What Are Bacterial Spores?

Bacterial spores are a type of spore or spore-like structure that are produced by bacteria. These include endospores, thick-walled spores (of the filaments of cyanobacteria and green algae), and spores produced by actinomycetes and nitrogen-fixing bacteria .

In bacteria, spore formation is only a way to survive in harsh environments, not a way to reproduce. In the culture medium, bacteria develop from vegetative hyphae to aerial hyphae, aerial hyphae grow to a certain stage, and most of them differentiate into spore filaments that can form spores. When spore filaments grow to a certain stage, they form strings of meristem spore.

The spores are various in shape, including spherical, oval, columnar, melon seeds, fusiform and semilunar.

The spore colors are white, gray, yellow, orange, red, blue, and green. Observe the surface texture under the electron microscope, some are smooth, some have small warts or show folds, spines, hairs, scales. At present, it has been found that all straight or wave-shaped spore filaments produce smooth surface spores; spiral spore filaments produce smooth surface spores, and some produce spiny or hair-like spores. Therefore, the structural characteristics of the spore surface can also be used as an important basis for identifying the species. Various spore filaments of actinomycetes are shown in Figure 1-31, and various spore shapes are shown in Figure 1-32.

Bacterial spores have the following characteristics:

1. Ability to tolerate extreme dryness;

2. Part of it can survive at sub-zero temperatures;

3. Some can spread toxic compounds, such as the Cry toxin synthesized by thuringiensis .

4. Bacteria spores are highly environmentally resistant. for example,

   Ferns develop spontaneous gametophytes through spore germination. Gametophytes can form sperm organs and cervix, and then form new sporophytes through fertilization.

   Spore germination is a key step in the transformation of gametophyte generation to sporophyte generation during the life history of ferns. At the same time, this process is not only affected by a variety of environmental factors, but also a good model for studying unique cytological events such as nuclear polarity shift, asymmetric cell division, and pseudoroot growth. So far, people have discovered that a variety of environmental factors have an impact on the germination of spores in about 200 species of ferns. The effects of environmental factors on spore germination of ferns are summarized as follows:

   (1) In addition to the influence of light intensity, spore germination is mainly affected by light quality.The effect of light quality is mainly expressed in four ways: spore germination is regulated by red light stimulation and far red light suppression like a switch; spore germination is not Inhibited by far red light; Spore germination is inhibited by blue light; Spores can only germinate in dark conditions.

   (2) Gravity will affect the spore cell nucleus movement, which in turn affects the polarity of spore cell development.

   (3) GA can increase spore germination rate or help spores break dormancy. The spermatogenin has a similar effect to GA, initiating or promoting spore germination. The effects of abscisic acid (ABA), jasmonic acid (JA) and ethylene on spore germination were relatively small.

   (4) Different plant spores have their own optimal germination medium conditions. For example, different types of spores have different requirements for the content of inorganic salts, sucrose, and pH in MS medium. Ca2 +, Mn2 + and Mg2 + in the spore outer cover, Cd2 + and La3 + in the culture medium, as well as spore inoculation density and germination space CO2 content will also affect the spore germination.

   (5) Most fern spores can germinate at 15-30 , and the optimal germination temperature is 25 . (6) 4 and liquid nitrogen storage can prolong spore life and maintain high germination rate. ^[1]