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Functional responses of methanogenic archaea to syntrophic growth.

Walker CB, Redding-Johanson AM, Baidoo EE, Rajeev L, He Z, Hendrickson EL, Joachimiak MP, Stolyar S, Arkin AP, Leigh JA, Zhou J, Keasling JD, Mukhopadhyay A, Stahl DA - ISME J (2012)

Bottom Line: These measurements indicate a decrease in transcript abundance for energy-consuming biosynthetic functions in syntrophically grown M. maripaludis, with an increase in transcript abundance for genes involved in the energy-generating central pathway for methanogenesis.A common theme was an apparent increase in transcripts for functions using H(2) directly as reductant, versus those using the reduced deazaflavin (coenzyme F(420)).The greater importance of direct reduction by H(2) was supported by improved syntrophic growth of a deletion mutant in an F(420)-dependent dehydrogenase of M. maripaludis.

View Article: PubMed Central - PubMed

Affiliation: Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA.

ABSTRACT
Methanococcus maripaludis grown syntrophically with Desulfovibrio vulgaris was compared with M. maripaludis monocultures grown under hydrogen limitation using transcriptional, proteomic and metabolite analyses. These measurements indicate a decrease in transcript abundance for energy-consuming biosynthetic functions in syntrophically grown M. maripaludis, with an increase in transcript abundance for genes involved in the energy-generating central pathway for methanogenesis. Compared with growth in monoculture under hydrogen limitation, the response of paralogous genes, such as those coding for hydrogenases, often diverged, with transcripts of one variant increasing in relative abundance, whereas the other was little changed or significantly decreased in abundance. A common theme was an apparent increase in transcripts for functions using H(2) directly as reductant, versus those using the reduced deazaflavin (coenzyme F(420)). The greater importance of direct reduction by H(2) was supported by improved syntrophic growth of a deletion mutant in an F(420)-dependent dehydrogenase of M. maripaludis. These data suggest that paralogous genes enable the methanogen to adapt to changing substrate availability, sustaining it under environmental conditions that are often near the thermodynamic threshold for growth. Additionally, the discovery of interspecies alanine transfer adds another metabolic dimension to this environmentally relevant mutualism.

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Growth curves for wild-type and mutant M. maripaludis cultures on lactate. The error bars indicate s.d. of triplicate cultures. Wild type (filled squares); Δmtd (open triangles); Δhmd (closed triangles); ΔfruA (open diamonds); ΔfrcA (closed diamonds); and ΔfrcAΔfruA (closed circles).
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fig3: Growth curves for wild-type and mutant M. maripaludis cultures on lactate. The error bars indicate s.d. of triplicate cultures. Wild type (filled squares); Δmtd (open triangles); Δhmd (closed triangles); ΔfruA (open diamonds); ΔfrcA (closed diamonds); and ΔfrcAΔfruA (closed circles).

Mentions: Given the significant increases of both transcript and protein abundance, the roles of the Fru/c hydrogenases were examined using the corresponding gene deletion mutants in syntrophic growth with D. vulgaris. The ΔfruA and ΔfrcA mutants each exhibited diminished growth rates and maximum cell densities during syntrophic growth on lactate (Figure 3). A deletion in both genes (a ΔfruΔfrcA mutant) produced highly variable maximum cell densities, but syntrophic growth still occurred, albeit at generally slower rates than in wild-type cocultures. All the three mutants demonstrated an increase in lag time prior to initiating exponential growth. In contrast, when pyruvate was the substrate for syntrophic growth, there were no differences in growth rate or maximum cell densities between the wild-type and the ΔfruA or ΔfrcA mutants, and there was only a slight decrease in maximum cell density for the ΔfrcAΔfruA double mutant (Supplementary Figure S2).


Functional responses of methanogenic archaea to syntrophic growth.

Walker CB, Redding-Johanson AM, Baidoo EE, Rajeev L, He Z, Hendrickson EL, Joachimiak MP, Stolyar S, Arkin AP, Leigh JA, Zhou J, Keasling JD, Mukhopadhyay A, Stahl DA - ISME J (2012)

Growth curves for wild-type and mutant M. maripaludis cultures on lactate. The error bars indicate s.d. of triplicate cultures. Wild type (filled squares); Δmtd (open triangles); Δhmd (closed triangles); ΔfruA (open diamonds); ΔfrcA (closed diamonds); and ΔfrcAΔfruA (closed circles).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3475374&req=5

fig3: Growth curves for wild-type and mutant M. maripaludis cultures on lactate. The error bars indicate s.d. of triplicate cultures. Wild type (filled squares); Δmtd (open triangles); Δhmd (closed triangles); ΔfruA (open diamonds); ΔfrcA (closed diamonds); and ΔfrcAΔfruA (closed circles).
Mentions: Given the significant increases of both transcript and protein abundance, the roles of the Fru/c hydrogenases were examined using the corresponding gene deletion mutants in syntrophic growth with D. vulgaris. The ΔfruA and ΔfrcA mutants each exhibited diminished growth rates and maximum cell densities during syntrophic growth on lactate (Figure 3). A deletion in both genes (a ΔfruΔfrcA mutant) produced highly variable maximum cell densities, but syntrophic growth still occurred, albeit at generally slower rates than in wild-type cocultures. All the three mutants demonstrated an increase in lag time prior to initiating exponential growth. In contrast, when pyruvate was the substrate for syntrophic growth, there were no differences in growth rate or maximum cell densities between the wild-type and the ΔfruA or ΔfrcA mutants, and there was only a slight decrease in maximum cell density for the ΔfrcAΔfruA double mutant (Supplementary Figure S2).

Bottom Line: These measurements indicate a decrease in transcript abundance for energy-consuming biosynthetic functions in syntrophically grown M. maripaludis, with an increase in transcript abundance for genes involved in the energy-generating central pathway for methanogenesis.A common theme was an apparent increase in transcripts for functions using H(2) directly as reductant, versus those using the reduced deazaflavin (coenzyme F(420)).The greater importance of direct reduction by H(2) was supported by improved syntrophic growth of a deletion mutant in an F(420)-dependent dehydrogenase of M. maripaludis.

View Article: PubMed Central - PubMed

Affiliation: Department of Civil and Environmental Engineering, University of Washington, Seattle, WA, USA.

ABSTRACT
Methanococcus maripaludis grown syntrophically with Desulfovibrio vulgaris was compared with M. maripaludis monocultures grown under hydrogen limitation using transcriptional, proteomic and metabolite analyses. These measurements indicate a decrease in transcript abundance for energy-consuming biosynthetic functions in syntrophically grown M. maripaludis, with an increase in transcript abundance for genes involved in the energy-generating central pathway for methanogenesis. Compared with growth in monoculture under hydrogen limitation, the response of paralogous genes, such as those coding for hydrogenases, often diverged, with transcripts of one variant increasing in relative abundance, whereas the other was little changed or significantly decreased in abundance. A common theme was an apparent increase in transcripts for functions using H(2) directly as reductant, versus those using the reduced deazaflavin (coenzyme F(420)). The greater importance of direct reduction by H(2) was supported by improved syntrophic growth of a deletion mutant in an F(420)-dependent dehydrogenase of M. maripaludis. These data suggest that paralogous genes enable the methanogen to adapt to changing substrate availability, sustaining it under environmental conditions that are often near the thermodynamic threshold for growth. Additionally, the discovery of interspecies alanine transfer adds another metabolic dimension to this environmentally relevant mutualism.

Show MeSH
Related in: MedlinePlus