What are Some Types of Bacteria?

Bacteria (scientific name: Bacteria) refers to one of the main groups of organisms and belongs to the bacterial domain . It is also the most abundant among all living things. It is estimated that the total number is about 5 × 10 ^ 30. Bacteria are quite diverse in shape, mainly spherical, rod-shaped, and spiral.

First, the basic form and size

(1) Cocci:

Cocci are spherical or oval-shaped bacteria with a diameter of 0.5 to 1 micron. There are the following types: Monococcus: it exists alone, such as urea micrococcus; diplococcus: such as pneumococcus; streptococcus: such as Streptococcus lactis; Tetracoccus: the four cells formed are arranged together, such as the word Tetracoccus; sarcococcus: such as urea sporocystis; staphylococcus: such as Staphylococcus aureus). ^[2]

Bacteria are very tiny and primitive organisms, so their propagation methods and growth on the medium are quite different from those of higher animal and plant cells.

I. Bacterial reproduction

Bacteria multiply in the form of asexual mitosis (schizontation), that is, the bacteria grow to a certain period, gradually form a septum in the middle of the cell, and a mother cell divides into two equal-sized daughter cells. Cell division is a continuous process. At the same time as the two daughter cells in the division form, a septum is formed in the middle of the daughter cells, and the second division of the bacteria begins. Some bacterial cells divide after dividing, forming a single bacterial body, while others do not, forming a certain arrangement, such as streptococcus, streptococcus and so on.

The use of electron microscopy to study the division of bacteria shows that bacterial cell division can be roughly divided into nuclear material and cytoplasmic division, the formation of transverse walls, and the separation of daughter cells. When a bacterial cell divides, the cytoplasmic DNA is connected to the mediator or the cell membrane. First, the DNA replicates and moves towards the two ends of the cell. At the same time, the bacterial cell membrane sags inward and forms a cytoplasmic membrane perpendicular to the long axis of the cell. The mass is evenly distributed among the two daughter cells. Secondly, the cells form a transverse wall, and when the cell membrane is continuously indented, the respective plasma membranes of the daughter cells are formed. At the same time, the cell wall of the mother cell gradually extends from the periphery to the center. Finally, the complete cell wall of each daughter cell is gradually formed. The daughter cells then divide to form two daughter cells of substantially equal size.

Bacteria multiply quickly. Generally, bacteria will divide once in about 20-30 minutes, which is a generation. Bacteria in the inoculum broth culture quickly grow and reproduce at a suitable temperature, and the broth can quickly become cloudy, indicating that there is a large number of bacteria growing. Some bacteria, such as Mycobacterium tuberculosis, have a slower reproduction rate and require 15- It takes 18 hours to breed a generation. ^[4]

It can be divided into three categories according to shape, namely:

Bacteria are both useful and harmful to the environment, humans and animals. Some bacteria become pathogens and cause

Common bacteria

Bacteria are very old creatures that appeared about 3.7 billion years ago.

Two in eukaryotic cells

Most bacteria are decomposers and are at the bottom of the biological chain. Some bacteria are consumers and producers. Like sulfur bacteria,

clinical

On March 28, 2016, scientists created an artificial bacterial genome in the laboratory, ^[7] including only the minimum number of genes needed for life. This result makes it possible to customize the genome's synthetic organisms for specific tasks, such as removing oil. This artificial bacteria is capable of metabolizing nutrients and self-replicating (dividing and multiplying). It has only 473 genes, compared with thousands of genes in nature. However, the research team does not yet know the exact function of 149 genes in the genome. ^[7]