Pseudomonas fluorescens is a widespread spoilage bacterium in food,and its spoilage characteristics and biofilm formation are regulated by N-acyl-homoserine lactone(AHLs)quorum sensing(QS)system.Quorum quenching(QQ)is...Pseudomonas fluorescens is a widespread spoilage bacterium in food,and its spoilage characteristics and biofilm formation are regulated by N-acyl-homoserine lactone(AHLs)quorum sensing(QS)system.Quorum quenching(QQ)is considered as an effective strategy to control the spoilage bacteria.Therefore,this study revealed a new QQ bacteria Lactiplantibacillus plantarumYP4-1-2.Notably,the crude cell extract(CCE)from L.plantarum YP4-1-2 showed strongly QQ activity against the AHLs of P.fluorescens.The degradation rate of AHLs(N-octanoyl-L-homoserine lactone)reached 25.90%,78.57%and 100%at theCCE protein concentrations of 57,86 and 114 g/mL,respectively.In addition,the CCE could drastically reduce the formation of biofilm,bacterial motility(swimming and swarming),and the release of extracellular protease and biogenic amines of P.fluorescens.Real-time polymerase chain reaction(PCR)results revealed that the CCE downregulated QS-related genes(rhlI,rhlR,aprX,algA,orm,flgA,and ldcA).Finally,using whole-genome sequencing analysis,the active substance in the CCE was identified to be penicillin V acylase(PVA)and named LpPVA.Meanwhile,homologous modeling and molecular docking analysis showed that the binding effect of LpPVA on long-chain AHLs was better than that on short-chain AHLs.This study demonstrated that L.plantarum YP4-1-2 could be considered as a promising QS inhibitor and antibiofilm agent against foodborne spoilage bacteria.展开更多
This paper deals with dynamic airspace sectorization （DAS） problem by an improved genetic algorithm （iGA）. A graph model is first constructed that represents the airspace static structure. Then the DAS problem is ...This paper deals with dynamic airspace sectorization （DAS） problem by an improved genetic algorithm （iGA）. A graph model is first constructed that represents the airspace static structure. Then the DAS problem is formulated as a graph-partitioning problem to balance the sector workload under the premise of ensuring safety. In the iGA, multiple populations and hybrid coding are applied to determine the optimal sector number and airspace sectorization. The sector constraints are well satisfied by the improved genetic operators and protect zones. This method is validated by being applied to the airspace of North China in terms of three indexes, which are sector balancing index, coordination workload index and sector average flight time index. The improvement is obvious, as the sector balancing index is reduced by 16.5 %, the coordination workload index is reduced by 11.2 %, and the sector average flight time index is increased by 11.4 % during the peak-hour traffic.展开更多
In parallel and distributed computing, development of an efficient static task scheduling algorithm for directed acyclic graph (DAG) applications is an important problem. The static task scheduling problem is NP-compl...In parallel and distributed computing, development of an efficient static task scheduling algorithm for directed acyclic graph (DAG) applications is an important problem. The static task scheduling problem is NP-complete in its general form. The complexity of the problem increases when task scheduling is to be done in a heterogeneous environment, consisting of processors with varying processing capabilities and network links with varying bandwidths. List scheduling algorithms are generally preferred since they generate good quality schedules with less complexity. But these list algorithms leave a lot of room for improvement, especially when these algorithms are used in specialized heterogeneous environments This paper presents an hybrid genetic task scheduling algorithm for the tasks run on the network of heterogeneous systems and represented by Directed Acyclic Graphs (DAGs). First, the algorithm assigns a coupling factor to each task to present the tasks should be scheduled onto the same processor by avoiding the large communication time. Second, the algorithm generate some high quality initial solution by scheduling the tasks which are strongly coupled with each other onto the same processor, and improve the quality of the solution by using coupling initial solutions, random solution, near optimal solutions obtained by the list scheduling algorithm in the crossover and mutation operator. The performance of the algorithm is illustrated by comparing with the existing effectively scheduling algorithms.展开更多
This study screened for the inhibitory peptides from the collagen of barracuda fish skin then determined its inhibitory effect on hyperlipidemia.The results showed that the collagen was type I,mainly containingα1,α2...This study screened for the inhibitory peptides from the collagen of barracuda fish skin then determined its inhibitory effect on hyperlipidemia.The results showed that the collagen was type I,mainly containingα1,α2,andβchains.Scanning electron microscopy revealed the fiber structure,sheet structure,multilayer aggregation structure,which was loose and porous.For an optimal enzymatic digestion process the pH was 10,the dosage of alkaline protease was 3000 U/g,and the temperature 50℃,with a degree of hydrolysis of 26.03%.The peptides of less than 1 KDa were selected by protein ultrafiltration and LC-MS identification revealed 220 peptides.The results indicated that GAPGFPGPR can be the best inhibitory peptide based on its bioactivity,water solubility,toxicity,ADMET and molecular docking technology.In vitro experiment showed that the GAPGFPGPR had significant inhibitory effects on the cholesterol ester transfer protein.The zebrafish experiment further verified that the GAPGFPGPR significantly reduced the total cholesterol,triacylglycerol,low-density lipoprotein cholesterol levels and increased the high-density lipoprotein cholesterol levels in the hyperlipidemia model.Therefore,the study has demonstrated the potented for developing health care products or drugs to improve hyperlipidemia.展开更多
As predominant culprits in food spoilage,Pseudomonas spp.,primarily Pseudomonas fluorescens,can form biofilms on food contact surfaces or in food-processing environments.This biofilm matrix can act as a protective bar...As predominant culprits in food spoilage,Pseudomonas spp.,primarily Pseudomonas fluorescens,can form biofilms on food contact surfaces or in food-processing environments.This biofilm matrix can act as a protective barrier for viable bacteria to prevent the penetration of antibacterial agents.This emphasizes the need to develop effective strategies to control Pseudomonas fluorescens biofilms.Natural products are considered the main source of eco-friendly antibiofilm agents.In this review,recent findings examining the effects of promising multi-targeted natural products against Pseudomonas fluorescens biofilms are summarized.Hopefully,this review can provide valuable insights into potential research targets and antibiofilm agents for further application in the food industry.展开更多
The changes in microbial composition of salmon slices during storage at 4◦C were measured using high-throughput sequencing(HTS),and biogenic amine(BA)-producing bacteria were isolated from salmon slices to evaluate th...The changes in microbial composition of salmon slices during storage at 4◦C were measured using high-throughput sequencing(HTS),and biogenic amine(BA)-producing bacteria were isolated from salmon slices to evaluate their ability to produce BAs.Fresh salmon slices had the highest bacterial diversity,which decreased with the extension of the refrigerated storage time.Phenylobacterium was the dominating genus in fresh salmon slices,followed by Photobacterium and Burkholderia,while Brochothrix became the dominant bacterium in the later stages of the storage period.Seven strains of BA-producing bacteria were isolated and determined,which varied greatly in BA production.Among these,Brochothrix thermosphacta(B5)exhibited the strongest BA-producing ability,producing 98.32 mg/mL of putrescine and 78.81 mg/mL of cadaverine,and Photobacterium phosphoreum showed a stronger histamine-producing ability(77.07 mg/mL).This study explored the microbial composition in salmon slices and offer insight into the relationship between microorganisms and BAs in salmon slices.This study provides a theoretical basis for developing antibacterial agents,decreasing the amount BAs,and extending the shelf-life of salmon slices.展开更多
基金supported by the Open Foundation of Oceanology Research Institute of Bohai University(BDHYYJY2020002).
文摘Pseudomonas fluorescens is a widespread spoilage bacterium in food,and its spoilage characteristics and biofilm formation are regulated by N-acyl-homoserine lactone(AHLs)quorum sensing(QS)system.Quorum quenching(QQ)is considered as an effective strategy to control the spoilage bacteria.Therefore,this study revealed a new QQ bacteria Lactiplantibacillus plantarumYP4-1-2.Notably,the crude cell extract(CCE)from L.plantarum YP4-1-2 showed strongly QQ activity against the AHLs of P.fluorescens.The degradation rate of AHLs(N-octanoyl-L-homoserine lactone)reached 25.90%,78.57%and 100%at theCCE protein concentrations of 57,86 and 114 g/mL,respectively.In addition,the CCE could drastically reduce the formation of biofilm,bacterial motility(swimming and swarming),and the release of extracellular protease and biogenic amines of P.fluorescens.Real-time polymerase chain reaction(PCR)results revealed that the CCE downregulated QS-related genes(rhlI,rhlR,aprX,algA,orm,flgA,and ldcA).Finally,using whole-genome sequencing analysis,the active substance in the CCE was identified to be penicillin V acylase(PVA)and named LpPVA.Meanwhile,homologous modeling and molecular docking analysis showed that the binding effect of LpPVA on long-chain AHLs was better than that on short-chain AHLs.This study demonstrated that L.plantarum YP4-1-2 could be considered as a promising QS inhibitor and antibiofilm agent against foodborne spoilage bacteria.
基金funded by the Joint Funds of the National Natural Science Foundation of China (61079001)
文摘This paper deals with dynamic airspace sectorization （DAS） problem by an improved genetic algorithm （iGA）. A graph model is first constructed that represents the airspace static structure. Then the DAS problem is formulated as a graph-partitioning problem to balance the sector workload under the premise of ensuring safety. In the iGA, multiple populations and hybrid coding are applied to determine the optimal sector number and airspace sectorization. The sector constraints are well satisfied by the improved genetic operators and protect zones. This method is validated by being applied to the airspace of North China in terms of three indexes, which are sector balancing index, coordination workload index and sector average flight time index. The improvement is obvious, as the sector balancing index is reduced by 16.5 %, the coordination workload index is reduced by 11.2 %, and the sector average flight time index is increased by 11.4 % during the peak-hour traffic.
文摘In parallel and distributed computing, development of an efficient static task scheduling algorithm for directed acyclic graph (DAG) applications is an important problem. The static task scheduling problem is NP-complete in its general form. The complexity of the problem increases when task scheduling is to be done in a heterogeneous environment, consisting of processors with varying processing capabilities and network links with varying bandwidths. List scheduling algorithms are generally preferred since they generate good quality schedules with less complexity. But these list algorithms leave a lot of room for improvement, especially when these algorithms are used in specialized heterogeneous environments This paper presents an hybrid genetic task scheduling algorithm for the tasks run on the network of heterogeneous systems and represented by Directed Acyclic Graphs (DAGs). First, the algorithm assigns a coupling factor to each task to present the tasks should be scheduled onto the same processor by avoiding the large communication time. Second, the algorithm generate some high quality initial solution by scheduling the tasks which are strongly coupled with each other onto the same processor, and improve the quality of the solution by using coupling initial solutions, random solution, near optimal solutions obtained by the list scheduling algorithm in the crossover and mutation operator. The performance of the algorithm is illustrated by comparing with the existing effectively scheduling algorithms.
基金supported by the Open Fund of Institute of Ocean Research,Bohai University(BDHYYJY2024003).
文摘This study screened for the inhibitory peptides from the collagen of barracuda fish skin then determined its inhibitory effect on hyperlipidemia.The results showed that the collagen was type I,mainly containingα1,α2,andβchains.Scanning electron microscopy revealed the fiber structure,sheet structure,multilayer aggregation structure,which was loose and porous.For an optimal enzymatic digestion process the pH was 10,the dosage of alkaline protease was 3000 U/g,and the temperature 50℃,with a degree of hydrolysis of 26.03%.The peptides of less than 1 KDa were selected by protein ultrafiltration and LC-MS identification revealed 220 peptides.The results indicated that GAPGFPGPR can be the best inhibitory peptide based on its bioactivity,water solubility,toxicity,ADMET and molecular docking technology.In vitro experiment showed that the GAPGFPGPR had significant inhibitory effects on the cholesterol ester transfer protein.The zebrafish experiment further verified that the GAPGFPGPR significantly reduced the total cholesterol,triacylglycerol,low-density lipoprotein cholesterol levels and increased the high-density lipoprotein cholesterol levels in the hyperlipidemia model.Therefore,the study has demonstrated the potented for developing health care products or drugs to improve hyperlipidemia.
基金supported by the Open Fund of Institute of Ocean Research,Bohai University(BDHYYJY2023005)Doctoral Research Foundation of Bohai University(05013/0523bs019).
文摘As predominant culprits in food spoilage,Pseudomonas spp.,primarily Pseudomonas fluorescens,can form biofilms on food contact surfaces or in food-processing environments.This biofilm matrix can act as a protective barrier for viable bacteria to prevent the penetration of antibacterial agents.This emphasizes the need to develop effective strategies to control Pseudomonas fluorescens biofilms.Natural products are considered the main source of eco-friendly antibiofilm agents.In this review,recent findings examining the effects of promising multi-targeted natural products against Pseudomonas fluorescens biofilms are summarized.Hopefully,this review can provide valuable insights into potential research targets and antibiofilm agents for further application in the food industry.
基金This work was supported by the National Key Research and Development Program of China(Grant Number 2019YFD0901702).
文摘The changes in microbial composition of salmon slices during storage at 4◦C were measured using high-throughput sequencing(HTS),and biogenic amine(BA)-producing bacteria were isolated from salmon slices to evaluate their ability to produce BAs.Fresh salmon slices had the highest bacterial diversity,which decreased with the extension of the refrigerated storage time.Phenylobacterium was the dominating genus in fresh salmon slices,followed by Photobacterium and Burkholderia,while Brochothrix became the dominant bacterium in the later stages of the storage period.Seven strains of BA-producing bacteria were isolated and determined,which varied greatly in BA production.Among these,Brochothrix thermosphacta(B5)exhibited the strongest BA-producing ability,producing 98.32 mg/mL of putrescine and 78.81 mg/mL of cadaverine,and Photobacterium phosphoreum showed a stronger histamine-producing ability(77.07 mg/mL).This study explored the microbial composition in salmon slices and offer insight into the relationship between microorganisms and BAs in salmon slices.This study provides a theoretical basis for developing antibacterial agents,decreasing the amount BAs,and extending the shelf-life of salmon slices.
