Set 4: Environmental Factors - pH, Pressure, and Others

Define acidophiles based on their optimum pH ranges.

Optimum pH 0-5.5.

Ex: Thiobacillus ferrooxidans (pH 1.5-2.0).

Define neutrophiles based on their optimum pH ranges.

Optimum pH 5.5-7.

Define Alkalinophiles based on their optimum pH ranges.

Optimum pH 8.5-11.5.

Provide 2 examples organisms that can modify its environmental pH.

• Helicobacter in the stomach produces an enzyme that raises pH

• Proteus spp. neutralize acidic urine = able to colonize the urinary system

What is a halophile?

organisms that thrive in high NaCl concentrations.

What is a famous example of an environment of halophile and where are they found?

Dead Sea, where Halobacterium grows.

What is Bartolerant microbes?

Adversely affected by increased pressure but can still grow (better than non-tolerant organisms).

What is Barophilic microbes?

Require or grow more rapidly in the presence of increased pressure (e.g., 400-500 atm in the deep sea).

Besides providing energy for phototrophs, what significant effect does radiation (like UV and ionizing radiation) have on most microbes?

Ultraviolet and ionizing radiation (short wavelengths) are lethal and can be used to kill microbes.

What is a biofilm?

A biofilm is a complex community of microorganisms attached to a surface.

What type of microbial association does a biofilm represent?

It represents the epitome of synergism, where the collective interaction benefits the community.