furthermore, when the 114 PASHs compounds were divided into calibration and test sets in the ratio of 2:1, the statistical analysis showed our models possesses almost equal statistical quality, the very similar regression coefficients and the good robustness. The quantitative structure-retention relationship (QSRR) model established may provide a convenient and powerful method for predicting the gas chromatographic retention of PASHs.

[Relationship between the laccase production of Pleurotus ostreatus and the full wavelength scan for the fermentation liquid].

Laccase, widely distributed in fungi lacking high substrate specificity, plays an important role in lignin degradation in nature and environmental protection. In order to determine or estimate the laccase production during the fermentation of liquid media, the authors studied the full-length wave scan on the rough fermentation liquid of the Pleurotus ostreatus, which produces laccase high. Combined with the normal chemical method and diameter of the laccase and mycelium stain, which grew on the PDA (potato dextrose agar) plate with guaiacol added, we could get the exact information of laccase production. The result showed that the laccase activity increased in a rapid way in the first 5 days during the fermentation process, remained almost at the same level in the following 4 days, then increased rapidly until the 11 day, which was 148.7 U x L(-1), increased 17.9 times. The diameter of laccase and mycelium stain increased with the culture time. The number of the wave peaks around 300 nm had a positive correlation with the laccase production; the peak width of OD over 1.5 around 300 nm had a positive correlation with the laccase production, which ranges from 5 nm on the first day to 80 nm on the 11th day. The light absorption line between the wavelengths 300 and 400 nm had a positive correlation with the laccase production with peaks at 349, 365 and 388 nm, and at 365 the peak gets its highest. Using these parameters, the authors could get the general production of the laccase production of liquid fermentation. Compared with the normal chemical method, the full-length wave scan method is much easier, cheap and simple. Furthermore, there are no special chemical substances used. It is really a new method for the evaluation and determination of laccase.