Dynamics of Microbial Growth

These flashcards cover essential concepts related to microbial growth, methods of cultivation, and various environmental and nutritional factors influencing microorganisms.

What methods did Robert Koch develop to cultivate bacteria in the 1880s?

Koch developed methods for cultivating bacteria on cut surfaces of potatoes, gelatin, and ultimately on agar.

What is the primary solidifying agent used in microbiological media today?

Agar.

What is microbial growth?

Microbial growth is the increase in the number of cells in a population.

How do prokaryotic cells divide?

Prokaryotic cells divide by binary fission, where a cell increases in size, replicates its DNA, and then divides.

What does exponential growth in a microbial population mean?

Exponential growth refers to the pattern where the population doubles with each division.

What is generation time?

Generation time is the time it takes for a microbial population to double.

What factors influence microbial growth in nature?

Cells respond to changes in their environment by sensing various chemicals and producing materials appropriate for growth.

What are biofilms?

Biofilms are complex relationships among microorganisms where free cells adhere to surfaces and multiply.

How do biofilms affect medical infections?

Microbes within biofilms are often resistant to the immune system and antibiotics, complicating infections.

What is a pure culture?

A pure culture is a population of cells derived from a single cell, grown to study specific functions of species.

What is the importance of the lag phase in the bacterial growth curve?

In the lag phase, the number of cells does not increase as cells prepare for growth.

What is the relationship between temperature and microbial growth?

Each microbial species has an optimum temperature range for growth, categorized into five groups: psychrophiles, psychrotrophs, mesophiles, thermophiles, and hyperthermophiles.

What characterizes obligate aerobes?

Obligate aerobes require O2 to grow.

What are the effects of pH on microbial growth?

Most bacteria grow best at near-neutral pH, but some can thrive in acidic or alkaline environments.

What role does water availability play in microbial growth?

Water is essential for growth; osmotic pressure can cause plasmolysis in high solute concentrations.

What are nutritional factors that affect microbial growth?

Nutritional factors include essential elements, growth factors, and energy sources.

How are macronutrients differentiated in microbial nutrition?

Macronutrients (CHNOPS) are important for cellular components, while carbon sources differentiate between heterotrophs and autotrophs.

What is selective media in microbiology?

Selective media inhibit the growth of certain species while allowing others to grow.

How can bacterial growth be detected in the laboratory?

Techniques for detecting growth include direct cell counts, viable cell counts, measuring biomass, and detecting metabolic products.