CN111534438A

CN111534438A - Method for efficiently killing protozoa in living unicellular algae and application

Info

Publication number: CN111534438A
Application number: CN202010301432.1A
Authority: CN
Inventors: 于宗赫; 刘文广; 张晓勇; 马文刚; 许强
Original assignee: South China Agricultural University
Current assignee: South China Agricultural University
Priority date: 2020-04-16
Filing date: 2020-04-16
Publication date: 2020-08-14

Abstract

The invention discloses a method for efficiently killing protozoa in living unicellular algae and application thereof. The method directly kills protozoa in living unicellular algae by electrifying the unicellular algae liquid, can kill protozoa in the unicellular algae by 100 percent, has simple and convenient operation, is economic and environment-friendly, can greatly reduce the labor intensity and improve the working efficiency, can directly feed the aquatic product culture animals without generating any toxic and side effect because the processed unicellular algae has no change in components. The method is green and environment-friendly, is very suitable for removing enemy organisms such as protozoa and the like in the unicellular algae, and has important application value for the culture of the unicellular algae and the aquaculture industry utilizing the unicellular algae.

Description

Method for efficiently killing protozoa in living unicellular algae and application

Technical Field

The invention relates to the technical field of aquaculture. More particularly, relates to a method for efficiently killing protozoa in live unicellular algae and application thereof.

Background

The unicellular algae is easy to culture and rich in nutrition, and is a starter for various aquaculture animals such as fish, shrimp, shellfish, sea cucumber and the like. In practical production, the culture of the unicellular algae is mostly carried out in an open large space for cost control, and the unicellular algae cultured in the environment is particularly easy to infect protozoa, copepods and other harmful organisms, especially in high-temperature seasons. Direct feeding of monadian algae infected with hostile organisms may cause a range of hazards to aquaculture animals: including competing for feed and space, and also secreting toxins that affect the growth of the farmed animals, even when the farmed animals prey on their larvae directly.

The enemy organisms in the unicellular algae culture process cannot be prevented well, and no good solution exists at present. For large individual harmful organisms such as copepods, the conventional physical methods such as filtration can be used for removing the harmful organisms from the algae liquid, but the filtration method is ineffective for small protozoa. At present, chemical methods such as hydrochloric acid or formaldehyde are mostly adopted to kill the small protozoa, but the methods not only introduce harmful substances, but also damage the components of the bait microalgae and even damage the fed breeding animals. In addition, in recent years, methods for introducing nitrogen or carbon dioxide into water bodies for cultivating the unicellular algae appear, and the methods have high requirements on equipment, so that the high cost determines that the method is not suitable for large-scale production.

Therefore, in order to eliminate protozoan and other harmful insects in the monad and control the potential harm of the feed alga infecting the protozoa to the cultured animals, a method which is efficient and economic and does not have any influence on the components of the alga is found, and the method has important application value for the culture of the monad and the aquaculture industry using the monad as the feed.

Disclosure of Invention

The invention aims to provide a method for efficiently killing protozoa in living unicellular algae and application thereof. The method is economic, efficient, green and environment-friendly, and is very suitable for removing enemy organisms such as protozoa and the like in the unicellular algae.

The primary object of the present invention is to provide a method for efficiently killing protozoa in living chlamydomonas.

It is another object of the present invention to provide the use of the above method for killing protozoa.

In order to achieve the purpose, the invention is realized by the following scheme:

the invention provides a method for efficiently killing protozoa in living unicellular algae, which is to kill the protozoa in the living unicellular algae by electrifying unicellular algae solution.

The method is simple, can directly and efficiently kill enemy organisms in the unicellular algae, and the components of the processed unicellular algae are not influenced, and the processed algae liquid can be directly fed to aquaculture animals.

Preferably, the electrifying is to electrify the algae liquid with 100-500V voltage and 1-20A current.

Most preferably, the energisation is to energise the algal solution with a voltage of 200 volts, and a current of 1.5 amps.

The invention discovers that when the voltage and the current are enhanced, although the protozoa can be effectively killed, the protozoa can also damage the unicellular algae; when the voltage and current are reduced, protozoa in live chlamydomonas cannot be killed completely.

Preferably, the ratio of the time of the electrification to the volume of the algae liquid is 10-20 s: 50-200L.

Most preferably, the ratio of the time of the energization to the volume of the algae liquid is 10 s: 100L.

Preferably, the unicellular algae are one or more of chaetoceros, chrysophyceae, chlorella, dunaliella salina or Platymonas sp.

The protozoa are common enemies in the process of culturing unicellular algae such as Trichodina, Tenebrio molitor, Proteus, paramecium and the like.

Preferably, the electrification is carried out by using an electric fishing rod, specifically, in the using process, the front end electrode of the electric fishing rod is inserted into the water body cultured by the unicellular algae, and the algae liquid is uniformly stirred during the electrification so as to kill the protozoa.

Further preferably, the electric fishing rod is a seawater electric fishing rod or a fresh water electric fishing rod, and the seawater electric fishing rod is used for seawater unicellular algae, and the fresh water electric fishing rod is used for fresh water unicellular algae.

Electric fishing rods are preferred primarily because of their ease of operation, safety, reliability, and economy and efficiency.

The invention also claims the application of the method in killing protozoa.

Compared with the prior art, the invention has the beneficial effects that:

compared with the traditional methods of physical filtration, chemical killing or nitrogen and carbon dioxide introduction, the method of the invention can efficiently kill protozoa in the unicellular algae, has simple and convenient operation, is economic and environment-friendly, can greatly reduce the labor intensity and improve the working efficiency, can directly feed aquaculture animals without changing the components of the processed unicellular algae, does not generate any toxic or side effect, and has important application value for the culture of the unicellular algae and the aquaculture industry utilizing the unicellular algae.

Drawings

FIG. 1 is a photograph of Chaetoceros cultured in a jar;

FIG. 2 is an electric fishing rod for killing harmful insects;

FIG. 3 is a photomicrograph at 100X magnification of Chaetoceros and protozoa prior to power-on treatment, in which the circles are live protozoa, swimming rapidly and out of focus; arrows indicate chaetoceros;

FIG. 4 is a photomicrograph at 100X magnification of a power-on treated Chaetoceros and protozoa in which killed protozoa are in the circle and lost motor ability to focus; arrows indicate chaetoceros;

FIG. 5 is a photograph of sea cucumber auricularia juveniles fed by the electrification-treated chaetoceros at a microscopic magnification of 100 times;

FIG. 6 is a photograph of Holothuria leucospilota larvae fed with untreated Chaetoceros at 100 Xmagnification.

Detailed Description

The invention is further described with reference to the drawings and the following detailed description, which are not intended to limit the invention in any way. Reagents, methods and apparatus used in the present invention are conventional in the art unless otherwise indicated.

Unless otherwise indicated, reagents and materials used in the following examples are commercially available.

Example 1A method for killing protozoa in Living Cellulomonas

1. Experimental methods

In summer of 2019, tropical sea cucumber artificial breeding is carried out in Shenzhen, Chaetoceros is used as one of baits in the larva cultivation process, a 200L cultivation cylinder is used for carrying out three-stage cultivation on Chaetoceros, and after 8 months and 12 days, the Chaetoceros is found to be dark in color by naked eyes, as shown in figure 1, the algae liquid is found to be infected with protozoan Trichoderma by microscopic examination, as shown in figure 3, wherein live protozoans are in circles. Then the electric fishing rod of fig. 2 is used to electrify the algae liquid for 10 seconds to kill the protozoa in the algae liquid, and the electric fishing rod can provide 200 volts and 1.5 amperes of current during the period of continuous uniform stirring.

2. Results of the experiment

Before electric shock treatment, protozoa mainly comprising the trichodina in the algae liquid always swim, so that focusing cannot be carried out under a microscope, and only larger shadows which move continuously can be observed, as shown in fig. 3; after the shock treatment, the protozoa all died and the immobile protozoan cadavers were observed with focus, as shown in fig. 4.

Standing the algae liquid after the electric shock treatment for 8 hours, and performing microscopic examination again, wherein no protozoan living bodies are found, which proves that the method can effectively kill enemy organisms.

FIGS. 5 and 6 are photographs taken at 14 th 9 th 2019, which are microscopic photographs of 100-fold enlarged sea cucumber ear-shaped larvae fed with processed and unprocessed chaetoceros after being fed for 10 days, and the two sea cucumber larvae are hatched from fertilized eggs of the same batch at 4 th 9 th 2019, and comparing FIGS. 5 and 6, it can be found that the number of harmful organisms such as protozoan spider bugs in the sea cucumber ear-shaped larva breeding pond fed with processed chaetoceros for 10 days is more than 80% lower than that in the untreated control group; in addition, under the condition of the same feeding strength, the individual size and the development degree of the sea cucumber auricular larvae cultured by using the treated algae liquid are obviously superior to those of the untreated group, wherein the sea cucumber larvae of the treated group are developed to the later stage of middle ear larvae, the control group is only small ear larvae, and the gastric fullness and survival rate of the treated group are also obviously superior to those of the untreated group.

The method is used for treating the algae liquid, harmful organisms in the unicellular algae can be fully killed, toxic and harmful substances are not introduced, and the components of the treated microalgae, including organic matters, chlorophyll a and the like, are not changed; the time for treating 200L of algae liquid is only about 10 seconds, which is far shorter than that of a physical filtration method and a chemical treatment method; the consumed electric quantity is only 0.0008 kilowatt hour, and the electric charge expense is far lower than that of the physical and chemical treatment method; the bait algae is treated by the method, so that the normal development of sea cucumber larvae can be ensured, and the economic and environmental benefits are higher.

Examples 2 to 5

1. The experimental procedure was the same as that of example 1, except that the conditions for culturing algae and electric shock were different, as shown in Table 1.

TABLE 1

	Example 2	Example 3	Example 4	Example 5
					Species of unicellular algae	Golden algae	Chlorella vulgaris	Platymonas subcordiformis (Fr.) Kuntze	Dunaliella salina
Volume (L)	100	300	400	200
					Voltage (V)	100	200	500	300
Current (A)	1	5	20	3
					Energization time(s)	10	15	20	18

2. Results of the experiment

In the above embodiment, before the electric shock treatment, protozoa such as rotifers, amoebas, weevils, paramecium and the like in the algae liquid swim all the time, and after the electric shock treatment, all protozoa die, and the unmovable protozoa corpses can be observed in a focused manner; after the algae liquid after the electric shock treatment is kept still for 8 hours, microscopic examination is carried out again, and no protozoan living bodies are found.

In each embodiment, the treated unicellular algae and untreated unicellular algae are respectively used for feeding holothuria leucospilota larvae, and the result shows that the number of protozoa, copepods and other harmful organisms in the holothuria leucospilota larvae breeding pond fed with the treated unicellular algae is 70-90% lower than that of the untreated control group; in addition, under the condition of the same feeding strength, the individual size and the development degree of the sea cucumber auricularia juveniles cultured by using the treated algae liquid are obviously superior to those of an untreated group, and the gastric fullness and survival rate of the treated group are also obviously superior to those of the untreated group.

Comparative examples 1 to 5

1. Experimental methods

The experimental procedure of example 1 was followed except that the conditions of electric shock were different, as shown in Table 2.

TABLE 2

2. Results of the experiment

Before the electric shock treatment is carried out under the conditions, protozoa such as the Trichodina in the algae liquid swim all the time, after the electric shock treatment, the protozoa can be effectively killed under the voltage and current conditions of comparative examples 4-5, but the unicellular algae can be damaged at the same time, which is shown in that the algae are easy to settle and decompose, and part of the unicellular algae is proved to be killed; and the electric shock is carried out by the scheme of the comparative examples 1 to 3, the protozoa in the living unicellular algae can not be killed completely, and 30 to 60 percent of the protozoa still swim under microscopic examination.

The above examples only represent some embodiments of the present invention, and the description thereof is more specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

1. A method for killing protozoa in living unicellular algae with high efficiency is characterized in that the protozoa in the living unicellular algae is killed by electrifying algae liquid of the unicellular algae.

2. The method according to claim 1, wherein the electric current is applied to the algae liquid at a voltage of 100-500V and a current of 1-20A.

3. The method according to claim 2, wherein the ratio of the electrifying time to the volume of the algae liquid is 10-20 s: 50-200L.

4. The method of claim 1, wherein the unicellular algae is one or more of chaetoceros sp, chrysophyceae sp, chlorella sp, dunaliella sp, or tetraselmis sp.

5. The method of claim 1, wherein the protozoan is one or more of the group consisting of rotifers, weevils, amoebas, paramecium.

6. The method according to any one of claims 1 to 5, wherein the energization is performed by means of an electric fishing rod.

7. The method of claim 6, wherein the electric fishing rod is a sea water electric fishing rod or a fresh water electric fishing rod.

8. Use of a method according to any one of claims 1 to 7 for killing protozoa.