Bacteria that are considered halophiles are capable of growth in salt concentrations greater than 3%
A in salt concentrations greater than 7%
B in salt concentrations greater than 1%
C in salt concentrations greater than 11%
Bacteria capable of growth in both 1% and 7% salt concentrations are O considered
A obligate halophiles
B extreme halophiles
C facultative halophiles
D non-halophiles
The Correct Answer and Explanation is :
The correct answer is C: facultative halophiles.
Explanation:
Bacteria capable of growth in both 1% and 7% salt concentrations are classified as facultative halophiles. These organisms do not require high salt concentrations for growth but can tolerate and grow in environments with elevated salinity. Their ability to thrive in a range of salt concentrations allows them to inhabit diverse environments, from low-salinity habitats to those with higher salt content.
Classification of Halophilic Bacteria:
- Obligate Halophiles: These bacteria require high salt concentrations for growth, typically above 3% NaCl. (Quizlet)
- Extreme Halophiles: A subset of obligate halophiles, extreme halophiles thrive in environments with salt concentrations exceeding 15% NaCl. (Wikipedia)
- Facultative Halophiles: These bacteria can grow in both the presence and absence of high salt concentrations. They are not dependent on salt for growth but can tolerate and grow in saline environments.
- Non-Halophiles: These organisms cannot tolerate high salt concentrations and typically grow best in environments with low or no salt.
Adaptations of Facultative Halophiles:
Facultative halophiles possess specific adaptations that enable them to survive and grow in varying salt concentrations:
- Osmotic Regulation: They can adjust their internal osmotic pressure to balance the external environment, preventing cellular damage due to osmotic stress.
- Compatible Solutes: These bacteria often accumulate compatible solutes—small organic molecules that do not interfere with cellular processes—to maintain osmotic balance without disrupting cellular functions.
- Cell Wall Composition: Some facultative halophiles have cell wall structures that are more resistant to osmotic pressure changes, allowing them to withstand fluctuations in external salinity.
Understanding the classification and adaptations of halophilic bacteria is crucial in microbiology, as it informs their ecological roles, industrial applications, and potential in biotechnology.