Effects of alkalinity, extremely low carbon dioxide concentration and irradiance on spectral properties, phycobilisome, photosynthesis, photosystems and functional groups of the native cyanobacterium Calothrix sp. ISC 65
In this research, Calothrix sp. ISC 65 was characterized physiologically by the combination of extremely low irradiance (2 μE·m⁻²·s⁻¹), different alkalinity (pH 7, 9, 11), and extremely limited carbon dioxide concentration (no aeration, no carbon dioxide enrichment). In this research, Calothrix sp...
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Інститут ботаніки ім. М.Г. Холодного НАН України
2019
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| Цитувати: | Effects of alkalinity, extremely low carbon dioxide concentration and irradiance on spectral properties, phycobilisome, photosynthesis, photosystems and functional groups of the native cyanobacterium Calothrix sp. ISC 65 / B. Abbasi, Sh. Shokravi, M.Ah. Golsefidi, A. Sateiee, E. Kiaei // Альгология. — 2019. — Т. 29, № 1. — С. 40-58. — Бібліогр.: 50 назв. — англ. |
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irk-123456789-1592332019-09-28T01:25:34Z Effects of alkalinity, extremely low carbon dioxide concentration and irradiance on spectral properties, phycobilisome, photosynthesis, photosystems and functional groups of the native cyanobacterium Calothrix sp. ISC 65 Abbasi, B. Shokravi, Sh. Golsefidi, M.Ah. Sateiee, A. Kiaei, E. Физиология, биохимия, биофизика In this research, Calothrix sp. ISC 65 was characterized physiologically by the combination of extremely low irradiance (2 μE·m⁻²·s⁻¹), different alkalinity (pH 7, 9, 11), and extremely limited carbon dioxide concentration (no aeration, no carbon dioxide enrichment). In this research, Calothrix sp. ISC 65 was characterized physiologically by the combination of extremely low irradiance (2 μE·m⁻²·s⁻¹), different alkalinity (pH 7, 9, 11), and extremely limited carbon dioxide concentration (no aeration, no carbon dioxide enrichment). Исследован физиологический ответ штамма Calothrix sp. ISC 65 на культивирование в условиях сверхнизкой освещенности (2 μE·м⁻²·с⁻¹) при различных значениях рН (7, 9, 11) и низкой концентрации углекислого газа (без аэрации и обогащения углекислым газом). 2019 Article Effects of alkalinity, extremely low carbon dioxide concentration and irradiance on spectral properties, phycobilisome, photosynthesis, photosystems and functional groups of the native cyanobacterium Calothrix sp. ISC 65 / B. Abbasi, Sh. Shokravi, M.Ah. Golsefidi, A. Sateiee, E. Kiaei // Альгология. — 2019. — Т. 29, № 1. — С. 40-58. — Бібліогр.: 50 назв. — англ. 0868-8540 DOI: https://doi.org/10.15407/alg29.01.040 http://dspace.nbuv.gov.ua/handle/123456789/159233 en Альгология Інститут ботаніки ім. М.Г. Холодного НАН України |
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Физиология, биохимия, биофизика Физиология, биохимия, биофизика |
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Физиология, биохимия, биофизика Физиология, биохимия, биофизика Abbasi, B. Shokravi, Sh. Golsefidi, M.Ah. Sateiee, A. Kiaei, E. Effects of alkalinity, extremely low carbon dioxide concentration and irradiance on spectral properties, phycobilisome, photosynthesis, photosystems and functional groups of the native cyanobacterium Calothrix sp. ISC 65 Альгология |
| description |
In this research, Calothrix sp. ISC 65 was characterized physiologically by the combination of extremely low irradiance (2 μE·m⁻²·s⁻¹), different alkalinity (pH 7, 9, 11), and extremely limited carbon dioxide concentration (no aeration, no carbon dioxide enrichment).
In this research, Calothrix sp. ISC 65 was characterized physiologically by the combination of extremely low irradiance (2 μE·m⁻²·s⁻¹), different alkalinity (pH 7, 9, 11), and extremely limited carbon dioxide concentration (no aeration, no carbon dioxide enrichment). |
| format |
Article |
| author |
Abbasi, B. Shokravi, Sh. Golsefidi, M.Ah. Sateiee, A. Kiaei, E. |
| author_facet |
Abbasi, B. Shokravi, Sh. Golsefidi, M.Ah. Sateiee, A. Kiaei, E. |
| author_sort |
Abbasi, B. |
| title |
Effects of alkalinity, extremely low carbon dioxide concentration and irradiance on spectral properties, phycobilisome, photosynthesis, photosystems and functional groups of the native cyanobacterium Calothrix sp. ISC 65 |
| title_short |
Effects of alkalinity, extremely low carbon dioxide concentration and irradiance on spectral properties, phycobilisome, photosynthesis, photosystems and functional groups of the native cyanobacterium Calothrix sp. ISC 65 |
| title_full |
Effects of alkalinity, extremely low carbon dioxide concentration and irradiance on spectral properties, phycobilisome, photosynthesis, photosystems and functional groups of the native cyanobacterium Calothrix sp. ISC 65 |
| title_fullStr |
Effects of alkalinity, extremely low carbon dioxide concentration and irradiance on spectral properties, phycobilisome, photosynthesis, photosystems and functional groups of the native cyanobacterium Calothrix sp. ISC 65 |
| title_full_unstemmed |
Effects of alkalinity, extremely low carbon dioxide concentration and irradiance on spectral properties, phycobilisome, photosynthesis, photosystems and functional groups of the native cyanobacterium Calothrix sp. ISC 65 |
| title_sort |
effects of alkalinity, extremely low carbon dioxide concentration and irradiance on spectral properties, phycobilisome, photosynthesis, photosystems and functional groups of the native cyanobacterium calothrix sp. isc 65 |
| publisher |
Інститут ботаніки ім. М.Г. Холодного НАН України |
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2019 |
| topic_facet |
Физиология, биохимия, биофизика |
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http://dspace.nbuv.gov.ua/handle/123456789/159233 |
| citation_txt |
Effects of alkalinity, extremely low carbon dioxide concentration and irradiance on spectral properties, phycobilisome, photosynthesis, photosystems and functional groups of the native cyanobacterium Calothrix sp. ISC 65 / B. Abbasi, Sh. Shokravi, M.Ah. Golsefidi, A. Sateiee, E. Kiaei // Альгология. — 2019. — Т. 29, № 1. — С. 40-58. — Бібліогр.: 50 назв. — англ. |
| series |
Альгология |
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| fulltext |
Abbasi B. et al.
40
ISSN 0868-854 (Print)
ISSN 2413-5984 (Online). Аlgologia. 2019, 29(1): 40—58
https://doi.org/10.15407/alg29.01.040
ABBASI B.1, SHOKRAVI Sh.1, GOLSEFIDI M.Ah.2, SATEIEE A.1, KIAEI E.1
1Department of Biology, Gorgan Branch, Islamic Azad University, Gorgan, Iran
2Department of Chimistry, Gorgan Branch, Islamic Azad University, Gorgan, Iran
shadmanshokravi@gorgan.iau.ac.ir
EFFECTS OF ALKALINITY, EXTREMELY LOW CARBON DIOXIDE
CONCENTRATION AND IRRADIANCE ON SPECTRAL
PROPERTIES, PHYCOBILISOME, PHOTOSYNTHESIS,
PHOTOSYSTEMS AND FUNCTIONAL GROUPS OF THE NATIVE
CYANOBACTERIUM CALOTHRIX SP. ISC 65
In this research, Calothrix sp. ISC 65 was characterized physiologically by the combination
of extremely low irradiance (2 μEm-2s-1), different alkalinity (pH 7, 9, 11), and extremely
limited carbon dioxide concentration (no aeration, no carbon dioxide enrichment).
Spectroscopical analysis showed that pH 9, after 96 hours, caused a significant increase in
growth rate, chlorophyll, and phycocyanin production. A lower (pH of 7) caused a decrease
of phycobilisome production even after 24 hours. Excitation of the light harvesting complex
and the reaction center of photosystems resulted from a pH of 9. Phycocyanin seems to be
the main part of phycobilisome but pH 9 caused phycoerythrin and allophycocyanin
production excitation in the outer part of the photosynthetic antenna as well. A fluorimetric
and photosynthesis-irradiance curve analysis showed that increasing alkalinity (up to pH 9)
caused an increase in photosynthesis efficiency and a decrease of non-photochemical
fluorescence especially after 96 hours. PSII : PSI ratio increased by increasing alkalinity
from pH 7 to 9 and reached the highest level after 96 hours. Surface response plot analysis
showed that there is a narrow border line around pH 9 and 96 hours which caused the
highest PSII : PSI ratio. FTIR analysis showed that alkalinity caused configuration changes
of the functional groups. The difference of the functional group patterns between pH 7 and
11 was significant especially after 24 hours. Differences in asymmetric carbon vibration,
lipid stretching and OH bending of the polysaccharides occurred with both pH 9 and 11
treatments. pH 9 caused the most physiological activities in Calothrix sp. ISC 65 at
extremely limited irradiance and carbon dioxide concentration.
K e y w o r d s : alkalinity, Calothrix, cyanobacteria, dissolved inorganic carbon, limited
irradiance
A b b r e v i a t i o n s : APC allophycocyanin, CCM carbon dioxide concentrating mechanism,
DIC dissolved inorganic carbon, PBS phycobilisome, PC phycocyanin, PE phycoerythrin,
PSI, PSII photosystems I and II
© Abbasi B., Shokravi Sh., Golsefidi M.Ah., Sateiee A., Kiaei E., 2019
Effects of alkalinity
41
Introduction
Under natural conditions in rice fields and petroleum polluted soils,
cyanobacteria are exposed to the combined influences of several factors such
as alkalinity, irradiance and dissolved inorganic carbon fluctuations, which
may vary even on a daily basis (Shokravi, Soltani, 2011). Growth,
biochemical and physiological characteristics of cyanobacteria are influenced
by these environmental factors. Furthermore, widely fluctuating environmental
parameters, including light level and quality, as well as temperature and
mineral nutrient availability, interact to influence growth, molecular resource
allocation, and photosynthesis through complex adaptation strategies. For
example, Gan et al. (2014) believed that cyanobacteria can alter their total
Chl. and PBS content; adjust their PSI to PSII ratio; perform non-
photochemical quenching using the orange carotenoid protein; and modify
their light-harvesting complexes in response to nutrient stresses (S, N, and Fe
limitation).
Light is evidently one of the most important factors that determine the
natural distribution of cyanobacteria. As other photosynthetic organisms,
cyanobacteria are able to adapt to variations in light intensity; nevertheless,
little work has been done in this area (Shokravi, Soltani, 2011). Authors
Baсares-Espaсa et al. (2013) believed that cyanobacteria capable of forming
surface blooms cannot cope as well with high-light stress as well as green algae
can. This cyanobacterium acclimated to the light field by changing both its
size and the number of its photosynthetic units. In rice fields, light reaching
the floodwater varies both daily and over the crop cycle because of the
variation in light transmission caused by changes in rice canopy height. In
Iran, the drop of sunlight in rice-fields seems relatively harder (for example
measurements at Golestan province at the north of Iran) showed a declining
rate from 1000 μmol photonm-2s-1 early in the growth of the crop to 2 and
even 0.5 μmol photonm-2s-1 when the crop was matured, especially on cloudy
and rainy days. Therefore, the acclimation of cyanobacteria to such an
extremely low light condition seems important and basic (Shokravi and
Soltani, 2011).
The alkalinity of the soils is one of the most important problems in both
north and south Iran (Amirlatifi et al., 2013). We have no special information
about behaviors of different strains of native Rivulariaceae to alkalinity
fluctuations other than what (at species level) has been reported for other
cyanobacteria. For example, Padhi et al. (2011) have studied the effect of
alkalinity on the biomass of different species of Anabaena and have shown
special behaviors of each species. Authors Shokravi et al. (2010), studying
Abbasi B. et al.
42
acclimation of the native cyanobacterium Haplosiphon sp. FS 44 to combined
effects of carbon dioxide concentration, acidity, and alkalinity showed that
differences of growth rates seemed insignificant between acidic and alkaline
conditions but carbon dioxide enrichments caused a significant increase in the
growth rate. Phycobilisome system of this strain lack phycoerythrin, however
it may complete its structure both at the core and the rode at alkaline
conditions. However, it seems that most of the cyanobacteria including
Rivulariaceae prefer neutral to alkaline environments (Poza-Carriуn et al.,
2001; Soltani et al., 2006). Preliminary tests showed that the strain of
Calothrix is similar to another cyanobacterium studied from the northern
paddy-fields of Iran, resembled an alkalophile strain. Microscopic observations
showed that with pH 5, at the end of the first week, most of the filaments
degenerated, and their colors changed to yellow. Irradiance and DIC
fluctuations had no effect on this (Abbasi et al., unpublished data). This was
compatible with our previous results as well (Soltani et al., 2007; Shokravi et
al., 2014; Safaie et al., 2015). Regarding the above, we avoided using acidic
conditions in spite of the previous papers (Soltani et al., 2007; Iranshahi et
al., 2014; Shokravi et al., 2014).
Fast and high amplitude changes in light happen in the context of a
variable environmental Ci concentration, influenced by water temperature,
pH, exchange with the atmosphere, photosynthetic and respiratory activities of
the plankton and benthos, and import from terrestrial sources (Cole et al.,
1994). To maintain a high intracellular Ci concentration across variable
environmental Ci concentrations, cyanobacteria can induce powerful carbon
concentrating mechanisms (CCM) to actively concentrate sparse environ-
mental Ci into the cell using energy from photosynthesis, and then release
internal Ci as CO2 near Rubisco at concentrations sufficient for efficient
assimilation into organic form by the Calvin cycle (Tyler et al., 2004).
The aim of this work was to establish the combined influence of alkalinity
and DIC limitation on growth, photosynthesis, and photosynthetic pigmentation,
of the new collected, and identified cyanobacterium Calothrix sp. strain ISC
65 which for the first time, was isolated from oil polluted soils of Iran (Soltani
et al., 2012) and has been recently collected and determined (but not
reported) from paddy fields of Iran at different alkalinities, extremely limited
DIC, and with irradiance more or less similar to natural rice-field of Golestan
province when maturing of the crop takes place (2 μmol photonm-2s-1). We
focused on extreme representative alkalinity values in Iranian rice fields (pH
7, 9 and rarely 11). In addition, we added time as an important factor,
especially for the influence of irradiance. Authors Soltani et al. (2007) showed
Effects of alkalinity
43
that the longtime photosynthesis differed completely at combinations of
alkalinity and irradiance after 24 and especially 96 hours.
Materials and Methods
Isolation of strain
Calothrix sp. was isolated for the first time from endaphic and epilithic forms
in Khuzestan province (Khark Island, south of Iran and near the Persian
Gulf). Recently we collected and identified such a strain from paddy-fields of
Golestan Province as well. The complete descriptions of the stations and their
geographical and environmental conditions have been reported in Soltani et
al. (2012). The collected sampleswere culturedby ordinary methods (Kaushik,
1987). After colonization and isolation, the cyanobacteria Calothrix sp. ISC 65
was purified and became axenic (Kaushik, 1987). Morphologically
identification and determination were done according to Desikachary (1959),
Prescott (1962), Tiffany and Britton (1971), Komárek and Anagnostidis
(1989), and John et al. (2003). Molecular identification was done by 16S
rDNA according to Dezfulian et al. (2010). PCR-identification of Calothrix
sp. ISC 65 was isolated from south of Iran. NCBI: GU591756.
Stock cultures were grown in N-free medium. BG110 solid medium was
used for culturing (materials for BG110 medium: MgSO4 · 7H2O, 0.3 mM;
CaCl2 · 2H2O, 0.25 mM; K2HPO4 · 3H2O, 0.18 mM; Na2Mg · EDTA,
0.003 mM, Citrate ferric 0.02 mM; Acid Citric, 0.029 mM; Na2CO3 ·
0.188 mM; microelements 1 mL · L-1). The pH was then raised to 7.2 by
adding of NaOH, and the solution was autoclaved. Purification and the axenic
culture method were controlled microscopically (Shokravi, Soltani, 2011).
Incubation conditions and treatments
Stock cultures were grown in the BG110 culture medium. Temperature
was maintained at 30 °C and cultures were incubated under a constant light
intensity of 60 μmol photonm-2s-1 supplied by three fluorescent lamps (Poza-
Carrion et al., 2001). Cells in the logarithmic phase of growth were collected
from stock cultures and used as inoculate for experiments. Cells from the
stock culture were inoculated in 300 mL of BG110 medium in 500 mL
Erlenmeyer flasks stoppered with cotton plugs. Cultures were illuminated via
different numbers of nets between light source and flasks. Illumination was
supplied with 40 W cool white fluorescent tubes to attain a desired low
irradiance (2 μmol photonm-2 · s-1). Light measurements were made with
Licor LI-1000 Datalogger equipped with a quantum sensor. Aliquots were
taken and used for determinations when cells adapted to the light regime in
Abbasi B. et al.
44
logarithmic phase. Finally, we compared cultures without supplementary
aeration or stirring (standing condition, extremely DIC limitation) (Shokravi
et al., 2014). Alkalinity treatments were made using NaOH at three ranges
(pH 7, 9, and 11) which were prepared in different flasks.
Analytical methods
Growth measurements, pigment composition, and PBS system were
analyzed spectroscopically after 24, 48, 72, and 96 hours of alkalinity
treatments according to Fraser et al. (2013). Photosystem ratios and
characteristics were done spectrofluorimetrically according to Zorz et al.
(2015) and Inoue-Kashino et al. (2005). For absorption spectra of intact cells;
after harvesting the cells, the pellets were suspended in 3 mL of reaction
buffer. This cell suspension was taken for scanning the absorption spectra
from 360 nm to 800 nm. The absorption spectra of intact cell suspension were
taken using a Hitachi-557 double beam spectrophotometer. At 750 nm the
absorption of the cell suspension was adjusted to give approximately the same
reading. Room temperature fluorescence emission spectra of the cells were
recorded on a Perkin-Elmer LS-5 spectrofluorimeter following Tiwari and
Mohanty (1996). PSII : PSI ratio analysis was done by spectrofluorimetry
according to Gan et al. (2014), and Amirlatifi et al. (2018). The fluorimetric
analysis was operated using Marvizadeh et al. (2013). For FTIR analysis,
1.5 mL from the suspension was centrifuged at 10000 rpm for 10 min. The
pellet was dried using lyophilization and the 100 mg were mixed with 1000 mg
KBr the disc was prepared and the total fatty acids were evaluated using FTIR
(Ray leight-510) (Kiaei et al., 2013).
Statistical analysis
Data are the means and standard deviation of at least four replicates.
Statistical analyseswere examined using Designs-Expert Ver.7 and 10. One
factor and multifactor RSP analysis were done according to Ghobadian et al.
(2015).
Results and Discussion
The growth of Calothrix sp. ISC 65 continued at neutral (pH 7) and alkaline
(pH 9) conditions in log phase to 96 hours (Table 1). The biomass production
rate was influenced by alkalinity under both conditions. The rate of
chlorophyll production seemed compatible with the growth at extreme
conditions. This was not true for chlorophyll contents per cell and the peak of
chlorophyll absorption. Despite this; the effect on PBS (normalized to
chlorophyll) seemed more outstanding. DIC limitation could not change the
Effects of alkalinity
45
pattern of biomass production in Calothrix sp. ISC 65. Alkaline condition
(pH 9) and limited irradiance, caused the maximum biomass production and
growth rate. The role of alkalinity was more outstanding than irradiance
because pH 7 caused the decline in biomass production under the same
conditions of DIC and irradiance. Comparing optical densities at 750 nm
after 24 hours showed that cyanobacterium had a better ability for acclimation
at pH 9. This is in agreement with Soltani et al. (2007). Results for the
response of the toxic cyanobacterium Dolichospermum sp. to lowered pH (−0.4
units by adding CO2) and elevated temperature (+4 °C) in an experimental
set-up were examined. Growth rate, microcystin concentration and oxidative
stress were measured. The growth rate and intracellular toxin concentration
increased significantly as a response to temperature. When Dolichospermum
was exposed to the combination of elevated temperature and high CO2/low
pH, lipid peroxidation increased and antioxidant levels decreased (Brutemark
et al., 2015).
Spectroscopical analysis showed that the effect of alkalinity on
phycobilisome production was outstanding especially after 96 hours (Table 1).
After 24 hours, the difference between the effect of pH 7 and 9 was not
significant. After 96 hours, the high alkaline condition caused excitation of
phycobilisome production. This was not true under neutral condition. The
production of phycobilisomes depended on the alkalinity under long periods
and not for short periods. The role of time seemed more outstanding than
DIC and irradiance (Fig. 1).
Table 1
Spectral characteristics of Calothrix sp. ISC 65 over 24 and 96 hours alkalinity treatments
pH 9 pH 7 Time, hours Spectral characteristics
-1.78 -1.46 24
-1.35 -1.23 96
ln (A750)
-3.25 -3.78 24
-2.24 -3.69 96
ln (A680-A750)
0.23 0.10 24
0.19 0.17 96
(A680-A750)/A750
685 685 24
688 686 96
Chl (λmax)
1.28 1.21 24 (A630-A750)/(A680-A750)
Abbasi B. et al.
46
Design-Expert® Software
Factor Coding: Actual
PBS
2.95
0.09
X1 = A: pH
X2 = B: time
Actual Factor
C: PSII/PSI = 1.7785
24
33
42
51
60
69
78
87
96
7
7.5
8
8.5
9
-2
-1
0
1
2
3
4
5
P
B
S
A: pHB: time (hours)
Fig. 1. RSP-analysis of PBS in Calothrix sp. ISC 65 at different alkalinities and time
treatments
Collectively, we can say, the effect of alkalinity in the growth rate and
phycobilisome production in this strain seemed essential and this did not
depend on extremely limited DIC and irradiance. This was not true for
Fischerella sp. FS 18 (Soltani et al., 2007) and Hapalosiphon sp. FS 44
(Shokravi et al., 2014) collected from the same region.
Table 2 shows the effect of alkalinity on pigment composition of Calothrix
sp. ISC 65. Results emphasized that alkalinity treatments caused excitation of
both light-harvesting complex and phycobilisome system. Pigmentation is the
main phenotypic difference within the similarly sized, planktonic freshwater
picocyanobacteria.
Table 2
Absorption ratios of Calothrix sp. ISC 65 after 24 and 96 hours alkalinity treatments
time course
Absorption ratio of Calothrix pH
440/680 480/680 621/680
24 96 24 96 24 96
7
1.308 1.370 1.367 1.160 1.031 1.943
9 1.379 1.395 1.422 1.315 1.054 1.945
Effects of alkalinity
47
Red PE-rich picocyanobacteria use phycoerythrin, and green PC-rich
picocyanobacteria use phycocyanin as major light-harvesting pigments (Moser
et al., 2009). The number of carotenoids and phycocyanin increased under
alkaline conditions, especially after 96 hours. This was true for chlorophyll
especially in the red region which forms essential parts of the main
photosynthetic reaction center and light harvesting system. Phycocyanin
contents appeared as the main part of phycobilisome and were more stable
during time and alkalinity fluctuations. It was interesting that alkalinity at
limited DIC and irradiance treatments excited phyco-biliproteins and
carotenoid production. Phycocyanin was the most concentrated under the
extreme values of the treatments comparing the other parts of phycobilisome
system: phycoerythrin and allophycocyanin. The highest rates of alkalinity,
especially after long periods of time, caused the highest rates of phycocyanin
production but the difference between short and long time periods was not
significant (Table 2).
Synechocystis sp. strain PCC 6803 grows photoatrophically across a broad
pH range (Summerfield et al., 2013). The mutant of this strain cannot tolerate
pH 7 (Summerfield et al., 2013). In spite of Calothrix sp. ISC 65, the
sensitivity of growth, pigment production and photosynthetic apparatus in
Fischerella sp. FS 18 (Soltani et al., 2011) and Hapalosiphon sp. FS 44 and 56
(Shokravi et al., 2012, 2014) collected from the same region to extremely
limited irradiance was noticeable. In Soltani et al. (2007) the amount of
chlorophyll production at relatively limited DIC (aeration condition) was
about 11.99 µgmg dw-1 (at 3 μEm-2s-1) and 8.32 µgmg dw-1 (at 300μE
m-2s-1). Decreasing irradiance to 2 (instead of 3 μEm-2s-1) and limitation of
DIC to non-aeration conditions caused different amounts of chlorophyll
production especially under alkaline conditions (pH 9). Safaie et al. (2015)
showed that in Fischerella sp. the higher amount of chlorophyll production
at pH 9 belonged to 2 μEm-2s-1 when DIC was not limited but to 300
μEm-2s-1 when DIC was extremely limited. In the case of Nostoc sp.
UAM205, it has been reported that the maximum growth rate was at pH 9
and increased with increasing light intensity at this pH (Fernández-Valiente
and Leganés, 1989).
But results of experiments with Nostoc sp. UAM 206 showed that the
effect of pH and light intensity depended on the availability of DIC, in such a
way that under conditions of DIC limitation growth increased with pH but
light conditions had no effect; on the contrary, when DIC was available
growth increased with increasing light but not effect of pH was observed
(Poza-Carriуn et al., 2001). Therefore, apparently the effects of irradiance and
alkalinity significantly depend on the species studied and, on growth
conditions (Soltani et al., 2007). It may be species-specific characteristics of
Abbasi B. et al.
48
photosynthetic apparatus helping dominance of the strain at DIC
concentration tensions, especially at different environmental conditions
include light and alkalinity (Deblois et al., 2013). Tyler et al. (2004) showed
that Synechococcus elongatus cells grown bubbled with air (approximately 370
mmol CO2 mol) induced a high-affinity CCM with a Km of 14 mmol Ci,
which maintained growth rates nearly as high as S. elongatus cells grown
bubbled with 50,000 mmol CO2 mol-1 air, which had a Km of 281 mmol Ci.
Thus, synthesis and maintenance of the CCM required significant investments
and rearrangements for cells growing in low-Ci environments, but
nonetheless, under steady light and nutrient supplies, low-Ci cells could
maintain photosynthesis and growth at levels comparable to high-Ci cells
without the same energetic and metabolic constraints of the induced CCM.
They hypothesized that the induced CCM in low-Ci cells would, however,
constrain the rate and amplitude of light acclimation (Tyler et al., 2004).
In the opposite of Fischerella sp. FS 18 (Soltani et al., 2007), the amounts
of PE and APC seemed high in Calothrix sp. ISC 65. The complete structure
of the core and rode parts of PBS, and the ratio between two parts depended
on the alkalinity (Table 3). But the effect of alkalinity was not significant. It
seemed that under neutral conditions (pH 7), the production of PE was high
and even more than PC. It was in dependent on the time. Only high alkalinity
for long periods could excite PC production and increase the PC : PE ratio.
This was nearly the same for APC. Alkalinity especially for long intervals
caused excitation of PC production which seemed compatible with the
findings of Amirlatifi et al. (2013) and Iranshahi et al. (2014).
Table 3
Absorption ratios of the rode and core parts of the phycobilisome of Calothrix sp. ISC 65
after 24 and 96 hours of alkalinity treatments at specific time intervals
Absorption ratio of Calothrix
(PC+PE)/APC PC/APC PC/PE
Time, hour pH
2.28 1.06 0.87 24
2.11 0.92 0.78 96
7
2.10 1.04 0.99 24
2.27 1.54 1.24 96
9
In Soltani et al. (2007), Fischerella sp. FS 18 had no APC at pH 7 and
limited carbon dioxide concentration. In Iranshahi et al. (2014), Shokravi et
al. (2014), and Safaie et al. (2015), this strain (and Hapalosiphon sp. FS 44)
had a large amount of APC. This must be related to irradiance and carbon
dioxide concentration. In Soltani et al. (2007) there was no limitation of
Effects of alkalinity
49
irradiance and carbon dioxide concentration and this possibly caused new
pattern of PBS behaviors. The distribution pattern of PBS (Fig. 1), showed
that except for a narrow border around combined pH 9 and 96 hours, the
distribution pattern of PBS seemed nearly uniform. We can suggest that PBS
production in such a strain is sensitive to the combination of time and
alkalinity at pH 9 under DIC and light limitation. From the applied point of
view, application of exact amount of alkalinity (pH 9) and time (96 hours) for
cultivation of this strain may significantly increase PBS production. This
coincides with Abbasi et al. (unpublished data) on Fischerella sp.
The sensitivity of pigment production and photosynthesis apparatus to
extremely limited irradiance was noticeable. Results (Table 4) showed that
although maximum photosynthesis normalized to chlorophyll was higher
under an alkaline (pH 9) condition, the degree of adaptation with limited
irradiance and consumed energy needed reaching to maximum photosynthesis
decreased at extremely high alkalinity (pH 11).
Table 4
Photosynthesis-irradiance curve parameters at different alkalinities in
Calothrix sp. ISC 65
pH Pmax (μmol O2 mg chl-1h-1) α Ik (μmol O2 mg chl-1h-1)
7 89 ± 8.23 1.3 ± 0.39 76 ± 12.23
9 227.99 ± 37.33 2.85 ± 0.18 48 ± 6.21
11 114.99 ± 17.39 1.35 ± 0.38 82.56 ± 9.11
Studies per biomass (not shown) revealed similar results in that the degree
of adaptation to limited irradiances (reaching the highest degree of
photosynthesis) was higher under alkaline conditions (pH 9). It seemed that
the efficiency of photosynthesis increased with alkalinity.
We could not observe photoinhibition even at extremely high light
intensities (more than 2000 μEm-2s-1) at pH 9. But treatment with both pH 7
and 11, caused photoinhibition below 1000 μEm-2s-1. This was the same as
relatively “limited and no limited” DIC concentration conditions at different
pH levels, irradiances and even nitrogen sources (Soltani et al., 2007, 2009).
Moser et al. (2009) studied freshwater picocyanobacteria acclimation to
irradiances from low (6 μEm-2s-1) to high (1500 μEm-2s-1), which showed
photoinhibition at high irradiance. The photosynthetic parameters varied
widely, both among the light acclimation treatments of each strain and
between the strains; Pmax of the LL (low light) culture from 4 to 19 times
higher than Pmax of the PC-rich cultures acclimated to LL. The initial slope of
Abbasi B. et al.
50
the P/E curve was highest and the saturation light intensity (Ik) was lowest in
the LL culture of BO8801. All cultures had significantly higher cell-specific
chlorophyll content in the LL than in the ML (mid-light intensity)
treatments. However, we can say alkalinity, up to pH 9, caused the maximum
photosynthesis of Calothrix sp. ISC 65, besides the higher quantum yield and
shade-adapted capacity and was another proof for increasing photosynthesis
and carbon dioxide concentration mechanism activity under this condition.
Alkalinity at the higher (pH 11) not only caused lower amounts of oxygen
liberation but also caused sensitivity to photoinhibition. It seemed that under
limitation of carbon dioxide concentration and irradiance, pH 9 treatments
caused the resistance of the photosynthetic apparatus against damages caused
by high number of irradiances.
In our study a light intensity of 2 μmol photonm-2s-1 was used, which is
lower than the one used by Lu and Vonshak (1999, 2002), Poza-Carrion et al.
(2001), Dhiab et al. (2007), Soltani et al. (2005), Soltani et al. (2007), and
many other papers. Strain Nostoc sp. UAM 205 and 206 have been
characterized at extremely limited carbon dioxide concentration but 60 μmol
photonm-2s-1 (Fernandez-Valiente, Leganes, 1989; Zeng, Vonshak, 1998;
Poza-Carrion et al., 2001) showed that at a higher light intensity, growing
cells had lower photosynthesis activity after photoinhibition under salinity
stress, compared with cells growing under lower light intensity condition
(Dhiab et al., 2007). However, the carbon dioxide conditions were not
considered in this research. The size of phycobilisomes and the relationship
between PSII and PSI (Yamanaka, Glazer, 1981; Poza-Carriуn et al., 2001;
Soltani et al., 2006) supported this but not completely. However, it was
obvious that the highest amount of PSII : PSI ratio and phycobilisome size
may be seen at pH 9. The high PSI : PSII (low PSII : PSI) ratio in
cyanobacteria caused the higher efficiency of energy transfer from PSII to
plastoquinone and then to PSI. In cyanobacteria there is usually more PSI for
each PSII. For example results revealed 2.3 in Synechococcus sp. and 2.5 for
Synechocystis sp. before iron starvation but decreased to 0.4 (Synechococcus
sp.) and 1.1 (Synechocystis sp.) after iron depletion (Gan et al., 2014). Ogawa,
Sonoike (2016) studying photosystem ratios in Synechocystis sp. PCC 6803, at
nitrogen deficiency, emphasized that photosystem stoichiometry was more or
less constant regardless of the change in growth media. PSI : PSII fluctuated
in this strain from nearly 3.5 to 4.5.
In Calothrix sp. FS 65, the highest rate of PSII : PSI, or the lowest
PSI : PSII, resulted under pH 9 after 96 hours (Table 5). Fluorimetric
analysis (Table 5) seemed compatible with photosynthesis efficiency (as a
whole) and photosystem ratios (as a special basic factor). A neutral condition
Effects of alkalinity
51
caused a sharp decline in PSII : PSI ratio and a decreased energy transfer
photochemically. Collectively, neutrality caused a decrease of energy in
photosynthesis and increased fluorescence. The relative fluorescence of PSI
chlorophyll (FPSI) of the mutant strains of Synechocystis PCC 6803 under
alkaline conditions (pH 8.2) was significantly lower than that of the wild-type
when normalized at 685 nm (Wang et al., 2008). We measured for pH 11
(data not shown) and the results were nearly the same but just like P-I curve
parameters, it seemed that neutrality (pH 7) caused more inefficiency
comparing extreme alkalinity (pH 11). The ratio of photosystems in this strain
was obviously less than Fischerella spp. (Soltani et al., 2007; Safaie et al.,
2015) Hapalosiphon spp. and Nostoc spp. (Shokravi et al., 2012, 2014; Kiaei et
al., 2013; Iranshahi et al., 2014).
Table 5
Fluorimetry and Photosystem ratio analysis of Calothrix sp. ISC 65 after 24 and 96 hours of
alkalinity treatments
Absorption ratio of Calothrix
PSII : PSI Fv'/Fm' Fv/Fm
pH
96 24 96 24 96 24
0.82 1.031 0.467 0.678 0.577 0.424
7
0.64 1.054 0.521 0.586 0.683 0.491 9
From applied aspects, increasing time (96 hours) and meanwhile
increasing alkalinity (pH 9) caused the highest ratio of PSII : PSI (Fig. 2). We
could increase the system’s efficiency simply by using a combination of pH 9
and 96-hour treatments. This may be the useful result for large-scale
cultivation in limited light and DIC concentration. PSI and naturally
reductant production and cyclic electron flow may increase considerably
more. For special situations which had to increase the activity of cyclic flow
or reductant pool of the strain, we can increase the time under alkalinity
conditions. This will provide more water photolysis ability and electron
transfer (besides energy) from PSII to Cyt.b6f. This coincides with Zorz et al.
(2015) who suggested that the abundance of Cyt b6f and PSI (besides the
relatively low level of PSII and Rubisco) are consistent with the increase in
cyclical electron flow around PSI in Prochlorococcus sp. MIT 9313.
FTIR spectrum comparison (Figs 1 and 2) showed the effect of alkalinity
on functional group productions at different times. It was interesting that both
(alkalinity and time) caused configurational pattern changes, but the influence
of time was more obvious.
Abbasi B. et al.
52
Design-Expert® Software
PSI/PSII
Design Points
2.3
0.2
X1 = A: pH
X2 = B: Time
7.00 7.50 8.00 8.50 9.00
24.00
42.00
60.00
78.00
96.00
PSI/PSII
A: pH
B
:
T
im
e
0.965333
1.16617
1.367
1.567831.76867
1.76867
55555
22
Fig. 2. RSP analysis of photosystem ratios in Calothrix sp. ISC 65 at different
alkalinities and time treatments
Different height of peaks revealed that changes in chemical functional
groups were caused by the combination of alkalinity and time. The bands
belong to Amide II groups and OH stretching for proteins and carbohydrates
showed different length of peaks after 96 hours. pH 11 caused the most
outstanding configuration changes. We showed differences around asymmetric
carbon vibration, lipid stretching and OH bending of the polysaccharides at
different alkalinities as well. Most these differences were revealed under pH
11. At this time, we cannot discuss the changes at fingerprint borders,
although the effect of alkalinity at this region seems important. The
combinations of extremely low irradiance, carbon dioxide concentration, and
alkalinity fluctuations produced different patterns in functional groups,
especially with carbohydrates and proteins in this strain in a short amount of
time. Differences appeared at the fingerprint regions after a long amount of
time.
FTIR analysis is rarely used in stress physiology (Figs 3 and 4). It is most
common in the papers on lipid biochemistry and profile especially for biofuel
application purposes. It's importance in the taxonomy of algae has been
suggested (Ratledge, Wilkinson, 1988; Cohen et al., 1995; Kenne, van der
Merwe, 2013; Borah et al., 2016) but further research is needed in the
taxonomy of cyanobacteria. Borah et al. (2016) believed that ATR-FTIR is
not a strong tool in chemotaxonomy of cyanobacteria. Bajwa and Bishnoi
Effects of alkalinity
53
(2015), studying the effect of salinity on the overproduction of lipids in
Chlorella pyrenoidosa, used FTIR analysis, and showed that 5 to 25 mM
salinity caused increases in lipid range (from 10 to 45%). They also suggested
that FTIR results showed high amounts of lipids, carbohydrates, and nucleic
acid contents in such a strain. Besides the strain, results seemed to confirm
our results.
FIG. 3. FTIR analysis of Calothrix sp. ISC 65 at different alkalinities after 24-hours
treatments (1 — pH 7; 2 — pH 9; 3 — pH 11)
Fig. 4. FTIR analysis of Calothrix sp. ISC 65 at different alkalinities after 96-hours
treatments (1 — pH 7; 2 — pH 9; 3 — pH 11)
Kiaei et al. (2013), for the first time, characterized four strain of native
Iranian cyanobacteria using FTIR analysis for evaluation of lipids in biofuel
projects.They studied the effect of organic and inorganic nitrogen nutrition in
lipid (especially fatty acid profiles) production of four cyanobacteria but
selected Synechococcus as a model strain. They concluded that treatments of
Synechococcus with different concentration of nitrate changed the profile of
fatty acids and amino acids. Peaks of the FTIR shifted and changed their
length at different concentrations of nitrogen sources especially the nitrate
form.
Abbasi B. et al.
54
The authors would like to thank Professor Neda Soltani (Shahid Beheshti
University, Iran), Dr. Ali Ebadi, Mr. Mohammad Aiineh, Dr. Davood Beig
Nejad, and Mrs. Malliheh Rasaie (Islamic Azad University, Gorgan), for their
kind collaboration in theoretical and laboratory studies.
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Поступила 23.11.2017
Подписал в печать А.И. Божков
ISSN 0868-854 (Print)
ISSN 2413-5984 (Online). Аlgologia. 2019, 29(1): 40—58
https://doi.org/10.15407/alg29.01.040
Аббаси Б., Шокрави Ш., Гольсефиди М.А., Сатей А., Къяи Е.
Кафедра биологии, филиал Горган, Исламский университет Азад, Горган, Иран
ВЛИЯНИЕ ЩЕЛОЧНОСТИ, СВЕРХНИЗКОЙ КОНЦЕНТРАЦИИ ДИОКСИДА
УГЛЕРОДА И ИНТЕНСИВНОСТИ ИЗЛУЧЕНИЯ НА СПЕКТРАЛЬНЫЕ
СВОЙСТВА, ФИТОБИЛИСОМЫ, ФОТОСИНТЕЗ, ФОТОСИСТЕМЫ И
ФУНКЦИОНАЛЬНЫЕ ГРУППЫ НАТИВНОЙ ЦИАНОБАКТЕРИИ CALOTHRIX
SP. ISC 65
Исследован физиологический ответ штамма Calothrix sp. ISC 65 на культивирование
в условиях сверхнизкой освещенности (2 μEм-2с-1) при различных значениях рН (7,
9, 11) и низкой концентрации углекислого газа (без аэрации и обогащения
углекислым газом). Спектроскопический анализ показал, что через 96 ч
культивирования при рН 9 значительно увеличивается скорость роста исследуемого
штамма и выработка им хлорофилла и фикоцианина. Снижение рН до нормального
Abbasi B. et al.
58
(7) вызывало уменьшение продукции фикобилисомы уже через 24 ч, при рН 9 —
возбуждение светособирающего комплекса и реакционного центра фотосистем.
Фикоцианин, по-видимому, являлся основным элементом фикобилисомы, но при
pH 9 увеличивалось продуцирование фикоэритрина и аллофикоцианина в качестве
внешней части фотосинтетической антенны. Флуориметрический анализ и анализ
кривых фотосинтеза и освещенности показали, что повышение щелочности до рН 9
(не выше 11) вызывает повышение эффективности фотосинтеза и снижение
нефотохимической флуоресценции, особенно через 96 ч. Соотношение ФС II: ФС I
увеличивалось при возрастании щелочности от рН 7 до 9 и достигало наивысшего
уровня через 96 ч. Анализ RSP показал, что вокруг pH 9 и 96 ч существует узкая
граница с самыми высокими показателями соотношения ФС II : ФС I. По данным
инфракрасной спектроскопии с преобразованием Фурье (ИК-Фурье), щелочные
условия вызывали изменения конфигурации функциональных групп. Разница в
структуре функциональных групп между pH 7 и 11 была совершенно очевидной,
особенно через 24 ч. Различия между асимметричной вибрацией углерода,
растяжением липидов и изгибанием ОН полисахаридов отмечались при pH 9 и рН
11. В целом, при крайне ограниченной освещенности и концентрации углекислого
газа щелочность pH 9 вызывала у Calothrix sp. ISC 65 наибольшую физиологическую
активность.
К л ю ч е в ы е с л о в а : Calothrix, цианобактерии, щелочность, растворенный
неорганический углерод, ограниченная освещенность
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