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Autotrophs

The Experts below are selected from a list of 288 Experts worldwide ranked by ideXlab platform

Nicole Dubilier – 1st expert on this subject based on the ideXlab platform

  • sulfur oxidizing symbionts without canonical genes for autotrophic co2 fixation
    Mbio, 2019
    Co-Authors: Brandon K B Seah, Chakkiath Paul Antony, Bruno Huettel, Jan Zarzycki, Lennart Schada Von Borzyskowski, Angela Kouris, Manuel Kleiner, Manuel Liebeke, Nicole Dubilier

    Abstract:

    ABSTRACT Since the discovery of symbioses between sulfur-oxidizing (thiotrophic) bacteria and invertebrates at hydrothermal vents over 40 years ago, it has been assumed that autotrophic fixation of CO2 by the symbionts drives these nutritional associations. In this study, we investigated “Candidatus Kentron,” the clade of symbionts hosted by Kentrophoros, a diverse genus of ciliates which are found in marine coastal sediments around the world. Despite being the main food source for their hosts, Kentron bacteria lack the key canonical genes for any of the known pathways for autotrophic carbon fixation and have a carbon stable isotope fingerprint that is unlike other thiotrophic symbionts from similar habitats. Our genomic and transcriptomic analyses instead found metabolic features consistent with growth on organic carbon, especially organic and amino acids, for which they have abundant uptake transporters. All known thiotrophic symbionts have converged on using reduced sulfur to gain energy lithotrophically, but they are diverse in their carbon sources. Some clades are obligate Autotrophs, while many are mixotrophs that can supplement autotrophic carbon fixation with heterotrophic capabilities similar to those in Kentron. Here we show that Kentron bacteria are the only thiotrophic symbionts that appear to be entirely heterotrophic, unlike all other thiotrophic symbionts studied to date, which possess either the Calvin-Benson-Bassham or the reverse tricarboxylic acid cycle for autotrophy. IMPORTANCE Many animals and protists depend on symbiotic sulfur-oxidizing bacteria as their main food source. These bacteria use energy from oxidizing inorganic sulfur compounds to make biomass autotrophically from CO2, serving as primary producers for their hosts. Here we describe a clade of nonautotrophic sulfur-oxidizing symbionts, “Candidatus Kentron,” associated with marine ciliates. They lack genes for known autotrophic pathways and have a carbon stable isotope fingerprint heavier than other symbionts from similar habitats. Instead, they have the potential to oxidize sulfur to fuel the uptake of organic compounds for heterotrophic growth, a metabolic mode called chemolithoheterotrophy that is not found in other symbioses. Although several symbionts have heterotrophic features to supplement primary production, in Kentron they appear to supplant it entirely.

  • sulfur oxidizing symbionts without canonical genes for autotrophic co2 fixation
    bioRxiv, 2019
    Co-Authors: Brandon K B Seah, Chakkiath Paul Antony, Bruno Huettel, Jan Zarzycki, Lennart Schada Von Borzyskowski, Angela Kouris, Manuel Kleiner, Manuel Liebeke, Nicole Dubilier, Harald R Grubervodicka

    Abstract:

    Since the discovery of symbioses between sulfur-oxidizing (thiotrophic) bacteria and invertebrates at hydrothermal vents over 40 years ago, it has been assumed that autotrophic fixation of CO2 by the symbionts drives these nutritional associations. In this study, we investigated Candidatus Kentron, the clade of symbionts hosted by Kentrophoros, a diverse genus of ciliates which are found in marine coastal sediments around the world. Despite being the main food source for their hosts, Kentron lack the key canonical genes for any of the known pathways for autotrophic fixation, and have a carbon stable isotope fingerprint unlike other thiotrophic symbionts from similar habitats. Our genomic and transcriptomic analyses instead found metabolic features consistent with growth on organic carbon, especially organic and amino acids, for which they have abundant uptake transporters. All known thiotrophic symbionts have converged on using reduced sulfur to generate energy lithotrophically, but they are diverse in their carbon sources. Some clades are obligate Autotrophs, while many are mixotrophs that can supplement autotrophic carbon fixation with heterotrophic capabilities similar to those in Kentron. We have shown that Kentron are the only thiotrophic symbionts that appear to be entirely heterotrophic, unlike all other thiotrophic symbionts studied to date, which possess either the Calvin-Benson-Bassham or reverse tricarboxylic acid cycles for autotrophy.

Brandon K B Seah – 2nd expert on this subject based on the ideXlab platform

  • sulfur oxidizing symbionts without canonical genes for autotrophic co2 fixation
    Mbio, 2019
    Co-Authors: Brandon K B Seah, Chakkiath Paul Antony, Bruno Huettel, Jan Zarzycki, Lennart Schada Von Borzyskowski, Angela Kouris, Manuel Kleiner, Manuel Liebeke, Nicole Dubilier

    Abstract:

    ABSTRACT Since the discovery of symbioses between sulfur-oxidizing (thiotrophic) bacteria and invertebrates at hydrothermal vents over 40 years ago, it has been assumed that autotrophic fixation of CO2 by the symbionts drives these nutritional associations. In this study, we investigated “Candidatus Kentron,” the clade of symbionts hosted by Kentrophoros, a diverse genus of ciliates which are found in marine coastal sediments around the world. Despite being the main food source for their hosts, Kentron bacteria lack the key canonical genes for any of the known pathways for autotrophic carbon fixation and have a carbon stable isotope fingerprint that is unlike other thiotrophic symbionts from similar habitats. Our genomic and transcriptomic analyses instead found metabolic features consistent with growth on organic carbon, especially organic and amino acids, for which they have abundant uptake transporters. All known thiotrophic symbionts have converged on using reduced sulfur to gain energy lithotrophically, but they are diverse in their carbon sources. Some clades are obligate Autotrophs, while many are mixotrophs that can supplement autotrophic carbon fixation with heterotrophic capabilities similar to those in Kentron. Here we show that Kentron bacteria are the only thiotrophic symbionts that appear to be entirely heterotrophic, unlike all other thiotrophic symbionts studied to date, which possess either the Calvin-Benson-Bassham or the reverse tricarboxylic acid cycle for autotrophy. IMPORTANCE Many animals and protists depend on symbiotic sulfur-oxidizing bacteria as their main food source. These bacteria use energy from oxidizing inorganic sulfur compounds to make biomass autotrophically from CO2, serving as primary producers for their hosts. Here we describe a clade of nonautotrophic sulfur-oxidizing symbionts, “Candidatus Kentron,” associated with marine ciliates. They lack genes for known autotrophic pathways and have a carbon stable isotope fingerprint heavier than other symbionts from similar habitats. Instead, they have the potential to oxidize sulfur to fuel the uptake of organic compounds for heterotrophic growth, a metabolic mode called chemolithoheterotrophy that is not found in other symbioses. Although several symbionts have heterotrophic features to supplement primary production, in Kentron they appear to supplant it entirely.

  • sulfur oxidizing symbionts without canonical genes for autotrophic co2 fixation
    bioRxiv, 2019
    Co-Authors: Brandon K B Seah, Chakkiath Paul Antony, Bruno Huettel, Jan Zarzycki, Lennart Schada Von Borzyskowski, Angela Kouris, Manuel Kleiner, Manuel Liebeke, Nicole Dubilier, Harald R Grubervodicka

    Abstract:

    Since the discovery of symbioses between sulfur-oxidizing (thiotrophic) bacteria and invertebrates at hydrothermal vents over 40 years ago, it has been assumed that autotrophic fixation of CO2 by the symbionts drives these nutritional associations. In this study, we investigated Candidatus Kentron, the clade of symbionts hosted by Kentrophoros, a diverse genus of ciliates which are found in marine coastal sediments around the world. Despite being the main food source for their hosts, Kentron lack the key canonical genes for any of the known pathways for autotrophic fixation, and have a carbon stable isotope fingerprint unlike other thiotrophic symbionts from similar habitats. Our genomic and transcriptomic analyses instead found metabolic features consistent with growth on organic carbon, especially organic and amino acids, for which they have abundant uptake transporters. All known thiotrophic symbionts have converged on using reduced sulfur to generate energy lithotrophically, but they are diverse in their carbon sources. Some clades are obligate Autotrophs, while many are mixotrophs that can supplement autotrophic carbon fixation with heterotrophic capabilities similar to those in Kentron. We have shown that Kentron are the only thiotrophic symbionts that appear to be entirely heterotrophic, unlike all other thiotrophic symbionts studied to date, which possess either the Calvin-Benson-Bassham or reverse tricarboxylic acid cycles for autotrophy.

O Holmhansen – 3rd expert on this subject based on the ideXlab platform

  • microbial autotrophic and heterotrophic eucaryotes in antarctic waters relationships between biomass and chlorophyll adenosine triphosphate and particulate organic carbon
    Marine Ecology Progress Series, 1990
    Co-Authors: Christopher D Hewes, Egil Sakshaug, Fmh Reid, O Holmhansen

    Abstract:

    M~croscopical examination of near-surface eucaryotic microbial populations in circumcontinental waters of Antarctica indicated that nanoplankton ((20 btm diameter) dominated in regions with low chlorophyll concentrations ( 20 pm diameter) was generally less significant. The variation in phytoplankton biomass was the result primarily of changes in cell density of pennate diatoms in the East Wind Drift, and of centric diatoms in the Weddell Sea and the Scotia Ridge region. Autotrophic and heterotrophic carbon as determined by microscopical analysis were compared with data for total particulate carbon, chlorophyll a, and adenosine triphosphate. Estimates for the C:chl ratio of Autotrophs increased with decreasing concentrations of chlorophyll a, with mean values of 46 in bloom waters and 144 in ‘blue water’. A C:ATP ratio for heterotrophic nanoplankton was estimated to be about 100, while that for heterotrophic microplankton may be lower. Algorithms, incorporating concentrations of chlorophyll a and ATP, are described which allow estimates of autotrophc and heterotrophic microbial biomass.