Basisversuche zur Gewinnung von Ethanol und Wasserstoff mit einem fotosynthetisch-fermentativen Verbundsystem aus Algen, Hefen und Bakterien

The potential productivity of an intended cooperative process for the production of the fuels ethanol and hydrogen was tested in separated trials. The intended process integrates green algae, clostridia, purple bacteria and yeast cells. The green algae produce sugar by photosynthesis from carbon dioxide and sun light. The produced sugar will be fermented to ethanol by yeast. Further the green algae shall function as a light filter, eliminating short waves of the light which are harmful to the purple bacteria located in an inner part of the photo-bioreactor. The purple bacteria produce hydrogen from organic acids which are provided by the fermentation of clostridia using waste material, like whey, as substrate. The results of this study show that the green algae Chlorella sp. SAG 241.80 produces maltose and glucose with production rates up to 476 mg of sugar per litre and day over several days under laboratory conditions. The photosynthetic activity of the green algae results in oxygen concentrations in the photo-bioreactor which are very much higher then the saturation by air. For that reason the application of respiration deficient yeasts with a high tolerance to increased oxygen concentration was necessary. In this study respiration deficient mutants of Saccharomyces cerevisiae did not show any differences in the productivity of ethanol to their wild types under anaerobic conditions. Under aerobic conditions the wild types remained clearly behind the respiration deficient strains in their productivity of ethanol. The saturation of the cultures with pure oxygen had no short-term effect on the productivity of the respiration deficient strains but it results in a decrease of the long-term stability of not growing cultures.In autotrophic co-cultures of algae and yeasts production rates of 1,02 g of sugar per litre and day and 421 mg of ethanol per litre and day were documented over several hours under laboratory conditions.For a significant production of organic acids from whey by Clostridium butyricum, an addition of yeast extract was necessary. Thereby production rates up to 0,30 g of butyrate per litre and hour, 0,16 g acetate per litre and hour and 0,49 l of gas per litre and hour with a hydrogen content up to 67% were documented. According to the dates from literature the produced organic acids are excellent electron donators for the hydrogen production by the anoxygenic photosynthesis of purple bacteria.By the basic tests in the present study the feasibility of individual processing steps of the intended cooperative process was shown and their production rates were investigated.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2006

Author dc:creator

• Ismar, Peer

Contributors dc:contributor

• Hartmeier, Winfried

• info:eu-repo/classification/ddc/660
• Technische Chemie
• Alternative Energiequelle
• Verbundsystem
• Wasserstoff
• Purpurbakterien
• Clostridium butyricum
• Saccharomyces cerevisiae
• Chlorella
• Ethanol
• atmungsdefekt
• respiration deficient

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

ger

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-122188%22

OAI identifier oai:identifier

oai:publications.rwth-aachen.de:60480