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Vincent Grossi - One of the best experts on this subject based on the ideXlab platform.

  • temperature dependent alkyl Glycerol Ether lipid composition of mesophilic and thermophilic sulfate reducing bacteria
    Frontiers in Microbiology, 2017
    Co-Authors: Arnauld Vinconlaugier, Cristiana Cravolaureau, Isabelle Mitteau, Vincent Grossi
    Abstract:

    The occurrence of non-isoprenoid alkyl Glycerol Ether lipids in Bacteria and natural environments is increasingly being reported and the specificity and diagenetic stability of these lipids make them powerful biomarkers for biogeochemical and environmental studies. Yet the environmental controls on the biosynthesis of these peculiar membrane lipids remain poorly documented. Here, the lipid composition of two mesophilic (Desulfatibacillum aliphaticivorans and D. alkenivorans) and one thermophilic (Thermodesulfobacterium commune) sulfate reducing bacteria - whose membranes are mostly composed of Ether lipids - was investigated as a function of growth temperature (20-40°C and 54-84°C, respectively). For all strains, the cellular lipid content (relative to proteins) was lower at sub- or supra-optimal growth temperature, but the relative proportions of dialkyl Glycerols, monoalkyl Glycerols and fatty acids remained remarkably stable whatever the growth temperature. Rather than changing the proportions of the different lipid classes, the three strains responded to temperature changes by modifying the average structural composition of the alkyl and acyl chains constitutive of their membrane lipids. Major adaptive mechanisms concerned modifications of the level of branching and of the proportions of the different methyl branched lipids. Specifically, an increase in temperature induced mesophilic strains to produce less dimethyl branched dialkyl Glycerols and 10-methyl branched lipids relative to linear structures, and the thermophilic strain to decrease the proportion of anteiso relative to iso methyl branched compounds. These modifications were in agreement with a regulation of the membrane fluidity. In one mesophilic and the thermophilic strains, a modification of the growth temperature further induced changes in the relative proportions of sn-1 vs sn-2 monoalkyl Glycerols, suggesting an unprecedented mechanism of homeoviscous adaptation in Bacteria. Strong linear correlations observed between different ratios of alkyl Glycerols and temperature allow to hypothesize the use of these specific lipids as indicators of temperature changes in the environment.

  • Temperature-dependent alkyl Glycerol Ether lipid composition of mesophilic and thermophilic sulfate-reducing Bacteria
    Frontiers in Microbiology, 2017
    Co-Authors: A. Vinçon-laugier, Isabelle Mitteau, Cristiana Cravo-laureau, Vincent Grossi
    Abstract:

    The occurrence of non-isoprenoid alkyl Glycerol Ether lipids in Bacteria and natural environments is increasingly being reported and the specificity and diagenetic stability of these lipids make them powerful biomarkers for biogeochemical and environmental studies. Yet the environmental controls on the biosynthesis of these peculiar membrane lipids remain poorly documented. Here, the lipid content of two mesophilic (Desulfatibacillum aliphaticivorans and Desulfatibacillum alkenivorans) and one thermophilic (Thermodesulfobacterium commune) sulfate-reducing bacteria— whose membranes are mostly composed of Ether lipids—was investigated as a function of growth temperature (20–40◦ C and 54–84◦ C, respectively). For all strains, the cellular lipid content was lower at sub- or supra-optimal growth temperature, but the relative proportions of dialkyl Glycerols, monoalkyl Glycerols and fatty acids remained remarkably stable whatever the growth temperature. Rather than changing the proportions of the different lipid classes, the three strains responded to temperature changes by modifying the average structural composition of the alkyl and acyl chains constitutive of their membrane lipids. Major adaptive mechanisms concerned modifications of the level of branching and of the proportions of the different methyl branched lipids. Specifically, an increase in temperature induced mesophilic strains to produce less dimethyl branched dialkyl Glycerols and 10-methyl branched lipids relative to linear structures, and the thermophilic strain to decrease the proportion of anteiso relative to iso methyl branched compounds. These modifications were in agreement with a regulation of the membrane fluidity. In one mesophilic and the thermophilic strains, a modification of the growth temperature further induced changes in the relative proportions of sn-2 vs sn-1 monoalkyl Glycerols, suggesting an unprecedented mechanism of homeoviscous adaptation in Bacteria. Strong linear correlations observed between different ratios of alkyl Glycerols and temperature allow to hypothesize the use of these specific lipids as indicators of temperature changes in the environment.

  • The alkyl Glycerol Ether lipid composition of heterotrophic sulfate reducing bacteria strongly depends on growth substrate
    Organic Geochemistry, 2016
    Co-Authors: A. Vinçon-laugier, Muriel Pacton, Vincent Grossi, Gilles Escarguel, Cristiana Cravo-laureau
    Abstract:

    Bacterial non-isoprenoid alkyl Glycerol Ether lipids (AGEs) are widespread in the environment but little is known about their biological precursors and mode of formation as a function of varying growth condi- tions. Here, we searched for the presence of AGEs in five pure strains of mesophilic (growth temperature between 20 and 40 C) and heterotrophic sulfate reducing bacteria from the family Desulfobacteraceae grown on a wide range of hydrocarbons and organic acids as sole carbon and energy source. Gas chro- matography–mass spectrometry (GC–MS) analysis of hydrolyzed cells revealed the presence of mono- alkyl Glycerols (MAGEs) in one Desulfatiferula species and of MAGEs and dialkyl Glycerols (DAGEs) in two Desulfatibacillum species. Species from the genus Desulfococcus did not produce AGEs. The Ether lipid composition appeared strongly dependent on the nature and the chain length of the carbon substrate, with few to > 50 homologues of AGEs formed from a single substrate. Growth on long chain n-alkyl com- pounds (C14 to C18 alk-1-enes and fatty acids) generated a much lower diversity of MAGEs and DAGEs than short chain substrates (nonanoate, octanoate and pyruvate) or isoprenoid alkenes (phytadienes). Such variation in alkyl Glycerol production could be linked to the distinct pathways involved in the meta- bolism of the different substrates. Despite this substrate-dependent AGE composition, the average chain length and level of branching of each class of Ether lipid remained remarkably stable whatever the growth substrate and the number of MAGE and DAGE homologues formed, indicating a compositional control of Ether lipids by heterotrophic bacteria to maintain optimal membrane properties.

  • correction for grossi et al mono and dialkyl Glycerol Ether lipids in anaerobic bacteria biosynthetic insights from the mesophilic sulfate reducer desulfatibacillum alkenivorans pf2803t
    Applied and Environmental Microbiology, 2015
    Co-Authors: Vincent Grossi, Damien Mollex, Arnauld Vinconlaugier, Florence Hakil, Muriel Pacton, Cristiana Cravolaureau
    Abstract:

    Volume 81, no. 9, p. 3157–3168, 2015. Page 3162, Table 1: The labeled fatty acid corresponding to the 1,1,2,2-D4-hexadecanol substrate (row 3, column 2) should appear as shown below (i.e., without the brackets and asterisks that previously suggested it was a growth substrate). ![Figure][1]

  • mono and dialkyl Glycerol Ether lipids in anaerobic bacteria biosynthetic insights from the mesophilic sulfate reducer desulfatibacillum alkenivorans pf2803t
    Applied and Environmental Microbiology, 2015
    Co-Authors: Vincent Grossi, Damien Mollex, Arnauld Vinconlaugier, Florence Hakil, Muriel Pacton, Cristiana Cravolaureau
    Abstract:

    Bacterial Glycerol Ether lipids (alkylGlycerols) have received increasing attention during the last decades, notably due to their potential role in cell resistance or adaptation to adverse environmental conditions. Major uncertainties remain, however, regarding the origin, biosynthesis, and modes of formation of these uncommon bacterial lipids. We report here the preponderance of monoalkyl- and dialkylGlycerols (1-O-alkyl-, 2-O-alkyl-, and 1,2-O-dialkylGlycerols) among the hydrolyzed lipids of the marine mesophilic sulfate-reducing proteobacterium Desulfatibacillum alkenivorans PF2803T grown on n-alkenes (pentadec-1-ene or hexadec-1-ene) as the sole carbon and energy source. AlkylGlycerols account for one-third to two-thirds of the total cellular lipids (alkylGlycerols plus acylGlycerols), depending on the growth substrate, with dialkylGlycerols contributing to one-fifth to two-fifths of the total Ether lipids. The carbon chain distribution of the lipids of D. alkenivorans also depends on that of the substrate, but the chain length and methyl-branching patterns of fatty acids and monoalkyl- and dialkylGlycerols are systematically congruent, supporting the idea of a biosynthetic link between the three classes of compounds. Vinyl Ethers (1-alken-1′-yl-Glycerols, known as plasmalogens) are not detected among the lipids of strain PF2803T. Cultures grown on different (per)deuterated n-alkene, n-alkanol, and n-fatty acid substrates further demonstrate that saturated alkylGlycerols are not formed via the reduction of hypothetic alken-1′-yl intermediates. Our results support an unprecedented biosynthetic pathway to monoalkyl/monoacyl- and dialkylGlycerols in anaerobic bacteria and suggest that n-alkyl compounds present in the environment can serve as the substrates for supplying the building blocks of Ether phospholipids of heterotrophic bacteria.

Cristiana Cravolaureau - One of the best experts on this subject based on the ideXlab platform.

  • temperature dependent alkyl Glycerol Ether lipid composition of mesophilic and thermophilic sulfate reducing bacteria
    Frontiers in Microbiology, 2017
    Co-Authors: Arnauld Vinconlaugier, Cristiana Cravolaureau, Isabelle Mitteau, Vincent Grossi
    Abstract:

    The occurrence of non-isoprenoid alkyl Glycerol Ether lipids in Bacteria and natural environments is increasingly being reported and the specificity and diagenetic stability of these lipids make them powerful biomarkers for biogeochemical and environmental studies. Yet the environmental controls on the biosynthesis of these peculiar membrane lipids remain poorly documented. Here, the lipid composition of two mesophilic (Desulfatibacillum aliphaticivorans and D. alkenivorans) and one thermophilic (Thermodesulfobacterium commune) sulfate reducing bacteria - whose membranes are mostly composed of Ether lipids - was investigated as a function of growth temperature (20-40°C and 54-84°C, respectively). For all strains, the cellular lipid content (relative to proteins) was lower at sub- or supra-optimal growth temperature, but the relative proportions of dialkyl Glycerols, monoalkyl Glycerols and fatty acids remained remarkably stable whatever the growth temperature. Rather than changing the proportions of the different lipid classes, the three strains responded to temperature changes by modifying the average structural composition of the alkyl and acyl chains constitutive of their membrane lipids. Major adaptive mechanisms concerned modifications of the level of branching and of the proportions of the different methyl branched lipids. Specifically, an increase in temperature induced mesophilic strains to produce less dimethyl branched dialkyl Glycerols and 10-methyl branched lipids relative to linear structures, and the thermophilic strain to decrease the proportion of anteiso relative to iso methyl branched compounds. These modifications were in agreement with a regulation of the membrane fluidity. In one mesophilic and the thermophilic strains, a modification of the growth temperature further induced changes in the relative proportions of sn-1 vs sn-2 monoalkyl Glycerols, suggesting an unprecedented mechanism of homeoviscous adaptation in Bacteria. Strong linear correlations observed between different ratios of alkyl Glycerols and temperature allow to hypothesize the use of these specific lipids as indicators of temperature changes in the environment.

  • correction for grossi et al mono and dialkyl Glycerol Ether lipids in anaerobic bacteria biosynthetic insights from the mesophilic sulfate reducer desulfatibacillum alkenivorans pf2803t
    Applied and Environmental Microbiology, 2015
    Co-Authors: Vincent Grossi, Damien Mollex, Arnauld Vinconlaugier, Florence Hakil, Muriel Pacton, Cristiana Cravolaureau
    Abstract:

    Volume 81, no. 9, p. 3157–3168, 2015. Page 3162, Table 1: The labeled fatty acid corresponding to the 1,1,2,2-D4-hexadecanol substrate (row 3, column 2) should appear as shown below (i.e., without the brackets and asterisks that previously suggested it was a growth substrate). ![Figure][1]

  • mono and dialkyl Glycerol Ether lipids in anaerobic bacteria biosynthetic insights from the mesophilic sulfate reducer desulfatibacillum alkenivorans pf2803t
    Applied and Environmental Microbiology, 2015
    Co-Authors: Vincent Grossi, Damien Mollex, Arnauld Vinconlaugier, Florence Hakil, Muriel Pacton, Cristiana Cravolaureau
    Abstract:

    Bacterial Glycerol Ether lipids (alkylGlycerols) have received increasing attention during the last decades, notably due to their potential role in cell resistance or adaptation to adverse environmental conditions. Major uncertainties remain, however, regarding the origin, biosynthesis, and modes of formation of these uncommon bacterial lipids. We report here the preponderance of monoalkyl- and dialkylGlycerols (1-O-alkyl-, 2-O-alkyl-, and 1,2-O-dialkylGlycerols) among the hydrolyzed lipids of the marine mesophilic sulfate-reducing proteobacterium Desulfatibacillum alkenivorans PF2803T grown on n-alkenes (pentadec-1-ene or hexadec-1-ene) as the sole carbon and energy source. AlkylGlycerols account for one-third to two-thirds of the total cellular lipids (alkylGlycerols plus acylGlycerols), depending on the growth substrate, with dialkylGlycerols contributing to one-fifth to two-fifths of the total Ether lipids. The carbon chain distribution of the lipids of D. alkenivorans also depends on that of the substrate, but the chain length and methyl-branching patterns of fatty acids and monoalkyl- and dialkylGlycerols are systematically congruent, supporting the idea of a biosynthetic link between the three classes of compounds. Vinyl Ethers (1-alken-1′-yl-Glycerols, known as plasmalogens) are not detected among the lipids of strain PF2803T. Cultures grown on different (per)deuterated n-alkene, n-alkanol, and n-fatty acid substrates further demonstrate that saturated alkylGlycerols are not formed via the reduction of hypothetic alken-1′-yl intermediates. Our results support an unprecedented biosynthetic pathway to monoalkyl/monoacyl- and dialkylGlycerols in anaerobic bacteria and suggest that n-alkyl compounds present in the environment can serve as the substrates for supplying the building blocks of Ether phospholipids of heterotrophic bacteria.

Arnauld Vinconlaugier - One of the best experts on this subject based on the ideXlab platform.

  • temperature dependent alkyl Glycerol Ether lipid composition of mesophilic and thermophilic sulfate reducing bacteria
    Frontiers in Microbiology, 2017
    Co-Authors: Arnauld Vinconlaugier, Cristiana Cravolaureau, Isabelle Mitteau, Vincent Grossi
    Abstract:

    The occurrence of non-isoprenoid alkyl Glycerol Ether lipids in Bacteria and natural environments is increasingly being reported and the specificity and diagenetic stability of these lipids make them powerful biomarkers for biogeochemical and environmental studies. Yet the environmental controls on the biosynthesis of these peculiar membrane lipids remain poorly documented. Here, the lipid composition of two mesophilic (Desulfatibacillum aliphaticivorans and D. alkenivorans) and one thermophilic (Thermodesulfobacterium commune) sulfate reducing bacteria - whose membranes are mostly composed of Ether lipids - was investigated as a function of growth temperature (20-40°C and 54-84°C, respectively). For all strains, the cellular lipid content (relative to proteins) was lower at sub- or supra-optimal growth temperature, but the relative proportions of dialkyl Glycerols, monoalkyl Glycerols and fatty acids remained remarkably stable whatever the growth temperature. Rather than changing the proportions of the different lipid classes, the three strains responded to temperature changes by modifying the average structural composition of the alkyl and acyl chains constitutive of their membrane lipids. Major adaptive mechanisms concerned modifications of the level of branching and of the proportions of the different methyl branched lipids. Specifically, an increase in temperature induced mesophilic strains to produce less dimethyl branched dialkyl Glycerols and 10-methyl branched lipids relative to linear structures, and the thermophilic strain to decrease the proportion of anteiso relative to iso methyl branched compounds. These modifications were in agreement with a regulation of the membrane fluidity. In one mesophilic and the thermophilic strains, a modification of the growth temperature further induced changes in the relative proportions of sn-1 vs sn-2 monoalkyl Glycerols, suggesting an unprecedented mechanism of homeoviscous adaptation in Bacteria. Strong linear correlations observed between different ratios of alkyl Glycerols and temperature allow to hypothesize the use of these specific lipids as indicators of temperature changes in the environment.

  • correction for grossi et al mono and dialkyl Glycerol Ether lipids in anaerobic bacteria biosynthetic insights from the mesophilic sulfate reducer desulfatibacillum alkenivorans pf2803t
    Applied and Environmental Microbiology, 2015
    Co-Authors: Vincent Grossi, Damien Mollex, Arnauld Vinconlaugier, Florence Hakil, Muriel Pacton, Cristiana Cravolaureau
    Abstract:

    Volume 81, no. 9, p. 3157–3168, 2015. Page 3162, Table 1: The labeled fatty acid corresponding to the 1,1,2,2-D4-hexadecanol substrate (row 3, column 2) should appear as shown below (i.e., without the brackets and asterisks that previously suggested it was a growth substrate). ![Figure][1]

  • mono and dialkyl Glycerol Ether lipids in anaerobic bacteria biosynthetic insights from the mesophilic sulfate reducer desulfatibacillum alkenivorans pf2803t
    Applied and Environmental Microbiology, 2015
    Co-Authors: Vincent Grossi, Damien Mollex, Arnauld Vinconlaugier, Florence Hakil, Muriel Pacton, Cristiana Cravolaureau
    Abstract:

    Bacterial Glycerol Ether lipids (alkylGlycerols) have received increasing attention during the last decades, notably due to their potential role in cell resistance or adaptation to adverse environmental conditions. Major uncertainties remain, however, regarding the origin, biosynthesis, and modes of formation of these uncommon bacterial lipids. We report here the preponderance of monoalkyl- and dialkylGlycerols (1-O-alkyl-, 2-O-alkyl-, and 1,2-O-dialkylGlycerols) among the hydrolyzed lipids of the marine mesophilic sulfate-reducing proteobacterium Desulfatibacillum alkenivorans PF2803T grown on n-alkenes (pentadec-1-ene or hexadec-1-ene) as the sole carbon and energy source. AlkylGlycerols account for one-third to two-thirds of the total cellular lipids (alkylGlycerols plus acylGlycerols), depending on the growth substrate, with dialkylGlycerols contributing to one-fifth to two-fifths of the total Ether lipids. The carbon chain distribution of the lipids of D. alkenivorans also depends on that of the substrate, but the chain length and methyl-branching patterns of fatty acids and monoalkyl- and dialkylGlycerols are systematically congruent, supporting the idea of a biosynthetic link between the three classes of compounds. Vinyl Ethers (1-alken-1′-yl-Glycerols, known as plasmalogens) are not detected among the lipids of strain PF2803T. Cultures grown on different (per)deuterated n-alkene, n-alkanol, and n-fatty acid substrates further demonstrate that saturated alkylGlycerols are not formed via the reduction of hypothetic alken-1′-yl intermediates. Our results support an unprecedented biosynthetic pathway to monoalkyl/monoacyl- and dialkylGlycerols in anaerobic bacteria and suggest that n-alkyl compounds present in the environment can serve as the substrates for supplying the building blocks of Ether phospholipids of heterotrophic bacteria.

Muriel Pacton - One of the best experts on this subject based on the ideXlab platform.

  • The alkyl Glycerol Ether lipid composition of heterotrophic sulfate reducing bacteria strongly depends on growth substrate
    Organic Geochemistry, 2016
    Co-Authors: A. Vinçon-laugier, Muriel Pacton, Vincent Grossi, Gilles Escarguel, Cristiana Cravo-laureau
    Abstract:

    Bacterial non-isoprenoid alkyl Glycerol Ether lipids (AGEs) are widespread in the environment but little is known about their biological precursors and mode of formation as a function of varying growth condi- tions. Here, we searched for the presence of AGEs in five pure strains of mesophilic (growth temperature between 20 and 40 C) and heterotrophic sulfate reducing bacteria from the family Desulfobacteraceae grown on a wide range of hydrocarbons and organic acids as sole carbon and energy source. Gas chro- matography–mass spectrometry (GC–MS) analysis of hydrolyzed cells revealed the presence of mono- alkyl Glycerols (MAGEs) in one Desulfatiferula species and of MAGEs and dialkyl Glycerols (DAGEs) in two Desulfatibacillum species. Species from the genus Desulfococcus did not produce AGEs. The Ether lipid composition appeared strongly dependent on the nature and the chain length of the carbon substrate, with few to > 50 homologues of AGEs formed from a single substrate. Growth on long chain n-alkyl com- pounds (C14 to C18 alk-1-enes and fatty acids) generated a much lower diversity of MAGEs and DAGEs than short chain substrates (nonanoate, octanoate and pyruvate) or isoprenoid alkenes (phytadienes). Such variation in alkyl Glycerol production could be linked to the distinct pathways involved in the meta- bolism of the different substrates. Despite this substrate-dependent AGE composition, the average chain length and level of branching of each class of Ether lipid remained remarkably stable whatever the growth substrate and the number of MAGE and DAGE homologues formed, indicating a compositional control of Ether lipids by heterotrophic bacteria to maintain optimal membrane properties.

  • correction for grossi et al mono and dialkyl Glycerol Ether lipids in anaerobic bacteria biosynthetic insights from the mesophilic sulfate reducer desulfatibacillum alkenivorans pf2803t
    Applied and Environmental Microbiology, 2015
    Co-Authors: Vincent Grossi, Damien Mollex, Arnauld Vinconlaugier, Florence Hakil, Muriel Pacton, Cristiana Cravolaureau
    Abstract:

    Volume 81, no. 9, p. 3157–3168, 2015. Page 3162, Table 1: The labeled fatty acid corresponding to the 1,1,2,2-D4-hexadecanol substrate (row 3, column 2) should appear as shown below (i.e., without the brackets and asterisks that previously suggested it was a growth substrate). ![Figure][1]

  • mono and dialkyl Glycerol Ether lipids in anaerobic bacteria biosynthetic insights from the mesophilic sulfate reducer desulfatibacillum alkenivorans pf2803t
    Applied and Environmental Microbiology, 2015
    Co-Authors: Vincent Grossi, Damien Mollex, Arnauld Vinconlaugier, Florence Hakil, Muriel Pacton, Cristiana Cravolaureau
    Abstract:

    Bacterial Glycerol Ether lipids (alkylGlycerols) have received increasing attention during the last decades, notably due to their potential role in cell resistance or adaptation to adverse environmental conditions. Major uncertainties remain, however, regarding the origin, biosynthesis, and modes of formation of these uncommon bacterial lipids. We report here the preponderance of monoalkyl- and dialkylGlycerols (1-O-alkyl-, 2-O-alkyl-, and 1,2-O-dialkylGlycerols) among the hydrolyzed lipids of the marine mesophilic sulfate-reducing proteobacterium Desulfatibacillum alkenivorans PF2803T grown on n-alkenes (pentadec-1-ene or hexadec-1-ene) as the sole carbon and energy source. AlkylGlycerols account for one-third to two-thirds of the total cellular lipids (alkylGlycerols plus acylGlycerols), depending on the growth substrate, with dialkylGlycerols contributing to one-fifth to two-fifths of the total Ether lipids. The carbon chain distribution of the lipids of D. alkenivorans also depends on that of the substrate, but the chain length and methyl-branching patterns of fatty acids and monoalkyl- and dialkylGlycerols are systematically congruent, supporting the idea of a biosynthetic link between the three classes of compounds. Vinyl Ethers (1-alken-1′-yl-Glycerols, known as plasmalogens) are not detected among the lipids of strain PF2803T. Cultures grown on different (per)deuterated n-alkene, n-alkanol, and n-fatty acid substrates further demonstrate that saturated alkylGlycerols are not formed via the reduction of hypothetic alken-1′-yl intermediates. Our results support an unprecedented biosynthetic pathway to monoalkyl/monoacyl- and dialkylGlycerols in anaerobic bacteria and suggest that n-alkyl compounds present in the environment can serve as the substrates for supplying the building blocks of Ether phospholipids of heterotrophic bacteria.

Cristiana Cravo-laureau - One of the best experts on this subject based on the ideXlab platform.

  • Temperature-dependent alkyl Glycerol Ether lipid composition of mesophilic and thermophilic sulfate-reducing Bacteria
    Frontiers in Microbiology, 2017
    Co-Authors: A. Vinçon-laugier, Isabelle Mitteau, Cristiana Cravo-laureau, Vincent Grossi
    Abstract:

    The occurrence of non-isoprenoid alkyl Glycerol Ether lipids in Bacteria and natural environments is increasingly being reported and the specificity and diagenetic stability of these lipids make them powerful biomarkers for biogeochemical and environmental studies. Yet the environmental controls on the biosynthesis of these peculiar membrane lipids remain poorly documented. Here, the lipid content of two mesophilic (Desulfatibacillum aliphaticivorans and Desulfatibacillum alkenivorans) and one thermophilic (Thermodesulfobacterium commune) sulfate-reducing bacteria— whose membranes are mostly composed of Ether lipids—was investigated as a function of growth temperature (20–40◦ C and 54–84◦ C, respectively). For all strains, the cellular lipid content was lower at sub- or supra-optimal growth temperature, but the relative proportions of dialkyl Glycerols, monoalkyl Glycerols and fatty acids remained remarkably stable whatever the growth temperature. Rather than changing the proportions of the different lipid classes, the three strains responded to temperature changes by modifying the average structural composition of the alkyl and acyl chains constitutive of their membrane lipids. Major adaptive mechanisms concerned modifications of the level of branching and of the proportions of the different methyl branched lipids. Specifically, an increase in temperature induced mesophilic strains to produce less dimethyl branched dialkyl Glycerols and 10-methyl branched lipids relative to linear structures, and the thermophilic strain to decrease the proportion of anteiso relative to iso methyl branched compounds. These modifications were in agreement with a regulation of the membrane fluidity. In one mesophilic and the thermophilic strains, a modification of the growth temperature further induced changes in the relative proportions of sn-2 vs sn-1 monoalkyl Glycerols, suggesting an unprecedented mechanism of homeoviscous adaptation in Bacteria. Strong linear correlations observed between different ratios of alkyl Glycerols and temperature allow to hypothesize the use of these specific lipids as indicators of temperature changes in the environment.

  • The alkyl Glycerol Ether lipid composition of heterotrophic sulfate reducing bacteria strongly depends on growth substrate
    Organic Geochemistry, 2016
    Co-Authors: A. Vinçon-laugier, Muriel Pacton, Vincent Grossi, Gilles Escarguel, Cristiana Cravo-laureau
    Abstract:

    Bacterial non-isoprenoid alkyl Glycerol Ether lipids (AGEs) are widespread in the environment but little is known about their biological precursors and mode of formation as a function of varying growth condi- tions. Here, we searched for the presence of AGEs in five pure strains of mesophilic (growth temperature between 20 and 40 C) and heterotrophic sulfate reducing bacteria from the family Desulfobacteraceae grown on a wide range of hydrocarbons and organic acids as sole carbon and energy source. Gas chro- matography–mass spectrometry (GC–MS) analysis of hydrolyzed cells revealed the presence of mono- alkyl Glycerols (MAGEs) in one Desulfatiferula species and of MAGEs and dialkyl Glycerols (DAGEs) in two Desulfatibacillum species. Species from the genus Desulfococcus did not produce AGEs. The Ether lipid composition appeared strongly dependent on the nature and the chain length of the carbon substrate, with few to > 50 homologues of AGEs formed from a single substrate. Growth on long chain n-alkyl com- pounds (C14 to C18 alk-1-enes and fatty acids) generated a much lower diversity of MAGEs and DAGEs than short chain substrates (nonanoate, octanoate and pyruvate) or isoprenoid alkenes (phytadienes). Such variation in alkyl Glycerol production could be linked to the distinct pathways involved in the meta- bolism of the different substrates. Despite this substrate-dependent AGE composition, the average chain length and level of branching of each class of Ether lipid remained remarkably stable whatever the growth substrate and the number of MAGE and DAGE homologues formed, indicating a compositional control of Ether lipids by heterotrophic bacteria to maintain optimal membrane properties.