In medicine, the discovery and application of penicillin is a revolution in the history of human health. But the effect of penicillin on Mycobacterium tuberculosis is not good. Streptomycin, discovered in 194310/019, was isolated by AlbertSchatz, a doctoral student at Rutgers University in the United States, when SelmanAbrahamWaksman, a famous microbiologist and father of antibiotics, was doing a research project sponsored by Merck.
Because of the remarkable effect of streptomycin on mycobacterium tuberculosis, it has been rapidly popularized in the United States and Britain. 1952 was used to control pear tree fire blight, which opened the door for the application of antibiotics in agriculture.
The so-called antibiotics refer to the chemical substances produced by microorganisms or higher animals and plants in the process of survival and life that can interfere with other biological cells. Penicillin, streptomycin and erythromycin we usually use belong to antibiotics.
At present, most antibiotics used in agriculture come from actinomycetes, especially from streptomycetaceae. Include streptomycin, zhongshengmycin, kasugamycin, mirex, midomycin, oxytetracycline, neomycin, chlortetracycline, polyoxin, Jinggangmycin, Nongkang 120, etc.
Most of these antibiotics achieve antibacterial and bactericidal effects by interfering with the synthesis of intracellular protein.
We know that protein is the basic substance of all life. The synthesis of protein is based on various amino acids. According to the genetic information of species, it is polymerized into peptide chains with unique structural characteristics, and multiple peptide chains are reassembled into polymer protein. Protein is synthesized on ribosomes in cytoplasm. RNA is responsible for the translation and transportation of genetic information in protein.
Many antibiotics can interfere with the protein synthesis of microorganisms, although the specific target sites are different.
streptomycin
The mechanism of action of streptomycin is that it irreversibly binds to the ribosome of bacteria and then interferes with the synthesis of protein. Moreover, unlike the bactericidal spectrum in which penicillin is only effective against gram-positive bacteria, Streptomyces is effective against both gram-positive and gram-negative bacteria.
Streptomycin was first applied in the United States in 1952 to control the fire blight of pears and apples. Later, it developed to 12 strain, which was used to control potato late blight, black shank disease, tobacco wildfire disease, cucumber angular leaf spot, downy mildew, celery bacterial blight, Chinese cabbage soft rot and so on.
The conductivity of streptomycin in plants is limited, so streptomycin has little effect on citrus Huanglongbing, grape perforation and other bacteria spread by sucking insects, which live in plant conduction tissues. Streptomycin can protect the uninfected plants from bacteria that infect vascular bundles in wounds caused by water, underground pests and agricultural management, such as tomato bacterial wilt, pulp necrosis and canker. However, it is difficult to be effective for people who are already sick. When spraying, attention should be paid to evenly covering all parts that may be infected by bacteria. Streptomycin has a good effect on local bacterial diseases and oomycetes in fungi.
High concentration of streptomycin is also prone to phytotoxicity. Therefore, the use of streptomycin includes seed treatment and spraying, but it is not suitable for injection into plant transport tissues.
Although streptomycin is a very good antibiotic agricultural fungicide, it is also easy to cause drug resistance of pathogenic bacteria. Different from other fungicides, the problem of streptomycin resistance is not only the risk of disease control effect in agricultural production after plant pathogens become resistant, but also the widespread use of streptomycin in agriculture, especially its abuse, will also promote human resistance to streptomycin and bring great risks to human health. Therefore, European and American countries have restricted the scope, frequency and safety interval of agricultural streptomycin through legal forms. China also blacklisted streptomycin in agricultural production.
kasugamycin
Kasugamycin, also known as kasugamycin, is an antibiotic with systemic bactericidal effect, which was fermented and extracted from Streptomyces kasugamushi (also known as actinomycetes in spring) in 1963. In 1964, actinomycetes aurea which can produce this antibiotic was also isolated from the soil of Taihe County, Jiangxi Province.
Kasugamycin also inhibits protein synthesis by irreversibly binding to ribosomes in the cytoplasm of pathogenic bacteria. However, unlike streptomycin, which was originally used to control pear fire blight and entered the agricultural field, kasugamycin was used to control rice blast for the first time in agricultural production, and the time was 1965.
Kasugamycin has protective and therapeutic effects on rice blast and can be used by seed treatment or spraying. Moreover, kasugamycin has little toxicity to plants and good plant safety.
Kasugamycin also has a good control effect on bacteria, such as cabbage soft rot, bean sheath blight, cucumber bacterial angular leaf spot and so on. However, the effect of using kasugamycin alone to control citrus canker is often not obvious, while the effect of using kasugamycin mixed with copper oxychloride is very good.
Kasugamycin inhibited the mycelium growth of Magnaporthe grisea in acidic medium, but hardly inhibited the mycelium growth in neutral medium. Rice leaves are slightly acidic. For plant pathogens, kasugamycin is more effective under neutral conditions than under acidic conditions.
Long-term high-dose and high-frequency use of kasugamycin can also lead to the emergence of drug-resistant strains of pathogenic bacteria, but it is found that these drug-resistant strains are not adaptable. After a period of interruption, the number of these resistant strains will be greatly reduced and the control effect will rise again.
blasticidin
Imiprodione, also an antibiotic discovered and isolated by the Japanese, comes from Streptomyces chromophilus and is a derivative of S benzyl aminobenzenesulfonate, so it is also called S Imiprodione, or Imiprodione S.
Mirex has broad-spectrum bacteriostasis, antibacterial, antiviral, antitumor and antifungal activities. Especially for Magnaporthe grisea, but almost ineffective for rice sheath blight. The results showed that a small part of the pesticides sprayed on the surface of rice plants were absorbed by the wounds on rice organs and quickly spread to the top of the plants, while most of them remained on the surface of the plants and were quickly decomposed by sunlight. Pesticides falling into the soil will be quickly decomposed into compounds that are harmless to the environment by microorganisms. But it is irritating to human skin and mucosa, so use it with caution.
Imiprodione is a good antibiotic, but it is easy to produce toxicity to plants other than rice, so it can only be used in rice.
Zhongshengmycin
Zhongshengmycin is an antibiotic isolated from Streptomyces lilacinus var. Hainan is under the responsibility of the former Institute of Biological Control of China Academy of Agricultural Sciences (now incorporated into the Institute of Plant Protection of Chinese Academy of Agricultural Sciences). With the restriction and prohibition of the use of streptomycin in China, the prospect of zhongshengmycin seems to become broader.
Zhongshengmycin also achieved antibacterial and bactericidal effects by inhibiting the protein synthesis of pathogenic bacteria, and its bactericidal spectrum was also extensive. It is effective against many kinds of bacteria and some fungi. Its function mode is mainly protection, but also infiltration.
Nongkang 120
Nongkang 120, Streptomyces echinosporus Beijing Variant antibiotic isolated by China Academy of Agricultural Sciences 1957, 1978 for industrial production.
Different from the above antibiotics, Nongkang 120 is mainly aimed at fungal pathogens, especially soil-borne fungi, such as Fusarium, and is also effective against powdery mildew, sheath blight, anthracnose and apple rot.
Nongkang 120 has both protective and therapeutic effects, and can stimulate plant growth.
Although Nongkang 120 is an old-fashioned antibiotic, it seems that its promotion in China is not very good, which may be related to the level of marketing and production technology.
label
There are many antibiotics in streptomycetaceae, some of which are not commercialized on a large scale for some reasons, some of which are eliminated due to toxicity or ecological risks, and some of which are not inhibited by protein's synthesis, such as Jinggangmycin and polyoxin.
Although a variety of antibiotics have been introduced above, almost none can be applied to grapes. Although streptomycin can be used in grape ear treatment with regulators, it has been banned at present.
Pierce's disease is a bacterial disease, but the pathogen of Pierce's disease is located in vascular bundle. At present, due to the weak systemic conductivity of antibiotics, or the toxicity and ecological safety of antibiotics to grapes, there is no suitable antibiotic product for preventing and treating Pierce's disease. Root cancer is also a bacterial disease, but it is difficult to control with these antibiotics at present.