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

Abstract: 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.