Large-scale phylogenomics of aquatic bacteria reveal molecular mechanisms for adaptation to salinity

The crossing of environmental barriers poses major adaptive challenges. Rareness of freshwater-marine transi-tions separates the bacterial communities, but how these are related to brackish counterparts remains elusive, as do the molecular adaptations facilitating cross-biome transitions. We conducted large-scale phylogenomic analysis of freshwater, brackish, and marine quality-filtered metagenome-assembled genomes (11,248). Average nucleotide identity analyses showed that bacterial species rarely existed in multiple biomes. In contrast, distinct brackish basins cohosted numerous species, but their intraspecific population structures displayed clear signs of geographic separation. We further identified the most recent cross-biome transitions, which were rare, ancient, and most commonly directed toward the brackish biome. Transitions were accompanied by systematic changes in amino acid composition and isoelectric point distributions of inferred proteomes, which evolved over millions of years, as well as convergent gains or losses of specific gene functions. Therefore, adaptive chal-lenges entailing proteome reorganization and specific changes in gene content constrains the cross-biome tran-sitions, resulting in species-level separation between aquatic biomes

Lipid engineering combined with systematic metabolic engineering of <i>Saccharomyces cerevisiae</i> for high-yield production of lycopene

Saccharomyces cerevisiae is an efficient host for natural-compound production and preferentially employed in academic studies and bioindustries. However, S. cerevisiae exhibits limited production capacity for lipophilic natural products, especially compounds that accumulate intracellularly, such as polyketides and carotenoids, with some engineered compounds displaying cytotoxicity. In this study, we used a nature-inspired strategy to establish an effective platform to improve lipid oil–triacylglycerol (TAG) metabolism and enable increased lycopene accumulation. Through systematic traditional engineering methods, we achieved relatively high-level production at 56.2 mg lycopene/g cell dry weight (cdw). To focus on TAG metabolism in order to increase lycopene accumulation, we overexpressed key genes associated with fatty acid synthesis and TAG production, followed by modulation of TAG fatty acyl composition by overexpressing a fatty acid desaturase (OLE1) and deletion of Seipin (FLD1), which regulates lipid-droplet size. Results showed that the engineered strain produced 70.5 mg lycopene/g cdw, a 25% increase relative to the original high-yield strain, with lycopene production reaching 2.37 g/L and 73.3 mg/g cdw in fed-batch fermentation and representing the highest lycopene yield in S. cerevisiae reported to date. These findings offer an effective strategy for extended systematic metabolic engineering through lipid engineering

Phylogenetic analysis of aquatic microbiomes : Evolution of the brackish microbiome

Microorganisms play crucial roles in aquatic environments in determining ecosystemstability and driving the turnover of elements essential to life. Understanding thedistribution and evolution of aquatic microorganisms will help us predict how aquaticecosystems will respond to Global Change, and such understanding can be gained bystudying these processes of the past. In this project, we investigate the evolutionaryrelationship between brackish water bacteria from the Baltic Sea and Caspian Seawith freshwater and marine bacteria, with the goal of understanding how brackishwater bacteria have evolved. 11,276 bacterial metagenome-assembled genomes(MAGs) from seven metagenomic datasets were used to conduct a comparativeanalysis of freshwater, brackish and marine bacteria. When clustering the genomes bypairwise average nucleotide identity (ANI) at the approximate species level (96.5%ANI), the Baltic Sea genomes were more likely to form clusters with the Caspian Seagenomes than with Swedish lakes genomes, even though geographic distancesbetween Swedish lakes and the Baltic Sea are much smaller. Phylogenomic analysisand ancestral state reconstruction showed that approximately half of the brackishMAGs had freshwater ancestors and half had marine ancestors. Phylogeneticdistances were on average shorter to freshwater ancestors, but when subsampling thetree to the same number of freshwater and marine MAG clusters, the distances werenot significantly different. Brackish genomes belonging to Acidimicrobiia,Actinobacteria and Cyanobacteriia tended to originate from freshwater bacteria, whilethose of Alphaproteobacteria and Bacteroidia mainly had evolved from marinebacteria.Mikroorganismer spelar avgörande roller i akvatiska ekosystem där de driverkretsloppen av näringsämnen. En ökad förståelse för hur mikroorganismer anpassarsig till miljöförändringar är viktigt för att förutsäga hur akvatiska ekosystem kommeratt förändras som en konsekvens av global uppvärmning, och sådan förståelse kanuppnås genom att studera tidigare skeenden i evolutionen. I detta projekt undersökervi det evolutionära förhållandet mellan brackvatten-bakterier från Östersjön ochKaspiska havet med sötvattens- och marina bakterier, med målet att förstå hurbrackvatten-bakterier har utvecklats. 11,276 bakteriella arvsmassor somrekonstruerats med metagenomik från sju data-set användes för att utföra enjämförande analys av bakterie-genom från söt-, brack och havsvatten. Klustring avgenomen baserat på parvis genomsnittlig nukleotididentitet (ANI) på ungefärligartnivå (96,5% ANI), grupperade Östersjöns bakterier tillsammans med Kaspiskahavets bakterier mer än med bakterier från svenska sjöar, trots att det geografiskaavståndet mellan svenska sjöar och Östersjön är mycket mindre. Fylogenetisk analysvisade att ungefär hälften av brackvatten arterna hade anfäder från sötvatten ochhälften från havsvatten. De fylogenetiska avstånden var i genomsnitt kortare tillanfaderna i sötvatten, men när man reducerade trädet till att ha samma antal sötvattenoch marina arter var avstånden inte längre signifikant olika. Brackvatten-arter somtillhörde Acidimicrobiia, Actinobacteria och Cyanobacteriia tenderade att härstammafrån sötvattenbakterier, medan de från Alphaproteobacteria och Bacteroidia främsthärstammade från marina bakterier

Phylogenetic analysis of aquatic microbiomes : Evolution of the brackish microbiome

Microorganisms play crucial roles in aquatic environments in determining ecosystemstability and driving the turnover of elements essential to life. Understanding thedistribution and evolution of aquatic microorganisms will help us predict how aquaticecosystems will respond to Global Change, and such understanding can be gained bystudying these processes of the past. In this project, we investigate the evolutionaryrelationship between brackish water bacteria from the Baltic Sea and Caspian Seawith freshwater and marine bacteria, with the goal of understanding how brackishwater bacteria have evolved. 11,276 bacterial metagenome-assembled genomes(MAGs) from seven metagenomic datasets were used to conduct a comparativeanalysis of freshwater, brackish and marine bacteria. When clustering the genomes bypairwise average nucleotide identity (ANI) at the approximate species level (96.5%ANI), the Baltic Sea genomes were more likely to form clusters with the Caspian Seagenomes than with Swedish lakes genomes, even though geographic distancesbetween Swedish lakes and the Baltic Sea are much smaller. Phylogenomic analysisand ancestral state reconstruction showed that approximately half of the brackishMAGs had freshwater ancestors and half had marine ancestors. Phylogeneticdistances were on average shorter to freshwater ancestors, but when subsampling thetree to the same number of freshwater and marine MAG clusters, the distances werenot significantly different. Brackish genomes belonging to Acidimicrobiia,Actinobacteria and Cyanobacteriia tended to originate from freshwater bacteria, whilethose of Alphaproteobacteria and Bacteroidia mainly had evolved from marinebacteria.Mikroorganismer spelar avgörande roller i akvatiska ekosystem där de driverkretsloppen av näringsämnen. En ökad förståelse för hur mikroorganismer anpassarsig till miljöförändringar är viktigt för att förutsäga hur akvatiska ekosystem kommeratt förändras som en konsekvens av global uppvärmning, och sådan förståelse kanuppnås genom att studera tidigare skeenden i evolutionen. I detta projekt undersökervi det evolutionära förhållandet mellan brackvatten-bakterier från Östersjön ochKaspiska havet med sötvattens- och marina bakterier, med målet att förstå hurbrackvatten-bakterier har utvecklats. 11,276 bakteriella arvsmassor somrekonstruerats med metagenomik från sju data-set användes för att utföra enjämförande analys av bakterie-genom från söt-, brack och havsvatten. Klustring avgenomen baserat på parvis genomsnittlig nukleotididentitet (ANI) på ungefärligartnivå (96,5% ANI), grupperade Östersjöns bakterier tillsammans med Kaspiskahavets bakterier mer än med bakterier från svenska sjöar, trots att det geografiskaavståndet mellan svenska sjöar och Östersjön är mycket mindre. Fylogenetisk analysvisade att ungefär hälften av brackvatten arterna hade anfäder från sötvatten ochhälften från havsvatten. De fylogenetiska avstånden var i genomsnitt kortare tillanfaderna i sötvatten, men när man reducerade trädet till att ha samma antal sötvattenoch marina arter var avstånden inte längre signifikant olika. Brackvatten-arter somtillhörde Acidimicrobiia, Actinobacteria och Cyanobacteriia tenderade att härstammafrån sötvattenbakterier, medan de från Alphaproteobacteria och Bacteroidia främsthärstammade från marina bakterier

Phylogenetic analysis of aquatic microbiomes : Evolution of the brackish microbiome

Microorganisms play crucial roles in aquatic environments in determining ecosystemstability and driving the turnover of elements essential to life. Understanding thedistribution and evolution of aquatic microorganisms will help us predict how aquaticecosystems will respond to Global Change, and such understanding can be gained bystudying these processes of the past. In this project, we investigate the evolutionaryrelationship between brackish water bacteria from the Baltic Sea and Caspian Seawith freshwater and marine bacteria, with the goal of understanding how brackishwater bacteria have evolved. 11,276 bacterial metagenome-assembled genomes(MAGs) from seven metagenomic datasets were used to conduct a comparativeanalysis of freshwater, brackish and marine bacteria. When clustering the genomes bypairwise average nucleotide identity (ANI) at the approximate species level (96.5%ANI), the Baltic Sea genomes were more likely to form clusters with the Caspian Seagenomes than with Swedish lakes genomes, even though geographic distancesbetween Swedish lakes and the Baltic Sea are much smaller. Phylogenomic analysisand ancestral state reconstruction showed that approximately half of the brackishMAGs had freshwater ancestors and half had marine ancestors. Phylogeneticdistances were on average shorter to freshwater ancestors, but when subsampling thetree to the same number of freshwater and marine MAG clusters, the distances werenot significantly different. Brackish genomes belonging to Acidimicrobiia,Actinobacteria and Cyanobacteriia tended to originate from freshwater bacteria, whilethose of Alphaproteobacteria and Bacteroidia mainly had evolved from marinebacteria.Mikroorganismer spelar avgörande roller i akvatiska ekosystem där de driverkretsloppen av näringsämnen. En ökad förståelse för hur mikroorganismer anpassarsig till miljöförändringar är viktigt för att förutsäga hur akvatiska ekosystem kommeratt förändras som en konsekvens av global uppvärmning, och sådan förståelse kanuppnås genom att studera tidigare skeenden i evolutionen. I detta projekt undersökervi det evolutionära förhållandet mellan brackvatten-bakterier från Östersjön ochKaspiska havet med sötvattens- och marina bakterier, med målet att förstå hurbrackvatten-bakterier har utvecklats. 11,276 bakteriella arvsmassor somrekonstruerats med metagenomik från sju data-set användes för att utföra enjämförande analys av bakterie-genom från söt-, brack och havsvatten. Klustring avgenomen baserat på parvis genomsnittlig nukleotididentitet (ANI) på ungefärligartnivå (96,5% ANI), grupperade Östersjöns bakterier tillsammans med Kaspiskahavets bakterier mer än med bakterier från svenska sjöar, trots att det geografiskaavståndet mellan svenska sjöar och Östersjön är mycket mindre. Fylogenetisk analysvisade att ungefär hälften av brackvatten arterna hade anfäder från sötvatten ochhälften från havsvatten. De fylogenetiska avstånden var i genomsnitt kortare tillanfaderna i sötvatten, men när man reducerade trädet till att ha samma antal sötvattenoch marina arter var avstånden inte längre signifikant olika. Brackvatten-arter somtillhörde Acidimicrobiia, Actinobacteria och Cyanobacteriia tenderade att härstammafrån sötvattenbakterier, medan de från Alphaproteobacteria och Bacteroidia främsthärstammade från marina bakterier

The effects of external cues on cross-border e-commerce product sales: An application of the elaboration likelihood model.

In response to the soaring demand for imported goods among Chinese consumers, this study innovatively investigates the role of external cues on consumer behavior on cross-border e-commerce platforms, utilizing advanced data crawling techniques to extract data from Tmall Global. Guided by the Elaboration Likelihood Model, this research unveils key determinants affecting consumer purchasing decisions, contributing novel insights to e-commerce literature and methodologies. Our analysis discovers that increased picture comments significantly boost sales and that source credibility, product collections, and price discounts also play pivotal roles, especially for experiential products. We further explore a nuanced, inverted U-shaped relationship between product title length and sales, offering a foundational understanding of non-linear relationships in consumer behavior and presenting practical implications for enhancing marketing strategies. This study, while acknowledging limitations like data access constraints, provides strategic insights into optimizing product information presentation and broadens understanding of consumer decision-making processes, thus adding substantial value to ongoing e-commerce discourse

Baseline regression.

In response to the soaring demand for imported goods among Chinese consumers, this study innovatively investigates the role of external cues on consumer behavior on cross-border e-commerce platforms, utilizing advanced data crawling techniques to extract data from Tmall Global. Guided by the Elaboration Likelihood Model, this research unveils key determinants affecting consumer purchasing decisions, contributing novel insights to e-commerce literature and methodologies. Our analysis discovers that increased picture comments significantly boost sales and that source credibility, product collections, and price discounts also play pivotal roles, especially for experiential products. We further explore a nuanced, inverted U-shaped relationship between product title length and sales, offering a foundational understanding of non-linear relationships in consumer behavior and presenting practical implications for enhancing marketing strategies. This study, while acknowledging limitations like data access constraints, provides strategic insights into optimizing product information presentation and broadens understanding of consumer decision-making processes, thus adding substantial value to ongoing e-commerce discourse.</div

Descriptive statistics.

In response to the soaring demand for imported goods among Chinese consumers, this study innovatively investigates the role of external cues on consumer behavior on cross-border e-commerce platforms, utilizing advanced data crawling techniques to extract data from Tmall Global. Guided by the Elaboration Likelihood Model, this research unveils key determinants affecting consumer purchasing decisions, contributing novel insights to e-commerce literature and methodologies. Our analysis discovers that increased picture comments significantly boost sales and that source credibility, product collections, and price discounts also play pivotal roles, especially for experiential products. We further explore a nuanced, inverted U-shaped relationship between product title length and sales, offering a foundational understanding of non-linear relationships in consumer behavior and presenting practical implications for enhancing marketing strategies. This study, while acknowledging limitations like data access constraints, provides strategic insights into optimizing product information presentation and broadens understanding of consumer decision-making processes, thus adding substantial value to ongoing e-commerce discourse.</div

Model variables and measures.

In response to the soaring demand for imported goods among Chinese consumers, this study innovatively investigates the role of external cues on consumer behavior on cross-border e-commerce platforms, utilizing advanced data crawling techniques to extract data from Tmall Global. Guided by the Elaboration Likelihood Model, this research unveils key determinants affecting consumer purchasing decisions, contributing novel insights to e-commerce literature and methodologies. Our analysis discovers that increased picture comments significantly boost sales and that source credibility, product collections, and price discounts also play pivotal roles, especially for experiential products. We further explore a nuanced, inverted U-shaped relationship between product title length and sales, offering a foundational understanding of non-linear relationships in consumer behavior and presenting practical implications for enhancing marketing strategies. This study, while acknowledging limitations like data access constraints, provides strategic insights into optimizing product information presentation and broadens understanding of consumer decision-making processes, thus adding substantial value to ongoing e-commerce discourse.</div