Gram Negative bacteria
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Questions and Answers

Which phylum is described as the largest and most diverse within Domain Bacteria?

  • Pseudomonadota (correct)
  • Actinobacteria
  • Firmicutes
  • Bacteroidetes

    • What is a characteristic of Enteric Bacteria?

  • They have distinct O, H, and K antigens. (correct)
  • They are always aerobic.
  • They are predominantly cocci.
  • They are strictly anaerobic.

    • Which of the following statements is true about Gram negative bacteria?

  • They have thick peptidoglycan layers.
  • They are all pathogenic.
  • They are classified into Pseudomonadota and Non-Pseudomonadota. (correct)
  • They lack metabolic diversity.

    • Which classification of bacteria includes facultative anaerobes and may possess peritrichous flagella?

    <p>Gammaproteobacteria (C)</p> Signup and view all the answers

    Which of the following is NOT a characteristic of the Pseudomonadota phylum?

    <p>All are Gram positive (A)</p> Signup and view all the answers

    What is the infectious disease caused by Salmonella that is characterized by a large infectious dose and non-bloody diarrhea?

    <p>Salmonellosis (C)</p> Signup and view all the answers

    Which characteristic is associated with Yersinia pestis?

    <p>Causes necrosis of tissue (A)</p> Signup and view all the answers

    What role do virulence plasmids play in Yersinia pestis?

    <p>Lyse red blood cells (C)</p> Signup and view all the answers

    What type of relationship does Aliivibrio fischeri have with its host?

    <p>Symbiotic (D)</p> Signup and view all the answers

    Which of the following characteristics differentiates Bdellovibrio from other bacteria?

    <p>Attacks Gram negative pathogens (D)</p> Signup and view all the answers

    What is the correct format for writing a Latin organism name?

    <p>Genus in upper-case, species in lower-case, italics if typed (A)</p> Signup and view all the answers

    Which of the following examples of a bacteria name is written correctly?

    <p>Bacillus subtilis (C)</p> Signup and view all the answers

    Which of the following statements is true about the naming of bacteria?

    <p>The genus name begins with an uppercase letter and must be in italics after the first use. (C)</p> Signup and view all the answers

    Identify the bacteria name written in the correct format: Helicobacter pylori.

    <p>Helicobacter pylori (D)</p> Signup and view all the answers

    What should you do when writing a Latin name for the first time?

    <p>Write both genus and species names in full. (A)</p> Signup and view all the answers

    Which of the following names is correctly abbreviated for further references?

    <p>Helicobacter pylori as H.pylori (B)</p> Signup and view all the answers

    What is the purpose of writing Latin names for bacteria?

    <p>To standardize their identification worldwide. (A)</p> Signup and view all the answers

    Which of the following options about the Pseudomonadota is correct?

    <p>Pseudomonadota can survive in extreme environments. (A)</p> Signup and view all the answers

    What is a key characteristic of Caulobacter?

    <p>It has stalked and swarmer cell forms. (D)</p> Signup and view all the answers

    Which group of bacteria are known for being obligately intracellular?

    <p>Chlamydiota (A)</p> Signup and view all the answers

    What is the primary environmental role of Cyanobacteria?

    <p>Nitrogen fixation and oxygen production. (A)</p> Signup and view all the answers

    What disease is primarily caused by Treponema pallidum?

    <p>Syphilis (B)</p> Signup and view all the answers

    Which of the following is a feature of the Spirochaetota phylum?

    <p>They have corkscrew motility. (B)</p> Signup and view all the answers

    Which feature is NOT characteristic of Chlamydia trachomatis?

    <p>Can be cultivated in standard laboratory conditions. (C)</p> Signup and view all the answers

    What is a distinguishing feature of Bacteroidota?

    <p>They are mostly anaerobic and commensal. (D)</p> Signup and view all the answers

    What can cyanotoxins cause?

    <p>Severe neurological and organ system effects. (C)</p> Signup and view all the answers

    In what context are Alistipes significant?

    <p>They correlate positively with cancer therapy outcomes. (B)</p> Signup and view all the answers

    What best describes the morphology of Cyanobacteria?

    <p>Coccus or disc-shaped, varying in size. (C)</p> Signup and view all the answers

    How are Treponema bacteria primarily categorized?

    <p>As anaerobic, mostly commensal organisms. (A)</p> Signup and view all the answers

    What benefit do cyanobacteria offer to aquatic ecosystems?

    <p>They provide oxygen and are a carbon sink. (A)</p> Signup and view all the answers

    What is a common use of penicillin in relation to Treponema infections?

    <p>To eradicate the bacterial infection. (A)</p> Signup and view all the answers

    Which of the following statements regarding Gram-negative bacteria is accurate?

    <p>They include a variety of diverse microorganisms. (C)</p> Signup and view all the answers

    Flashcards

    Pseudomonadota

    A large and diverse bacterial phylum, containing a wide variety of shapes and metabolic pathways.

    Gram-negative in Pseudomonadota

    All bacteria classified in the Pseudomonadota phylum are gram-negative. This means they lack a thick peptidoglycan layer in their cell wall.

    Gammaproteobacteria

    This class contains many important pathogens of humans, such as E. coli, Salmonella, and Shigella. They are often coccobacilli or bacilli in shape.

    Enteric Bacteria

    Enteric bacteria are a group of Gammaproteobacteria that are found in the intestines of humans and animals. They can be motile, have capsules, and can survive in both oxygen-rich and oxygen-poor environments.

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    O, H, and K antigens

    These are surface antigens commonly found in enteric bacteria, such as E. coli and Salmonella. They can help identify different strains within a species.

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    Salmonella

    A type of bacteria commonly found in birds, reptiles, and mammals, known for causing food poisoning and typhoid fever. It infects approximately 1/3 of chicken eggs.

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    Yersinia pestis

    A true pathogen responsible for bubonic and pneumonic plague, nicknamed 'black death', which has caused devastating epidemics throughout history.

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    Buboes

    Swollen lymph nodes characteristic of bubonic plague, caused by the bacteria Yersinia pestis.

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    Bdellovibrio

    A group of predatory bacteria that attack a wide range of Gram-negative pathogens.

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    Aliivibrio fischeri (Vibrio fischeri)

    A facultative anaerobic bacterium that emits light (bioluminescent) and forms symbiotic relationships with other organisms, like in the light organ of fish.

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    Linnaean Classification System

    The system used to classify all living organisms. It categorizes organisms into groups based on shared characteristics, starting with the broadest groups (domains, kingdoms) and becoming more specific. It helps us understand the relationships between organisms and the evolution of life on Earth.

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    Escherichia

    The genus Escherichia refers to a group of bacteria that includes the well-known E. coli, commonly found in the human gut.

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    Helicobacter

    The genus Helicobacter refers to a group of bacteria that include H. pylori, a spiral-shaped bacterium linked to stomach ulcers.

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    Pseudomonas

    The genus Pseudomonas refers to a group of bacteria that include P. aeruginosa, known for its ability to form biofilms and cause infections, especially in hospitals.

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    Burkholderia

    The genus Burkholderia refers to a group of bacteria that include B. cepacia, known for its opportunistic infections, particularly in individuals with compromised immune systems.

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    Writing Bacterial Names

    Bacillus Subtilis is correctly written as Bacillus subtilis. The genus name is capitalized and the species name is not. The entire name is italicized or underlined when handwritten.

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    Writing Bacterial Names

    Pseudomonas aeruginosa is correctly written as Pseudomonas aeruginosa. The genus name is capitalized and the species name is not. The entire name is italicized or underlined when handwritten.

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    Non-Pseudomonadota

    A way to classify gram-negative bacteria, excluding Pseudomonadota.

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    Cyanobacteriota (Cyanobacteria)

    A phylum of bacteria that are oxygenic phototrophs, capable of photosynthesis using water as an electron donor.

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    Importance of Cyanobacteriota

    An important source of oxygen, a sink for carbon dioxide, can fix nitrogen and contribute to the earthy smell after rain (geosmin)

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    Spirochaetota (Spirochetes)

    A phylum of bacteria with a corkscrew shape and unique flagella (axial filaments) that allow them to move.

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    Treponema

    A genus of spirochetes that includes the syphilis-causing bacterium, Treponema pallidum.

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    Syphilis

    A sexually transmitted disease caused by the bacterium Treponema pallidum that can affect various parts of the body.

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    Bacteroidota (Bacteroidetes)

    A phylum of bacteria commonly found in the intestines of humans and animals, often associated with health benefits.

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    Alistipes

    A genus of bacteria commonly found in the human gut, potentially linked to positive cancer treatment outcomes and depression.

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    Chlamydiota (Chlamydiae)

    A phylum of obligately intracellular bacteria, meaning they can only survive and reproduce inside other cells.

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    Chlamydia trachomatis

    A genus of bacteria known for causing a variety of infections, including trachoma and sexually transmitted diseases.

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    Yersinia pestis

    A genus of bacteria that causes a wide range of diseases, including bubonic plague and food poisoning.

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    Study Notes

    Gram-Negative Bacteria Overview

    • Gram-negative bacteria are a diverse group of prokaryotes.
    • Images show various shapes and structures of gram-negative bacteria.
    • These bacteria are a significant part of the classification system for prokaryotes.

    Learning Objectives

    • The presentation discusses the Linnaeus classification system and its application to prokaryotes.
    • Students need to learn how to properly name organisms using Latin binomial nomenclature.
    • The module covers several lineages of bacteria.
    • Key lineages include Pseudomonadota and gram-negative bacteria that aren't in the Pseudomonadota group.
    • Illustrations and examples support this information.

    Taxonomic Hierarchy

    • The presentation defines and illustrates the taxonomic hierarchy.
    • The hierarchy includes: Kingdom
    • Phylum, Class, Order, Family, Genus, and Species.
    • An example of a stag beetle, Lucanus cervus, illustrates this concept.

    Writing Latin Names

    • Bacteria are identified by their Latin names.
    • The genus name comes first, capitalized.
    • The species name comes next, lowercase.
    • Names are italicized when typed and underlined when handwritten.
    • The full name is used initially, later abbreviated.
    • An example is provided (Escherichia coli, also written as (E. coli)).

    Correct Latin Naming Examples

    • Correct examples of Latin bacterial names are shown and emphasized.
    • For example, Bacillus subtilis correctly follows the given naming rules.
    • This slide also reinforces what is and isn't the correct way to name the bacteria.

    Additional Bacteria Names

    • Helicobacter pylori, Pseudomonas aeruginosa and Burkholderia cepacia are Gram-negative bacteria.
    • Gram-negative bacteria are classified into several lineages.

    Classifying Prokaryotes

    • A phylogenetic tree diagrams the relationships between gram-negative and gram-positive bacteria, and archaea.
    • The tree highlights the importance of Gram-negative and gram-positive and archaea categorization.
    • The tree illustrates the lineages of gram-negative bacteria, including Pseudomonadota and non-Pseudomonadota.

    Phylum: Pseudomonadota (Proteobacteria)

    • Pseudomonadota (Proteobacteria) is a large, diverse phylum.
    • It includes several classes (alpha, beta, gamma, delta, epsilon).
    • Members vary in shape.
    • They are gram-negative.
    • They display diverse metabolic capabilities.

    Enteric Bacteria

    • Enteric bacteria are a group within the Gammaproteobacteria.
    • They often infect humans.
    • They include coccobacilli or bacilli shapes.
    • Often motile with peritrichous flagella.
    • Some have capsules and are facultative anaerobes. (These microorganisms can live with or without oxygen)
    • Examples include species of E. coli and Salmonella.

    Salmonella Species (Examples)

    • Salmonella are found in many animals.
    • Often found in chicken eggs
    • Salmonellosis, a common infection, is typically non-bloody diarrhea with a high infectious dose.
    • Typhoid fever, related to Salmonella, has a lower infectious dose, with the bacteria phagocytosed and spread through the bloodstream.

    Yersinia pestis

    • Yersinia pestis causes diseases like bubonic plague (or black death).
    • It also causes pneumonic plague.
    • The pathogen killed a considerable portion of the world's human population during the middle ages.
    • The bacteria is transmitted between rats and humans, often by fleas.

    Yersinia pestis (Characteristics)

    • Yersinia pestis causes buboes (swollen lymph nodes) and enters the bloodstream.
    • The pathogen causes tissue necrosis.
    • Yersinia pestis utilizes a type III secretion system to infect host cells, by secreting proteins.

    Non-Enteric Pseudomonadota

    • This group encompasses several subgroups, including Vibrio, Bdellovibrio, and Caulobacter.
    • Vibrio fischeri is an example, important for bioluminescence (producing light) in symbiosis with some organisms.

    Caulobacter (Key Characteristics)

    • Caulobacter is a common model organism for bacterial cell division.
    • They are aquatic, often freshwater.
    • Prosthecae are attachments, and are important for this organism's survival.

    Non-Pseudomonadota Classification

    • Non-Pseudomonadota is a way to classify other Gram-negative phyla, not a taxonomic group itself.
    • This group contains a variety of microorganisms with various roles in diverse processes, including disease and evolution.

    Cyanobacteria (Cyanobacteriota)

    • Cyanobacteria are a large and diverse group.
    • They have coccus or disc-shaped morphologies.
    • They often reach 1-10 μm in diameter.
    • Some species glide to move.
    • These species are oxygenic phototrophs and form lichens.
    • They are abundant in aquatic environments and are vital to those environments.

    Importance of Cyanobacteria Today

    • They fix nitrogen through heterocysts.
    • They are an important oxygen source and carbon dioxide sink.
    • They produce geosmin, which can cause a noticeable earthy odour.
    • Potential cyanotoxins produce toxins like neurotoxins, cytotoxins, endotoxins, and hepatotoxins.

    Spirochetes (Spirochaetota)

    • Spirochetes are thin (0.1-0.5 μm) and have a corkscrew shape.
    • Their axial filaments drive motility.
    • Three pathogenic genera are Treponema, Borrelia, and Leptospira.

    Treponema pallidum and Syphilis

    • Treponema pallidum causes syphilis.
    • It's anaerobic or microaerophilic
    • It is a human and animal commensal.
    • This bacterium has never been grown in the lab.

    Syphilis (Characteristics)

    • Syphilis is contracted sexually.
    • The primary stage is a chancre, while the secondary stage includes fever and rash.
    • The tertiary stage affects the central nervous system.
    • Adherence, hyaluronidase, and a capsule facilitate infection.
    • Treatment historically uses penicillin and doxycycline.

    Bacteriodota (Bacteroidetes)

    • Bacteriodota (Bacteroidetes) are anaerobic bacteria.
    • They are often commensal and found in the intestines.
    • The intestinal tract contains very high concentrations of these organisms per gram of feces (~1 billion).
    • These bacteria are more common in non-obese individuals.
    • Some strains may improve cancer treatment effectiveness.

    Alistipes

    • Alistipes are commonly found in the intestinal tract of humans and animals.
    • They can form part of a problematic dysbiosis.
    • Their presence may correlate with effective cancer therapy outcomes.
    • They are also more abundant in people with depression.

    Chlamydiae

    • Chlamydiae are obligate intracellular pathogens.
    • They infect humans and other animals.
    • These bacteria can't be grown in traditional lab media.

    Chlamydiae Microbiology

    • Chlamydiae are very small and have a small genome.
    • They have a reduced number of genes.
    • They often utilize plasmids from host cells.
    • They typically don't exist outside of host cells.
    • Elementary bodies are infectious forms (0.2-0.4 μm).
    • Reticulate bodies are the replicative form (0.6-1.5 μm).
    • Chlamydia trachomatis causes trachoma and is sexually transmitted.

    Learning Outcomes Summary

    • Students should learn the Linnaeus classification system applied to prokaryotes.
    • Students should be proficient in naming organisms with proper Latin binomial nomenclature.
    • Major bacterial lineages will be identified.
    • Key examples, such as Pseudomonadota and non-Pseudomonadota, are presented.
    • Bacteria groups' placements on the prokaryotic tree of life are explained.

    Extra Reading Recommendations

    • The slide lists recommended reading materials for deeper study of the covered Gram-negative bacteria, including chapters and sections of various textbooks.

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    Description

    Test your knowledge on the diverse phyla within Domain Bacteria, focusing on Enteric Bacteria, Gram-negative bacteria, and key characteristics of notable pathogens. This quiz also evaluates your understanding of the proper naming conventions in microbiology.

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