Difference between revisions of "Team:TU Darmstadt/Sustainable"
| Line 80: | Line 80: | ||
in wastewater treatment plants using an | in wastewater treatment plants using an | ||
enzyme-producing biofilm and came to the | enzyme-producing biofilm and came to the | ||
| − | decision that <I>Bacillus subtilis</i> is the best | + | decision that <I>Bacillus subtilis</i> is the best |
choice as our biofilm forming organism. | choice as our biofilm forming organism. | ||
</p> | </p> | ||
<p> | <p> | ||
| − | <i>B. subtilis</i> is a gram-positive bacterium which is usually found in soil. | + | <i>B. subtilis</i> is a gram-positive bacterium which is usually found in soil. |
Gram-positive bacteria only have one cell membrane and are thus often used for protein secretion<sup id="cite_ref-1"><a href="#cite_note-1">[1]</a></sup>. | Gram-positive bacteria only have one cell membrane and are thus often used for protein secretion<sup id="cite_ref-1"><a href="#cite_note-1">[1]</a></sup>. | ||
On the one hand, secreting proteins is beneficial in protein production because no cell disruption is | On the one hand, secreting proteins is beneficial in protein production because no cell disruption is | ||
| Line 91: | Line 91: | ||
other hand, and in our case specifically, we avoid the issue of bringing enzyme substrates across | other hand, and in our case specifically, we avoid the issue of bringing enzyme substrates across | ||
the membrane in the cell as well as potential cell toxicity of the substrate and degradation product. | the membrane in the cell as well as potential cell toxicity of the substrate and degradation product. | ||
| − | We want to leverage the ability of <i>B. subtilis</i> to secret proteins to immobilize our target enzymes | + | We want to leverage the ability of <i>B. subtilis</i> to secret proteins to immobilize our target enzymes |
in the biofilm matrix by fusing them to a matrix protein. This is easier to realize with | in the biofilm matrix by fusing them to a matrix protein. This is easier to realize with | ||
| − | <i>B. subtilis</i> as gram-positive model organism than with the gram-negative bacteria, | + | <i>B. subtilis</i> as gram-positive model organism than with the gram-negative bacteria, |
| − | e.g. <i>Escherichia coli</i>. In addition, <i>B. subtilis</i> is a facultative anaerobic | + | e.g. <i>Escherichia coli</i>. In addition, <i>B. subtilis</i> is a facultative anaerobic |
organism which means it can grow in oxygenic, as well as anaerobic conditions, | organism which means it can grow in oxygenic, as well as anaerobic conditions, | ||
which can be of advantage when using the biofilm underwater in the clarifier<sup id="cite_ref-3"><a href="#cite_note-3">[3]</a></sup>. | which can be of advantage when using the biofilm underwater in the clarifier<sup id="cite_ref-3"><a href="#cite_note-3">[3]</a></sup>. | ||
| Line 100: | Line 100: | ||
<p> | <p> | ||
| − | In nature <i>B. subtilis</i> forms biofilms on plant roots as it needs a nutrient source. The | + | In nature <i>B. subtilis</i> forms biofilms on plant roots as it needs a nutrient source. The |
| − | advantage for the plants is that <i>B. subtilis</i> protects it from pathogenic infections by funghi<sup id="cite_ref-4"><a href="#cite_note-4">[4]</a></sup>. | + | advantage for the plants is that <i>B. subtilis</i> protects it from pathogenic infections by funghi<sup id="cite_ref-4"><a href="#cite_note-4">[4]</a></sup>. |
| − | Since <i>B. subtilis</i> is a natural biofilm former, it has been used as model organism | + | Since <i>B. subtilis</i> is a natural biofilm former, it has been used as model organism |
for studying biofilms in the last years<sup id="cite_ref-4"><a href="#cite_note-4">[4]</a></sup>. By using this natural biofilm former, we do not have to | for studying biofilms in the last years<sup id="cite_ref-4"><a href="#cite_note-4">[4]</a></sup>. By using this natural biofilm former, we do not have to | ||
| − | worry about how our organism will form a biofilm. Furthermore, <i>B. subtilis</i> is classified as | + | worry about how our organism will form a biofilm. Furthermore, <i>B. subtilis</i> is classified as |
| − | generally recognized as safe (GRAS) by the American Food and Drug Administration (FDA)<sup id="cite_ref-5"><a href="#cite_note-5">[5]</a></sup>, unlike other | + | generally recognized as safe (GRAS) by the American Food and Drug Administration (FDA)<sup id="cite_ref-5"><a href="#cite_note-5">[5]</a></sup>, unlike other |
| − | bacteria which are often pathogenic like <i>E. coli</i> or <i>Staphylococcus aureus</i><sup id="cite_ref-6"><a href="#cite_note-6">[6]</a></sup>. It is very | + | bacteria which are often pathogenic like <i>E. coli</i> or <i>Staphylococcus aureus</i><sup id="cite_ref-6"><a href="#cite_note-6">[6]</a></sup>. It is very |
important for us to use an organism which is generally safe given the fact that we want to bring it | important for us to use an organism which is generally safe given the fact that we want to bring it | ||
into a wastewater treatment plant. | into a wastewater treatment plant. | ||
| Line 112: | Line 112: | ||
<p> | <p> | ||
| − | Another characteristic of <i>B. subtilis</i> is its ability to form endospores | + | Another characteristic of <i>B. subtilis</i> is its ability to form endospores |
when exposed to extreme environmental conditions<sup id="cite_ref-7"><a href="#cite_note-7">[7]</a></sup>. Spores are highly resistant | when exposed to extreme environmental conditions<sup id="cite_ref-7"><a href="#cite_note-7">[7]</a></sup>. Spores are highly resistant | ||
towards extreme temperature, desiccation, radiation and chemicals. This | towards extreme temperature, desiccation, radiation and chemicals. This | ||
Revision as of 12:33, 4 October 2020
Biofilms
Bacillus subtilis
We aim to convert micropollutants in wastewater treatment plants using an enzyme-producing biofilm and came to the decision that Bacillus subtilis is the best choice as our biofilm forming organism.
B. subtilis is a gram-positive bacterium which is usually found in soil. Gram-positive bacteria only have one cell membrane and are thus often used for protein secretion[1]. On the one hand, secreting proteins is beneficial in protein production because no cell disruption is necessary to collect the protein and the formation of inclusion bodies can be prevented[2]. On the other hand, and in our case specifically, we avoid the issue of bringing enzyme substrates across the membrane in the cell as well as potential cell toxicity of the substrate and degradation product. We want to leverage the ability of B. subtilis to secret proteins to immobilize our target enzymes in the biofilm matrix by fusing them to a matrix protein. This is easier to realize with B. subtilis as gram-positive model organism than with the gram-negative bacteria, e.g. Escherichia coli. In addition, B. subtilis is a facultative anaerobic organism which means it can grow in oxygenic, as well as anaerobic conditions, which can be of advantage when using the biofilm underwater in the clarifier[3].
In nature B. subtilis forms biofilms on plant roots as it needs a nutrient source. The advantage for the plants is that B. subtilis protects it from pathogenic infections by funghi[4]. Since B. subtilis is a natural biofilm former, it has been used as model organism for studying biofilms in the last years[4]. By using this natural biofilm former, we do not have to worry about how our organism will form a biofilm. Furthermore, B. subtilis is classified as generally recognized as safe (GRAS) by the American Food and Drug Administration (FDA)[5], unlike other bacteria which are often pathogenic like E. coli or Staphylococcus aureus[6]. It is very important for us to use an organism which is generally safe given the fact that we want to bring it into a wastewater treatment plant.
Another characteristic of B. subtilis is its ability to form endospores when exposed to extreme environmental conditions[7]. Spores are highly resistant towards extreme temperature, desiccation, radiation and chemicals. This resistance makes spores interesting for industrial processes, e.g. by displaying enzymes on the surface of spores which can then be used in harsh reaction conditions. Furthermore, they are metabolic inactive but can germinate once nutrients are sufficiently available or when they experience high pressure[8].
References
1.Liu, L.; Liu, Y.; Shin, H. D. Developing Bacillus Spp. as a Cell Factory for Production of Microbial Enzymes and Industrially Important Biochemicals in the Context of Systems and Synthetic Biology. Applied Microbiology and Biotechnology. Springer July 11, 2013, pp 6113–6127 Doi:10.1007/s00253-013-4960-4 2.Westers, L.; Westers, H.; Quax, W. J. Bacillus Subtilis as Cell Factory for Pharmaceutical Proteins: A Biotechnological Approach to Optimize the Host Organism. Biochimica et Biophysica Acta - Molecular Cell Research. Elsevier November 11, 2004, pp 299–310 Doi:10.1016/j.bbamcr.2004.02.011 3.Clements, L. D.; Miller, B. S.; Streips, U. N. Comparative Growth Analysis of the Facultative Anaerobes Bacillus Subtilis, Bacillus Licheniformis, and Escherichia Coli. Syst. Appl. Microbiol. 2002, 25 (2), 284–286 Doi:10.1078/0723-2020-00108 4. Vlamakis, H.; Chai, Y.; Beauregard, P. Sticking Together: Building a Biofilm the Bacillus Subtilis Way. Nature Reviews Microbiology. NIH Public Access March 2013, pp 157–168 Doi:10.1038/nrmicro2960 5. Microorganisms & Microbial-Derived Ingredients Used in Food (Partial List) | FDA https://www.fda.gov/food/generally-recognized-safe-gras/microorganisms-microbial-derived-ingredients-used-food-partial-list (accessed Aug 27, 2020) 6.Hobley, L.; Harkins, C.; MacPhee, C. E. Giving Structure to the Biofilm Matrix: An Overview of Individual Strategies and Emerging Common Themes. FEMS Microbiology Reviews. Oxford University Press June 8, 2015, pp 649–669 Doi:10.1093/femsre/fuv015 7. Karava, M.; Gockel, P.; Kabisch, J. Bacillus Subtilis Spore Surface Display of Photodecarboxylase for the Transformation of Lipids to Hydrocarbons. bioRxiv 2020, 2020.08.30.273821 Doi:10.1101/2020.08.30.273821 8.Black, E. P.; Koziol-Dube, K.; Guan, D. Factors Influencing Germination of Bacillus Subtilis Spores via Activation of Nutrient Receptors by High Pressure. Appl. Environ. Microbiol. 2005, 71 (10), 5879–5887 Doi:10.1128/AEM.71.10.5879-5887.2005Micropollutants in wastewater
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Laccases
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