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Optimization and effects of different culture conditions on growth of Halomicronema hongdechloris - a filamentous cyanobacterium containing chlorophyll f.

Li Y, Lin Y, Loughlin PC, Chen M - Front Plant Sci (2014)

Bottom Line: High performance liquid chromatography on H. hongdechloris pigments confirmed that chlorophyll a is the major chlorophyll and chlorophyll f constitutes ~10% of the total chlorophyll from cells grown under far-red light.The total photosynthetic oxygen evolution yield per cell showed no changes under different light conditions, which confirms the involvement of chlorophyll f in oxygenic photosynthesis.The implications of the presence of chlorophyll f in H. hongdechloris and its relationship with the ambient light environment are discussed.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, University of Sydney Sydney, NSW, Australia.

ABSTRACT
A chlorophyll f containing cyanobacterium, Halomicronema hongdechloris (H. hongdechloris) was isolated from a stromatolite cyanobacterial community. The extremely slow growth rate of H. hongdechloris has hindered research on this newly isolated cyanobacterium and the investigation of chlorophyll f-photosynthesis. Therefore, optimizing H. hongdechloris culture conditions has become an essential requirement for future research. This work investigated the effects of various culture conditions, essential nutrients and light environments to determine the optimal growth conditions for H. hongdechloris and the biosynthetic rate of chlorophyll f. Based on the total chlorophyll concentration, an optimal growth rate of 0.22 ± 0.02 day(-1)(doubling time: 3.1 ± 0.3 days) was observed when cells were grown under continuous illumination with far-red light with an intensity of 20 μE at 32°C in modified K + ES seawater (pH 8.0) with additional nitrogen and phosphor supplements. High performance liquid chromatography on H. hongdechloris pigments confirmed that chlorophyll a is the major chlorophyll and chlorophyll f constitutes ~10% of the total chlorophyll from cells grown under far-red light. Fluorescence confocal image analysis demonstrated changes of photosynthetic membranes and the distribution of photopigments in response to different light conditions. The total photosynthetic oxygen evolution yield per cell showed no changes under different light conditions, which confirms the involvement of chlorophyll f in oxygenic photosynthesis. The implications of the presence of chlorophyll f in H. hongdechloris and its relationship with the ambient light environment are discussed.

No MeSH data available.


Oxygen evolution rate of H. hongdechloris grown under (A) far-red light (FR) or (B) white light (WL), with either FR or WL light as the incident light source as indicated. Data are based on total chlorophyll content. A insert: oxygen evolution rate of H. hongdechloris cells at 25°C or 32°C with 67 μE white light illumination. (C) The oxygen evolution rate of H. hongdechloris cells grown under either FR or WL conditions based on biomass, using white light as the incident light source. Error bars represent SDs (n = 9).
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Figure 7: Oxygen evolution rate of H. hongdechloris grown under (A) far-red light (FR) or (B) white light (WL), with either FR or WL light as the incident light source as indicated. Data are based on total chlorophyll content. A insert: oxygen evolution rate of H. hongdechloris cells at 25°C or 32°C with 67 μE white light illumination. (C) The oxygen evolution rate of H. hongdechloris cells grown under either FR or WL conditions based on biomass, using white light as the incident light source. Error bars represent SDs (n = 9).

Mentions: To enhance the content of Chl f and the total biomass, different light intensities of FR light were tested and compared with the equivalent intensities of white light. The highest Chl f/Chl a index (A730-780 nm/A678-780 nm) of 0.29 is observed under the FR light intensities of 10–20 μE (Figure 6B). Increased FR light intensities resulted in a decreased Chl f/Chl a index of 0.13 and the increased carotenoids to Chl a index (Car/Chl a, A495-780 nm/A678-780 nm), which may indicate the culture was under high-light stress. Interestingly, the cells grown under WL light showed a more stable pigment content beside the increased Car/Chl a index under increased light intensities. The highest Car/Chl a index of ~1.9 was observed in the cells grown under FR light/60 μE light, suggesting the high-light stressed situation for H. hongdechloris cells (Figure 7B insert). The relatively stable amount of phycobiliprotein and the dramatic changes in Chl f concentration (Figure 6B insert) observed in cells grown under different intensities of FR light suggest that Chl f plays an important role in the capture and use of FR light for driving photosynthetic reactions. Increases in the Car/Chl a index observed in the cells under possible high-light stress agree well with the decreased growth rate for the cells grown under these higher intensities of either FR or WL light (Figures 3B,C). The optimized light condition for H. hongdechloris culture is FR light with lower light intensity of 10–20 μE.


Optimization and effects of different culture conditions on growth of Halomicronema hongdechloris - a filamentous cyanobacterium containing chlorophyll f.

Li Y, Lin Y, Loughlin PC, Chen M - Front Plant Sci (2014)

Oxygen evolution rate of H. hongdechloris grown under (A) far-red light (FR) or (B) white light (WL), with either FR or WL light as the incident light source as indicated. Data are based on total chlorophyll content. A insert: oxygen evolution rate of H. hongdechloris cells at 25°C or 32°C with 67 μE white light illumination. (C) The oxygen evolution rate of H. hongdechloris cells grown under either FR or WL conditions based on biomass, using white light as the incident light source. Error bars represent SDs (n = 9).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3934312&req=5

Figure 7: Oxygen evolution rate of H. hongdechloris grown under (A) far-red light (FR) or (B) white light (WL), with either FR or WL light as the incident light source as indicated. Data are based on total chlorophyll content. A insert: oxygen evolution rate of H. hongdechloris cells at 25°C or 32°C with 67 μE white light illumination. (C) The oxygen evolution rate of H. hongdechloris cells grown under either FR or WL conditions based on biomass, using white light as the incident light source. Error bars represent SDs (n = 9).
Mentions: To enhance the content of Chl f and the total biomass, different light intensities of FR light were tested and compared with the equivalent intensities of white light. The highest Chl f/Chl a index (A730-780 nm/A678-780 nm) of 0.29 is observed under the FR light intensities of 10–20 μE (Figure 6B). Increased FR light intensities resulted in a decreased Chl f/Chl a index of 0.13 and the increased carotenoids to Chl a index (Car/Chl a, A495-780 nm/A678-780 nm), which may indicate the culture was under high-light stress. Interestingly, the cells grown under WL light showed a more stable pigment content beside the increased Car/Chl a index under increased light intensities. The highest Car/Chl a index of ~1.9 was observed in the cells grown under FR light/60 μE light, suggesting the high-light stressed situation for H. hongdechloris cells (Figure 7B insert). The relatively stable amount of phycobiliprotein and the dramatic changes in Chl f concentration (Figure 6B insert) observed in cells grown under different intensities of FR light suggest that Chl f plays an important role in the capture and use of FR light for driving photosynthetic reactions. Increases in the Car/Chl a index observed in the cells under possible high-light stress agree well with the decreased growth rate for the cells grown under these higher intensities of either FR or WL light (Figures 3B,C). The optimized light condition for H. hongdechloris culture is FR light with lower light intensity of 10–20 μE.

Bottom Line: High performance liquid chromatography on H. hongdechloris pigments confirmed that chlorophyll a is the major chlorophyll and chlorophyll f constitutes ~10% of the total chlorophyll from cells grown under far-red light.The total photosynthetic oxygen evolution yield per cell showed no changes under different light conditions, which confirms the involvement of chlorophyll f in oxygenic photosynthesis.The implications of the presence of chlorophyll f in H. hongdechloris and its relationship with the ambient light environment are discussed.

View Article: PubMed Central - PubMed

Affiliation: School of Biological Sciences, University of Sydney Sydney, NSW, Australia.

ABSTRACT
A chlorophyll f containing cyanobacterium, Halomicronema hongdechloris (H. hongdechloris) was isolated from a stromatolite cyanobacterial community. The extremely slow growth rate of H. hongdechloris has hindered research on this newly isolated cyanobacterium and the investigation of chlorophyll f-photosynthesis. Therefore, optimizing H. hongdechloris culture conditions has become an essential requirement for future research. This work investigated the effects of various culture conditions, essential nutrients and light environments to determine the optimal growth conditions for H. hongdechloris and the biosynthetic rate of chlorophyll f. Based on the total chlorophyll concentration, an optimal growth rate of 0.22 ± 0.02 day(-1)(doubling time: 3.1 ± 0.3 days) was observed when cells were grown under continuous illumination with far-red light with an intensity of 20 μE at 32°C in modified K + ES seawater (pH 8.0) with additional nitrogen and phosphor supplements. High performance liquid chromatography on H. hongdechloris pigments confirmed that chlorophyll a is the major chlorophyll and chlorophyll f constitutes ~10% of the total chlorophyll from cells grown under far-red light. Fluorescence confocal image analysis demonstrated changes of photosynthetic membranes and the distribution of photopigments in response to different light conditions. The total photosynthetic oxygen evolution yield per cell showed no changes under different light conditions, which confirms the involvement of chlorophyll f in oxygenic photosynthesis. The implications of the presence of chlorophyll f in H. hongdechloris and its relationship with the ambient light environment are discussed.

No MeSH data available.