The key difference between cyst and spore is that cyst is a dormant stage of bacteria or protozoa that facilitates their survival during unfavourable environmental conditions, while spore is a reproductive structure that can develop into a new individual.
Microorganisms, especially bacteria, produce different structures such as cysts, endospores, etc. to survive and spread in different environments. Cysts are dormant structures that aid them to survive in harsh environmental conditions. It is not a reproductive structure. In contrast, a spore is a reproductive structure, which can give rise to a new individual. The aim of this article is to discuss the difference between cyst and spore.
CONTENTS
1. Overview and Key Difference
2. What is a Cyst
3. What is a Spore
4. Similarities Between Cyst and Spore
5. Side by Side Comparison – Cyst vs Spore in Tabular Form
6. Summary
What is a Cyst?
A cyst is a dormant structure of certain microorganisms such as bacteria and protozoa. It mainly facilitates the survival of a microorganism under unfavourable environmental conditions such as insufficient nutrients and oxygen, high temperature, presence of toxic chemicals and lack of moisture, etc. A cyst also has a thick wall. However, it is not a reproductive cell like a spore. The sole intention of the cyst is to ensure the survival of the organism until the environmental conditions return to normal and favourable levels.
Figure 01: Cyst of Entamoeba
Encystment is the process by which internal parasites, mostly in larval stages, get enclosed within a cyst. Therefore, the encystment process helps the microorganism to be easily dispersed to a favourable environment or to move from one host to another. When the microorganism reaches a favourable environment after encystment, the wall of the cyst ruptures by a process called excystation. Since cyst is a dormant structure, it is in an inactive form. In simple words, cyst ceases all the activities and slows down metabolism.
The cell wall composition of cyst varies according to different microorganisms. Bacterial cyst wall contains a thick peptidoglycan layer while the protozoan cyst wall contains chitin. Due to the presence of a thick wall in cysts, they are resistant to different types of sterilization methods such as chlorination and disinfection. Hence, microbial cysts, especially protozoan cysts, pose a serious health risk by contaminating foods, drinking water and waterways, etc.
What is Spore?
Spore is a reproductive cell of microorganisms which can give rise to a new individual. It is a metabolically dormant structure. However, it contains genetic material to produce a new individual. Spore formation mainly takes place as a response to nutrient deprivation in bacteria.
Figure 02: Bacterial Endospore
Similar to a cyst, a spore also has a thick wall. Hence, spores are resistant to adverse environmental conditions. Endospores of bacteria are the most resistant spores that cannot sterilize easily. Furthermore, some bacteria produce exospores outside the vegetative cell. Both these endospores and exospores are a threat to health and food safety.
What are the Similarities Between Cyst and Spore?
- Both cyst and spore are mainly microbial structures.
- These structures are resistant to adverse environmental conditions.
- Moreover, they are resistant to many physical and chemical sterilization methods.
- Hence, both cyst and spores pose a threat to food safety.
- Also, both are metabolically dormant.
- During unfavourable conditions, the vegetative cell converts into a spore or a cyst.
What is the Difference Between Cyst and Spore?
Cyst and spore are resting structures of microorganisms. Unlike cysts, spores are reproductive structures that can develop into a new individual. So, this is the key difference between cyst and spore. Furthermore, encystment is the formation process of cysts, while sporulation is the formation process of spores. Therefore, we can consider this also as a difference between cyst and spore.
Moreover, a further difference between cyst and spore is that the cyst formation predominantly occurs under different types of adverse environmental conditions. But, sporulation mainly occurs under nutrient deprivation.
Summary – Cyst vs Spore
A cyst is a dormant state of microorganisms. It facilitates the survival of microorganisms under unfavourable environmental conditions. Encystment is the process by which the internal parasites, mostly in larval stages, reside within a cyst. Spore is another dormant structure produced by microorganisms, mainly under nutrient deprivation. But, unlike a cyst, a spore is a reproductive structure which can develop into a new individual. However, both cyst and spore help microbes to withstand unfavourable conditions. Moreover, they contain resistant outer covers. Therefore, both structures cannot eliminate easily by many sterilization methods. So, this is the summary of the difference between cyst and spore.
Reference:
1. “Bacterial Spore: Structure, Types, Sporulation and Germination.” Online Biology Notes, 18 Dec. 2018, Available here.
2. “Microbial Cyst.” Wikipedia, Wikimedia Foundation, 5 Sept. 2017, Available here.
Image Courtesy:
1. “Entamoeba histolytica 01” By CDC/ Dr. George Healy – from the Centers for Disease Control and Prevention’s Public Health Image Library (PHIL) (Public Domain) via Commons Wikimedia
2. “OSC Microbio 02 04 Endospores” By CNX OpenStax – (CC BY 4.0) via Commons Wikimedia