Lasers—an effective artificial source of radiation for the cultivation of anoxygenic photosynthetic bacteria

Abstract

The laser diode (LD) is a unique light source that can efficiently produce all radiant energy within the narrow wavelength range used most effectively by a photosynthetic microorganism. We have investigated the use of a single type of LD for the cultivation of the well-studied anoxygenic photosynthetic bacterium, Rhodobacter capsulatus (Rb. capsulatus). An array of vertical-cavity surface-emitting lasers (VCSELs) was driven with a current of 25 mA, and delivered radiation at 860 nm with 0.4 nm linewidth. The emitted light was found to be a suitable source of radiant energy for the cultivation of Rb. capsulatus. The dependence of growth rate on incident irradiance was quantified. Despite the unusual nearly monochromatic light source used in these experiments, no significant changes in the pigment composition and in the distribution of bacteriochlorophyll between LHII and LHI-RC were detected in bacterial cells transferred from incandescent light to laser light. We were also able to show that to achieve a given growth rate in a light-limited culture, the VCSEL required only 30% of the electricity needed by an incandescent bulb, which is of great significance for the potential use of laser-devices in biotechnological applications and photobioreactor construction.

Domestic wastewater treatment with purple phototrophic bacteria using a novel continuous photo anaerobic membrane bioreactor

“…6.2 W m -2 (Chitapornpan et al 2013), 7.3 W m -2 (Basak and Das 2009), 14 and 20 Wm -2 (Suwan et al 2014) and 50 W m -2 (this study) have been applied compared to 100 -200 W m -2 in commercial algal photobioreactors (Gordon and Polle 2007). Additionally, the use of IR LEDs (> 800nm) saves up to 70% energy per photon compared to the UV-VIS range (200 -700nm) (Bertling et al 2006). At the same time the photon conversion efficiency (PCE Sol ) for algae is < 5% of the full spectrum (Zhu et al 2008) with outdoor efficiencies between 0.2% and 1.5% (Akkerman et al 2002) whereby PPB photon conversion efficiencies on full light spectrum were reported to be up to 8% (Miyake andKawamura 1987, Carlozzi andSacchi 2001).…”

Effects of irradiance of various wavelengths from light-emitting diodes on the growth of the harmful dinoflagellate Heterocapsa circularisquama and the diatom Skeletonema costatum

“…[10][11][12] Researchers have explored the possibility of obtaining live food for filter feeders by large-scale monocultures and photobioreactors using light sources with varying spectral characteristics. 8,[13][14][15][16][17] For instance, more amino acids and protein may be found in algal biomass produced under blue light than under equal levels of white light, whereas red light has been shown to favor glycogenesis over proteogenesis. 3 However, the physiological effects of light wavelengths on dinoflagellates remain unsolved because reports are rare, and some harmful dinoflagellates have a baneful influence on bivalve cultures.…”

Application note: A novel low-cost open-source LED system for microalgae cultivation

“…Chlorophylls, carotenoids (carotenes and xanthophylls) and phycobilins are three major classes of photosynthetic pigments in microalgae (Begum et al, 2015). The selection criteria of artificial light sources include high electrical efficiency, low heat dissipation, good reliability, high durability, reasonable compactness, low cost and spectral output falling within the absorption spectrum of the microorganism of interest (Bertling et al, 2006).…”