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Environmental Science & Technology 2018 Journal of Environmental Research
Page 32
March 29-31, 2018
Vienna, Austria
4th Edition of International Conference on
Environmental Science
& Technology 2018
With rising environmental pollution caused by persistent and
petroleum-based plastics, the interest in biodegradable
materials like poly-ß-hydroxybutyrate (PHB) increases. Currently,
PHB production is based on heterotrophic bacteria, using organic
carbon sources from crops. To avoid the competition to food
and feed production cyanobacteria, metabolizing CO2 e.g. from
exhaust gas, can be used. For cultivating cyanobacteria at larger
scales high amounts of mineral nutrients are needed. Due to
this reason alternative nutrient sources, such as digestate, are
required. In this study photoautotrophic PHB production with
cyanobacteria was investigated, with emphasis on increasing
the ecological and economic efficiency of the process by using
anaerobicdigestateasnutrient sourceaswell byusing the residual
biomass. The results obtained herein demonstrate that low solids
digestate, producedby anaerobicdigestion thin stillage, is suitable
to produce PHB with Synechocystis salina. By using digestate
supernatant diluted 1/3, biomass and PHB concentrations of
1.6 g/L and 89 mg/L, respectively, were achieved within 40 days
in a tubular photobioreactor system with a working volume of
200L. In mineral medium, optimised with regard to biomass and
PHB production in a single cultivation stage, biomass and PHB
concentrations of 2.1 g/L and 123 mg/L were obtained. The
PHB quality was hardly influenced when digestate was used
as nutrient source. Additionally, anaerobic digestion of residual
biomass yielded in 348 Nm³ CH4/t VS, being comparable with
maize silage, a frequently used substrate in biogas plants. Other
options would be to use the residual biomass as animal feed or
fertiliser, since it still contained lipids (14 mg/g TS), proteins (242
mg/g TS) and carbohydrates (6 mg/g TS). Based on these results
it can be concluded that photoautotrophic PHB production has a
high potential to be connected to already existing processes, at
which digestate and CO2 accrue.
Keywords - Biorefinery, digestate, polyhydroxy butyric acid,
Synechocystis slina
Recent Publications
1. Meixner K, Kovalcik A, Sykacek E, Gruber-Brunhumer M,
Zeilinger W, Markl K, Haas C, Fritz I, Mundigler N, Stelzer,
F, Neureiter, M, Fuchs W, Drosg B (2018) Cyanobacteria
Biorefinery - Production of poly(3-hydroxybutyrate) with
Synechocystis salina and utilisation of residual biomass.
J Biotechnol. 2018; 265:46-53
2. Kovalcik A, Meixner K, Mihalic M, Zeilinger W, Fritz
I, Fuchs W, Kucharczyk P, Stelzer F, Drosg, B (2017)
Characterization of polyhydroxyalkanoates produced by
Synechocystis salina from digestate supernatant. Int J
Biol Macromol. 2017; 102:497-504
3. Meixner, K; Fritz, I; Daffert, C; Markl, K; Fuchs, W; Drosg,
B (2016) Processing recommendations for using low-
solids digestate as nutrient solution for poly-beta-
hydroxybutyrate production with Synechocystis salina. J
BIOTECHNOL. 2016; 240: 61-67.
4. Wagner J, Bransgrove R, BeachamTA, Allen MJ, Meixner
K, DrosgB,TingVP, ChuckCJ(2016)Co-productionofbio-
oil and propylene through the hydrothermal liquefaction
of polyhydroxybutyrate producing cyanobacteria.
BIORESOURCE TECHNOL. 2016; 207: 166-174
5. Meixner K, Fuchs W, Valkova T, Svardal K, Loderer C,
Neureiter M, Bochmann G, Drosg B (2015) Effect of
precipitating agents on centrifugation and ultrafiltration
performance of thin stillage digestate. SEP PURIF
TECHNOL. 2015; 145: 154-160.
Biography
K. Meixner is PhD student at the Institute of Environmental Biotechnology
of University of Natural Resources, Vienna. Her research foci are algae/
cyanobacteria biotechnology, biorefinery, biogas production and digestate
treatment. Currently, she is “Junior Researcher” at the Austrian Research
Competence Centre “Bioenergy2020+” for the area “bioconversion and bio-
gas systems”.
PHOTOTROPHIC PHB PRODUCTION WITH CYANOBACTERIA BY USING LOW
SOLIDS DIGESTATE
K. Meixner1,2, C. Troschl2, I. Fritz2 and B. Drosg1,2
1BIOENERGY 2020+ GmbH, Austria
2University of Natural Resources and Life Sciences, Austria
K.Meixner et al., J Environ Res, Volume 2