As an alternative to antibodies, aptamers have a great potential as analytical tools for pesticide detection. In this work, aptamers targeting acetamiprid were selected by a specific systematic ...evolution of ligands by exponential enrichment (SELEX) strategy, where a single-stranded DNA (ssDNA) library was immobilized and target modification was eliminated. After 18 rounds of repeated selection, the ssDNA pool was enriched and then 14 sequences were selected and carefully identified. At last, an acetamiprid-specific aptamer with the apparent dissociation constant (K d) estimated to be 4.98 μM was successfully obtained. Further work is ongoing to develop an aptamer-based detection method for field determination of this pesticides in agricultural products and environmental samples.
The aim of this study was to evaluate probiotic properties of ten
Streptococcus thermophilus
strains (st1 to st10) isolated from pickles in China. These strains all had β-galactosidase activity, ...which laid foundation for studying their probiotic properties. In this study, the bile salt hydrolase activity, lysozyme resistance, tolerance to simulated gastric juice, bile salt tolerance, and bacterial adhesion capacity to the Caco-2 cells of these selected strains were detected in vitro conditions. The results indicated that the bile salt hydrolase activities of st2, st6, and st9 were higher than that for other strains. St10 showed the greatest lysozyme resistance (> 80% survival), followed by st9, st8, st7, st5, and st6. As for the tolerance to simulated gastric juice, st5 possessed the highest survival rate (35%), followed by st6 (30%). St6 was the best performer in both bile salt tolerance and bacterial adhesion capacity to the Caco-2 cells. The results of fluorescence microscope and electron microscope further confirmed previous studies and more intuitively demonstrated the st6 strain's tolerance to harsh environments. Overall, these strains were expected to possess beneficial properties and have the potentiality to be probiotics.
Oenococcus oeni
can exert its function in hostile wine conditions during the malolactic fermentation process. Therefore, it is an important microbial resource for exploring resistance genes. Hsp20 is ...an important small heat shock protein from
O. oeni
. The conserved consensus motif “A-x-x-x-x-G-x-L” of Hsp20 announced its role as a member of the small heat shock protein family. The
hsp20
gene from
O. oeni
SD-2a was cloned to create the recombinant plasmid pTriEx-Hsp20. The recombinant plasmid was transformed into
Escherichia coli
BL21(DE3) competent cells, and the Hsp20 protein was induced by isopropyl-β-
d
-thiogalactoside (IPTG). The
hsp20
gene from
O. oeni
SD-2a was successfully expressed, and a 20-kDa fusion protein was identified by SDS-PAGE. The purified Hsp20 protein was obtained using Ni-affinity chromatography. Additionally, BL21(DE3)/Hsp20 and BL21(DE3)/Ctrl were treated at high temperatures of 42 and 52 °C, at pH values of 2.0–12.0, under oxidative shock with 0.1% (v/v) and 0.2% (v/v) H
2
O
2
, and under an osmotic shock of 430 and 860 mM NaCl to compare the effects of heterologous expression of the Hsp20 protein from
O. oeni
SD-2a for stress resistance. Notably, Hsp20 overexpression showed enhanced resistance than the control strain did when confronted with different elevated stress conditions. The results demonstrated heterologous expression of the
hsp20
gene from
O. oeni
SD-2a significantly improved the resistance of the host
E. coli
bacteria against stress conditions.
► The anti-fatigue effect of β-glucan was investigated. ► β-Glucan can significantly reduce the weight gain of rats and prolong their maximum running time. ► β-Glucan decreased BUN, LA levels and ...increased the NEFA and liver glycogen contents. ► β-Glucan decreased CK activity, and increased lactic dehydrogenase activity in serum.
Oat β-glucan was purified from oat bran and its effects on running performance and related biochemical parameters were investigated. Four-week-old male Sparsgue–Dawley rats, fed with/without oat β-glucan (312.5mgkg−1d−1) for 7 weeks, were subjected to run on a treadmill system to make them exhausted. All rats were immediately sacrificed after prolonged exercise, and the major metabolic substrates were measured in serum and liver. The results showed feeding dietary oat β-glucan to rats could significantly reduce the body weight and increase the maximum running time compared with normal control (P<0.05). Furthermore, dietary oat β-glucan decreased the levels of blood urea nitrogen, lactate acid, and creatine kinase activity in serum, and increased the levels of non-esterified fatty acids, lactic dehydrogenase activity in serum, and the content of liver glycogen. Therefore, the present study demonstrated that dietary oat β-glucan can enhance the endurance capacity of rats while facilitating their recovery from fatigue.
Aroma compounds in fruits and related products are known to occur in free and glycosidically bound forms. In this study, free and bound volatiles in juices and wines of two kiwifruit cultivars,
...Actinidia deliciosa
‘Hayward’ and
A. chinensis
‘Hort16A’, were analyzed by solid-phase microextraction-gas chromatography-mass spectrometry. Results showed that 67 free and 79 bound volatiles were found in juices and wines. Alcohols were the most abundant free volatiles, while the most representative bound volatiles were terpenoids.
β-
Damascenone and 4-methyl-3-penten-2-one released from aroma precursors were found in ‘Hort16A’ juice for the first time. Fruity, floral, and sweet flavors appeared to be the characteristic aroma in kiwifruit juices and wines. Principal component analysis showed that kiwifruit wines had a great aroma potential. Cluster analysis revealed that juices and wines had different profile of free volatiles, while similar bound volatile compositions were found. Moreover, abundant bound volatiles were discovered in these two kiwifruit pomace for the first time, indicating their potential applications in food and cosmetics industry.
Alicyclobacillus
acidoterrestris
is a major concern in fruit juice industry due to its spoilage potential of acidic fruit juice. Quantifying the expression levels of functional genes by real-time ...quantitative polymerase chain reaction (RT-qPCR) is necessary to elucidate the response mechanisms of
A. acidoterrestris
to acid stress. However, appropriate reference genes (RGs) for data normalization are required to obtain reliable RT-qPCR results. In this study, eight novel candidate RGs were screened based on transcriptome datasets of
A. acidoterrestris
under acid stress. The expression stability of eight new RGs and commonly used RG 16s rRNA was assessed using geNorm, NormFinder, and BestKeeper algorithms. Moreover, the comprehensive analysis using the RefFinder program and the validation using target gene
ctsR
showed that
dnaG
and
dnaN
were the optimal multiple RGs for normalization at pH 4.0;
ytvI
,
dnaG
, and 16s rRNA at pH 3.5;
icd
and
dnaG
at pH 3.0; and
ytv
I,
dnaG
, and
spoVE
at pH 2.5. This study revealed for the first time that
A. acidoterrestris
had different suitable RGs under different acid conditions, with implications for further deciphering the acid response mechanisms of this spoilage-causing bacterium.
Molybdenum nitride coatings were synthesized by ion-beam-assisted-deposition (IBAD). The effects of nitrogen partial pressure and bombarding ion energy on the phase formation were investigated. The ...coefficient of friction and wear resistance of the coatings in different environments were studied.
The stoichiometric ratio of nitrogen to Mo of the molybdenum nitride phases increases with the nitrogen partial pressure, and higher bombarding ion energy was helpful to form single MoN phase. Mo2N, MoN or mixture of the two phases could be prepared by controlling of the ratio of nitrogen/argon and ion energy. The hardness, coefficient of friction, wear and oxidation resistance of MoN were superior to that of Mo2N coating. The coefficient of friction decreased with the increase of testing temperature, yet the wear resistance became lower. The change of friction in non-oxidation atmosphere was reversed to that in the open air, indicating that the low friction of MoN at elevated temperature depends on oxidation. The tribological performance of the MoO3 phase formed by oxidation annealing showed much higher coefficient of friction than that of as-deposited MoN in all the testing conditions, and the oxygen deficient oxides were implied to be the lubricious phases.
►High energy ion bombardment is necessary to form single MoN phase. ►MoN is superior to Mo2N both in oxidation resistance and mechanical properties. ►The MoO3 phase by oxidation treated MoN is not a lubricant. ►The lubricious phase should be a molybdenum oxide with lower stoichiometric ratio of oxygen.
Based on comprehensive studies in petrography, petrofabric analysis and geochemistry, this paper describes a unique and rare laminated micritic ferruginous primary dolostone crystallized and ...precipitated from the alkaline hot brine under the conditions of the Mesozoic faulted lake basin. The main rock-forming mineral of this dolostone is ferruginous dolomite with a micritic structure. This dolomite mostly exhibits laminae of 0.1-1 mm thick and is often discovered with other minerals, such as albite, analcite, barite and dickite, which have at least two types of interbedded laminae. Petrogeochemistry reveals that this dolostone contains a large number of typomorphic elements of hydrothermal sedimentation, including Sb, Ba, Sr, Mn, and V. In addition, the LREE is in relatively high concentrations and possesses the typical REE distribution pattern with negative Eu anomaly. Oxygen isotope values （C~ISOpDB） range from 5.89%~ to 14.15%o with an average of 9.69%0. The ratio of 87Sr/86Sr is between 0.711648 and 0.719546, with an average of 0.714718. These data indicate that the depositional environment is a stable, blocked, anoxic low-lying hot brine pool in the bottom of deep lake controlled by basement faults. The hydrothermal fluid is the alkaline hot brine formed by the combination of the infiltration lake water and mantle-derived magmatic water, consisting of many ions, including Ca2＋, Mg2＋ and Fe2＋. Under the driving flow power of magmatic heat, gravity and compaction, the hy- drothermal fluid overcame the overburden pressure and hydrostatic pressure of the lake water body, and boiled to explosion, and then the explosion shattered the original laminated micritic ferruginous primary dolostone near the vent and then formed a new type of dolostone called shattered ＂hydroexplosion breccias＂. In the low-lying, unperturbed hot brine pool, far from the vent, the laminated micritic ferruginous primary dolostone was quickly crystallized and chemicals precipitated from the hy- drotherm. This study of special rocks contributes to research into the causes of the formation of lacustrine carbonate rocks and dolostone. In particular, it provides new examples and research insights for future studies of the lacustrine dolomite from the similar Mesozoic and Cenozoic basins in China.
This study explored the feasibility of degrading aflatoxin B1 (AFB1) in contaminated peanut meal by extrusion cooking. Peanut meal contaminated with AFB1 (35.8 ± 1.5 μg/kg) was extrusion-cooked in a ...twin-screw extruder and AFB1 was quantified by ELISA. The effects of barrel temperature, material moisture content, feed rate, and screw speed as well as their interactions on the reduction rate of AFB1 in peanuts meal were evaluated by Response surface methodology (RSM) to optimize the extrusion conditions. Under the optimal conditions (barrel temperature of 150 °C, material moisture content of 40 g/100 g, feed rate of 17 g/min, and screw speed of 152 rpm), 77.6 ± 2.2% of AFB1 was degraded. The barrel temperature and material moisture have significant influences (P < 0.01) on the degradation rate of AFB1, while the feed rate or screw speed has no significant influence.
•Aflatoxin B1 (AFB1) in peanut meal was efficiently degraded by extrusion cooking.•Response surface methodology was used to optimize the extrusion conditions.•The temperature and moisture influenced the degradation rate of AFB1.
Phloretin-2'-O-glycosyltransferase (P2'GT) catalyzes the last glycosylation step in the biosynthesis of phloridzin that contributes to the flavor, color and health benefits of apples and processed ...apple products. In this work, a novel P2'GT of Malus x domestica (MdP2'GT) with a specific activity of 46.82 μkat/Kg protein toward phloretin and uridine diphosphate glucose (UDPG) at an optimal temperature of 30 °C and pH 8.0 was purified from the engineered Pichia pastoris broth to homogeneity by anion exchange chromatography, His-Trap affinity chromatography and gel filtration. The purified MdP2'GT was low N-glycosylated and secreted as a stable dimer with a molecular mass of 70.7 kDa in its native form. Importantly, MdP2'GT also exhibited activity towards quercetin and adenosine diphosphate glucose (ADPG), kaempferol and UDPG, quercetin and UDP-galactose, isoliquiritigenin and UDPG, and luteolin and UDPG, producing only one isoquercitrin, astragalin, hyperoside, isoliquiritin, or cynaroside, respectively. This broad spectrum of activities make MdP2'GT a promising biocatalyst for the industrial preparation of the corresponding polyphenol glycosides, preferably for their subsequent isolation and purification. Besides, MdP2'GT displayed the lowest K
and the highest k
/K
for phloretin and UDPG compared to all previously reported P2'GTs, making MdP2'GT favor phloridzin synthesis the most.
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