Yael Ihejirika
McClorey
SBI4U1
10-31-12
Unit 2 Response Question
How do symbiotic bacteria use metabolic processes to produce bio-hydrogen from food waste?
Sub Questions
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What are symbiotic bacteria?
What is bio hydrogen?
What are metabolic processes?
What processes do the bacteria perform in order to produce the bio-hydrogen?
Why is this significant? Who does bio-hydrogen benefit?
Notes/Rough Draft
What is symbiosis?
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relationship between two or more organisms of different species
four main types of symbiotic relationships:
o mutualistic, commensal, parasitic, and neutral.
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In a mutual relationship, both organisms benefit.
In a commensal relationship, one organism benefits, while the other is unaffected.
In a parasitic relationship, one organism benefits, while the other is adversely affected.
In a neutral relationship, neither is affected.
Symbiotic bacteria = mutualistic relationship with another organism or host.
This is common in mammals that can’t digest cellulose.
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, the symbiotic bacteria help the animal to digest the cellulose and in return, the bacteria get a
comfortable environment to live in and sustenance.
Source: Meyer
Bio Hydrogen
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Hydrogen = renewable energy.
harmless to environment.
Upon combustion, H2 produces water
pollution-free fuel. However
two main ways to produce H2 are industrially and biologically.
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industrial methods of producing H2 are the electrolysis of water and the thermo-catalytic
reformation of substrates that are rich in hydrogen.
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Electrolysis of water involves using an electric current to force the decomposition of water.
Thermo-catalytic reformation is when steam is used to reform a compound; methane (CH4)
simple to perform, but, highly energy dependent.
When H2 is produced biologically, it is called bio-hydrogen.
The bio-hydrogen production (BHP) methods are photo-fermentation, dark fermentation, direct
& indirect photolysis;  alternative without fossil fuels.
methods off-set carbon emissions by using carbon rich compounds in their processes.
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Source: Herwig
Direct Photolysis
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photo-system 1 and 2 (PS1 and PS2)  convert light energy into chemical energy (H2)
light energy and water is absorbed by PS1 and PS2.
PS1 excites electrons, causing them to move through a cyclic cycle that produces ATP.
light energy absorbed by PS2 produces electrons  go to ferredoxin using the energy from PS1.
ferredoxin,  the electrons get taken by the enzyme hyrdogenase which uses them to form
hydrogen (H2).
Indirect Photolysis
This occurs in two stages.
Stage one: This is almost the same as the process that occurs in direct photolysis except, the electrons
go to the ferredoxin and then through cell material, rather than straight to the hydrogenase.
Stage two: Fermentation occurs resulting in 2 electrons which then go through hydrogenase to become
H2. This can be seen in figure.
biological methods=good  use a wide variety of types of biomass.
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These include: crops, crop waste, animal waste, mill waste, trees/shrubbery, industrial waste
(sewage and waste water).
improved waste management.
deducing landfill waste.
Metabolic processes = necessary for life.
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catabolic processes break apart molecules to release energy.
anabolic processes build molecules  put energy into them.
Fermentation yields energy; takes place in the absence of oxygen.
requires a substrate (typically a sugar).
On a molecular level, fermentation is like glycolysis with the exception that the H atoms from
NADH get transferred to other molecules, rather than the electron transport chain, in order to
recycle NAD+.
Source: Guiseppe et al
Photo-fermentation
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photosynthetic bacteria via the enzyme nitrogenase.
uses light energy and biomass (in this case, food waste).
Light energy and the biomass go into a bacterial photo-system which produces 2 electrons and 4
ATP molecules.
transferred to the nitrogenase where they are used to produce H2.
Dark Fermentation
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biomass (in this case, food waste) as the substrate.
undergoes normal fermentation but without light energy
resultant molecules are H2 and CO2.
Efficiency depends on the pH and partial pressure,
fermentation remains the most time and space effective method of BHP.
Source: Meng Ni et al
Chemical Engineer
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manufacturing company
coming up with processes and machines to achieve chemical goals
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EDU = is a bachelor’s degree in chemical engineering.
The starting salary is on average $85,000-$100,000.
Source: Career Cruising
Environmental Tech
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a the government, engineering firms or waste management companies.
test samples for pollution levels and write reports and suggestions for change
edu= diploma in environmental technology; however, a bachelor’s degree provides more
quality job opportunities
starting salary ranges from $25,000-$65,000.
Source: Career Cruising
Works Cited
"Chemical Engineer." Career Cruising. Anaca Technologies, n.d. Web. 29 Oct. 2012.
<https://www.careercruising.com/Careers/JobDetails.aspx?LoginID=2b57c946-1e4b-4acb-9c2941ade90326c3-5&OccNumber=88&field=AtaGlance>. Career cruising is a resource used by
Ontario school boards to assist students in making choices for their future. It uses government
information to provide student with information on various careers. From this source, I was able
to understand the implications of being a chemical engineer. This source is secondary as it is
based on primary sources. It is a very valid and relevant source, because this site is promoted by
Ontario school boards for the education of high school students. The information is not biased in
any way.
Di, Giuseppe Maurice. Nelson Biology 12. Toronto: Nelson Thomson Learning, 2003. Print. The
information I used from the source was the definition of metabolic processes (catabolic and
anabolic). I also used some information about the end step of fermentation and how it differs
from glycolysis. This is a secondary source because it was written based on analysis of primary
sources. It is very valid because it is a very current textbook used across the York region district
school board to educate thouseands of students. All the writters are distinguished in their field
of study. There is no bias evident, because just facts are given to inform. All the information is
current and all the facts are clearly verifiable.
"Environmental Tech." Career Cruising. Anaca Technologies, n.d. Web. 30 Oct. 2012.
<https://www.careercruising.com/Careers/JobDetails.aspx?LoginID=2b57c946-1e4b-4acb-9c2941ade90326c3-5&OccNumber=168&field=AtaGlance>. Career cruising is a resource used by
Ontario school boards to assist students in making choices for their future. It uses government
information to provide student with information on various careers. From this source, I was able
to understand the implications of being an environmental tech. This source is secondary as it is
based on primary sources. It is a very valid and relevant source, because this site is promoted by
Ontario school boards for the education of high school students. The information is not biased.
Herwig, Christoph, and Simon Rittmann. "A Comprehensive and Quantitative Review of Dark
Fermentative Biohydrogen Production." Microbial Cell Factories 11 (2012): 115. Gale. Web. 29
Oct. 2012. From this source, I found and used information about bio-hydrogen production and
its importance in our world. This source is a primary source because was written scientists who
performed a lab experiment. This source is legitimate becuase the authors, are distinguished
professors who have been published in a well respected scientific journal called Microbial Cell
Factories. Therefore this source can be considered very valid and accurate. It was written
recently and its primary purpose is to inform students and scholars of the results of their
experiments. There is no identifyable bias in this paper because the authors present the
material objectively, simply stating the facts, without any opinions.
Meyer, John R. "SYMBIOTIC RELATIONSHIPS." Symbiosis. NC State University - Department of
Entomology, 3 Jan. 1998. Web. 29 Oct. 2012.
<http://www.cals.ncsu.edu/course/ent591k/symbiosis.html>. The information I used from the
source about the differnt kinds of symbiotic relationships in nature and about how symbiotic
bacteria have mutualistic relationships with hosts. This is a secondary source because it was
written based on analysis of primary sources. It is valid because the info is fairly current and
because it is from a distinguished professor at NC State University, who is published in multiple
scientific journals. There is no bias evident, because just facts are given with objective analysis.
It is intended to inform students and adults.
Ni, Meng, Dennis Leung, Michael Leung, and K. Sumathy. "An Overview of Hydrogen Production from
Biomass." Fuel Processing Technology 87 (2005): 461-72. Scienzechimiche. Department of
Mechanical Engineering, The University of Hong Kong, 2006. Web. 30 Oct. 2012. From this
source, I found and used information about the four main bio-hydrogen production methods:
photo-fermentation, dark fermentation, direct and indirect biophotolysis. This source is a
primary source because it was written by scientists who performed their own experiment. This
source is legitimate becuase the authors, are distinguished professors from The University of
Hong Kong who have been published in a well respected scientific journal. Therefore this source
can be considered very valid and accurate. It was also written recently. Its primary purpose is to
inform students and scholars of the results of their experiments. There is no identifyable bias in
this paper because the authors presented the material without any opinions.