The Use Of Water- And Pocket-Pulse Amplitude Modulation In Investigating Photophysiology And Nutrient Limitations In Microalgae
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Date
2018-05
Authors
Muhamad Darif, Nur Aqilah
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
Investigating photosynthesis and nutrient limitations of microalgae allow for
insight into how cells will respond to different environmental or physical stressors
particularly nutrients. Advances in chlorophyll fluorescence techniques have provided
a means for rapid and non-invasive measurement of microalgal ecophysiology.
Furthermore, available Pulse Amplitude Modulation (PAM) fluorometers in the
market present different technical characteristics and configuration which may lead to
different photosynthetic parameters output. Here the photosynthetic activities of
microalgae were observed using both Water-PAM and Pocket-PAM to validate the
differences between these two fluorometers. Microalgal community samples were
collected from Teluk Bahang and Pantai Jerejak while single species laboratory
cultures were obtained from the Centre for Marine and Coastal Studies (CEMACS),
Penang. For both field and laboratory studies, maximum quantum yield (Fv/Fm),
maximum relative electron transport rate (rETRmax) and photoacclimation index (Ek)
of Water-PAM were significantly different (P < 0.05), about 50% to those of Pocket-
PAM. For example, in Pantai Jerejak community sample, photosynthetic rates
(rETRmax) increased by four-fold when using Water-PAM (67.5 ± 3.7) by comparison
to Pocket-PAM (16.6 ± 2.1). Similarly, nutrient-induced fluorescence transient (NIFT)
using Water-PAM and Pocket-PAM were different in terms of the response output.
This study showed that care should be taken when interpreting results using different
PAM fluorometers because they are different in terms of technical characteristics such
as approximate detection limit, configuration and actinic light colour. To further
understand the effect of silica on photosynthesis of microalgae, silica concentrations
were manipulated in two species of diatoms: tropical Actinocyclus octonarius and
polar Chaetoceros neglectus.
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Keywords
Investigating photosynthesis and nutrient limitations , how cells will respond to different environmental