Classifications

• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N1/00—Microorganisms, e.g. protozoa; Compositions thereof; Processes of propagating, maintaining or preserving microorganisms or compositions thereof; Processes of preparing or isolating a composition containing a microorganism; Culture media therefor
  • C12N1/12—Unicellular algae; Culture media therefor
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
  • C12M21/00—Bioreactors or fermenters specially adapted for specific uses
  • C12M21/02—Photobioreactors
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12M—APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS
  • C12M31/00—Means for providing, directing, scattering or concentrating light
  • C12M31/10—Means for providing, directing, scattering or concentrating light by light emitting elements located inside the reactor, e.g. LED or OLED
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N1/00—Microorganisms, e.g. protozoa; Compositions thereof; Processes of propagating, maintaining or preserving microorganisms or compositions thereof; Processes of preparing or isolating a composition containing a microorganism; Culture media therefor

Definitions

• the invention relates to a method of cultivating a phototrophic aquatic organism in an aqueous environment, in which method there is provided for illumination of the organism during cultivation of the organism in the aqueous environment.
• Light can be used as a source of energy for growth by a wide range of organisms, including many aquatic organisms.
• phototrophic aquatic organisms are phototrophic bacteria, cyanobacteria, algae and diatoms.
• cyanobacteria of the genera Gloeothece and Svnechococcus and algae belonging to the genera Chlorococcus.
• Dunaliella and Scenedesmus in principle offer great possibilities, concerning both autotrophically and heterotrophically growing phototrophic organisms. Thus, they could for instance be used to remove all kinds of organic contaminations ⁇ e.g. fatty acids, citrate, aldrin, dieldrin, PCBs, chlorinated naphthalenes) and inorganic compounds (e.g. nitrate, phosphate and heavy metals) from city sewage or industrial waste water.
• organic contaminations ⁇ e.g. fatty acids, citrate, aldrin, dieldrin, PCBs, chlorinated naphthalenes
• inorganic compounds e.
• Some cyanobacteria can also bind molecular nitrogen and other nitrogen-containing gases, such as ammonia.
• the object of the invention is to provide a both economically and otherwise acceptable method of cultivating phototrophic aquatic organisms, which method can be used for the abovementioned applications.
• this object is realized with a method of cultivating a phototrophic aquatic organism in an aqueous environment, in which there is provided for illumination of the organism during cultivation of the organism in the aqueous environment, which method is characterized according to the invention in that the organism is illuminated with artificial light of one or more selected wavelengths, coming from monochromatic light sources, the choice of the wavelengths depending on pigments or photosystems of the organism.
• artificial light of a wavelength such that the light quanta can be absorbed by pigments or photosystems of the organism involved in photosynthesis is preferable to use.
• the energy consumption for illumination for the purpose of photosynthesis can be minimized.
• Another preferred embodiment of the invention is to use - artificial light of a wavelength such that the formation of certain pigments is stimulated or inhibited.
• one option could for instance be the cultivation of aqueous organisms in two steps.
• an illumination is chosen for optimum growth, for instance red light.
• the second step in which the formation of a certain pigment is stimulated, for instance the formation of ⁇ -carotene under the influence of blue light.
• the invention partly relies on the fact that phototrophic organisms take up the light energy necessary for growth by means photosystems comprising pigments, in which each of the pigments involved generally absorbs only a limited number of specific wavelengths of the total light spectrum. This means that only a small part of the energy of incident sunlight or normal artificial light is absorbed by the pigments. The rest of the energy of incident sunlight or normal artifical light is not usefully employed. Further, a part of the energy absorbed by pigments is lost, depending on the wavelength, primarily because the photoreaction centres, where photosynthesis takes place, use specific amounts of energy that correspond with the energy amount of red light photons.
• Light quanta in the yellow and particularly the blue range of the spectrum contain more energy per photon relative to red light, but this extra energy is not used in the photoreaction centres and is lost.
• a second factor concerns the transfer of energy from the pigments to the photoreaction centres.
• the efficiency hereof is virtually 100% for yellow and red light quanta, but much lower for blue light quanta.
• the limited use of light energy is obviated in accordance with the invention by the using, during the cultivation of the phototrophic aquatic organism in an aqueous environment, monochromatic sources of illumination that essentially emit only light of wavelengths appropriate for the organism to be cultivated.
• sources of illumination of low energy consumption are used, which are capable of substantially converting the energy supplied to them into light of the desired wavelength.
• One particular example is the use of a collection of light emitting diodes
• LEDs These save an enormous amount of energy in comparison with normal sources of artificial light, which cover a much larger section of the light spectrum and, moreover, convert a large part of the energy supplied to them into heat.
• the LEDs preferred as sources of illumination use only little energy and can optionally be supplied with electricity coming from solar cells.
• the current solar cells convert 10-15% of the incident solar energy into electric energy, which via LEDs can be used efficiently by phototrophic organisms. In- his way, it is possible to use sunlight more effectively.
• the cultivation of the phototrophic aquatic organism is carried out in large volumes of aqueous medium, sufficient illumination can be ensured by (also) arranging illumination sources in the aqueous medium (ie. below the surface) , the illumination sources, if necessary, being arranged in a casing transparent to light.
• the illumination sources if necessary, being arranged in a casing transparent to light.
• Most phototrophic organisms have two interconnected photosystems which use light energy together. One system binds carbon dioxide, the other releases oxygen from water. The two photosystems each absorb light of one or more specific wavelengths, which are different for the two systems.
• an appropriate choice of wavelength can favour the production of certain substances, such as the production of carotenoids using blue light (420-450 nm) and the production of phytoerythrins using green light (500 or 550 nm) .
• An additional advantage of the use of a limited number of different wavelengths may be the prevention of the development of certain undesirable types of phototrophic organisms, which require different wavelengths for growth. More concretely, many phototrophic organisms have a photosystem involved in binding carbon dioxide, which absorbs in particular light of a wavelength of about 700 nm. In additon, they have a separate photosystem involved in the production of oxygen, which contains in the reaction centre a chlorophyll pigment exhibiting a strong absorption at 680 nm.
• This reaction centre can be excited directly by light of a wavelength of 680 nm or indirectly via the antenna pigments, also present.
• the light absorption by the antenna pigments differs between the different groups and types of organisms.
• the antenna pigments exhibit the strongest absorption towards red light of a wavelength of about 680 nm and blue light of a wavelength of about 450 nm.
• the reaction centre can be excited both with red light and with blue light, excitation with red light being the most efficient from an energetic point of view.
• the antenna pigments mainly absorb light of a wavelength of about 550 nm, depending on the type.
• phototrophic organisms having only one photosystem, which normally exhibits a maximum light absorption at a wavelength of about 800 nm.
• These organisms can produce all kinds of substances, which can occur under the influence of light of a different specific wavelength than that of the light that is necessary for photosynthesis. If illumination is effected using sunlight or normal artificial light, the production of these substances occurs concomitantly with photosynthesis or alternately by day and by night.
• illumination is effected using sunlight or normal artificial light
• the production of these substances occurs concomitantly with photosynthesis or alternately by day and by night.
• artificial light of specific wavelengths the same situation can be realized, but, if so desired, the two processes can also be made to occur one after the other under conditions that are optimal for each of these processes.
• the illumination sources are switched on periodically for 50 ⁇ sec at most and are switched off for at least as long an interval, up to a maximum of 2 sec.
• the illumination sources are periodically switched on and off according to a time schedule in correspondence with the growth pattern of the organism, so as to adjust the light intensity to the density of the phototrophic organisms and thereby to prevent unnecessary illumination within a system in which the organism grow optimally.
• a further option is to vary, whether periodically or not, the wavelengths of the emitted artificial light.
• the invention is not limited to certain embodiments. If LEDs are used, large numbers of LEDs can be used simultaneously and they may be of the same or dif erent type, may or may not be assembled to form tubes, strips or panels that can be placed in the aqueous environment or be arranged outside a bioreactor with a wall transparent to light.
• a collection of LEDs can for instance be arranged together on flat, curved, cylindrical or differently designed panels, and may or may not be arranged in some configuration relative to each other.
• Each LED may contain one or more light-emitting sources.
• the space in which the phototrophic aquatic organism is cultivated can be formed by open troughs or basins, or by closed containers or tanks, which prevents undesirable ingress of other substances and organisms and undesirable egress of reaction components and products and enables more accurate control of process conditions, such as temperature, pressure and composition of the gas above the aqueous environment.
• the space may or may not be accessible to sunlight, depending on the objects to be realized and on the possibilities.

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Cited By (9)

Citations (5)

• 1990
  • 1990-06-06 NL NL9001277A patent/NL9001277A/nl not_active Application Discontinuation
• 1991
  • 1991-06-05 WO PCT/NL1991/000092 patent/WO1991018970A1/en unknown

Patent Citations (5)

Non-Patent Citations (2)

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