Bacillus（Bacillus），BacteriaA genus of, capable of formingSpore（Endospore）。Their harmful factors to the outside worldResistanceStrong, widely distributed, existing in soil, wateratmosphereAnd animal intestines.
Bacillus has the characteristics of high temperature resistance, rapid reactivation and strong secretion of enzymes, and can survive in both aerobic and anaerobic conditions.stayNutritional deficiency, drought and other conditions to form spores, which can germinate again when conditions are appropriateVegetative body[2]。
BacillustoBacillus familyBacillus, a kind of bacteria that can produce resistanceEndosporeOfGram positive bacteriaThe cells are rod shaped and covered with a lot ofPyridine dicarboxylic acidCalcium.Its cortex is located between the core and the spore shell, which is rich inPeptidoglycan；The core is a highly concentrated and inert chromosome;The outermost outer wall is a layer of peptidoglycan wall, and one or more layers of components are protein spore coat.Because the spore has a thick and low water content multi-layer structure, it has strong refraction, is not easy to dye, has good stability, is resistant to oxidation, extrusion, and high temperature, can withstand 60 ℃ high temperature for a long time, can survive at 120 ℃ for 20 minutes, and is resistant to acid and alkali. It can maintain its activity in gastric acid environment, which may be related to the unique high content of pyridine dicarboxylic acid in the spore.At the same time, it also has broad-spectrum bacterial activity, which can produce bacteriocin and inhibit pathogenic bacteria.At present, there are many applicationsBacillus subtilis、Bacillus licheniformis, Bacillus cereus, etc[3]。
Spore
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SporeAlso known asSpore。It was first found by Cohn in Bacillus subtilis, and then KochBacillus anthracisFound and described in.Cohn described the heat resistance of Bacillus subtilis, while Koch described the spore forming cycle of Bacillus anthracis in detail.As spores are formed inside cells, they are also called endospores. Eventually, spores are released from mother cells or sporangia[5]。
Spores are the most tolerant cells found in nature.The dormant spores have strong resistance to heat, drying, radiation, acid, alkali, organic solvents and other bactericidal factors.Spores can survive for more than ten years, even tens of thousands of years, under adverse environmental conditions.When the environmental conditions are suitable, the spores can germinate to form bacterial cells that can divide and reproduce[5]。
application
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Bacillus is widely used in industry, agriculture and medicine production[6]。
agricultural production
Bacillus
Antibacterial substances produced by Bacillus can prevent and control a variety of plant diseases. Some biocontrol strains of Bacillus have been commercialized or have obtained limited commercial production and application permits.Bacillus thuringiensisA kind ofParasporal crystal, it has become the world's largest productionMicrobial insecticide。Brevibacillus laterosporus Some strains ofCrystallinAnd enzymes, which have toxic effects on invertebrates.Bacillus has the ability to dissolve phosphorus, potassiumnitrogen fixationetc.biological activity, which is conducive to improving crop yield, and Bacillus has good stress resistance,Bacillus megaterium、Bacillus mucilaginosus , nitrogen fixing bacillusBacillus sphaericus、Brevibacillus laterosporus It is widely used to produce biological fertilizer.Antibacterial substances produced by Bacillus have the effects of promoting growth, health care and disease treatment on livestock and poultry, which are non-toxic side effects, residue free and non pathogenicBacterial resistanceIt is a kind of environmentally friendly preparation.The bactericidal mechanism of antimicrobial peptides produced by Bacillus is very unique. Pathogens are not easily resistant to antimicrobial peptides, so antimicrobial peptides as a new typefeed additive Is a new research and development direction of the feed industry[6]。
Food processing and preservation
Antibacterial substances produced by Bacillus spp. have broad-spectrum bactericidal activity, and can be used for many kinds of food relatedGram negative bacteriaAnd positive bacteria have strong bactericidal effect, and generally have good thermal stability, which can be used to prevent other bacteria from polluting in the process of hot processing food, and can also be used to preventPasteurizationIt can also be used in food fermentationhybrid bacteriumPollution.In addition, some kinds of bacillus produceL-lysineAvailable forfood additives。Bacillus can also be used for fermented food. In China, Bacillus coagulans is used for low salt picklingPotherb mustard[6]。
industrial production
Using Bacillus fermentation to obtain high activity and high purityamylase、proteaseThe method of[6]。
BacillusThere are many natural strains that can provide different genes with high biological activity.Bacillus subtilis, Bacillus pumilus and Bacillus licheniformis can also be used asgenetic engineeringReceptor bacteria。Bacillus subtilis alone expressed nearly 200 speciesProkaryoteandEukaryoteProtein gene of biological origin.Bacillus subtilis, whether in production or ongenomeAnd physical atlas play an important role in the research[6]。
harm
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Most Bacillus bacteria are harmless, but some are pathogenic to humans and animals.Bacillus cereusMay causefood poisoning, Symptoms andStaphylococcus aureusFood poisoning is similar.Some strains can produce thermotolerant toxin in food, which is related to spore germination, and vomiting symptoms appear 1~5h after ingestion.Other strains produce heat resistanceenterotoxinAnd cause diarrhea within 10-15h after ingestion.Bacillus cereus is known to causeBacteremiaAnd other symptoms such as vomiting and diarrhea.Bacillus anthracisCan cause people and animalsanthrax[1]。
