Advanced

Exploring Anaerobic Bacteria for Industrial Biotechnology - Diversity Studies, Screening and Biorefinery Applications

Aragao, Rosa LU (2013)
Abstract (Swedish)
Popular Abstract in English

Look around and notice how many items have been manufactured or transported using petroleum-based products. In modern life, it is almost an impossible task to exclude them from our daily routine. They are present in plastics, cosmetics, cleaning products, medicaments, food, etc. To diminish our dependence on the demanded black liquid, a lot of research efforts have been focused on replacing oil derived chemicals by renewable sources.

Many microorganisms can naturally produce compounds that are considered as building blocks, comparable to “Lego® pieces”, for the industrial production of several items. These compounds can replace oil-based products. Moreover, microorganisms can also... (More)
Popular Abstract in English

Look around and notice how many items have been manufactured or transported using petroleum-based products. In modern life, it is almost an impossible task to exclude them from our daily routine. They are present in plastics, cosmetics, cleaning products, medicaments, food, etc. To diminish our dependence on the demanded black liquid, a lot of research efforts have been focused on replacing oil derived chemicals by renewable sources.

Many microorganisms can naturally produce compounds that are considered as building blocks, comparable to “Lego® pieces”, for the industrial production of several items. These compounds can replace oil-based products. Moreover, microorganisms can also produce fuels, for example ethanol. Among the vast diversity of microorganisms, anaerobic bacteria (which thrive in environments without oxygen) have been pioneers in industrial production of chemicals and fuels. With the urge to replace oil products, they gain once more interest due to their ability to naturally transform what can be considered as waste (such as crop parts which are not used for food) into valuable products. This is achieved thanks to a complex metabolism which allows them to consume different types of substrates. However, their sensitivity to oxygen and their peculiar metabolism has restricted the ability to cultivate these bacteria in the laboratory, and potentially limit their examination in comparison to their aerobic counterpart.

This thesis concerns about studies on anaerobic bacteria and their applications in industrial biotechnology. In particular, targeting the production of compounds relevant to a biorefinery, which is the counterpart of the petroleum refinery based on renewable feedstock. For that, the microorganisms from an unexplored environment, the stomach of the llama, were investigated for their potential use as producers of chemical compounds. The stomach of herbivores such as llamas is considered one of the most efficient natural processes for transformation of plants and is colonised by anaerobic microorganisms. These are likely to produce valuable industrially relevant compounds. However, it is not possible to cultivate all bacteria under laboratory conditions and therefore, a new method for cultivating single bacterial cells inside capsules was developed. This method can potentially allow the growth of “slow” microorganisms, be used to isolate bacteria and at the same time, speed up the detection of the industrially important ones.

Finally, the bacteria were used for the production of valuable compounds for the biorefinery sector, such as 1,3-propanediol (1,3-PD) and butanol, which can be used as solvents, building blocks and fuel. Bacteria were cultivated via different strategies, which can be used to improve industrial production, aiming to take a little step forward towards a bio-based economy. (Less)
Abstract
Depletion of easily accessible fossil energy resources, threat of climate change and political priority to achieve energy self-sufficiency and sustainable solutions prioritize a conscious and smart use of renewable resources to generate a bio-based economy. Bio-based compounds can replace chemicals and fuels that are now mainly produced from crude oil. Efficient processes for the conversion of plant biomass into compounds of interest to the biorefinery industry occur naturally in anaerobic environments such as in the forestomach of herbivores. Exploration of anaerobic microorganisms for industrial biotechnological applications creates the possibility to convey efficient and flexible processes, with lower implementation and running costs,... (More)
Depletion of easily accessible fossil energy resources, threat of climate change and political priority to achieve energy self-sufficiency and sustainable solutions prioritize a conscious and smart use of renewable resources to generate a bio-based economy. Bio-based compounds can replace chemicals and fuels that are now mainly produced from crude oil. Efficient processes for the conversion of plant biomass into compounds of interest to the biorefinery industry occur naturally in anaerobic environments such as in the forestomach of herbivores. Exploration of anaerobic microorganisms for industrial biotechnological applications creates the possibility to convey efficient and flexible processes, with lower implementation and running costs, making it also applicable to developing and emerging economies.



Despite the growing interest in anaerobic microorganisms for applications in industrial biotechnology, there is less information available concerning their diversity and function compared to what is known for their aerobic counterparts. To counter this, microbial diversity studies on an unexplored environment for microbial applications, was investigated by molecular and traditional cultivation techniques. The bacterial diversity of the forestomach of the llama, showed differences in the prokaryotes populations according to the complexity of the material type digested. Bacterial isolates were selected by their ability to produce compounds such as organic acids and alcohols and hydrolytic enzymes.



Also, a new strategy for cultivation of anaerobic microorganisms with the potential for an improved isolation rate and screening has been developed in this thesis work. The technique is based on single cell entrapment in alginate microbeads. A method was optimized for simple preparation under anaerobic conditions and successful cultivation of single cells was observed.



Further applications of anaerobic bacteria towards the biorefinery were also studied. The production of 1,3-propanediol, a compound used as building block for polymer materials, was investigated from selected llama isolates. The use of wheat straw as co-substrate and/or support material improved the concentration of 1,3-propanediol by 29% for C. butyricum BSL59 and 65% for C. butyricum BSL61 in comparison to using sole glycerol in the medium. The use of wheat straw was also superior in comparison to addition of pure sugars. Moreover, the solid residue from sequence batch fermentation using wheat straw as co-substrate showed to have high methane potential yield. Demonstrating that agriculture residue can be used in an integrated process for the production of valuable chemical compounds and energy carriers. Finally, a new method for cell immobilization forming a

macroporous material was evaluated for butanol production which reaches high yields and allows repeated use of the cell-based material. (Less)
Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Associate Professor Stougaard, Peter, Department of Plant and Environmental Sciences, University of Copenhagen, Denmark
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Anaerobic bacteria, industrial biotechnology, biorefinery, microbial diversity, single cell entrapment, llama rumen
pages
170 pages
defense location
Sölvegatan 39, Lecture Hall B at the Center for Chemistry and Chemical Engineering, Lund University Faculty of Engineering
defense date
2013-12-05 13:30
ISBN
987-91-89627-890-1
language
English
LU publication?
yes
id
39ebc2ca-e8f8-4506-89e7-94979b00ec7b (old id 4146454)
date added to LUP
2013-11-11 13:46:21
date last changed
2016-09-19 08:45:17
@phdthesis{39ebc2ca-e8f8-4506-89e7-94979b00ec7b,
  abstract     = {Depletion of easily accessible fossil energy resources, threat of climate change and political priority to achieve energy self-sufficiency and sustainable solutions prioritize a conscious and smart use of renewable resources to generate a bio-based economy. Bio-based compounds can replace chemicals and fuels that are now mainly produced from crude oil. Efficient processes for the conversion of plant biomass into compounds of interest to the biorefinery industry occur naturally in anaerobic environments such as in the forestomach of herbivores. Exploration of anaerobic microorganisms for industrial biotechnological applications creates the possibility to convey efficient and flexible processes, with lower implementation and running costs, making it also applicable to developing and emerging economies.<br/><br>
<br/><br>
Despite the growing interest in anaerobic microorganisms for applications in industrial biotechnology, there is less information available concerning their diversity and function compared to what is known for their aerobic counterparts. To counter this, microbial diversity studies on an unexplored environment for microbial applications, was investigated by molecular and traditional cultivation techniques. The bacterial diversity of the forestomach of the llama, showed differences in the prokaryotes populations according to the complexity of the material type digested. Bacterial isolates were selected by their ability to produce compounds such as organic acids and alcohols and hydrolytic enzymes.<br/><br>
<br/><br>
Also, a new strategy for cultivation of anaerobic microorganisms with the potential for an improved isolation rate and screening has been developed in this thesis work. The technique is based on single cell entrapment in alginate microbeads. A method was optimized for simple preparation under anaerobic conditions and successful cultivation of single cells was observed. <br/><br>
<br/><br>
Further applications of anaerobic bacteria towards the biorefinery were also studied. The production of 1,3-propanediol, a compound used as building block for polymer materials, was investigated from selected llama isolates. The use of wheat straw as co-substrate and/or support material improved the concentration of 1,3-propanediol by 29% for C. butyricum BSL59 and 65% for C. butyricum BSL61 in comparison to using sole glycerol in the medium. The use of wheat straw was also superior in comparison to addition of pure sugars. Moreover, the solid residue from sequence batch fermentation using wheat straw as co-substrate showed to have high methane potential yield. Demonstrating that agriculture residue can be used in an integrated process for the production of valuable chemical compounds and energy carriers. Finally, a new method for cell immobilization forming a<br/><br>
macroporous material was evaluated for butanol production which reaches high yields and allows repeated use of the cell-based material.},
  author       = {Aragao, Rosa},
  isbn         = {987-91-89627-890-1},
  keyword      = {Anaerobic bacteria,industrial biotechnology,biorefinery,microbial diversity,single cell entrapment,llama rumen},
  language     = {eng},
  pages        = {170},
  school       = {Lund University},
  title        = {Exploring Anaerobic Bacteria for Industrial Biotechnology - Diversity Studies, Screening and Biorefinery Applications},
  year         = {2013},
}