# How to extract oxygen from grow chamber

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I have been developing LED grow lights for a year or so and one of the things I am trying to do is to build a grow chamber where I can control temperature, humidity, light intensity and quality and levels of $$ce{CO2}$$ and $$ce{O2}$$. I don't have any problems with most of the variables except the gases. I can inject $$ce{CO2}$$ and monitor the gas, but as the chamber is hermetically sealed, how do I get rid of excess oxygen produced by the plants? Is there something similar to the $$ce{CO2}$$ scrubbers used in aquariums? As a matter of fact, plants also need oxygen for their metabolic processes occurring during darkness, but they produce oxygen in excess of this requirement during the day. It is the excess of oxygen the one I want to extract, and not the whole amount of oxygen in the air of the chamber.

The whole idea is that through the chamber, I can adjust light conditions to each crop based on performance. Gas exchange is an important proxy for Chlorophyll fluorescence and has shown a good correlation with performance.

Any ideas?

Absolutely, this is actually looking more as an engineering problem rather than a biology one.

In any case, I think I have found a satisfactory answer on a paper from the 1997 Proceedings of the Sixth European Symposium on Space Environmental Control Systems. The article is called: Oxygen Scrubbing and Sensing in Plant Growth Chambers using Solid Oxide Electrolyzers.

Basically, a disk of non-porous yttria stabilised zirconia (YSZ) is sandwiched between platinum electrodes and inserted in the chamber half-way, with the other half enclosed in whatever will store the extracted oxygen. The electrodes must be porous to allow gas diffusion. The only problem is, that sort of electrolysis cell needs to be maintained at an elevated temperature (800 to 1000 Celsius) in order to work.

By means of electrocatalysis and thermal dissociation the oxygen molecule dissociates to form two oxygen atoms, these in turn pick up two electrons from the cathode and become ions. The ion is then transported by the electrolyte (YSZ) by means of electron vacancies located in the crystal lattice (basically a similar process to that of a N-doped semiconductor whereby impurities create electron holes).

I think I am satisfied with the above explanation. Doable at home? No way, but it does answer the core question.

It's going to be tricky to strictly regulate CO2 and oxygen in a chamber.

We use a palladium catalyst to maintain an anaerobic environment for microbiology purposes, but this requires a source of hydrogen to work, and it doesn't work well for fine adjustments, but rather for maintaining extremely low oxygen conditions. We also have a hypoxic chamber that regulates O2 concentrations with good precision (0.1%), but it's expensive to maintain, and requires sensors for oxygen, CO2, and nitrogen, and an automatic gas injection system for each component.

A simpler design would probably be to have some gas exchange with the room your chamber is in, using a tyvek membrane to minimize water loss (and HEPA filters if you're worried about pathogen contamination). My friend who farms oyster mushrooms did something similar, and also rigged up a humidity sensor to a humidifier using a RaspberryPi to manage the moisture loss.

However, if you're dead set on having a strictly regulated atmosphere for you grow chamber, you might want to consider consulting with Coy Labs. When we needed a chamber with the ability to tightly regulate oxygen levels for microbiology research, they came to the lab and worked with us on our specific needs and together we develop their first working model nearly from scratch (we modified one of their existing anaerobic chambers). But it worked so well that they now sell hypoxic chambers as part of their standard line of products. As far as I know, they haven't done any work with plant grow chambers, but they're a small company with a lot of experience building contained atmospheric control systems. Pretty much every order is custom built, so they're used to answering a lot of questions and tailoring their products to the specific needs of a customer, and they're very helpful and responsive with maintenance and upkeep. Just know that they're products aren't cheap.

https://coylab.com/

## Hyperbaric oxygen treatment: Clinical trial reverses two biological processes associated with aging in human cells

A new study from Tel Aviv University (TAU) and the Shamir Medical Center in Israel indicates that hyperbaric oxygen treatments (HBOT) in healthy aging adults can stop the aging of blood cells and reverse the aging process. In the biological sense, the adults' blood cells actually grow younger as the treatments progress.

The researchers found that a unique protocol of treatments with high-pressure oxygen in a pressure chamber can reverse two major processes associated with aging and its illnesses: the shortening of telomeres (protective regions located at both ends of every chromosome) and the accumulation of old and malfunctioning cells in the body. Focusing on immune cells containing DNA obtained from the participants' blood, the study discovered a lengthening of up to 38% of the telomeres, as well as a decrease of up to 37% in the presence of senescent cells.

The study was led by Professor Shai Efrati of the Sackler School of Medicine and the Sagol School of Neuroscience at TAU and Founder and Director of the Sagol Center of Hyperbaric Medicine at the Shamir Medical Center and Dr. Amir Hadanny, Chief Medical Research Officer of the Sagol Center for Hyperbaric Medicine and Research at the Shamir Medical Center. The clinical trial was conducted as part of a comprehensive Israeli research program that targets aging as a reversible condition.

The paper was published in Aging on November 18, 2020.

"For many years our team has been engaged in hyperbaric research and therapy -- treatments based on protocols of exposure to high-pressure oxygen at various concentrations inside a pressure chamber," Professor Efrati explains. "Our achievements over the years included the improvement of brain functions damaged by age, stroke or brain injury.

"In the current study we wished to examine the impact of HBOT on healthy and independent aging adults, and to discover whether such treatments can slow down, stop or even reverse the normal aging process at the cellular level."

The researchers exposed 35 healthy individuals aged 64 or over to a series of 60 hyperbaric sessions over a period of 90 days. Each participant provided blood samples before, during and at the end of the treatments as well as some time after the series of treatments concluded. The researchers then analyzed various immune cells in the blood and compared the results.

The findings indicated that the treatments actually reversed the aging process in two of its major aspects: The telomeres at the ends of the chromosomes grew longer instead of shorter, at a rate of 20%-38% for the different cell types and the percentage of senescent cells in the overall cell population was reduced significantly -- by 11%-37% depending on cell type.

"Today telomere shortening is considered the 'Holy Grail' of the biology of aging," Professor Efrati says. "Researchers around the world are trying to develop pharmacological and environmental interventions that enable telomere elongation. Our HBOT protocol was able to achieve this, proving that the aging process can in fact be reversed at the basic cellular-molecular level."

"Until now, interventions such as lifestyle modifications and intense exercise were shown to have some inhibiting effect on telomere shortening," Dr. Hadanny adds. "But in our study, only three months of HBOT were able to elongate telomeres at rates far beyond any currently available interventions or lifestyle modifications. With this pioneering study, we have opened a door for further research on the cellular impact of HBOT and its potential for reversing the aging process."

## Cultivation of Aerobic and Anaerobic Bacteria

Anaerobic Chamber

Last updated on April 9th, 2020

### A. Aerobic Bacteria

#### B. Cultivation of Anaerobic Bacteria

• Bottles or tubes filled completely to the top with culture medium and provided with tightly fitting stopper. Suitable for organisms not too sensitive to small amounts of oxygen.
• Addition of a reducing agent that reacts with oxygen and reduces it to water e.g., Thioglycolate in thioglycolate broth. After thioglycolate reacts with oxygen throughout the tube, oxygen can penetrate only near the top of the tube where the medium contacts air.
• Obligate aerobes grow only at the top of such tubes.
• Facultative organisms grow throughout the tube but best near the top.
• Microaerophiles grow near the top but not right at the top.
• Anaerobes grow only near the bottom of the tube, where oxygen cannot penetrate.

1. Pre-reduced media
During preparation, the culture medium is boiled for several minutes to drive off most of the dissolved oxygen. A reducing agent e.g., cysteine, is added to further lower the oxygen content. Oxygen free N2 is bubbled through the medium to keep it anaerobic. The medium is then dispensed into tubes which are being flushed with oxygen – free nitrogen, stoppered tightly, and sterilized by autoclaving. Such tubes are continuously flushed with oxygen free CO2 by means of a cannula, restoppered, and incubated.
2. Anaerobic Chambers

## The Best Books About the Human Body

This isn't the first time doctors have put patients into pressurized oxygen chambers. Hyperbaric oxygen therapy (HBOT) has been used for almost a century to treat a number of illnesses, including decompression sickness in deep-sea divers and carbon monoxide poisoning.

The therapy involves breathing pure oxygen in a pressurized chamber, which causes blood and tissues in your body to become saturated with oxygen. Strangely enough, this can trigger similar physiological effects that occur when your body is starved of oxygen, known as hypoxia. While previous research shows these effects can stimulate your brain and increase your cognitive abilities, this is the first study to show the therapy may also reverse aging.

&ldquoSince telomere shortening is considered the 'Holy Grail' of the biology of aging, many pharmacological and environmental interventions are being extensively explored in the hopes of enabling telomere elongation,&rdquo said study coauthor Shai Efrati, a professor at the Sackler School of Medicine at Tel Aviv University. He continued:

This also isn't the first time scientists have claimed to reverse aging. Several studies using pharmacological drugs, such as danazol, have been shown to elongate telomeres. Additionally, lifestyle changes, including exercise and healthy diets, have been shown to have small effects on the growth of telomeres.

"Until now, interventions such as lifestyle modifications and intense exercise were shown to have some inhibition effect on the expected telomere length shortening. However, what is remarkable to note in our study, is that in just three months of HBOT, we were able to achieve such significant telomere elongation&mdashat rates far beyond any of the current available interventions or lifestyle modifications," study coauthor Amir Hadanny, a neurosurgeon at the Sagol Center of Hyperbaric Medicine and Research in Israel, explained in the press release.

The therapy could be an inexpensive alternative to more intrusive treatments using pharmaceuticals. However, the idea of spending many hours per day in a pressurized chamber may turn away patients. Would you try it? Sound off in the comments. ⬇

## Breakthrough oxygen therapy reverses aging process in humans

TEL AVIV, Israel — What would you do to stop the hands of time? As scientists continue to work at slowing the aging process, a team in Israel says the answer may be as simple as taking a deep breath. In a groundbreaking clinical trial, researchers from Tel Aviv University reveal hyperbaric oxygen treatments (HBOT) can stop the blood cells from aging in healthy adults.

Their study finds specific treatments using high-pressure oxygen in a pressure chamber can actually make the cells grow younger. Specifically, the three-month experiment stopped each patient’s telomeres from getting shorter. These protective caps on the end of chromosomes normally get shorter as humans age. The treatments also reversed the accumulation of old and malfunctioning cells.

When looking at blood samples containing DNA in the group’s immune cells, researchers discovered telomeres grew by up to 38 percent and the number of aging cells had decreased by 37 percent.

“For many years our team has been engaged in hyperbaric research and therapy – treatments based on protocols of exposure to high-pressure oxygen at various concentrations inside a pressure chamber,” Professor Shai Efrati explains in a university release.

“Our achievements over the years included the improvement of brain functions damaged by age, stroke or brain injury. In the current study we wished to examine the impact of HBOT on healthy and independent aging adults, and to discover whether such treatments can slow down, stop or even reverse the normal aging process at the cellular level,” the founder and director of the Sagol Center of Hyperbaric Medicine adds.

### Discovering the ‘Holy Grail’ of aging

Thirty-five healthy adults over the age of 64 participated in the hyperbaric trial, undergoing 60 sessions in 90 days. Researchers took blood samples before, during, and after the completion of the experiment. They also collected additional samples from the patients after more time had passed to see how the treatments held up.

Their findings confirm that high-pressure oxygen therapy is a more effective way of stopping and reversing the aging process than standard lifestyle adjustments. Telomeres in the study group increased in length by between 20 and 38 percent during the 90 days. The presence of senescent cells in the body dropped by between 11 and 37 percent.

“Today telomere shortening is considered the ‘Holy Grail’ of the biology of aging,” Prof. Efrati says. “Researchers around the world are trying to develop pharmacological and environmental interventions that enable telomere elongation. Our HBOT protocol was able to achieve this, proving that the aging process can in fact be reversed at the basic cellular-molecular level.”

“Until now, interventions such as lifestyle modifications and intense exercise were shown to have some inhibiting effect on telomere shortening,” study author Dr. Amir Hadanny adds. “But in our study, only three months of HBOT were able to elongate telomeres at rates far beyond any currently available interventions or lifestyle modifications. With this pioneering study, we have opened a door for further research on the cellular impact of HBOT and its potential for reversing the aging process.”

## MATERIALS NEEDED: per table

• 1 thioglycollate broth per table
• 3 TSA plates (divide into pie-shaped sections)
• GasPak container for entire lab + GasPak sachet for the jar + methylene blue indicator strip candle jar for entire lab
• cultures
• a strict aerobe + a strict anaerobe used as controls

Your instructor will give you the names at beginning of lab

Your instructor will set up the strict aerobe and the strict anaerobe cultures in thioglycollates for the class to view.

## Introduction

Clostridium difficile is a Gram-positive, spore-forming bacterium that is an obligate anaerobe and a potentially fatal gastrointestinal pathogen of humans and animals. Initially described in 1935 as a commensal organism found in fecal samples from newborns 1 , C. difficile was later demonstrated to be the causative agent of pseudomembranous colitis associated with antibiotic treatment 2 . C. difficile infections (CDI) are typically preceded by antibiotic treatment which results in the disruption of the normal colonic flora, creating a niche for C. difficile to thrive 2 . C. difficile is transmitted as a dormant spore via the fecal-oral route and subsequently germinates within the gastrointestinal tract, producing vegetative cells capable of generating several toxins and causing severe disease and colitis 3 . CDI are often refractory to conventional treatments and these infections are frequently recurrent 4 . As a result, CDI are responsible for up to \$4.8 billion in health care costs in the United States 5-7 .

C. difficile is very sensitive to even low levels of oxygen in the environment. For C. difficile to persist in the environment and be efficiently transmitted from host to host, the formation of a metabolically inactive spore is critical 8 . Because the laboratory maintenance and manipulation of C. difficile requires a controlled, anaerobic environment, these techniques necessitate the use of an anaerobic chamber. Use of anaerobic chambers has resulted in increased recovery and isolation of obligate anaerobes 9-11 , and has allowed a number of molecular techniques to be performed in an anaerobic atmosphere.

In addition to C. difficile, the anaerobic chamber use and maintenance described here are applicable to other obligate anaerobes such as other Clostridial species (e.g. C. perfringens), other gastrointestinal species (e.g. Bacteroides species 12 ) and periodontal pathogens (e.g. Peptostreptococcus species 13 ).

## How Plants Extract Nutrients

Over the past few years it has become clear that plants are able to extract nutrients directly from soil microorganisms in their roots. This nutrient extraction process was outlined recently in an article published online in the journal Microorganisms. The process is called the ‘rhizophagy cycle’ (pronounced ‘rye-zo-FAY-gee’). In the rhizophagy cycle, microbes cycle between the soil and a phase inside root cells. Microbes acquire nutrients in the soil nutrients are extracted from microbes through exposure to plant-produced reactive oxygen inside root cells. Nutrients like nitrogen and minerals are provided to plants directly from microbes through the rhizophagy cycle.

### The Rhizophagy Cycle

In the rhizophagy cycle, plants ‘farm’ bacteria and fungi to get nutrients from them. Initially microbes grow on the root in a zone outside the root tip meristem where roots secrete carbohydrates and other nutrients to cultivate them. Microbes enter root tip meristem cells, locating within the periplasmic spaces (the space between the cell wall and plasma membrane). In the periplasmic spaces of root cells, microbes lose cell walls, becoming naked protoplasts. As root cells mature, microbes are doused with reactive oxygen (superoxide) produced on the root cell plasma membranes. Reactive oxygen degrades some of the microbes, also inducing electrolyte leakage, effectively extracting nutrients from microbes. Surviving bacteria in root epidermal cells trigger root hair elongation, and as hairs elongate, microbes exit at the hair tips, reforming cell walls as microbes emerge into the soil where they may obtain additional nutrients. This sustainable cycle occurs in all root tips of plants. Plants with more root tips obtain more nutrients from the rhizophagy cycle.

A root of Bermuda grass with bacteria growing around the root and entering the root cells at the root tip meristem. Reactive oxygen (brown coloration) is evident in the root cells at the root tip.

### What Does This Mean For Gardeners?

The rhizophagy cycle shows that plants develop an intimate connection with microbes, to the extent that microbes enter into the plant root cells themselves. Through the rhizophagy cycle plants obtain nutrients, but also the rhizophagy cycle microbes suppress plant pathogens in soils and increase oxidative stress tolerance in plants. Basically, the rhizophagy cycle results in healthy plants, and without it plants may be poorly developed and more susceptible to disease and stress. The rhizophagy cycle functions automatically in plants most of the time.

Gardeners could encourage functioning of the rhizophagy cycle by increasing microbial activity in the soil with organic amendments. It is possible to suppress the rhizophagy cycle by use of sterilized or chemically treated seeds that remove or inhibit the symbiotic microbes on seeds. This is what happens in cotton where seeds are treated with acids that kill symbiotic microbes leaving seedlings that grow poorly and are vulnerable to diseases. Potting mixes with antimicrobials should probably be avoided because that might inhibit the rhizophagy cycle.

The prevailing view of plant nutrition (dogma) has been that plants only absorb into their roots inorganic nutrients (like nitrates or phosphates) that are soluble in soil water. However, organic gardeners have long believed that increasing organic material in soils results in better plant growth and that plants get nutrients from the soil organics. The rhizophagy cycle shows how plants get nutrients from organic materials added to soils in providing a linkage between soil organic material, soil microbes and plants. In the rhizophagy cycle, symbiotic microbes go from plants into the soil, acquire nutrients of various kinds, and carry nutrients back to plants, enter plant root cells where plants oxidatively extract nutrients from microbes, then plants deposit microbes back into the soil from tips of root hairs to continue the cycle.

Yeast (Rhodotorula sp.) exiting the tips of root hairs of a clover seedling. The smaller spherical structures in root hairs are the yeast protoplasts.

### The Future?

The rhizophagy cycle is definitely more evidence that healthy soils with diverse microbes and organic materials are better for plants, but also microbes that vector on seeds are important. Many of the seed microbes function in the rhizophagy cycle, so we want to conserve the microbes on seeds. In addition we may be able to learn how to manage the rhizophagy cycle so that we can increase plant growth significantly without use of inorganic fertilizers or with minimal use of inorganic fertilizers. Some of the rhizophagy microbes increase growth of their particular host plant but inhibit growth of other plant species. Here, we may be able to develop these microbes into ‘bioherbicides’ to favor growth of some plants, but inhibit weedy plants. In the future it may be possible to cultivate plants using only microbes to increase plant growth, and suppress diseases and weeds.

James Francis White Jr. , is a professor at the Department of Plant Biology at Rutgers University, New Brunswick, New Jersey.

## Scientists Cook Up a New Way to Make Breathable Oxygen on Mars

The tech could someday aid crewed Red Planet exploration.

Scientists have found a new way that future Mars explorers could potentially generate their own oxygen.

Mars is a long way from Earth, so being able to create breathable air on-site would save money and effort in having to haul oxygen all the way from our own planet.

A research team discovered this new oxygen-generating reaction by studying comets. Most of these small icy worlds originate in a distant area of the solar system known as the Oort Cloud, far beyond the orbit of Neptune. If a comet's orbit brings it close to the sun, heat begins pushing cometary ice off into space. This reaction produces long tails that can stretch for thousands of miles.

A team of researchers from the California Institute of Technology (Caltech) in Pasadena found a new way to explain how comets generate molecular oxygen, the two atoms of oxygen that come together to form breathable air.

One already-known method is through kinetic energy. A sublimating comet is a busy environment, where the solar wind (the constant stream of particles emanating from the sun) can push floating water molecules into the comet's surface at high speed. If there are oxygen-containing compounds on the surface, careening water molecules can rip oxygen atoms off and produce molecular oxygen.

Molecular oxygen can also be produced through carbon dioxide reactions, the team found. (Carbon dioxide contains a single carbon atom and two oxygen atoms.) Former Caltech postdoctoral fellow Yunxi Yao and current Caltech chemical engineering professor Konstantinos Giapis simulated this reaction by crashing carbon dioxide into gold foil. Since gold foil cannot be oxidized, by itself it should not produce any molecular oxygen. But when carbon dioxide careens into the foil at high speed, the gold surface emits molecular oxygen.

"This meant that both atoms of oxygen come from the same CO2 [carbon dioxide] molecule, effectively splitting it in an extraordinary manner," Caltech representatives said in a statement.

To better understand how carbon dioxide can break down into molecular oxygen, Caltech chemistry professor Tom Miller and postdoctoral fellow Philip Shushkov created a computer simulation.

One challenge in modeling the reaction is that the reacting molecules are very "excited," meaning they vibrate and rotate in a complex way, the researchers said.

"In general, excited molecules can lead to unusual chemistry, so we started with that," Miller said in the statement. "But, to our surprise, the excited state did not create molecular oxygen. Instead, the molecule decomposed into other products."

Rather, the scientists discovered that extremely "bent" carbon dioxide molecules &mdash those with an unusual geometry &mdash can be created without exciting the carbon dioxide. This in turn would produce oxygen.

When Yao and Giapis smashed the carbon dioxide molecules into gold foil, they electrically charged the individual carbon dioxide molecules and then accelerated them using an electric field. However, Giapis said the reaction could take place at a slower speed as well, which could account for why there is some oxygen floating high in the Martian atmosphere.

"You could throw a stone with enough velocity at some CO2 [carbon dioxide] and achieve the same thing," he said in the statement. "It would need to be traveling about as fast as a comet or asteroid travels through space."

Before, scientists thought that Mars' tiny concentration of atmospheric oxygen is probably generated after ultraviolet light from the sun hits carbon dioxide molecules in the Red Planet's air. Giapis theorizes, however, that Martian oxygen could also be generated when dust particles, accelerated to high speed in the atmosphere, crash into molecules of carbon dioxide.

The reactor Giapis used is very low-yield, generating only one or two oxygen molecules for every 100 carbon dioxide molecules careening through the accelerator. Giapis said, however, that perhaps his reactor could be modified one day to create breathable air for astronauts on Mars. And on Earth, the reactor may be useful to pull carbon dioxide (which is also a potent greenhouse gas, and the main driver of global warming) out of the atmosphere and convert it into oxygen.

"Is it a final device? No. Is it a device that can solve the problem with Mars? No," he said. "But it is a device that can do something that is very hard. We are doing some crazy things with this reactor."

A paper based on the research, led by Yao, was published last week in the journal Nature Communications.

By the way, NASA is about to give oxygen-generating tech a test run on Mars. A technology demonstrator called MOXIE (Mars Oxygen In situ resource utilization Experiment) will fly aboard the agency's 2020 Mars rover, which is scheduled to launch next summer and land on the Red Planet in February 2021. MOXIE will split atmospheric carbon dioxide electrochemically, and NASA wants to see if the method could be scaled up to help support people on the Red Planet.

## Further information:

Ph.D.-student Stefano Scilipoti, Center for Electromicrobiology at Aarhus University mail: ss@bio.au.dk phone: +45 9148 9338.

Professor Lars Peter Nielsen, Center for Electromicrobiology at Aarhus University mail: lpn@bio.au.dk phone: +45 6020 2654.

Cable bacteria moving at the oxygen front. Notice how only a minor part of the cells reach oxygen and how the shorter cable bacteria frequently withdraw completely to the oxygen free layer. The video is speeded up 150 times and in reality, the entire sequence is 12 hours.