1, turbid growth: most bacteria, such as Escherichia coli and Shigella.
2. Precipitation growth: A few bacteria are arranged in chains, such as Streptococcus and Bacillus anthracis.
3. Membrane growth (surface growth): obligate aerobic bacteria, such as Bacillus subtilis, Mycobacterium tuberculosis and Pseudomonas aeruginosa.
There are two ways of bacterial nutrition: autotrophic and heterotrophic, among which heterotrophic saprophytic bacteria are important decomposers in the ecosystem, which make the carbon cycle go smoothly. Some bacteria will carry out nitrogen fixation to transform nitrogen into a form that can be used by organisms. Bacteria also have a great influence on human activities.
On the one hand, bacteria are the pathogens of many diseases, including tuberculosis, gonorrhea, anthrax, syphilis, plague and trachoma. However, human beings often use bacteria, such as the production of cheese and yogurt, the production of some antibiotics and the treatment of wastewater, which are all related to bacteria. Bacteria are also widely used in the field of biotechnology.