Bacterial nutrition and growth (Lec 2) (Set 2)
30 Questions
2 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

True or false: Bacteriostatic agents kill bacteria.

False

True or false: Mesophiles grow best at temperatures above 80 °C.

False

True or false: Acidophiles grow best in acidic habitats.

True

True or false: Halophiles grow in habitats with high salt concentration.

<p>True</p> Signup and view all the answers

True or false: A hyperthermophile grows best at temperatures above 80 °C.

<p>True</p> Signup and view all the answers

True or false: Autotrophs use organic molecules made by other organisms as their principal carbon source?

<p>False</p> Signup and view all the answers

True or false: Obligate anaerobes cannot grow in the presence of oxygen?

<p>True</p> Signup and view all the answers

True or false: Psychrophiles grow best below 15°C and can grow below 0°C?

<p>True</p> Signup and view all the answers

True or false: Alkaliphiles grow best in acidic habitats?

<p>False</p> Signup and view all the answers

True or false: Halophiles grow with 15-30% NaCl?

<p>False</p> Signup and view all the answers

True or false: Bacteria require macroelements in large amounts for growth?

<p>True</p> Signup and view all the answers

True or false: Bacteria require microelements in small amounts for growth?

<p>True</p> Signup and view all the answers

True or false: Chemically defined media have an unknown chemical composition?

<p>False</p> Signup and view all the answers

True or false: Bacterial generation time is the time needed for a bacterial population to double?

<p>True</p> Signup and view all the answers

True or false: Exponential growth is characterized by a constant doubling time?

<p>True</p> Signup and view all the answers

True or false: Viable but nonculturable bacteria are in a state of very high metabolic activity and are able to divide and form colonies on solid media?

<p>False</p> Signup and view all the answers

True or false: Obligate aerobes require oxygen for growth?

<p>True</p> Signup and view all the answers

True or false: Facultative anaerobes can grow with and without oxygen?

<p>True</p> Signup and view all the answers

True or false: Hyperthermophiles grow best between 45-80°C?

<p>False</p> Signup and view all the answers

True or false: Halophiles grow in habitats with low salt concentration?

<p>False</p> Signup and view all the answers

Which type of bacteria grows best at temperatures below 15°C and cannot grow above 20°C?

<p>Psychrophiles</p> Signup and view all the answers

Which type of bacteria grows best between 20-40°C and is commonly found in the human body?

<p>Mesophiles</p> Signup and view all the answers

Which type of bacteria grows best between 45-80°C and is commonly found in hot springs and compost heaps?

<p>Thermophiles</p> Signup and view all the answers

Which type of bacteria grows best above 80°C and is able to survive at least 2 hours at 130°C?

<p>Hyperthermophiles</p> Signup and view all the answers

Which type of bacteria grows best in alkaline habitats such as soda lakes and carbonate soils?

<p>Alkaliphiles</p> Signup and view all the answers

Which type of bacteria grows best between 20-40°C and is commonly found in the human body?

<p>Mesophiles</p> Signup and view all the answers

What is the principal carbon source for autotrophs?

<p>CO2</p> Signup and view all the answers

Which type of bacteria grows best below 15°C and cannot grow above 20°C?

<p>Psychrophiles</p> Signup and view all the answers

What is a facultative aerobe?

<p>Bacteria that do not require oxygen but grow better with it</p> Signup and view all the answers

What is a useful enzyme produced by thermophilic bacteria?

<p>Taq polymerase</p> Signup and view all the answers

Study Notes

Nutritional Requirements of Bacteria

  • Bacteria require nutrients to synthesize cell materials, categorized into macroelements and microelements.
  • Macroelements (macronutrients) are required in large amounts and include carbon, oxygen, hydrogen, nitrogen, phosphorus, sulfur, potassium, calcium, magnesium, and iron.
  • Microelements (micronutrients, trace elements) are needed in small quantities and include copper, zinc, nickel, vanadium, and selenium.

Types of Bacterial Media

  • Culture Media: Nutrient solutions providing essential elements for bacterial growth.
  • Chemically Defined Media: Precise chemical composition known, allowing for controlled growth environments.
  • Complex Media: Composition unknown; derived from digests of materials like milk protein, beef, soybeans, and yeast.

Bacterial Growth in the Laboratory

  • Solid Media: Utilized through nutrient agar plates contained in Petri dishes, requiring aseptic techniques.
  • Liquid Media: Employed in Erlenmeyer flasks and test tubes for bacterial multiplication.

Bacterial Multiplication and Growth Phases

  • Most bacteria reproduce through binary fission, with one cell dividing into two new cells.
  • The generation time varies; E. coli divides approximately every 20 minutes at 37°C, while others may take hours to weeks.
  • Growth can be exponential under optimal conditions, characterized by constant doubling time.
  • A typical growth curve in batch culture includes lag phase, exponential phase, stationary phase, and death phase, influenced by nutrient availability and waste product accumulation.

Measuring Bacterial Growth

  • Culturable Bacteria: Defined as those which can be grown on either liquid or solid media.
  • Viable but Nonculturable (VBNC): Bacteria in low metabolic activity that do not divide but can become culturable upon resuscitation.
  • Methods of counting bacteria include total count (stains all bacteria), viable count (using fluorescent activity dyes), and culturable count (colonies on solid media).

Turbidity as a Measurement

  • Turbidity indicates bacterial growth; a cloudy suspension reflects cell density.
  • Spectrophotometers measure the optical density to estimate bacterial concentration.

Environmental Effects on Bacterial Growth

  • Oxygen Requirement:
    • Obligate aerobes require oxygen.
    • Obligate anaerobes cannot tolerate oxygen.
    • Facultative anaerobes can grow with or without oxygen.
    • Aerotolerant anaerobes do not need oxygen but can tolerate it.
  • Temperature Preferences:
    • Psychrophiles thrive below 15°C; mesophiles prefer 20-40°C; thermophiles grow best between 45-80°C; hyperthermophiles flourish above 80°C.
  • pH Tolerance:
    • Acidophiles prefer acidic environments; alkaliphiles thrive in alkaline conditions.
  • Osmolarity:
    • Halophiles adapt to high salt concentrations, classified into mild, moderate, and extreme halophiles based on salt tolerance.

Applications and Key Terms

  • Taq polymerase, derived from Thermus aquaticus, is a significant enzyme used in PCR (Polymerase Chain Reaction).
  • Understanding bacterial metabolic classifications aids in laboratory work and can inform treatments for diseases caused by specific bacteria, such as cholera caused by Vibrio cholerae.

Cholera Overview

  • Cholera is an acute diarrheal disease caused by Vibrio cholerae, affecting 1.3 to 4 million people annually with a significant death toll. Safe water monitoring is crucial to prevent outbreaks.### Measuring Bacterial Growth
  • Microscopy techniques include total cell count using DAPI, Acridine Orange, and Live-Dead staining.
  • Culturable count obtained through agar plates involves spreading a mixed sample, incubating, and counting colonies.
  • Serial dilution method involves diluting samples in broth (e.g., 1 ml of sample mixed with 9 ml of broth), used to obtain appropriate colony numbers.
  • Ideal plate count should yield 20-200 CFU (colony-forming units) per plate for accurate analysis.

Cholera Overview

  • Caused by Vibrio cholerae serogroups O1 or O139; it is an acute diarrheal illness.
  • Global annual cases estimated at 1.3 to 4 million, with deaths ranging from 21,000 to 143,000 (WHO).
  • Monitoring for Vibrio cholerae involves assessing water safety—positive cultures indicate unsafe water, while negative cultures may still have pathogenic potential.

Bacterial Growth Measurement Techniques

  • Turbidity indicates growth; a spectrophotometer measures light scattering in cell suspensions.
  • Microbial growth is influenced by antimicrobial agents, with variables like bacteriolytic and bacteriocidal effects recorded over time.
  • Measurement includes total cell count (stains all types of cells) and viable count (counts metabolically active cells).

Bacterial Metabolic Classification

  • Carbon Sources:
    • Heterotrophs require organic molecules;
    • Autotrophs utilize CO2.
  • Energy Sources:
    • Phototrophs harness light energy;
    • Chemotrophs oxidize compounds for energy.

Environmental Effects on Bacterial Growth

  • Oxygen Requirements:
    • Obligate aerobes need O2;
    • Obligate anaerobes are inhibited by O2;
    • Facultative anaerobes grow with or without O2.
  • Temperature Classification:
    • Psychrophiles thrive below 15 °C, mesophiles between 20-40 °C, thermophiles between 45-80 °C, and hyperthermophiles above 80 °C.
    • Geogemma barossii, a hyperthermophile, thrives from 80-121 °C and survives at 130 °C.
  • pH Tolerance:
    • Acidophiles grow optimally in acidic environments, while alkaliphiles prefer alkaline conditions.
  • Osmolarity:
    • Halophiles flourish in high salt concentrations, with classifications from mild to extreme based on salt tolerance.

Bacterial Growth and Culture Requirements

  • Nutritional requirements consist of macroelements (e.g., carbon, nitrogen) in large amounts and microelements (e.g., zinc, copper) in trace quantities.
  • Types of culture media:
    • Chemically defined media have known compositions;
    • Complex media are derived from digests of biological materials like soybeans and yeast.

Bacterial Multiplication and Division

  • Growth involves binary fission, where one cell divides into two, proceeding through stages of replication, elongation, septum formation, and separation.
  • Generation time is the duration required for a population to double, with E. coli approximating 20 minutes at 37 °C.
  • Bacterial growth is exponential under ideal conditions with specific phases occurring in closed batch cultures.

Viable and Culturable Bacteria

  • Culturable cells can reproduce on media, while viable but non-culturable (VBNC) cells are alive but inactive under standard conditions.
  • Counting methods differentiate between total count, viable count, and culturable count, essential for assessing bacterial populations accurately.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Quiz Team

Related Documents

BIOL121 Lecture 2 2023-24 PDF

Description

Test your knowledge on the nutritional requirements of bacteria in this quiz. Explore the macro and micro elements necessary for bacterial growth and how they contribute to the synthesis of cell material. Learn about the main nutritional elements that play a crucial role in the culture and development of bacteria.

More Like This

Use Quizgecko on...
Browser
Open
Browser
Browser