Wide range of uses of Bacillus subtilis

Bacillus subtilisis a species of the genus Bacillus, CAS number 68038-70-0. A single cell is 0.7 to 0.8 × 2 to 3 microns, and is evenly colored. No capsule, peritrichous flagella, capable of movement. Gram-positive bacteria can form endophytic resistant spores. The spores are 0.6 to 0.9 × 1.0 to 1.5 microns, elliptical to columnar, located in the center of the bacterial body or slightly offset. The bacterial body does not expand after spore formation. It grows and reproduces quickly, and the surface of the colony is rough and opaque, white or slightly yellow. When growing in liquid culture medium, wrinkles are often formed, and it is an aerobic bacterium. 

Proteins, various sugars and starches can be used to decompose tryptophan to form indole. It is widely used in genetic research, and the synthesis pathway and regulatory mechanism of purine nucleotides in this bacterium have been clearly studied. It is widely distributed in soil and decaying organic matter, and easily reproduces in hay juice, hence the name.

Some strains are important producers of α-amylase and neutral protease; some strains have enzyme systems that strongly degrade nucleotides, so they are often used as parent strains for breeding nucleoside-producing bacteria or for preparing 5'-nucleotides. Enzyme strains.

Main features

Bacillus subtilis is a species of Bacillus, which is widely distributed in soil and decaying organic matter. It is easy to multiply in subtilis juice, hence its name. A single cell of this bacterium is (0. 7 ~ 0. 8) μm × (2 ~ 3) μm, and the color is uniform. No capsule, flagellated, motile, Gram stain positive, spores (0. 6 ~ 0. 9) μm × (1. 0 ~ 1. 5) μm, located in the center or slightly side of the bacterial body, spore formation The bacterial cells do not expand afterward. The surface of the colony is rough and opaque, white or slightly yellow, and often forms wrinkled walls when growing in liquid culture medium. It is an aerobic bacteria. Can utilize proteins, various sugars, and decompose tryptophan. Among them, B. subtilis has great potential in biological control. Under suitable conditions such as temperature and ventilation, a large number of spores are formed in young cells. In addition, Bacillus subtilis grows quickly, has relatively low nutritional requirements, can efficiently secrete many proteins and metabolites, and does not produce toxins, making it a safe and non-pathogenic microorganism. It is widely used in medicine, health and food. In microbial experiments, the culture medium formula for detecting and observing Bacillus subtilis is commonly used: 1 L distilled water + 20 g glucose + 15 g peptone + 5 g sodium chloride + 0. 5 g beef extract + 20 g agar.

Bacillus subtilis has two growth stages: a spore dormant period and a reproductive growth period. Bacillus subtilis will enter the spore dormant period in unsuitable environments such as harsh growth environments and lack of nutrients, and form a spore dormant period that has strong resistance to stress and is resistant to high temperatures. spores that can survive in polar environments such as acid and alkali, thus adapting to the environment and surviving. Once the environment becomes suitable for growth and nutrients are sufficient, the spores will automatically enter the reproductive growth phase, and the spores will re-grow into Bacillus subtilis. 

main effect

1. Active substances such as subtilisin, polymyxin, nystatin, and gramicidin are produced during the growth of Bacillus subtilis. These active substances have obvious effects on pathogenic bacteria or opportunistic pathogens of endogenous infections. inhibitory effect.

2. Bacillus subtilis rapidly consumes free oxygen in the intestine, causing intestinal hypoxia, promoting the growth of beneficial anaerobic bacteria, and indirectly inhibiting the growth of other pathogenic bacteria.

3. Stimulate the growth and development of animal (human) immune organs, activate T and B lymphocytes, increase immunoglobulin and antibody levels, enhance cellular immunity and humoral immunity, and improve group immunity.

4. Bacillus subtilis itself synthesizes α-amylase, protease, lipase, cellulase and other enzymes, which work together with digestive enzymes in animals (human beings) in the digestive tract.

5. It can synthesize vitamins B1, B2, B6, niacin and other B vitamins, and improve the activity of interferon and macrophages in animals (humans).

6. Bacillus subtilis performs spore-promoting and micro-encapsulation treatment on special bacteria. It has good stability in the spore state and is resistant to oxidation; resistant to extrusion; resistant to high temperatures, and can withstand high temperatures of 60°C for a long time and 120°C It can survive for 20 minutes; it is resistant to acid and alkali, can maintain activity in acidic gastric environment, and can withstand the attack of saliva and bile. It is 100% of the viable bacteria among microorganisms that can directly reach the large and small intestines.

Mechanism

competition effect

The competitive effect of Bacillus subtilis mainly includes two aspects: nutritional competition and spatial site competition. Bacillus subtilis has more advantages in competition for spatial sites, that is, it can multiply and colonize rapidly and in large quantities on the surface of animal tissues or inside plants and in the soil where plants grow, effectively preventing the reproduction of pathogenic microorganisms and interfering with the invasion of plant pathogenic microorganisms. Infection, destroy the colonization of pathogenic microorganisms on plants, thereby achieving antibacterial and disease control effects.

bacteriolysis

Bacillus subtilis can be adsorbed on the hyphae of pathogenic fungi and grow together with the hyphae. During the growth process, lytic substances will be produced to digest the mycelium. Generally, it will cause hyphae to break, disintegrate, or cytoplasm to be digested; or secondary metabolites will dissolve the cell wall of pathogenic bacteria spores, resulting in cell wall perforation and deformity.

produce antibacterial substances

Produce antibiotic substances that can inhibit the growth of bacteria, viruses, fungi and pathogens. These antibacterial substances are mainly antibiotics such as phospholipids, amino sugars, peptides and lipopeptides. Among them, lipopeptide antibiotics are the most important antibacterial substances of Bacillus subtilis.

Biological oxygen

Bacillus subtilis is a Gram-positive aerobic bacterium that can rapidly consume free oxygen in the intestinal tract of animals, thereby effectively improving the utilization efficiency of nutrients. Bacillus subtilis can also secrete a variety of endogenous enzymes such as amylase, lipase, protease, and cellulase, providing animals with a large amount of endogenous enzymes, which can make up for the lack of endogenous enzymes in animals to a certain extent.

Application scope

aquaculture

Bacillus subtilis has a strong inhibitory effect on harmful microorganisms such as Vibrio, Escherichia coli and baculovirus in aquaculture. It can secrete a large amount of chitinase to decompose toxic and harmful substances in aquaculture ponds, purify water quality, and simultaneously decompose Remaining bait, feces, organic matter, etc. in the pool have a strong effect in cleaning up small particles of garbage in the water. Bacillus subtilis is also widely used in feed. It has strong protease, lipase, and amylase activities, which can promote the degradation of nutrients in feed and make aquatic animals more fully absorb and utilize feed.

Bacillus subtilis can reduce the occurrence of shrimp diseases and greatly increase shrimp yields, thereby improving economic benefits. It is biologically environmentally friendly, stimulates the development of immune organs of aquatic animals, and enhances the body's immunity. It can reduce the occurrence of shrimp diseases, significantly increase shrimp yields, and thus improve economic benefits . , purify water quality, no pollution, no residue.

Plant disease resistance

Bacillus subtilis successfully colonizes the rhizosphere, body surface or body of plants, competes with pathogenic bacteria for nutrients around the plant, secretes antibacterial substances to inhibit the growth of pathogenic bacteria, and induces the plant defense system to resist the invasion of pathogenic bacteria, thereby achieving the purpose of biocontrol. Bacillus subtilis can mainly inhibit a variety of plant diseases caused by plant pathogenic bacteria such as filamentous fungi. Bacillus subtilis strains reported to be isolated and screened from the rhizosphere soil, root surface, plants and leaves of crops have antagonistic effects on many fungal and bacterial diseases of different crops. Such as rice sheath blight, rice blast, wheat sheath blight, and legume root rot in grain crops. Vegetable diseases include tomato leaf disease, fusarium wilt, cucumber fusarium wilt, downy mildew, eggplant gray mold and powdery mildew, pepper blight, etc. Bacillus subtilis can also control a variety of postharvest fruit diseases, such as apple mold core, citrus penicillium, nectarine brown rot, strawberry gray mold and powdery mildew, banana wilt, crown rot, anthracnose, apple pear Penicillium, black spot, canker, and goldenrod fruit rot. In addition, Bacillus subtilis is also effective against poplar canker, rot, tree black spot and anthracnose, tea ring spot, tobacco anthracnose, black shank, red star disease, root rot, cotton blight, and fusarium wilt. Better prevention and control effect.

animal feed production

Bacillus subtilis is a probiotic strain often added to animal feed. It is added to animal feed in the form of spores. Spores are living cells in a dormant state that can withstand the adverse environment during feed processing. They are stable and easy to store after being prepared into inoculants, and can quickly recover and reproduce after entering the animal intestines. After Bacillus subtilis resuscitates and proliferates in the animal intestines, it can exert its probiotic properties, including improving the animal's intestinal flora, enhancing the body's immunity, and providing a variety of enzymes needed by animals, etc., which can make up for the lack of endogenous enzymes in the animal body. Promote the growth and development of animals and have significant probiotic effects.

Medical field

A variety of extracellular enzymes secreted by Bacillus subtilis have been applied in many different fields, among which lipase and serine fibrinolytic protease (i.e., nattokinase) are widely used in the pharmaceutical industry. Lipase has a variety of catalytic abilities, and it works together with the originally existing digestive enzymes in the digestive tract of animals or humans to keep the digestive tract in a healthy balance. Nattokinase is a serine protease secreted by Bacillus subtilis natto. This enzyme has the functions of dissolving blood clots, improving blood circulation, softening blood vessels, and increasing blood vessel elasticity.

water purification

Bacillus subtilis can be used as a microbial regulator to improve water quality, inhibit harmful microorganisms, and create an excellent aquatic ecological
environment. Due to the long-term high-density breeding of animals in aquaculture water bodies, a large amount of pollutants such as feed residues, animal remains, and fecal sediments accumulate, which can easily cause the deterioration of water quality and endanger the health of farmed animals, and even reduce production and cause losses, which has a negative impact on the sustainability of the aquaculture industry. The harm of sustained development is huge. Bacillus subtilis can colonize water bodies and form dominant bacterial groups through nutrient competition or competition for spatial sites, inhibiting the growth and reproduction of harmful pathogenic bacteria (such as Vibrio, Escherichia coli) and other harmful microorganisms in water bodies, thus changing the water body and environment. The number and structure of microorganisms in the sediment can effectively prevent aquatic animal diseases caused by deterioration of water quality. At the same time, Bacillus subtilis is a strain that can secrete extracellular enzymes. The various enzymes it secretes can effectively decompose organic matter in water and improve water quality. For example, the active substances chitinase, protease and lipase produced by Bacillus subtilis can decompose organic matter in water and degrade nutrients in animal feed. Not only do animals fully absorb and utilize nutrients in feed, but they can also greatly Improve water quality; Bacillus subtilis can also adjust the pH value of culture water.

other

Bacillus subtilis is also widely used in sewage treatment and biofertilizer fermentation or fermentation bed production. It is a multifunctional microorganism.

1. Municipal and industrial sewage treatment, industrial circulating water treatment, septic tank, septic tank and other treatment, livestock and animal waste and odor treatment, fecal treatment system, garbage, manure pit, manure tank and other treatment;

2. Livestock, poultry, special animals and pet breeding; 

3. It can be mixed with a variety of bacterial strains and plays an important role in agricultural production.