Latin scientific name: (Salmonella Lignieres, 1900)
Description: Orthobacillus, 0.7 ~ 1.5 μ m× 2.0 ~ 5.0 μ m, conforms to the general definition of Enterobacteriaceae. Gram negative. Exercise at ordinary times (flagella week). Facultative anaerobic. The colony diameter is generally 2 ~ 4 mm. Nitrate is reduced to nitrite. Gas is usually produced by glucose, and hydrogen sulfide is usually produced on iron trisaccharide agar. Indole is negative, and citrate is often used as the only carbon source. Usually lysine and ornithine decarboxylase are positive. Urease negative. Non-oxidative deamination of phenylalanine and tryptophan. Sucrose, salicin, inositol and amygdalin are usually not fermented. Does not produce lipase and deoxyribonuclease. It is pathogenic to humans, causing typhoid fever, gastroenteritis and septicemia, and may also infect many other animals except humans. Some serum variants are strictly adapted to the host.
The G+G mol% of DNA is 50 ~ 53 (HPLC, Tm, Bd)(Hill, 1966). The differences between subgenus are shown in Table 3-7.
Model species: Salmonella choleraesuis.
salmonella
1 genus of Enterobacteriaceae. It was named after the American pathologist D.E. Salmonella discovered the swine cholera in 1884. This genus of bacteria is a group of Gram-negative bacilli with similar antigenic structure and biological characteristics. There are many kinds of bacteria, and more than 2000 serotypes have been found. It can bring diseases to people and some warm-blooded animals.
The cell size is (0.6 ~ 0.9) × (1 ~ 3) micron, and there is generally no membrane, except Salmonella pullorum and Salmonella typhimurium, most of them have flagella. Nutritional requirements are not high, and intestinal selective identification medium is often used for separation and culture. Biochemical reaction has important reference significance for the identification of this genus (see table). It does not liquefy gelatin, decompose urea, produce indole, ferment lactose and sucrose, and can ferment glucose, mannitol, maltose and viagra. Most of them produce acid and gas, and a few only produce acid and do not produce gas. VP test was negative, and there was lysine decarboxylase. The G+C content of DNA is 50 ~ 53%. The heat resistance is not strong, and it can be fatal at 60℃ 15 minutes. Survive in water for 2 ~ 3 weeks. In 5% carbolic acid, he died within 5 minutes.
According to biochemical reaction, this genus is divided into 4 subgenera. Subgenus ⅰ is the most typical and common salmonella in biochemical reactions; Subgenera ⅱ and ⅳ are salmonella with atypical biochemical reaction; Subgenus Ⅲ is Salmonella Arizona.
The antigen structure of Salmonella is complex, which can be generally divided into three types: bacterial (O) antigen, flagella (H) antigen and surface (Vi) antigen.