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O. Pulz and K. Scheibenbogen
Furthermore, a number of light-regulated mechanisms is available which
make the metabolic cycles of photosynthesis more flexible, although, requiring
additional energy. The information and energy content of light influence the
thioredoxin system or the development of secondary messengers [25]. Thus,
quantity and quality of the light are of decisive influence to a defined cultivation
of phototrophic microorganisms.
3.2 Qualitative Light Requirements of Phototrophic
Microorganisms
The qualitative light requirements of the organisms are mainly determined by
their photosynthetically active pigments. The pigment spectrum of algae and
higher plants is within the visual range from 380 to 700 rim, some phototrophic
purple bacteria also absorb in the near IR range.
Investigations of the growth behaviour of algae at light irradiation of
different quality have led to controversial results. Prokop et al. [26] have
cultivated the green alga Chlorella sorokiniana at monochromatic conditions
of high light intensity and confirmed with highest growth rates in the
yellow-red spectral range the chromatic growth maxima of Kubin et al.
[27]. Kohl and Nicklisch [28] have pointed out that the frequently postulated theory of a chromatic adaptation according to a specific distribution
in depth of marine algal species begins to waver. Chromophyta, adapted
to the blue light of the oceans, under irradiation by shortwave light,
have a higher pigment content and a higher growth rate, but a green mutant
of the red macroalga Gracilaria tikvahiae, under green and white light, did
not show growth differing from that of the red wild type. Numerous other
algae adapted to low light intensity have shown a growth independent of
the PAR spectrum. Similar results were achieved by Richardson et al. [29]
who emphasized the distinct influence of light quality on certain metabolic processes - the production of arachidonic acid [-30], the UV-induction
of mycosporine-ike amino acids [31], and the effect on morphology and
pigment synthesis [32, 33] being typical examples - whereas the
importance of light quantity to microalgal growth was rated even higher
by them.
3.3 Quantitative Light Requirements of Microalgae
As the activity of photosynthesis within light-induced electron transport
is limited by the redox reaction of the plastoquinone pool, the cell division
rate approaches a limit with increasing light energy. A comparison of the
various mathematical models, which define the light intensity dependent
growth curves, revealed the exponential model according to Mitscherlich [166]
O. Pulz and K. Scheibenbogen
Furthermore, a number of light-regulated mechanisms is available which
make the metabolic cycles of photosynthesis more flexible, although, requiring
additional energy. The information and energy content of light influence the
thioredoxin system or the development of secondary messengers [25]. Thus,
quantity and quality of the light are of decisive influence to a defined cultivation
of phototrophic microorganisms.
3.2 Qualitative Light Requirements of Phototrophic
Microorganisms
The qualitative light requirements of the organisms are mainly determined by
their photosynthetically active pigments. The pigment spectrum of algae and
higher plants is within the visual range from 380 to 700 rim, some phototrophic
purple bacteria also absorb in the near IR range.
Investigations of the growth behaviour of algae at light irradiation of
different quality have led to controversial results. Prokop et al. [26] have
cultivated the green alga Chlorella sorokiniana at monochromatic conditions
of high light intensity and confirmed with highest growth rates in the
yellow-red spectral range the chromatic growth maxima of Kubin et al.
[27]. Kohl and Nicklisch [28] have pointed out that the frequently postulated theory of a chromatic adaptation according to a specific distribution
in depth of marine algal species begins to waver. Chromophyta, adapted
to the blue light of the oceans, under irradiation by shortwave light,
have a higher pigment content and a higher growth rate, but a green mutant
of the red macroalga Gracilaria tikvahiae, under green and white light, did
not show growth differing from that of the red wild type. Numerous other
algae adapted to low light intensity have shown a growth independent of
the PAR spectrum. Similar results were achieved by Richardson et al. [29]
who emphasized the distinct influence of light quality on certain metabolic processes - the production of arachidonic acid [-30], the UV-induction
of mycosporine-ike amino acids [31], and the effect on morphology and
pigment synthesis [32, 33] being typical examples - whereas the
importance of light quantity to microalgal growth was rated even higher
by them.
3.3 Quantitative Light Requirements of Microalgae
As the activity of photosynthesis within light-induced electron transport
is limited by the redox reaction of the plastoquinone pool, the cell division
rate approaches a limit with increasing light energy. A comparison of the
various mathematical models, which define the light intensity dependent
growth curves, revealed the exponential model according to Mitscherlich [166]