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Nutrient requirements and growth physiology of the photoheterotrophic Acidobacterium, Chloracidobacterium thermophilum.

Tank M, Bryant DA - Front Microbiol (2015)

Bottom Line: Mixtures of other AAs and 2-oxoglutarate stimulate growth.As suggested from genomic sequence data, C. thermophilum requires a reduced sulfur source such as thioglycolate, cysteine, methionine, or thiosulfate.The organism can be grown in a defined medium at 51(∘)C (Topt; range 44-58(∘)C) in the pH range 5.5-9.5 (pHopt = ∼7.0).

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, Eberly College of Science, The Pennsylvania State University PA, USA.

ABSTRACT
A novel thermophilic, microaerophilic, anoxygenic, and chlorophototrophic member of the phylum Acidobacteria, Chloracidobacterium thermophilum strain B(T), was isolated from a cyanobacterial enrichment culture derived from microbial mats associated with Octopus Spring, Yellowstone National Park, Wyoming. C. thermophilum is strictly dependent on light and oxygen and grows optimally as a photoheterotroph at irradiance values between 20 and 50 μmol photons m(-2) s(-1). C. thermophilum is unable to synthesize branched-chain amino acids (AAs), l-lysine, and vitamin B12, which are required for growth. Although the organism lacks genes for autotrophic carbon fixation, bicarbonate is also required. Mixtures of other AAs and 2-oxoglutarate stimulate growth. As suggested from genomic sequence data, C. thermophilum requires a reduced sulfur source such as thioglycolate, cysteine, methionine, or thiosulfate. The organism can be grown in a defined medium at 51(∘)C (Topt; range 44-58(∘)C) in the pH range 5.5-9.5 (pHopt = ∼7.0). Using the defined growth medium and optimal conditions, it was possible to isolate new C. thermophilum strains directly from samples of hot spring mats in Yellowstone National Park, Wyoming. The new isolates differ from the type strain with respect to pigment composition, morphology in liquid culture, and temperature adaptation.

No MeSH data available.


Related in: MedlinePlus

Branched chain AAs are essential for growth of C. thermophilum. Growth of C. thermophilum strain BT with peptone, 20 common AAs and common AA without the branched chain AAs l-isoleucine, l-leucine, and l-valine. Note that no growth occurred in the absence of branched chain AAs. The asterisks for cysteine and methionine indicate that one of these AAs is essential in the absence of a reduced sulfur source. Tyrosine is essential under very low oxygen concentrations.
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Figure 7: Branched chain AAs are essential for growth of C. thermophilum. Growth of C. thermophilum strain BT with peptone, 20 common AAs and common AA without the branched chain AAs l-isoleucine, l-leucine, and l-valine. Note that no growth occurred in the absence of branched chain AAs. The asterisks for cysteine and methionine indicate that one of these AAs is essential in the absence of a reduced sulfur source. Tyrosine is essential under very low oxygen concentrations.

Mentions: C. thermophilum grew well on plates and in liquid culture when yeast extract was replaced by 100 mg L-1 peptone, which confirmed that C. thermophilum requires AAs for growth. In order to produce a completely defined growth medium for C. thermophilum, and to determine which AAs are utilized by C. thermophilum, we conducted growth experiments with axenic cultures, in which we tested different combinations of AAs, e.g., alpha-keto acids of the branched chain AAs plus ammonium, branched chain AAs only, and AAs without branched chain AAs. We also tested the essentiality of all 20 AAs individually. Growth of C. thermophilum is strictly dependent upon the branched chain AAs, l-isoleucine, l-leucine, and l-valine (Figure 7), and interestingly, l-lysine is also essential. When these four AAs were omitted from any growth medium, minimal or no growth of C. thermophilum occurred after the first transfer. The essentiality of l-isoleucine, l-leucine, l-lysine, and l-valine is consistent with the genomic sequence data that had predicted that C. thermophilum would be unable to synthesize these four AAs (Garcia Costas et al., 2012a). On the other hand C. thermophilum still grew after the third transfer into medium that contained these four AAs as sole nitrogen source, confirming that these AAs are capable of providing all nitrogen required for growth. All other AAs can be synthesized by C. thermophilum, which could be demonstrated in experiments in which one or more of the other sixteen AAs were omitted. In addition, HPLC analyses of AA utilization revealed that C. thermophilum is able to metabolize at least 18 of the 20 common AAs (Figure 4). Over a period of 14 days all AAs were consumed to varying extents except aspartic acid and glutamate, which actually seemed to be produced and excreted rather than being consumed. AA uptake ranged from a minimal value of 55% (l-threonine) to ∼95% (l-proline). As observed for the S- and C-sources, the response to N-source of C. thermophilum showed an oligotrophic behavior that is common among Acidobacteria (Eichorst et al., 2007; Fierer et al., 2007). Growth was not improved by simply adding a higher concentration of AAs to the medium at the start of cultivation. However, cultures produced higher biomass when they were supplemented with AAs over the time course for growth (Figure 8) Although they are common, natural, nitrogen-rich substances, putrescine, betaine, and DNA were not utilized as N-sources by C. thermophilum.


Nutrient requirements and growth physiology of the photoheterotrophic Acidobacterium, Chloracidobacterium thermophilum.

Tank M, Bryant DA - Front Microbiol (2015)

Branched chain AAs are essential for growth of C. thermophilum. Growth of C. thermophilum strain BT with peptone, 20 common AAs and common AA without the branched chain AAs l-isoleucine, l-leucine, and l-valine. Note that no growth occurred in the absence of branched chain AAs. The asterisks for cysteine and methionine indicate that one of these AAs is essential in the absence of a reduced sulfur source. Tyrosine is essential under very low oxygen concentrations.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4376005&req=5

Figure 7: Branched chain AAs are essential for growth of C. thermophilum. Growth of C. thermophilum strain BT with peptone, 20 common AAs and common AA without the branched chain AAs l-isoleucine, l-leucine, and l-valine. Note that no growth occurred in the absence of branched chain AAs. The asterisks for cysteine and methionine indicate that one of these AAs is essential in the absence of a reduced sulfur source. Tyrosine is essential under very low oxygen concentrations.
Mentions: C. thermophilum grew well on plates and in liquid culture when yeast extract was replaced by 100 mg L-1 peptone, which confirmed that C. thermophilum requires AAs for growth. In order to produce a completely defined growth medium for C. thermophilum, and to determine which AAs are utilized by C. thermophilum, we conducted growth experiments with axenic cultures, in which we tested different combinations of AAs, e.g., alpha-keto acids of the branched chain AAs plus ammonium, branched chain AAs only, and AAs without branched chain AAs. We also tested the essentiality of all 20 AAs individually. Growth of C. thermophilum is strictly dependent upon the branched chain AAs, l-isoleucine, l-leucine, and l-valine (Figure 7), and interestingly, l-lysine is also essential. When these four AAs were omitted from any growth medium, minimal or no growth of C. thermophilum occurred after the first transfer. The essentiality of l-isoleucine, l-leucine, l-lysine, and l-valine is consistent with the genomic sequence data that had predicted that C. thermophilum would be unable to synthesize these four AAs (Garcia Costas et al., 2012a). On the other hand C. thermophilum still grew after the third transfer into medium that contained these four AAs as sole nitrogen source, confirming that these AAs are capable of providing all nitrogen required for growth. All other AAs can be synthesized by C. thermophilum, which could be demonstrated in experiments in which one or more of the other sixteen AAs were omitted. In addition, HPLC analyses of AA utilization revealed that C. thermophilum is able to metabolize at least 18 of the 20 common AAs (Figure 4). Over a period of 14 days all AAs were consumed to varying extents except aspartic acid and glutamate, which actually seemed to be produced and excreted rather than being consumed. AA uptake ranged from a minimal value of 55% (l-threonine) to ∼95% (l-proline). As observed for the S- and C-sources, the response to N-source of C. thermophilum showed an oligotrophic behavior that is common among Acidobacteria (Eichorst et al., 2007; Fierer et al., 2007). Growth was not improved by simply adding a higher concentration of AAs to the medium at the start of cultivation. However, cultures produced higher biomass when they were supplemented with AAs over the time course for growth (Figure 8) Although they are common, natural, nitrogen-rich substances, putrescine, betaine, and DNA were not utilized as N-sources by C. thermophilum.

Bottom Line: Mixtures of other AAs and 2-oxoglutarate stimulate growth.As suggested from genomic sequence data, C. thermophilum requires a reduced sulfur source such as thioglycolate, cysteine, methionine, or thiosulfate.The organism can be grown in a defined medium at 51(∘)C (Topt; range 44-58(∘)C) in the pH range 5.5-9.5 (pHopt = ∼7.0).

View Article: PubMed Central - PubMed

Affiliation: Department of Biochemistry and Molecular Biology, Eberly College of Science, The Pennsylvania State University PA, USA.

ABSTRACT
A novel thermophilic, microaerophilic, anoxygenic, and chlorophototrophic member of the phylum Acidobacteria, Chloracidobacterium thermophilum strain B(T), was isolated from a cyanobacterial enrichment culture derived from microbial mats associated with Octopus Spring, Yellowstone National Park, Wyoming. C. thermophilum is strictly dependent on light and oxygen and grows optimally as a photoheterotroph at irradiance values between 20 and 50 μmol photons m(-2) s(-1). C. thermophilum is unable to synthesize branched-chain amino acids (AAs), l-lysine, and vitamin B12, which are required for growth. Although the organism lacks genes for autotrophic carbon fixation, bicarbonate is also required. Mixtures of other AAs and 2-oxoglutarate stimulate growth. As suggested from genomic sequence data, C. thermophilum requires a reduced sulfur source such as thioglycolate, cysteine, methionine, or thiosulfate. The organism can be grown in a defined medium at 51(∘)C (Topt; range 44-58(∘)C) in the pH range 5.5-9.5 (pHopt = ∼7.0). Using the defined growth medium and optimal conditions, it was possible to isolate new C. thermophilum strains directly from samples of hot spring mats in Yellowstone National Park, Wyoming. The new isolates differ from the type strain with respect to pigment composition, morphology in liquid culture, and temperature adaptation.

No MeSH data available.


Related in: MedlinePlus