Green algae are autotrophic organisms that perform photosynthesis, producing oxygen. Most types are unicellular and are a crucial food source for fish and marine life, forming the base of food webs.
Some microorganisms develop symbiotic and mutualistic relationships that are beneficial for both parties, such as interactions between microalgae and bacteria, or algae and fungi. But can these relationships be described as friendships?
In a study conducted by researchers from Friedrich Schiller University Jena and the Leibniz Institute for Natural Product Research and Infection Biology, published in April on the National Academy of Sciences website, a triadic relationship among microorganisms was highlighted. The study showed that the microalgae Chlamydomonas support the growth of the bacteria Methylobacterium, which in turn enhances the growth of Chlamydomonas in a mutualistic relationship.
Based on this relationship, the friendly Methylobacterium bacteria protect the algae from the antagonistic Pseudomonas bacteria. Pseudomonas secretes chemicals that kill and decompose the microalgae and remove their flagella.
Therefore, Methylobacterium plays a dual role for the algae: it not only supports the growth of Chlamydomonas algae but also protects them from Pseudomonas bacteria.
How Do Algae and Bacteria Benefit Nutritionally From Each Other?
A mutualistic relationship arises between Methylobacterium bacteria and Chlamydomonas algae. While the algae secrete vitamins B1, B3, and B5, as well as organic sulfur in the form of methionine, the Methylobacterium bacteria benefit from these substances necessary for their growth. In return, Methylobacterium enhances the growth of the algae.
However, it is still unknown how Methylobacterium stimulates algae growth. One possibility is that the carbon dioxide produced by the bacteria stimulates algae growth.
How Do Methylobacterium Bacteria Neutralize the Toxins Secreted by Pseudomonas?
Using various scientific methods, researchers found that Methylobacterium saves the algae from antagonistic bacteria by splitting the toxic lipid peptide ester bond secreted by the antagonistic bacteria and converting it into a linear form. This resulting compound does not increase cellular calcium ions, which would otherwise lead to the algae’s decomposition. Consequently, the algae remain mobile and can swim away from the antagonistic bacteria, surviving the attack.
Where Are These Three Types of Microbes Found?
The genera Chlamydomonas, Pseudomonas, and Methylobacterium are found in nature. This type of Chlamydomonas was first isolated from a potato field. The microorganisms present in the roots of potatoes in the high Andes mountains also include Pseudomonas as well as Methylobacterium species alongside Chlamydomonas.
Interestingly, other species of Pseudomonas also act antagonistically against Chlamydomonas, while other species of Methylobacterium also serve as helper bacteria for Chlamydomonas.
mutualistic relationships among microorganisms
