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There are more kinds of microalgae, more than 60,000 kinds are found in nature, there are more than 6,000 kinds of records, in fact, only a few dozen kinds of cyanobacteria can be applied in the production workshop, including cyanobacteria, green algae, golden algae, diatoms, red algae and other kinds of algae. The spirulina commonly seen belongs to cyanobacteria, chlorella belongs to green algae, and large algae have red algae and brown algae, such as triangular brown finger algae and small cyclic algae belong to diatoms.
Microalgae applications
1. Functional food: As a health food, there are mainly spirulina, chlorella, erythrococcus, etc., spirulina cyanobin can be immune-enhanced, antioxidant, anti-cancer; pyroteococcus astaxanthin is the world's strongest antioxidant; lutein in chlorella can make retinal cells change color in the necessary pigment; the brown pigment in diatoms is fucoxanthin. Spirulina polysaccharides are antioxidant polysaccharides, purple bulbous polysaccharides can account for more than 50% of dry weight, is a strong antiviral and anti-cancer effect, so in functional food is currently the most widely used in microalgae.
2. Aquatic feed: Aquaculture, including aquatic seedlings, water adjusters and feed industry, such as the bait industry is mainly for fish, shrimp, crabs and shellfish to provide open bait, the so-called opening is after the animal's eggs hatch, the first thing to eat, like baby breast milk, and then grow up like a baby to add some rice paste, milk powder, rice soup and other foods, for fry is secondary bait, such as rotifers, copepods, branches of these secondary bait food sources are bait microalgae, so it is a biological bait system, so it is a biological bait system, Very widely used. Feed for large animals, land animals pigs, cattle, sheep, horses, rabbits, chickens and other nutritional needs are mainly proteoglysaccharides, oils; the same is true for aquatic animals, especially polysaturated fatty acids are necessary in the process of crustacean metamorphosis, as well as anti-cold, anti-stress effect is very important, so the nutritional components of microalgae as feed and feed additives are very widely used.
3. Biofuels: There are many types of biofuels, such as biodiesel, bioethanol, biogas (methane), photosynthetic hydrogen production is a hot spot in international research, and technology has been in reserve.
4. Environmental remediation: In more and more application areas, it is in environmental remediation, including carbon dioxide emission reduction, wastewater treatment, resource utilization, soil remediation, etc. are very good application areas for microalgae.
5. Biometallurgy: Heavy metals can be absorbed from water bodies and rock culture media through the cultivation of microalgae, and microalgae itself has a strong ability to enrich metals, and the metal content in the body is hundreds to thousands of times that of extracellular. Therefore, it is also widely used in the field of biometallurgy of microalgae.
Application of microalgae in aquaculture
The application of microalgae in aquaculture: fresh bait for aquatic animal fry; microalgae water adjuster degrades nitrogen and phosphorus in the water body, produce dissolved oxygen, dissolve oxygen in the water body, and inhibit harmful pathogenic organisms, give the water body a healthy water environment, provide a good water environment for aquaculture animals, and promote healthy breeding; as secondary bait, form an overall food chain for rotifers, branches, and brine worms as bait, so it is the bait of fish, shrimp and crabs, mainly including rotifer copepods, worms, branches, horns, etc. In special culture, it is widely used in the purification of sea cucumbers, abalone and shellfish.
Application of microalgae in aquatic animal breeding
first part
The core position of microalgae in aquaculture is irreplaceable because it is not only nutritional, but also biologically active, which determines the success or failure of seedlings, and improves the success rate of seedlings and the quality of seedlings.
1. Microalgae are comprehensive and rich in nutrients, and are the best live bait, which is the open bait for fish, shrimp, crabs, shellfish and other farmed animals in the water body.
2. Improve the stock rate of seedling measurement.
3. To ensure the normal development and metamorphosis of seedlings, microalgae biological activity and nutrition can provide the necessary nutrients for their survival and normal metamorphosis.
4. Many bioactive substances of microalgae can improve the growth rate, body length, weight and other traits.
5. Microalgae improve the immunity of seedlings.
6. Microalgae can purify the water body of seedlings to reduce the number of harmful microorganisms, now take more factory breeding seedlings without contact with the outside world of such a seedling workshop, in fact, also need to purify the water body, usually with physical, chemical methods are more effective than biological methods, but to ensure that the water adjuster, bait algae is fresh, healthy, otherwise if the bait is unhealthy, leading to the breeding of bacteria or the production of diseases will also cause harm to the seedlings.
7. Microalgae can be used to strengthen the nutrition of animal bait, such as microalgae nutrition can be passed to juvenile animals for consumption by secondary bait organisms such as rotifers.
First, common microalgae species
There are many common types of bait microalgae, and the major types of bait microalgae are more common, such as spirulina can be used for secondary bait, but it depends on the size of the animal body, as the cultivation of secondary bait can be fed rotifers, branches, copepods. It can also be used as a bait for shrimp nursery in the later stages of bran shrimp. But too small a farmed animal is uncomfortable, but spirulina fragments, such as one spiral or two spirals or smaller fragments as primary bait. There are many types of diatoms, such as bone stripe algae, algae, sea chain algae, etc., mainly in shrimp, shellfish can be used as bait for life, therefore, Zhejiang, Jiangsu beach shellfish farming on the demand for diatoms is larger. There are many varieties of green algae, such as chlorella, salt algae, etc. can be used as shrimp, shellfish, rotifers and other bait, and can also be used as a water adjuster for fertilizer water. The individuals in cryptoalgae are larger and more nutritious, and can be used as nursery for shellfish and shrimp, and the cell density is low. Golden algae such as equilateral golden algae and pavella are commonly used in shellfish and shrimp nursery, and can also be used as water adjusters. Micrococcus micrococcus (seawater chlorella), shellfish nursery more used. However, shrimp nursery and water conditioners are useful. Shrimp nursery when the concentration can not be large, if the concentration is high will be hung on the body of the juvenile shrimp, but will cause some unnecessary problems, other algal phases, such as cryptomycetes, fissocens can be used as secondary bait culture, used to strengthen the nutritional content of the secondary bait of rotifers.
Second, the biochemical composition of microalgae
The biochemical composition of microalgae is rich, protein, carbohydrates, fats and chlorophyll, which is the most important component of pigment and is also very powerful in function. Chlorella has the function of detoxification, especially the discharge of heavy metals, which is achieved through chlorophyll metabolites, so eating more green vegetables and chlorella can be detoxified, especially heavy metals, environmental toxins (pesticide residues, drug residues, animal residues, dioxins) and so on. Different microalgae have more varieties, with different nutrient content, and the nutritional composition of a certain type of microalgae is different. The fatty acid part of diatoms is a relatively prominent ingredient. Erythricoccus raining down accumulates astaxanthin and is the main functional component. Microalgae as a bait is best to be able to compound the use, that is, when feeding bait, do not feed a single one, such as feeding only one kind of chlorella, will cause nutritional incompleteness, chlorella is containing protein, the longest chain of fatty acids to 18 carbon, and then epa, arachidonic acid, etc. basically no, which is genetically determined, so it is necessary to match other microalgae, such as diatoms, golden algae protein and fatty acids and other pigments. Even if you can use high-grade ornamental fish, astaxanthin, algae pulp, etc. can be used. Therefore, according to the needs of the farmed species and the nutrients needed in the process of animal metamorphosis and development, they are used as a benchmark for compound use and compound feeding to improve the quality of the seedlings.
Third, polyunsaturated fatty acids, vitamins
The main role of polyunsaturated fatty acids is to increase the concentration of pufa in the nursery body, ensure normal development, and promote growth. Fatty acids are necessary when dehulling animals such as shrimp. For cold-water fish low temperature tolerance is a must for polyunsaturated fatty acids, Japanese people like to eat sashimi, winter in the snow walk and their diet is related, they often eat sashimi cold water fish more, so the body polyunsaturated fatty acids more, anti-cold, antifreeze. Such as bone stripe algae, pavella, golden algae, algae, etc. have different polyunsaturated fatty acids, the concentration is different, some fatty acid content is more special species are more special, such as micro-pseudococcus high energy Epa, no dha, so it is the best algae species to produce high purity EPA. Chytridium fissionate has a high content of DHA. According to the nutritional needs of different animals, it is very important to use microalgae varieties in combination with their healthy breeding and normal metamorphosis. In addition, there are rich vitamins, the type and content of vitamins are very important for the growth and development of seedlings, different microalgae have different vitamin content, different farmed animals, in different breeding cycles on the needs of vitamins are different. In the compound formula feed are added to the vitamin, if you can add microalgae into, vitamins, minerals, biological activity, etc. have it, in the fry it can not eat artificial pellet feed, so most of the microalgae, so the content of vitamins is more sufficient, like cold water fish, astaxanthin is also its must, shrimp crab shelling metamorphosis of astaxanthin, is also a must, for crustacean The source of vitamin H is microalgae in nature, but the content of different microalgae is different, Therefore, artificial feed is basically the addition of synthetic pigments, but more and more countries, such as Europe has banned the use of chemical synthetic pigments, China has not completely banned, but also does not advocate the use of. It looks like a color, but has no biological function, and it is advocated to use pigments such as all-natural astaxanthin, which not only has biological functions, but also has biological activity.
Fourth, the application of microalgae in seedlings
1. The application of microalgae in shrimp nursery, the body length and weight of different shrimp development periods are different. The body length metamorphosis of algae and no algae is also different, and the number, concentration and variety of microalgae needed in different periods can be matched, so that it can be used scientifically, and it is necessary to see some professionally reported literature to improve the use of microalgae in shrimp nursery. Usually the order of magnitude is around 10 to the 4th power. The concentration is not very high, so the bait needs to be able to choose concentrate, algae cake or fresh culture solution, mainly depending on the dilution of the water body, but the bait should be fresh, if not fresh, it will bring some bacteria to the seedlings are harmful.
2. Microalgae in shellfish nursery applications are actually very extensive, like Australia has done some such experiments, in fact, in the production is also used in this way, can add some fresh concentrate to use, different concentrations, different doses of shellfish metamorphosis body length, weight have a lot of research. In fact, fresh algae liquid and concentrate are OK, and the effect is very good. In addition, the application of shellfish purification, green shellfish breeding, fertilization, spawning and other aspects are very good. Especially in terms of shellfish purification, shellfish are dug out of the pond soil before the table must be purified, the intestines in the sand, soil, etc. spit out, then if you do not eat anything, you will definitely lose weight, then you also have to maintain fat and increase quality, the taste, meat quality can not be reduced, so shellfish fattening and quality growth is in the purification process must be achieved, and the sea intestines are the same, so the application of microalgae in this regard is very important, but also to ensure the quality of aquatic products.
3. The application of abalone seedlings: abalone mainly eats some benthic algae, such as boat-shaped algae and other benthic microalgae covered on the surface of the rock to eat, so there are also more studies and comparisons at home and abroad, which have been reported. Cultivating ark-shaped algae is very good to use some attachment to the surface, such as brushes, floors, plastic plates and other surfaces.
4. The application of microalgae in sea cucumber seedlings also has a very important attempt, foreign countries have made it into a concentrated solution of the product to feed the sea cucumber, in addition to the seedlings need microalgae varieties more, usually used algae, pavella, golden algae, etc., cell density is not very high. Different periods of metamorphosis are also alive, stored, and concentrated. The effect of feeding algae and not feeding algae is different.
5. In the application of fish fry is also more extensive, in fact, and the species of fish, the dosage is related, different fish species on the microalgae requirements are also different, like loach and other varieties and quantities of algae are different. According to the scientific selection of different animal breeds and developmental periods, it is reported that the growth rate of body weight with algae and those without algae in different periods is different, and the growth rate is obvious, indicating that microalgae play a significant role in fish seedlings. The vast majority of nursery farms have production workshops, the number and output of algae cultivation workshops are difficult to count, according to the 2010 Aquatic Yearbook, rough estimates, in the marine aquaculture industry seedlings on the bait of the seedlings of the demand for bait can reach a total demand of 16,000 tons a year, to spirulina, chlorella and other microalgae industry in a year less than 10,000 tons of dry weight annual production, the entire annual output to seawater fry are not enough, the gap is larger. Therefore, it is promising to do seed bait in the company, because the gap in the market is very large and the business opportunities are unlimited.
Application of microalgae in water adjusters
second part
Water conditioner usually uses concentrate, the degree of concentration of concentrate depends on many factors, the length of transportation, the conditions of preservation and shelf life, variety, etc., so the concentrate is not recommended to be very concentrated, because the concentration in the sealed environment for a longer time The vitality of the cells will decline, so it is recommended to use the appropriate concentration of fresh algae liquid directly when doing the water conditioner, so the vitality can be guaranteed to the highest. As an algae species that establishes and maintains the algal phase of the aquaculture water body, the water conditioner plays a role in purifying the water quality, increasing dissolved oxygen, inhibiting harmful microorganisms, fertilizing the water and providing bait, and building an ecosystem of the aquaculture water body.
Commonly used bait algae can also be used as water modulators, such as chlorella, haematococcus, micrococcus, equilateral golden algae, pavella, etc. can be used as different water modulators. There are green algae water, diatom water, silicium green algae water, golden algae water and other different water colors, in fact, the adjustment of water color is mainly to provide different microalgae seeds on the one hand, have biodiversity in the water body, provide nutrition, this source is the primary productivity, on the other hand, through the health activities of beneficial algae to inhibit harmful algae, even harmful pathogens, the outbreak of harmful algae and so on. Therefore, the use of beneficial algae to control the outbreak of harmful algae and harmful bacteria is actually the best ecological regulation project.
The importance of water adjuster in the breeding ecosystem: microalgae is a part of the biological floc, that is, and some micro-ecological bacterial bacteria form a biological floc, the bacteria to reproduce can use fish, shrimp, crab feces, residual bait, etc. as nutrition, while nitrification and denitrification of the ammonia nitrogen, nitrogen, phosphorus and other nutrients can be used as a nutrient for bacterial growth nutrients, beneficial bacteria will form biological flocculents after the propagation of algae, then the biological flocculent in the purification of water quality to provide bait, feed, Plankton plankton to form a food chain, this link is very important, that is to say, algae and bacteria can not exist alone in the water body, it is basically a balanced dynamic biological flocculent way to exist, it and the bacteria together with the function is more powerful.
The role of the water adjuster: the bait of the filter feeding animals, because the biological flocculent is not a single cell in the water body after the formation of the biological flocculent, some gel particles will be formed, which will increase the volume and then the filter-feeding animals can eat. Therefore, the biological flocculents will not be deposited in the water body, and they can reproduce on their own, which is a good food for filter animals. It can also be used as indirect food for rotifers, copepods, and branches. In reducing the content of ammonia nitrogen, nitrous nitrogen, nitrite, phosphate in the water body. Because so living cells need nutrients during the reproductive process, this nutrient comes from various elements in the water body, especially nitrogen and phosphorus. Carbon dioxide in the water body is usually animal breathing must be produced, therefore, the water body is also rich in carbon dioxide, in the water body both nitrogen, phosphorus and carbon dioxide in the case of algae is very easy to grow up, the formation of biological flocculent after the ability to purify the water body will be further improved, but also can stabilize the pH of the water body, can provide oxygen, the formation of oxygen-rich water environment. At the same time, it can inhibit the reproduction of harmful bacteria, enhance immunity, and also have a strong inhibition of harmful bacteria and even the outbreak of harmful cyanobacteria. Common water colors are green, emerald green, light yellow, gold, etc., mainly depending on the types of algae containing different species, so the construction of a healthy water color, algal phase, algae balance after the health of the water body is guaranteed.
1. In the application of shrimp farming, the water transfer agent culture method is widely used in shrimp culture, if it is clear water and the use of water transfer agent to compare the growth, survival rate and feed coefficient of farmed animals have obvious differences. There was a natural disaster in the Philippines one year, the entire shrimp farming production decreased, some people used the amount of water transfer agent, some did not use, the net income and loss of the pond using the water transfer agent were reduced a lot. Although the net income was negative, its losses were minimized. Shrimp and tilapia can be polycultured, and after polyculture of fish and shrimp, they can coexist with algae in an environment and three-dimensional culture, which is also a breeding mode promoted in recent years.
2. The impact of the water adjuster on the growth of the fry compared with the sample of artificial feed, and it was found that the fertilizer and water of the equilateral golden algae and micro-pseudococcus algae were significantly increased compared with the survival rate, body length and weight of the artificial feed, which showed that the breeding mode of the fish fry on the water transfer agent was also required for aquaculture. The amount of water conditioners for microalgae blenders in aquaculture is difficult to estimate and difficult to calculate, but it is also based on the aquatic yearbook. According to the calculation of the breeding area, each mu is used twice a year, each time 1 kg of algae mud, the dry weight of the water transfer agent required is 8000 tons. Counting the evolutionary requirements of shellfish, the biomass is at least 10,000 tons, which is equivalent to the total biomass production of the microalgae industry at present, and there is a huge market demand space for the demand for microalgae in this regard.
3. Some of the influencing factors in the application of microalgae water adjuster, of course, are microalgae growth can be used as water regulator, produce dissolved oxygen, inhibit harmful bacteria are directly related to the growth of microalgae. If the algae does not grow, on the one hand, there may be no nutrition, on the other hand, there is no light, the temperature is not suitable or the pH value is not suitable. So how to use a good water conditioner? According to the situation to consider, such as what kind of algae species of water adjuster needs what kind of salinity, light, temperature, etc. have as far as possible to adapt to the algae to the environment, while giving some fertilizer and nutrition, can not be water directly sprinkled algae into, so in the use of water transfer agent such as chlorella as far as possible in the sunny sunshine is better, the temperature is better when the water adjuster product is expanded and then under the pond, do not directly go to the pond, to have a buffer reproduction process and then the effect of the pond is better, in addition to the use of algae fertilizer to be used together.
There are many algae agents, such as nitrogen, phosphorus and potassium fertilizers, organic fertilizers, trace element fertilizers and fungal agents, etc., first of all, we must first identify the water adjuster, first observe whether there is live algae, the most intuitive way is to use a microscope to observe, and then take a sample to observe whether it can be expanded. Concentrated algae liquid or green water can not see any cells can be called a water conditioner, but it is actually a fake. Live algae in dry powder should also be cultivated in pure water, plus nutrients. Now there are many aquatic products on the market, and everyone must choose the nutrition of algae and algae through learning and science.
Author: Professor Wei Dong
Unit: South China University of Technology
(Invasion and deletion)
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