haberlandt2008

DIY Spectophotometer

Measurement of light absorption by a spectrophotometer is used to detect and identify molecules and to measure their concentration in solution. The fraction of the incident light absorbed by a solution at a given wavelenght is related to the thickness of the absorbing species.

Instructions at:

RSC

Parts list

·Photometer

Printed circuit board, plug-board, or photoresist board
Voltmeter or digital multimeter
Plastic or glass cuvettes
Total cost for photometer consumables is under £4.00

·Spectrophotometer

White light source
Diffraction grating, prisms or coloured filters. (Note: gratings are available at modest cost and work better than prisms.)
Lenses
Optical bench or stands and clamps; black cloth
Resistors: 4.7 k; 2.2 k; 1.0 k
LED: orange, 5 mm
LDR
Op amp: 3140
Socket: eight-pin
Battery clips
Soldering iron, solder,
Blu-Tack, tape and card

Pros
Way to go. Did arduino 101. Quantitatively precise. Totally DIYBio. The rest of the blablabLAB members are doing electronics. Fun. Must definitely Do.

Cons
Electronics are hard

pHmeter

When cultivated in aqueous culture the cell growth can be determined by following the optical density.
On the other hand, when produced by solid cultivation the growth can be determined only indirectly, such as, through determination of the protein content of the fermenting solids. In this work the possibility of estimating cell growth by pH determination was verified. From the results it was concluded that pH and protein production (solid or surface culture) or cell content (liquid culture) correlate well, therefore pH determination seems to be a good method to determine cell growth.

Pros
Cheap, easy, fast. Useful as a state of the batch measure.

Cons
We are not able to adjust pH continuously for optimum spirulina performance.

Pressure measurement, or how to use balloons in science
Estimate growth of A. platensis by measuring the oxygen produced by connecting the bioreactor to a balloon.

Pros
Very easy, very cheap, qualitatively accurate. Must Do

Cons
Quantitatively innacurate.

T.S.

References

Cogne G et al. (2001). Growth monitoring of a photosynthetic micro-organism (Spirulina platensis) by pressure measurement. Biotechnology Letters 23(16):1309-1314

Helena L et al. (2002). Spirulina platensis growth estimation by pH determination at different cultivations conditions. Journal of Biotechnology 5(3):251-257

Tavener SJ, Thomas-Oates JE (2007). Build Your Own Spectrophotometer. Education In Chemistry 44(5)

Nelson DL, Cox MM. (2000). Lehninger Principles of Biochemistry. 3^rded. Worth Publishers, New York.

In order to have a microscope to check the cultivated cells we’ve been experimenting inverting camera lenses to get some magnifications, here are the first results.

In this case we are using a Minolta reflex zoom lens at 28mm and infinite focus placed upside down in front of a Sony H20 compact camera with the optical zoom at x10. A support is essential to have a stable image.

A higher magnification and a built-in microscope is required though.

Seeing the results from the guys of Hackteria we got motivated to build something really similar. So once we get our webcam we’ll try out.

Coming soon new images!

The system is built to mantain the pH of the tank solution stable by droping acid or base depending on the measurements of the pHmeter. An Arduino controlled servo motor (90º rotation) is tied to a hospital valve to open and close the duct.

We’re testing the lapse between drops and the volume of each drop to see how the system responds and how we will adjust it to our needs.

Every time a drop is delivered it leaves the next one about to fall  due to the tube’s surface tension, making the system very reliable in short time releases. In my room conditions, the hanging drop starts evaporating, making the next drop to stall.

These are the results right before and after a drop release:

1h>drop falls

(pending)12h- drop falls

24h- drop doesn’t fall

48h- drop doesn’t fall

Conclusion
After a few hours without releasing a drop we are going to program it to release a double volume of liquid to push out the single drop we need.
This results could change once the tank is sealed due to increases in relative humidity inside the bioreactor.

after a quick prototype the fittest parts are being collected and few drawings developed in order to test a precise solution

breast pumps are still to be worked-out

Spherification from blablabLAB on Vimeo.

First experiments conducted with coffee-liquor, alginate and calcium chloride (CaCl₂).

Results are disappointing taste-wise but spherification/encapsulation definitely works.

Protocol
Sodium alginate is mixed with the solution of interest (coffee & liquor) for spherification, some patience is required, since dry alginate lumps form, and those are hard to dissolve. Heating solution helps. Experiment was carried with 2 g Na⁺Alginate/250 ml volume concentration.

A solution of CaCl₂ on distilled water was prepared for the gelation process with a 4g CaCl₂/500 ml concetration.

It seems that speed of alginate gelation is positively correlated with salt concentration. In this case, after 5 minutes the external layer was still a little bit weak.

A  3D experiment must be designed to study the degree of gelation (hardness of the sphere) plotted against alginate and calcium chloride concentrations.

We have to work to improve the method to drop the mix without losing the rounded shape to avoid non encapsulation.

A sphere size that intensifies organoleptic values must be determined.

blablabLAB

since the schematics of this cheap phmeter are unknows we  decided to rip it apart

it all turn to be quite simple

the meter generates a voltage, but its too litte

so, op-amps are under study, with the great help of Alex Posada (Hangar)

This post covers the eight major environmental factors that influence the productivity of Arthrospira platensis: Luminosity, temperature, salinity, pH, inoculation size, stirring speed,  water quality, and macro and micronutrient presence (water and nutrients will be reviewed in the next post of the Arthrospira series).

A.platensis is found in soil, marshes, freshwater, brackish water, seawater and thermal springs. Alkaline, saline water (>30 g/l) with high pH (8.5– 11.0) favour good production of Spirulina, especially where there is a high level of solar radiation at altitude in the tropics. A. platensis thrives in highly alkaline lakes where the cyanobacteria population is practically monospecific. The higher the pH and the conductivity of the water, the greater is the likely predominance of Arthrospira spp.

Optimum Growth Ranges

· Iluminosity or illuminace is a measure of the intensity, as perceived by the human eye, of light that hits or passes through a surface. It is measured in lux (lx). A. platensis optimal illuminance ranges from 2,500 – 10,000 lx.

Light is an important factor but full sunlight may not the be the best rate of illumination, 30% of full sun light is actually better, except that more may be required to quickly heat up the culture in the morning (it cannot stand a strong light when cold -below 15°C-).

Individual A.platensis filaments are destroyed by prolonged strong illumination (“photolysis”), therefore it is necessary to agitate the culture in order to minimize the time they are exposed to full sunlight.

Artificial light and heating may be used to grow A. platensis, although they are not economical. Fluorescent tubes and halogen lamps are both convenient. Lamps can illuminate and heat the culture simultaneously.

· The best photo-period or light-hours is 16/12 (Day/Night). Growth only takes place in light (photosynthesis), but illumination 24 hours a day is not recommended. During dark periods, chemical reactions take place within A.platensis, like synthesis of proteins and respiration.

Respiration decreases A.platensis’s biomass; and its rate is much greater at high temperature so cool nights are better on that account, but in the morning beware of cold temperatures and sensitivity to light.

· In many regions of the world, temperature may represent the main limitation for high biomass production rates in outdoor open ponds of A. platensis cultures. An outdoor algal culture undergoes a diurnal cycle which in areas out of the tropics may show a difference of 20 ºC. In the morning, the pond temperature may only be in the range of 15 – 20 ºC, an optimal temperature, in the range of 29 – 38 ºC is reached only in the early afternoon. Even in the tropics where the culture reaches the optimal temperature, during a significant part of the day the temperature will still be much below the optimum.

· Salinity is the dissolved salt content of a body of water. It is a general term used to describe the levels of different salts such as sodium chloride, magnesium and calcium sulfates, and bicarbonates. A. platensis’s optimal salinity is 20 to 70 g/L but it can withstand much higher concentrations.

· The potentiometric hydrogen ion concentration ([H⁺]) or pH measures the acidity (or basicity) of a solution. Optimal values for A. platensis fall inside a 8.5 to 10.5 range with 9.5 giving a peak value of growth whenever the rest of conditions are optimal.

·Inoculation size

·Stirring speed

T.S.

Arthorspira platensis, commonly know as spirulina is the main organism of our self-sustaining vending machine, the Haberlandt 2008. In this series of posts we will describe the biological characteristics that make it interesting as a whole food and also the materials and methods used during the process of the bioreactor development.

Cyanobacteria comprise a group of oxygenic autophototrophic bacteria, that is, they use energy obtained from light to transform CO₂ into biomass while producing O₂. Arthrospira is one of those filamentous cells (Oscillatoria group) that divide by binary fission in a single plane. They form large colonies in tropical and sub-tropical surface waters with high carbonate and bicarbonate levels.

Why A. platensis?

The cyanobacterium Arthrospira platensis can be cultivated autotrophically for the production of biomass with high protein content. Technologically it exhibits advantages in the methods of cultivation. Among these, the capability to grow under alkaline and highly salty conditions is an important factor in the prevention of external contamination, while the easy separation of biomass from the cultivation medium, because of its spiral form and large size, reduces the costs of its recovery.

Spirulina requires less energy input per kilo than soy, corn or beef, including solar and generated energy. Its energy efficiency is 5 times higher than soy, 2 times higher than corn, and over 100 times higher than grain-fed beef.

Composition of Spirulina

Spirulina is very high in protein, very low in calories and cholesterol, and high in minerals (iron, calcium, sodium and magnesium), and phenolic acids, which have antioxidant properties (see Table).

In that sense it is a complete protein source since it contains almost all the essential amino acids (the ones we cannot synthesize by ourselves), though with reduced amounts of methionine, cysteine, and lysine when compared to the proteins of meat, eggs, and milk. It is, however, superior to typical plant protein, such as that from legumes. It offers good digestibility and a low nucleic acid concentration (smaller that 5%).

Besides, it contains vitamins A, B, C, E, and K, polyunsaturated fatty acids, carotenoids, and other antioxidants.

Table. For every 10 g of dry Spirulina:

Disclaimer: The bioavailability of vitamin B12 in Spirulina is in dispute. Several biological assays have been used to test for the presence of vitamin B12 and have shown Spirulina to be a minimal source of bioavailable vitamin B12. However, this assay does not differentiate between true B12 (cobalamin) and similar compounds (corrinoids) that cannot be used in human metabolism and interfere with the true form absorption. The American Dietetic Association and Dietitians of Canada in their position paper on vegetarian diets state that Spirulina can not be counted on as a reliable source of active vitamin B12. Long term Vitamin B12 deficiency can potentially cause severe and irreversible damage

Recommended Dietary Allowance (RDA)

The RDA is the daily dietary intake level of a nutrient considered sufficient by the Food and Nutrition Board to meet the requirements of nearly all healthy individuals in each life-stage and gender group. 100 g of dry Spirulina satisfy 100% of the protein and 15 % of the carbohydrate RDA recommendations for an adult male, fat and fiber are far from being met by consumption of Spirulina alone.

Human consumption

The benefits of Spirulina as a low-calorie, high-protein, mineral and vitamin food supplement are now well established and recognized worldwide. Studies have shown that Spirulina can lower cholesterol levels, stimulate the immune system and be effective in the treatment of obesity, heart disease, premenstrual stress, arthritis, anaemia and osteoporosis. Spirulina is also a rich source of betacarotene, a natural antioxidant, which the body converts to vitamin A and which plays a protective role in the human organism. Recent studies have concluded that a diet rich in vitamin A and provitamin A can lower the risk of cancer. Betacarotene is considered a more effective antioxidant than synthetic trans betacarotene. Positive results have also been seen in performance and stamina levels when Spirulina is taken as a sports supplement; the blue-green alga has a high level of biotin, which is an inhibitor of lactic acid in muscles.

References

FAO

USDA Food & Nutrition Information Center

Dante L, et al. (2006) Influence of pH, Temperature, and Urea Molar Flowrate on Arthrospira platensis Fed-Batch Cultivation: A Kinetic and Thermodynamic Approach. Biotechnology and Bioengineering 96(4): 702-711 DOI 10.1002/bit.21097

T.S

Experiments were conducted in Barcelona, Spain (41º 23′ N 2º 11′ E)

Adjust to your local conditions: http://www.wmo.int/

The Source: Or how we got our Arthrospira platensis

On March 2010 we contacted Dr. Jaume Cambra of the Plant Biology Department at the Faculty of Biology, Universitat de Barcelona. He informed us about the presence of A. platensis in a channel at the Natural Park of Llobregat. The 7^th of March of 2010 blablabLAB went on a scientific expedition to extract the cyanobacterium, obtaining, with permission of the park authorities, almost a total of 4 L of water from different points of the channel.

The water was checked under a microscope from the library of the Faculty of Biology and presence of A. platensis was confirmed. No cell count was done on the sample, but it would have been a good idea to assess the initial population of A. platensis.

The water was left at room temperature and office light conditions for almost a week, it would be appropriate to move A. platensis as soon as possible to a selective medium (a medium that allows for preferential growth of a desired organism).

The selective medium was prepared based on the nutritional requirements estimated and artificial light was used to illuminate.