However, many tropical and subtropical fruits, such as bananas, mango and litchi, are prone to chilling at low temperatures and can not be preserved by cryopreservation, and the low-temperature storage cost is high, and the low-temperature storage, Energy consumption is large, the quality of instability; chemical treatment can be a good fruit and vegetable picking after the preservation, but the chemical reagents and the use of toxic fungicides, to bring people food safety problems, daunting. In the past 10 years, bio-fresh products have become the focus of research and research at home and abroad, the use of microbial antagonistic bacteria for fresh products have been listed: Blossom-Protec; CandiFruit; Shemer; Bio-Save; MUSCODORTM, affecting microbial preservation of commercial production One of the factors is: the actual production and use, the degradation of bacteria, in storage and harsh environment resistance to decline. In this paper, the methods of preservation of microbial strains were reviewed in detail, which reduced the variation and degradation of the preserved bacteria in the production and preservation process.
  1 passages
  Submerged species is one of the most commonly used methods for microbial preservation. Many microorganisms in the low temperature or dry treatment, will soon die, in order to preserve the activity of bacteria, it is necessary to continue the regular transfer of bacteria, culture and then save. We drink yogurt is used in this way to produce the bacteria to save. This kind of bacteria that produce acidic substances, in the subculturing culture in the medium to add a small amount of calcium carbonate. In the process of subculture, the nutrients to be cultivated should not be too rich, and the cultivation temperature should be slightly lower than the optimum growth temperature of the spores. The method of preserving microbes is easy and can be achieved without the need for special equipment. It is the most commonly used method for the preservation of various types of microbes in the laboratory. But this method also has some shortcomings, such as the culture medium is easy to dry; bacteria tube is often other mold contamination occurs mildew; bacteria in the process of repeated gene mutation, can not guarantee the transmission of good traits; The spore activity in the process is getting weaker.
  2 liquid paraffin covered
  In order to pass the preservation, to reduce the infection of bacteria, the use of liquid paraffin to cover the cover, that is, in the slope of the medium, when the most suitable culture conditions to cultivate a robust cell, add sterilized liquid paraffin Oil, and the slope of the culture medium stored in low temperature conditions. As the surface of the culture covered with liquid paraffin can be isolated from the air, thus reducing the microbial cell metabolism, delay the aging of cells, but also to prevent the evaporation of media culture, is a simple method of preservation of bacteria. Many of the filamentous bacteria that produce low spores are preserved in this way. This method of making a simple method, do not often need to pass the passage. For most species of species preservation effect is ideal. Fungi, actinomycetes, spores bacteria can be preserved for more than 2 years, no spores of bacteria can be used to save this method for about 1 year, some difficult to preserve the bacteria such as meningococcal, you can use this method to save at least 3 Month or more. However, the use of paraffin-covered preservation of the species to carry inconvenient, save a lot of space to ensure that the medium can be placed upright. When the culture is removed, the paraffin is generally thawed by flame burning, which may cause the culture to splash with the paraffin oil and have a safety hazard.
  3 freeze-dried deposit
  The freeze-drying method is one of the most effective methods for the preservation of bacteria, and is suitable for the general vitality of microorganisms and their spores and non-spores. This method is suitable for long-term preservation of bacteria, generally can be stored for several years to more than ten years. Because freeze-drying method to bacteria in an anaerobic vacuum environment, microbes can not be normal metabolism, only in a dormant state. When the environment becomes suitable for the growth, will continue to proliferate and grow. So the preservation period is relatively long. At present, such as kasugamycin, cephalosporin, kanamycin and other antibiotic strains are not easy to produce spores of filamentous fungi, are used to freeze the dry method. In addition, most of our biological products are used in the preservation of the law.
  4 liquid nitrogen ultra-low temperature preservation
  Liquid nitrogen cryopreservation method is the most effective and reliable method for long-term preservation of bacteria. Liquid ultra-low temperature preservation method is the bacteria contained in the bottle containing frozen protective agent, the ampoule bottle placed in liquid nitrogen (-196 ℃) in the preservation. As the mycelia at -196 ° C, its metabolism decreased to a completely stopped state. Glycerol, serum protein, dimethyl sulfoxide, polyethylene nitrogen pentyl ring, dextrin, Tween 80 and so can be used as liquid nitrogen cryopreservation of the protective agent, which glycerin into and out of cells when the speed is very slow, resulting in a strong Of the dehydration, thus protecting the cells, is the most commonly used protective agent. Different microorganisms to choose a different protective agent, and then through the experiment to determine the concentration of protective agent, in principle, is not limited to cause the concentration of microbial lethal, generally glycerol 10% -20%, dimethyl sulfoxide 5% - 10%, and the polyethylene nitrogen pentene ring was 0.4 mmol / L.
  5 distilled water storage
  The method of preserving the method of distilled water is commonly used in medical microbes, food microbes and industrial microorganisms such as dermatophytes, yeast, mold and actinomycetes, and is also mentioned in the preservation of mushroom mushroom. The method is: the bacteria suspended in distilled water, you can save at room temperature for several years, this method should pay attention to avoid the evaporation of water.
  6 Conclusion
  In view of the above, the passage of preservation, liquid paraffin cover preservation, freeze-drying preservation, liquid nitrogen ultra-low temperature preservation, distilled water preservation and other species preservation methods have their own advantages, for different antagonistic bacteria characteristics and preservation purposes, select The best way to save. At present, the biggest problem of the preservation of antagonistic bacteria is: how to ensure the stability of the bacteria in the production process, to avoid the production of multi-generation products after the degradation and aging of bacteria, especially industrial production of biological preservation products in the shelf during the storage. Therefore, the use of antagonistic bacteria preservation of the factory product storage, will be a preservation of biological preservation of an important part of the study.
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