CN1557166A - A preparation method of yeast biological agent for preventing and treating postharvest diseases of citrus - Google Patents

Abstract

The invention discloses a method for preparing yeast biological preparations for preventing and treating post-harvest diseases of citrus. The thallus of Rhodotorula viscosus is cultured on a shaker in a wort medium, centrifuged and separated, and the thallus is collected and directly prepared into 1×10 ^8-5 × ¹⁰⁸ /mL yeast suspension, or freeze-dried at minus 40°C-45°C with a freeze dryer to make dry powder for storage. The yeast biological preparation in the present invention can withstand harsh environments such as high temperature and low temperature, can be used before harvesting or after harvesting, and can effectively prevent and treat diseases of fruits and vegetables, especially citrus. Moreover, the product is convenient to prepare, flexible and instant to use. Moreover, the use of the product has no influence on the quality of the fruit and does not cause harm to the human body. Therefore, the use of the yeast biological preparation product of the present invention is safe and is a brand-new disease prevention and control measure.

Description

A preparation method of yeast biological agent for preventing and treating postharvest diseases of citrus

technical field

The invention relates to microbial fungi and extracts thereof, in particular to a method for preparing yeast biological preparations for preventing and treating citrus postharvest diseases.

Background technique

Post-harvest rot of fruits and vegetables is mostly caused by fungi, and the method of preventing and treating fungal diseases for a long time is mainly to use chemical fungicides (pesticides). However, due to the long-term use of chemical fungicides, pathogenic bacteria will develop resistance to the fungicides and reduce the effect of pesticide use. What is more serious is that the use of pesticides will cause harm to public health, and pesticide residues will pollute the environment. At present, Chemical fungicides have been banned in many countries. In order to improve the fresh-keeping period of fruits, people have to seek safe, non-toxic and effective new methods that can replace the current chemical fungicides. In recent years, my country has attached great importance to food safety, and projects of safe vegetables, safe meat, and safe fruits have been implemented in various places. Green fruits that do not use chemical fertilizers and pesticides have become the first choice of consumers. In addition, my country has joined the WTO, and foreign countries have strict regulations on pesticide residues on fruits. In particular, in order to protect their own economic interests, some countries implement trade barriers and implement almost harsh regulations on pesticide residues on fruits. All of these require us to develop safe, pollution-free and efficient fruit biological preservatives. Safe disease control measures are one of the important contents of implementing safe food production. Biological fungicides can not only reduce the infection of harmful microorganisms on fruits and vegetables, but also protect the environment, and are an effective way to produce safe food. Therefore, the study of natural biological sterilization instead of pesticides in the prevention and control of postharvest diseases of fruits and vegetables has profound significance for reducing pesticide residues in food, protecting the environment, ensuring human health, and increasing the export of fruits and vegetables.

Biocides can be divided into three types: plant fungicides, animal fungicides and microbial fungicides. The biological control of postharvest diseases with microorganisms is a new research field developed abroad in recent years. Since Guter first reported that Bacillus subtilis has antagonism on fruit pathogens, foreign scholars have been interested in using microbial antagonists to control fruits and vegetables. Postharvest disease control has been extensively studied.

From foreign literature, it can be seen that the effective microorganisms instead of chemical fungicides have shown great application prospects in the prevention and control of fruits and vegetables after harvesting. The biological control of fruits and vegetables after harvesting has become a new research hotspot. However, the current research mainly focuses on the disease prevention and control of apples and peaches, and there are still problems such as low antibacterial effect, short antibacterial time, poor adhesion on the fruit surface and the safety of antagonistic bacteria, which limit their wide use, especially The antibacterial mechanism of antagonistic microorganisms is not yet clear, so screening safe strains with high activity, long survival time and good adhesion is the key to improving the biological control effect of harvested fruits and vegetables. At the same time, it is also very important to understand the mechanism of biological control of postharvest diseases.

Among the numerous antagonistic microorganisms such as: antagonistic bacteria, antagonistic fungi and antagonistic actinomycetes, the focus of people's attention has gradually shifted from antagonistic bacteria to yeast biological agents in antagonistic fungi. Because antagonistic yeast has the following advantages: yeast will not produce antibiotics and will not cause harm to the human body; it can occupy and grow on the surface of fruits and vegetables for a long time under dry conditions; it can produce extracellular polysaccharides to enhance its own viability; It can quickly use nutrients to reproduce and grow rapidly. The antibacterial mechanism of yeast is mainly through the competition between it and pathogenic bacteria for nutrients and space to achieve the inhibitory effect on pathogenic bacteria.

Contents of the invention

In order to replace chemical fungicides or minimize the amount of chemical fungicides used, the object of the present invention is to provide a method for preparing yeast biological preparations for preventing and treating postharvest diseases of citrus. According to the principle of mutual growth and mutual restraint between microorganisms, yeast is used to inhibit the growth of disease fungi on fruits and vegetables to achieve the effect of inhibiting rot.

Technical scheme of the present invention: in the wort culture medium of 10-12°Brix, the thalline of Rhodotorula viscosus is shaken at 180-220 rev/min in a shaker for 20-26 hours at 26-30°C, and cultivated, Centrifuge at 2500-3000 rpm for 10-15 minutes, collect the bacteria, and directly prepare a yeast suspension of 1×10 ⁸ -5×10 ⁸ cells/ml, or use a freeze dryer at minus 40-45°C Freeze-dry to make dry powder and store.

The beneficial effects of the present invention are: the biological preparation can prevent and treat diseases caused by two main pathogenic fungi on citrus, and after use, it will not affect the quality of the fruit and will not endanger human health; , can well inhibit the growth and reproduction of pathogenic fungi, and itself can well adapt to the wound environment of citrus, adapt to the harsh field environment before harvest, such as high temperature, dryness and the use of chemical fungicides; or adapt to the storage environment after harvest , such as low temperature environment. And play a long-term antibacterial effect; after eating the pear fruit that uses the yeast biological preparation, it will not affect health, because the yeast biological preparation is safe and non-toxic to the human body; yeast cells can be better attached to On the surface of citrus fruit, it will not fall off easily; after using the Rhodotorula viscosus biological agent on citrus fruit, it will not affect the flavor, appearance and other qualities of citrus.

Detailed ways

The yeast biological antistaling agent Rhodotorula glutinis provided by the invention has red thalline color, is safe, and is nontoxic and harmless to human body. The yeast has been tested for biocontrol in foreign countries and proved to be safe, but its application in citrus has not been reported.

Rhodotorula viscosus used in the present invention, confirmed by experimental research, has inhibitory action to many pathogenic bacteria, to two kinds of main pathogenic fungi that cause citrus rot to mean penicillium digitatum (Penicillium digitatum) and Italian penicillium (Penicillium italicum) have very good effect Good inhibitory effect, and can grow on citrus wound environment at room temperature and at low temperature of refrigeration.

Rhodotorula viscosus can still grow slowly on fruits at low temperatures, and can still play a role in biological control at low temperatures, so it can be used together with low-temperature storage; this Rhodotorula viscosus can tolerate certain chemical fungicides at lower concentrations, Therefore, it can be used in combination to reduce the amount of chemical fungicides used; in addition, the Rhodotorula glutinosa can be used in combination with some metal ions to improve the antibacterial effect.

Example 1: the Rhodotorula viscosus thalline was shaken at 200 rpm at 28°C in wort medium at 12°C Brix, cultured and activated for 20 hours, centrifuged at 3000 rpm for 10 minutes, and the thalline was collected. Directly prepare a yeast suspension of 1× ¹⁰⁸ /ml, separate the cells and suspend them in sterile saline, prepare a yeast suspension with a concentration of 2× ¹⁰⁸ /ml, and spray directly .

Example 2: the Rhodotorula viscosus thalline was shaken at 190 rpm at 28°C in wort medium at 12°C Brix, cultured and activated for 22 hours, centrifuged at 2800 rpm for 10 minutes, and the thalline was collected. Directly prepare a yeast suspension of 1× ¹⁰⁸ /ml, separate the cells and suspend them in sterile saline, prepare a yeast suspension with a concentration of 3× ¹⁰⁸ /ml, and spray directly .

Example 3: the Rhodotorula viscosus thallus was shaken at 10°C Brix wort medium at 29°C at 180 rpm, cultured and activated for 24 hours, centrifuged at 2500 rpm for 12 minutes, and the thalline was collected. Use a lyophilizer to freeze-dry at minus 40°C to make a dry powder, and store it at 4°C for later use. When used, the dry powder is directly suspended in sterile saline to prepare a yeast suspension with a concentration of 2× ¹⁰⁸ /ml, and directly Spray to use.

Example 4: the Rhodotorula viscosus thalline was shaken at 190 rpm at 28°C in a wort medium of 10°Brix, cultured and activated for 23 hours, centrifuged at 3000 rpm for 10 minutes, and the thalline was collected. Use a lyophilizer to freeze-dry at minus 40°C to make a dry powder, and store it at 4°C for later use. When in use, directly suspend the dry powder in sterile saline to make a yeast suspension with a concentration of 5× ¹⁰⁸ /ml, and directly Spray to use.

Claims (1)

1, a kind of yeast biological formulation preparation method who is used to prevent and treat the oranges and tangerines postharvest disease, it is characterized in that: with rhodotorula glutinis bacterium thalline in the malt extract medium of 10-12 ° of Brix under 26-30 ℃ in shaking table 180-220 rev/min shook 20-26 hour, cultivate, at 2500-3000 rev/min of following centrifugation 10-15 minute, collect thalline, directly be mixed with 1 * 10 ⁸-5 * 10 ⁸The saccharomycete suspension of individual/milliliter perhaps adopts freeze drier to make dry powder in a subzero 40-45 ℃ freeze drying, storage.