Universität zu Köln

Li, Tong ORCID: 0000-0002-6943-0741, Piltz, Bastian, Podola, Bjoern, Dron, Anthony, de Beer, Dirk ORCID: 0000-0001-5274-1781 and Melkonian, Michael (2016). Microscale profiling of photosynthesis-related variables in a highly productive biofilm photobioreactor. Biotechnol. Bioeng., 113 (5). S. 1046 - 1056. HOBOKEN: WILEY. ISSN 1097-0290

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Abstract

In the present study depth profiles of light, oxygen, pH and photosynthetic performance in an artificial biofilm of the green alga Halochlorella rubescens in a porous substrate photobioreactor (PSBR) were recorded with microsensors. Biofilms were exposed to different light intensities (50-1,000mol photons m(-2) s(-1)) and CO2 levels (0.04-5% v/v in air). The distribution of photosynthetically active radiation showed almost identical trends for different surface irradiances, namely: a relatively fast drop to a depth of about 250 mu m, (to 5% of the incident), followed by a slower decrease. Light penetrated into the biofilm deeper than the Lambert-Beer Law predicted, which may be attributed to forward scattering of light, thus improving the overall light availability. Oxygen concentration profiles showed maxima at a depth between 50 and 150m, depending on the incident light intensity. A very fast gas exchange was observed at the biofilm surface. The highest oxygen concentration of 3.2mM was measured with 1,000mol photons m(-2) s(-1) and 5% supplementary CO2. Photosynthetic productivity increased with light intensity and/or CO2 concentration and was always highest at the biofilm surface; the stimulating effect of elevated CO2 concentration in the gas phase on photosynthesis was enhanced by higher light intensities. The dissolved inorganic carbon concentration profiles suggest that the availability of the dissolved free CO2 has the strongest impact on photosynthetic productivity. The results suggest that dark respiration could explain previously observed decrease in growth rate over cultivation time in this type of PSBR. Our results represent a basis for understanding the complex dynamics of environmental variables and metabolic processes in artificial phototrophic biofilms exposed to a gas phase and can be used to improve the design and operational parameters of PSBRs. Biotechnol. Bioeng. 2016;113: 1046-1055. (c) 2015 Wiley Periodicals, Inc.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Li, Tong UNSPECIFIED orcid.org/0000-0002-6943-0741 UNSPECIFIED Piltz, Bastian UNSPECIFIED UNSPECIFIED UNSPECIFIED Podola, Bjoern UNSPECIFIED UNSPECIFIED UNSPECIFIED Dron, Anthony UNSPECIFIED UNSPECIFIED UNSPECIFIED de Beer, Dirk UNSPECIFIED orcid.org/0000-0001-5274-1781 UNSPECIFIED Melkonian, Michael UNSPECIFIED UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-277505
DOI:	10.1002/bit.25867
Journal or Publication Title:	Biotechnol. Bioeng.
Volume:	113
Number:	5
Page Range:	S. 1046 - 1056
Date:	2016
Publisher:	WILEY
Place of Publication:	HOBOKEN
ISSN:	1097-0290
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language ATTACHED CULTIVATION; WASTE-WATER; SPATIAL-RESOLUTION; LIGHT PENETRATION; OXYGEN; MICROALGAE; RESPIRATION; MICROSENSOR; IRRADIANCE; INTENSITY Multiple languages Biotechnology & Applied Microbiology Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/27750