Optimization of four types of antimicrobial agents to increase the inhibitory ability of marine Arthrobacter oxydans KQ 11 dextranase mouthwash

We adopted the response surface methodology using single factor and orthogonal experiments to optimize four types of antimicrobial agents that could inhibit biofilm formation by Streptococcus mutans, which is commonly found in the human oral cavity and causes tooth decay. The objective was to improve the function of marine Arthrobacter oxydans KQ11 dextranase mouthwash(designed and developed by our laboratory). The experiment was conducted in a three-level, four-variable central composite design to determine the best combination of Zn SO_4, lysozyme, citric acid and chitosan. The optimized antibacterial agents were 2.16 g/L Zn SO_4, 14 g/L lysozyme, 4.5 g/L citric acid and 5 g/L chitosan. The biofilm formation inhibition reached 84.49%. In addition, microscopic observation of the biofilm was performed using scanning electron microscopy and confocal laser scanning microscopy. The optimized formula was tested in marine dextranase Arthrobacter oxydans KQ11 mouthwash and enhanced the inhibition of S. mutans. This work may be promoted for the design and development of future marine dextranase oral care products.

Insights into microbiota community dynamics and flavor development mechanism during golden pomfret(Trachinotus ovatus)fermentation based on single-molecule real-time sequencing and molecular networking analysis

Popular fermented golden pomfret(Trachinotus ovatus)is prepared via spontaneous fermentation;however,the mechanisms underlying the regulation of its flavor development remain unclear.This study shows the roles of the complex microbiota and the dynamic changes in microbial community and flavor compounds during fish fermentation.Single-molecule real-time sequencing and molecular networking analysis revealed the correlations among different microbial genera and the relationships between microbial taxa and volatile compounds.Mechanisms underlying flavor development were also elucidated via KEGG based functional annotations.Clostridium,Shewanella,and Staphylococcus were the dominant microbial genera.Forty-nine volatile compounds were detected in the fermented fish samples,with thirteen identified as characteristic volatile compounds(ROAV>1).Volatile profiles resulted from the interactions among the microorganisms and derived enzymes,with the main metabolic pathways being amino acid biosynthesis/metabolism,carbon metabolism,and glycolysis/gluconeogenesis.This study demonstrated the approaches for distinguishing key microbiota associated with volatile compounds and monitoring the industrial production of high-quality fermented fish products.

Analysis of quality-related proteins in golden pompano(Trachinotus ovatus)fillets with modified atmosphere packaging under superchilling storage

Here,we aimed to study the changes in proteome of golden pompano fillets during post-mortem storage.Tandem mass tags(TMT)-labeled quantitative proteomic strategy was applied to investigate the relationships between protein changes and quality characteristics of modified atmosphere packaging(MAP)fillets during superchilling(-3°C)storage.Scanning electron microscopy was used to show that the muscle histology microstructure of fillets was damaged to varying degrees,and low-field nuclear magnetic resonance was used to find that the immobilized water and free water in the muscle of fillets changed significantly.Total sulfhydryl content,TCA-soluble peptides and Ca2+-ATPase activity also showed that the fillet protein had a deterioration by oxidation and denaturation.The Fresh(FS),MAP,and air packaging(AP)groups were set.Total of 150 proteins were identified as differential abundant proteins(DAPs)in MAP/FS,while 209 DAPs were in AP/FS group.The KEGG pathway analysis indicated that most DAPs were involved in binding proteins and protein turnover.Correlation analysis found that 52 DAPs were correlated with quality traits.Among them,8 highly correlated DAPs are expected to be used as potential quality markers for protein oxidation and water-holding capacity.These results provide a further understanding of the muscle deterioration mechanism of packaging golden pompano fillets during superchilling.

Novel insight into the formation and inhibition mechanism of dipeptidyl peptidase-Ⅳ inhibitory peptides from fermented mandarin fish(Chouguiyu)

Fermented foods are a potential source to produce novel dipeptidyl peptidase-IV inhibitory peptides(D4IPs).In this study,the fermented mandarin fish(Chouguiyu)was used to screen D4IPs and their formation mechanism was studied by metagenomics and peptidomics.A total of 400 D4IPs with DPP-IV inhibition structure and high hydrophobicity were identified.The correlation network map showed that Lactococcus,Bacillus,Lysobacter,Pelagivirga,Kocuria,Escherichia,Streptococcus,and Peptostreptococcus were significantly correlated with the most D4IPs.Four stable D4IPs,including KAGARALTDAETAT,GEKVDFDDIQK,VVDADEMYLKGK,and GQKDSYVGDEAQ were respectively from the precursor proteins parvalbumin,troponin,myosin,and actin,and were mainly formed by the hydrolysis of subtilisin(EC 3.4.21.62),aspartic proteinase(EC 3.4.23.1),thermolysin(EC 3.4.24.27),oligopeptidase B(EC 3.4.21.83),and proteinase P1(EC 3.4.21.96)from Bacillus,Kocuria,Lysobacter,Lactococcus,and Peptostreptococcus.The inhibition mainly resulted from the hydrogen bond and salt bridge between D4IPs and DPP-IV enzyme.This study provides important information on the proteases and related microbial strains to directionally prepare D4IPs in Chouguiyu.

A Rapid and Accurate CRISPR/Cas12b-Mediated Genotyping Assay for the Methylenetetrahydrofolate Reductase Gene Polymorphism C677T

Human methylenetetrahydrofolate reductase(MTHFR),an essential enzyme in folate metabolism,catalyzes the conversion of5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate.Several polymorphisms in the MTHFR gene have been found to be associated with reduced enzyme activity and related to folic acid intake in relevant populations[1].

Duplex Detection of Vibrio Cholerae and Vibrio Parahaemolyticus by Real-time Recombinase Polymerase Amplification

Vibrio cholerae and Vibrio parahaemolyticus are the two most commonly reported pathogens in seafood[1]. Consuming raw or undercooked seafood contaminated with these two Vibrio species can cause food poisoning, posing the risk of severe gastrointestinal illness and death[2-3]. Therefore,precise and reliable methods for detecting V. cholerae and V. parahaemolyticus contamination in seafood are essential for controlling food safety.

In vitro Antioxidant Effects of Porphyra haitanensis Peptides on H_2O_2-Induced Damage in HepG2 Cells

In this study,protein from Porphyra haitanensis was used as raw material to prepare an antioxidant peptide,and its antioxidant activity was evaluated in vitro.A model of H_2O_2-induced oxidative damage in Hep G2 cells was established,and the effects of Porphyra haitanensis hydrolysates (PHHs) on superoxide dismutase (SOD) activity and malondialdehyde (MDA) content were detected.Finally,the structure of PHHs was identified by ESI-MS/MS.The results showed that the 1,1-diphenyl-2-pyridylhydrazine(DPPH)-free radical-scavenging ability of PHHs was the strongest (59.28%at 1.0 mg m L~(-1)) when hydrolyzed with an acidic protease for 4 h.PHHs with different concentrations had protective effects on H_2O_2-induced damage to Hep G2 cells,and the protective effect was enhanced with increasing concentrations.When the level was 400μg m L~(-1),the cell survival rate was as high as 88.62%.Moreover,PHHs can significantly reduce oxidative damage to Hep G2 cells by H_2O_2,improve SOD activity,and reduce MDA content.The tetrapeptide Asp-Lys-Ser-Thr,with a molecular weight of 448 Da,was identified as an important fraction of PHHs by high-resolution mass spectrometry.

Mitochondrial genome of Chthamalus challengeri(Crustacea:Sessilia): gene order comparison within Chthamalidae and phylogenetic consideration within Balanomorpha

Acorn barnacles are important model species in researches on intertidal ecology, larval development and biofouling. At present, with the development of mitochondrial genomics, it is helpful to understand the phylogenetic relationship from the mitogenomic level. The complete mitochondrial genome of Chthamalus challengeri was presented. The genome is a circular molecule of 15 358 bp. Compared with other species in Balanomorpha, the non-coding region is longer, while the length of the genes is similar to the other species. The overall A+T content of the mitochondrial genome of C. challengeri is 70.5%. There are variations of initiation and stop codons in the known Balanomorpha mitochondrial genomes. The C. challengeri and C. antennatus within the same genus share the identical gene arrangement. However, the gene arrangement of different genera in Chthamalidae is different, as there is a translocation between two tRNA genes and an inversion involving a large gene block. In particular, both srRNA and lrRNA of the two species in Chthamalus are encoded in the heavy strand, differing from the former Balanomorpha species. The topology and gene arrangement in Chthamalidae support each other. Phylogenetic analysis indicates that the Chthamalidae is monophyletic, while the Balanidae and Archaeobalanidae are polyphyletic.

Studies on the comparative pharmacokinetic of three phenolic acids of Salvia miltiorrhiza Bunge in normal and hyperlipidemic rats by liquid chromatography-tandem mass spectrometry

The hydrophilic phenolic acid is the main component of Salvia miltiorrhiza Bunge against cardiovascular diseases.A validated and sensitive liquid chromatography-tandem mass spectrometry(LC-MS/MS)method was established to simultaneously determinate three phenolic acids(danshensu,protocatechuic acid and rosmarinic acid)in rats to investigate their pharmacokinetic profiles firstly.The values for limit of quantification were in range of 0.25-1.25μg/L.Meanwhile,the suitable intra-day and inter-day precision as well as extraction recoveries were also obtained.And such an established method was finally successfully applied to compare the pharmacokinetic behaviors of three phenolic acids in normal and hyperlipidemic rats after oral administration of Salvia miltiorrhiza Bunge.The results showed there were significant differences in pharmacokinetic parameters between normal and hyperlipidemic groups.In especial,the plasma level of three phenolic acids in hyperlipidemic groups was significantly higher than normal ones.This comparative pharmacokinetic study provided direct evidence for improving clinical rational use of Salvia miltiorrhiza Bunge.

Liensinine attenuates inflammation and oxidative stress in spleen tissue in an LPS-induced mouse sepsis model

Sepsis is a complex syndrome caused by multiple pathogens and involves multiple organ failure,particularly spleen dysfunction.In 2017,the worldwide incidence was 48.9 million sepsis cases and 1l million sepsis-related deaths were reported(Rudd et al.,2020).Inflammation,oxidative stress,and apoptosis are the most common pathologies seen in sepsis.Liensinine(LIE)is a bisbenzylisoquinoline-type alkaloid extracted from the seed embryo of Nelumbo nucifera.Lotus seed hearts have high content of LIE which mainly has antihypertensive and antiarrhythmic pharmacological effects.It can exert anti-carcinogenicactivityby regulating cell.

Scutellarin prevents acute alcohol-induced liver injury via inhibiting oxidative stress by regulating the Nrf2/HO-1 pathway and inhibiting inflammation by regulating the AKT,p38 MAPK/NF-κB pathways

Alcoholic liver disease(ALD)is the most frequent liver disease worldwide,resulting in severe harm to personal health and posing a serious burden to public health.Based on the reported antioxidant and anti-inflammatory capacities of scutellarin(SCU),this study investigated its protective role in male BALB/c mice with acute alcoholic liver injury after oral administration(10,25,and 50 mg/kg).The results indicated that SCU could lessen serum alanine aminotransferase(ALT)and aspartate aminotransferase(AST)levels and improve the histopathological changes in acute alcoholic liver;it reduced alcohol-induced malondialdehyde(MDA)content and increased glutathione peroxidase(GSH-Px),catalase(CAT),and superoxide dismutase(SOD)activity.Furthermore,SCU decreased tumor necrosis factor-α(TNF-α),interleukin-6(IL-6),and IL-1βmessenger RNA(mRNA)expression levels,weakened inducible nitric oxide synthase(iNOS)activity,and inhibited nucleotide-binding oligomerization domain(NOD)-like receptor protein 3(NLRP3)inflammasome activation.Mechanistically,SCU suppressed cytochrome P450 family 2 subfamily E member 1(CYP2E1)upregulation triggered by alcohol,increased the expression of oxidative stress-related nuclear factor erythroid 2-related factor 2(Nrf2)and heme oxygenase-1(HO-1)pathways,and suppressed the inflammation-related degradation of inhibitor of nuclear factor-κB(NF-κB)-α(IκBα)as well as activation of NF-κB by mediating the protein kinase B(AKT)and p38 mitogen-activated protein kinase(MAPK)pathways.These findings demonstrate that SCU protects against acute alcoholic liver injury via inhibiting oxidative stress by regulating the Nrf2/HO-1 pathway and suppressing inflammation by regulating the AKT,p38 MAPK/NF-κB pathways.

Rapid visual detection of Vibrio parahaemolyticus by combining LAMP-CRISPR/Cas12b with heat-labile uracil-DNA glycosylase to eliminate carry-over contamination

Vibrio parahaemolyticus is a major pathogen frequently found in seafood.Rapid and accurate detection of this pathogen is important for the control of bacterial foodborne diseases and to ensure food safety.In this study,we established a one-pot system that combines uracil-DNA glycosylase(UDG),loopmediated isothermal amplification(LAMP),and clustered regularly interspaced short palindromic repeats(CRISPR)/CRISPR-associated protein 12b(Cas12b)for detecting V.parahaemolyticus in seafood.This detection system can effectively perform identification using a single tube and avoid the risk of carryover contamination.

Light history modulates growth and photosynthetic responses of a diatom to ocean acidification and UV radiation

To examine the synergetic effects of ocean acidification(OA)and light intensity on the photosynthetic performance of marine diatoms,the marine centric diatom Thalassiosira weissflogii was cultured under ambient low CO_(2)(LC,390μatm)and elevated high CO_(2)(HC,1000μatm)levels under low-light(LL,60μmol m^(-2)s^(-1))or high-light(HL,220μmol m^(-2)s^(-1))conditions for over 20 generations.HL stimulated the growth rate by 128 and 99%but decreased cell size by 9 and 7%under LC and HC conditions,respectively.However,HC did not change the growth rate under LL but decreased it by 9%under HL.LL combined with HC decreased both maximum quantum yield(FV/FM)and effective quantum yield(ΦPSII),measured under either low or high actinic light.When exposed to UV radiation(UVR),LL-grown cells were more prone to UVA exposure,with higher UVA and UVR inducing inhibition ofΦPSII compared with HL-grown cells.Light use efficiency(α)and maximum relative electron transport rate(rETRmax)were inhibited more in the HC-grown cells when UVR(UVA and UVB)was present,particularly under LL.Our results indicate that the growth light history influences the cell growth and photosynthetic responses to OA and UVR.

Pseudomonas aeruginosa-induced mitochondrial dysfunction inhibits proinflammatory cytokine secretion and enhances cytotoxicity in mouse macrophages in a reactive oxygen species(ROS)-dependent way

Pseudomonas aeruginosa belongs to the genus Pseudomonas and is a common Gram-negative,exclusively aerobic,conditionally pathogenic bacterium with the characteristics of easy colonization,mutation,and multidrug resistance(Deng et al.,2015;Azam and Khan,2019;Jurado-Martin et al.,2021).

Ameliorative effect of scutellarin on acute alcohol brain injury in mice

Drinking culture has high significance in both China and the world,whether in the entertainment sector or in social occasions;according to the World Health Organization's 2018 Global Alcohol and Health Report,about 3 million people died from excessive drinking in 2016,accounting for 5.3%of the total global deaths that year.Oxidative stress and inflammation are the most common pathological phenomena caused by alcohol abuse(Snyder et al.,2017).

Fluorescence characterization and microbial degradation of dissolved organic matter leached from salt marsh plants in the Yellow River Delta

盐沼植被是沿海水体中溶解有机物(Dissolved Organic Matter,DOM)的重要贡献者。然而,不同盐沼植物释放DOM的动力学特征尚缺乏系统研究和比较。黄河三角洲湿地是中国东海岸面积最大,保护最完善的沿海生态系统之一。本论文研究了2016年10月从黄河三角洲(Yellow River Delta,YRD)盐沼中采集的三种常见沼泽植物(芦苇(Phragmites australis),碱蓬(Suaeda salsa)和獐茅(Aeluropus littoralis)的DOM释放过程。通过测定溶解有机碳(Dissolved Organic Carbon,DOC)和溶解氮(Dissolved Nitrogen,DN)发现,植物叶片释放的DOM浓度远高于其根和茎。在27天的培养期内,平均有15%的生物碳和30%的生物氮以DOC和DN的形式通过植物叶片释放。从植物中释放的DOM非常不稳定,在27天的培养期内,细菌共消耗了92.4%-98.1%的DOC和88.0%-94.6%的DN。植物释放DOM的荧光特性表明,发色溶解的有机物(Chromophoric Dissolved Organic Matter,CDOM)是DOM的主要组分,而类蛋白组分是植物释放CDOM的主要组分。细菌的降解作用改变了DOM的荧光性质和化学组成。上述的室内研究结果得到了实地调查的充分支撑,表明在深秋时期黄河口湿地有大量DOM溢出。本研究结果表明,盐沼植物释放的DOM是沼泽和沿海水域DOC和DN的重要来源,而且易降解DOC和DN为黄河口湿地和邻近沿海水域中的微生物群落提供了重要的食物来源。

Novel potential XOD inhibitory peptides derived from Trachinotus ovatus:Isolation,identification and structure-function analysis

This study aimed to isolate and identify the novel potential Xanthine oxidase(XOD)inhibitory peptides derived from Trachinotus ovatus hydrolysate(TOH)(hydrolysis by neutral protease),and investigate their structure-function relationship.Initially,TOH was separated to four fractions(F1–F4)by gel filtration chromatography and F4 was chosen with higher XOD inhibitory rate(85.16%±0.566,25 mg/mL)and lower molecular weight(95.73%,<1000 Da).F4 was further characterized by reversed-phase high performance liquid chromatography(RP-HPLC)coupled with Nano-HPLC-MS/MS and four peptides(FPAW,LLPW,WLLP and FHLP)were identified with IC50 value of 3.81±0.18 mM,4.17±0.12 mM,43.06±0.73 mM,and over 50.00 mM respectively.It can be concluded that Trp-containing peptides especially located in C-terminal could inhibit XOD effectively.Moreover,the XOD-inhibiting actions of these peptides involvedπ-πstacking(Phe914 and Phe1009 in XOD),hydrogen bonding via molecular docking.Lineweaver-Burk equation showed the inhibition type of FPAW was a mixed inhibition.Circular dichroism(CD)spectra indicated FPAW could combine and change the secondary structure of XOD.Therefore,two peptides of FPAW and LLPW might have potential to be used to alleviate hyperuricemia in the future.

Development of environmentally friendly biological algicide and biochemical analysis of inhibitory effect of diatom Skeletonema costatum

Skeletonema costatum is a diatom widely distributed in red tide microalgae blooms and as one of the main algae causing harmful algal blooms,because of their rapid reproduction and production of toxic and harmful substances,often play a negative role in aquatic ecosystems,and human health and wellbeing.Bacillomycin D is a nonribosomal cyclic antifungal lipopeptide in the iturins family.In this study,Bacillomycin D was tested for its ability to inhibit the growth of S.costatum.The EC_(50 24h) of Bacillomycin D on S.costatum was 24.70μg/mL.The chlorophyll fluorescence parameters F_(v)/F_(m),F_(v)/F_(o),and yield of the diatoms decreased significantly with increasing concentrations of Bacillomycin D.Study of the mechanism showed that Bacillomycin D induced cell death by changing cell membrane permeability,promoting the release of cellular contents.In this study,transcriptomic analysis showed Bacillomycin D significantly inhibited the photosynthesis and metabolism of S.costatum.These findings investigated the inhibitory effect of Bacillomycin D on the growth of S.costatum and provided a theoretical foundation for the development of new environmentally friendly biological algicide.

Polymorphisms in the FOXO gene are associated with growth traits in the Sanmen breeding population of the razor clam Sinonovacula constricta

We identified the FOXO gene and five single-nucleotide polymorphisms(SNPs)in its coding region in the Sanmen breeding population of the razor clam Sinonovacula constricta.The ScFOXO gene encodes a protein of 625 amino acids in length that contains a conserved DNA-binding domain.Real-time polymerase chain reaction analysis showed that ScFOXO mRNA is widely expressed in adult tissues,with higher expression in the siphons and gills.Of the SNPs,c.879G>C(Val293Val)and c.1725A>G(Ser575Ser)are synonymous mutations,and c.543C>T(Phe181Leu),c.848A>G(Tyr283Cys),and c.1625G>C(Gly542Phe)are non-synonymous mutations.The SNPs all show significant associations with total body weight,shell length,shell width,and shell height(SH)in this population.Polymorphic parameter analysis showed that all SNPs except c.848A>G(Tyr283Cys)exhibit complete linkage.The SNP c.1625G>C(Gly542Phe)was used for genetic linkage mapping and demonstrates the strongest linkage(logarithm of the odds[LOD]value:41.46)with the marker 96616(37.02 cM)in the linkage group 9.The LOD value of this marker in relation to growth traits ranges from 1.04 to 1.53;only markers with a LOD value
3 were considered to be linked with growth traits in the razor clam linkage map.In summary,ScFOXO may be a growth trait-related gene and may represent a marker for Sanmen breeding group selection.