Bergey’s Classification Of Bacteria: Overview, Systematic Bacteriology

Edited By Irshad Anwar | Updated on Jul 02, 2025 05:20 PM IST

Bergey’s Manual of Systematic Bacteriology is a widely used guide which helps classify bacteria based on features such as shape, cell wall type, reproduction, etc. It is an important tool for students, doctors, and scientists to know and understand different types of bacteria. This classification system helps to have a clear understanding of the study of bacteria.

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Bergey’s Manual of Systematic Bacteriology
Basis of Bergey’s Classification of Bacteria
Volumes and Organisation of Bergey’s Manual of Systematic Bacteriology
Significance of Bergey’s Manual in Systematic Bacteriology
Applications of Bergey’s Manual of Systematic Bacteriology

Bergey’s Classification Of Bacteria: Overview, Systematic Bacteriology

The manual explains how bacteria are grouped and how the system is useful. It also gives a step-by-step way to find and study bacteria based on their specific characteristic. Bacteria are microorganisms which are very diverse, and their classification is one of the important things for students studying biology or preparing for competitive exams like NEET.

Bergey’s Manual of Systematic Bacteriology

Bergey's Manual of Systematic Bacteriology, popularly known as Bergey's Manual, is considered an important reference guide in which bacteria are categorised into groups based on their genetic and phenotypic features. It is a scientific tool used in systematic bacteriology that refers to the subdivision of biology focused on the identification and classification of bacteria. The first edition of Bergey's Manual emerged in the early 20th century; however, it has undergone various versions, taking into account the developments in bacterial taxonomy. This guide comprises a broad system of classification, from the commonly known pathogens to the newly identified species of bacteria.

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Basis of Bergey’s Classification of Bacteria

The classification in Bergey's Manual is based on the characteristics of morphology, staining properties, metabolic pathways, genetic makeup, and ecological roles. The following is a summary of the major criteria used for classification in Bergey's Manual:

Cell Wall Composition: The bacteria were initially classified based on the structure of the cell wall; they are hence divided into Gram-positive bacteria and Gram-negative bacteria.

Shape and Form: Bacteria are primarily classified according to their shape as dictated by Bergey's Manual, which indicates shapes like cocci (spherical), bacilli (rod-shaped), spirilla (spiral shape), etc.

Nutritional Requirements: Whether the bacteria are autotrophs, that is, able to make their food or heterotrophic, that is, require organic compounds as a food source.

Genetic Analysis: Bargey's Manual of Systematic Bacteriology also provides for DNA sequencing. It groups bacteria at the molecular level.

Volumes and Organisation of Bergey’s Manual of Systematic Bacteriology

The Bergey's Manual of Systematic Bacteriology is divided into several volumes, each specialising in a group of bacteria. Although the modern systematic classification is based generally on genetic similarities or dissimilarities, it leads to major groups known as phyla. Here's a simple table of some of those interesting groups:

Volume	Bacterial Phyla	Characteristics
Volume I	Actinobacteria	High G+C Gram-positive bacteria
Volume II	Proteobacteria	Diverse groups include many pathogens
Volume III	Firmicutes	Low G+C Gram-positive bacteria
Volume IV	Bacteroidetes, Spirochaetes	Includes anaerobes and spiral-shaped bacteria
Volume V	Cyanobacteria, Chlamydiae	Photosynthetic bacteria, obligate intracellular

Significance of Bergey’s Manual in Systematic Bacteriology

The book Bergey's Manual of Systematic Bacteriology stands as a base for systematic bacteriology, allowing practising scientists and students to make precise classification and identification of bacteria. Understanding Bergey's classification of bacteria gives them the basic framework with which they could go deep into the field of microbiology.

Bergey's Manual classification guides how unknown bacteria can be identified through a systematic procedure.
Bergey's Manual of Systematic Bacteriology understands the evolutionary relationships existing between bacteria based on genetic and phenotypic characteristics.
Accuracy in bacterial classification is important for developing treatments, understanding disease pathways, and establishing beneficial bacteria in areas.

Applications of Bergey’s Manual of Systematic Bacteriology

Bergey's Manual of Systematic Bacteriology has several applications in medicine, agriculture, and biotechnology. With its extensive use, some of the important applications are as follows:

Disease Diagnosis: Medical microbiologists make use of Bergey's Manual to identify pathogens and start respective treatments.
Agriculture: The beneficial bacteria in Bergey's Manual have been studied based on their contribution to soil fertility as well as plant growth.
Environmental Science: It will help in identifying the bacteria that fix nitrogen, decompose wastes, and fulfil other functions.
Biotechnology: This category, according to Bergey's Manual, describes the bacteria which have industrial uses, such as the fermenting bacteria.

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Composition of Bacterial Cell Wall	Five Kingdom Classification
Gram Staining	Archaebacteria
Cell Envelope	Bacterial Viruses

Frequently Asked Questions (FAQs)

1. How does Bergey's manual classify bacteria?

The manual offers identification (determining) techniques based on factors such as cell wall composition, morphology, differential staining, oxygen requirement, and biochemical tests but does not categorise bacteria according to evolutionary relatedness.

2. What are the 2 classifications of bacteria?

Bacteria come in a variety of forms and sizes, ranging from spherical (cocci) to rod-shaped (bacilli) to filamentous and spiral, and they can be divided into two main groups based on how they react to Gram stains that is either bacteria could be gram positive or gram negative.

3. What are the 5 classifications of bacteria?

Spherical (cocci), rod-shaped (bacilli), spiral-shaped (spirilla), comma-shaped (vibrios), and corkscrew-shaped (bacilli) are the five fundamental shapes of bacteria (spirochaetes).

4. What are 3 methods used to identify bacteria?

Modern Techniques for Microbe Identification Using PCR, including Real-Time PCR, to Identify Bacteria PCR is arguably the most popular molecular method for identifying microbes.

● Microarray-Based Identification.

● Immune system recognition.

● Analytical/Chemical Identification.

5. How is Bergey’s Manual used in medical microbiology?

Bergey’s Manual helps in the identification of pathogens, aiding in the diagnosis and treatment of bacterial infections.

6. What is the role of bacterial cell inclusions in Bergey's classification system?

Bacterial cell inclusions, such as storage granules, gas vesicles, or magnetosomes, are considered in Bergey's classification system. The manual provides information on the presence, composition, and function of these inclusions in different bacterial species. While not primary classification criteria, these characteristics can be important for identifying certain bacterial groups and understanding their physiological adaptations.

7. What is the role of bacterial genome size in Bergey's classification system?

Genome size is considered in Bergey's classification system as part of the overall genetic characterization of bacterial species. The manual includes information on genome sizes, which can vary significantly between different bacterial groups. While not a primary classification criterion, genome size can provide insights into a bacterium's evolutionary history, metabolic capabilities, and potential for genetic plasticity.

8. How does Bergey's Manual incorporate information on bacterial bioluminescence?

Bergey's Manual includes information on bioluminescent bacteria as part of species descriptions. It provides details on the bioluminescence systems, including the genes involved, the chemical nature of the light-emitting compounds, and the ecological significance of this trait. While bioluminescence is not a primary classification criterion, it is an important characteristic for identifying certain bacterial groups, particularly in marine environments.

9. What is the significance of bacterial osmotolerance in Bergey's classification system?

Bacterial osmotolerance is an important characteristic in Bergey's classification system, particularly for identifying and classifying bacteria that live in high-salt environments. The manual provides information on the osmotic tolerance ranges of different species, their mechanisms for osmoregulation, and any specialized adaptations for surviving in high-osmolarity conditions. This information is crucial for accurately classifying halophilic and halotolerant bacteria.

10. What is the significance of bacterial cell size and shape in Bergey's classification?

Bacterial cell size and shape are fundamental characteristics in Bergey's classification system. The manual provides detailed information on cell morphology, including size ranges, shapes (e.g., cocci, bacilli, spirilla), and arrangements (e.g., chains, clusters). These characteristics are often the first step in identifying unknown bacteria and play a crucial role in differentiating between various bacterial groups.

11. What is the role of metabolic diversity in Bergey's classification of bacteria?

Metabolic diversity plays a significant role in Bergey's classification of bacteria. The manual includes detailed information on various metabolic pathways, energy sources, and biochemical reactions characteristic of different bacterial groups. This information is used to differentiate between species and genera, especially in cases where morphological or genetic data alone may not be sufficient for accurate classification.

12. What role do bacterial spores play in Bergey's classification system?

Bacterial spores are important characteristics in Bergey's classification system, particularly for certain groups like Bacillus and Clostridium. The manual provides detailed information on spore-forming bacteria, including spore morphology, resistance properties, and germination conditions. These characteristics are used to differentiate between spore-forming species and are crucial for their accurate identification and classification.

13. What is the importance of bacterial motility in Bergey's classification system?

Bacterial motility is an important characteristic in Bergey's classification system. The manual provides information on various types of bacterial motility, including flagellar movement, gliding motility, and twitching motility. These characteristics are used to differentiate between species and can be crucial for identifying certain bacterial groups. The presence, number, and arrangement of flagella are also considered in the classification process.

14. What is the role of bacterial pigments in Bergey's classification system?

Bacterial pigments are important characteristics in Bergey's classification system. The manual includes information on various pigments produced by bacteria, their chemical nature, and their biological functions. Pigment production can be a key identifying feature for certain bacterial groups and is used in conjunction with other characteristics for accurate classification. This is particularly important for groups like Pseudomonas, Serratia, and various photosynthetic bacteria.

15. What is Bergey's Manual of Systematic Bacteriology?

Bergey's Manual of Systematic Bacteriology is a comprehensive reference guide for identifying and classifying bacteria. It provides detailed information on bacterial taxonomy, including descriptions of bacterial species, their characteristics, and methods for identification. The manual is widely used by microbiologists and serves as a standard reference for bacterial classification.

16. How does Bergey's classification system differ from traditional taxonomic approaches?

Bergey's classification system differs from traditional taxonomic approaches by focusing on bacterial characteristics rather than evolutionary relationships. It uses a polyphasic approach, incorporating phenotypic, genotypic, and phylogenetic data to classify bacteria. This method allows for more accurate and comprehensive classification, especially for microorganisms that cannot be easily classified using traditional methods.

17. What are the main groups of bacteria according to Bergey's Manual?

Bergey's Manual classifies bacteria into major groups based on their characteristics. The main groups include Gram-positive bacteria, Gram-negative bacteria, Archaea, and bacteria that lack cell walls (e.g., Mycoplasma). These groups are further divided into subgroups based on various criteria such as cell shape, metabolism, and genetic similarities.

18. How does Bergey's Manual handle the classification of newly discovered bacterial species?

Bergey's Manual is regularly updated to include newly discovered bacterial species. When a new species is identified, researchers submit detailed information about its characteristics, genetic makeup, and phylogenetic relationships. This information is reviewed by experts, and if accepted, the new species is incorporated into the appropriate section of the manual in subsequent editions.

19. What role does 16S rRNA sequencing play in Bergey's classification system?

16S rRNA sequencing plays a crucial role in Bergey's classification system. This technique allows for the comparison of genetic similarities between different bacterial species by analyzing the highly conserved 16S ribosomal RNA gene. The sequence data helps in determining phylogenetic relationships and is used alongside other characteristics to classify bacteria accurately.

20. How does Bergey's Manual address the issue of bacterial species that cannot be cultured in laboratories?

Bergey's Manual acknowledges the challenge of classifying unculturable bacteria and incorporates molecular techniques to address this issue. It includes information on bacteria identified through culture-independent methods, such as metagenomics and environmental DNA sequencing. This approach allows for the classification of bacteria that cannot be grown in laboratory conditions but can be detected and characterized through their genetic material.

21. What is the significance of phenotypic characteristics in Bergey's classification system?

Phenotypic characteristics, such as cell morphology, biochemical reactions, and growth requirements, remain important in Bergey's classification system. These observable traits provide valuable information for identifying and differentiating bacterial species, especially in clinical and environmental settings where rapid identification is crucial. Phenotypic data is used in conjunction with genetic information to create a comprehensive classification scheme.

22. How does Bergey's Manual handle bacterial species that exhibit high genetic diversity?

Bergey's Manual addresses bacterial species with high genetic diversity by recognizing subspecies and strains within a species. It provides detailed information on the genetic variations and phenotypic differences observed within these diverse groups. In some cases, highly diverse species may be reclassified into separate species or genera based on accumulated evidence of significant genetic and phenotypic differences.

23. What is the importance of chemotaxonomy in Bergey's classification system?

Chemotaxonomy, the study of chemical constituents of organisms for classification purposes, is an important component of Bergey's classification system. It involves analyzing cellular components such as cell wall composition, fatty acid profiles, and specific biochemical markers. This approach provides additional data for distinguishing between closely related bacterial species and helps in creating more accurate classification schemes.

24. How does Bergey's Manual address the classification of extremophiles?

Bergey's Manual includes specific sections dedicated to extremophiles, bacteria that thrive in extreme environments. It provides detailed information on their unique adaptations, metabolic capabilities, and genetic characteristics. The classification of extremophiles often requires specialized techniques and considerations, which are outlined in the manual to ensure accurate identification and classification of these unique organisms.

25. What is the difference between Bergey's Manual of Systematic Bacteriology and Bergey's Manual of Determinative Bacteriology?

Bergey's Manual of Systematic Bacteriology is a comprehensive reference that provides detailed taxonomic information and descriptions of bacterial species. In contrast, Bergey's Manual of Determinative Bacteriology is a more concise guide focused on the identification of unknown bacteria using simplified keys and tables. The Systematic Bacteriology manual is used for in-depth research and classification, while the Determinative Bacteriology manual is more practical for routine laboratory identifications.

26. How does Bergey's classification system handle bacterial endosymbionts?

Bergey's classification system includes information on bacterial endosymbionts, which are bacteria that live within the cells of other organisms. The manual provides details on their unique characteristics, genetic makeup, and host relationships. Classification of endosymbionts often requires special considerations due to their reduced genomes and dependence on host organisms, which are addressed in the manual's guidelines for their identification and classification.

27. How does Bergey's Manual address the classification of bacteria with unusual cell wall structures?

Bergey's Manual provides specific sections for bacteria with unusual cell wall structures, such as Mycoplasma (which lack cell walls) or Archaea (with unique cell wall compositions). The manual details the specific characteristics of these organisms, including their unique structural features, genetic makeup, and biochemical properties. This information is crucial for accurate classification and identification of these atypical bacteria.

28. What is the significance of bacterial plasmids in Bergey's classification system?

Bacterial plasmids, while not directly used for classification, are considered in Bergey's system for their potential impact on bacterial characteristics. The manual includes information on plasmid-borne traits that may affect a bacterium's phenotype, such as antibiotic resistance or metabolic capabilities. This information helps in understanding the full range of a bacterial species' potential characteristics and their implications for classification.

29. How does Bergey's Manual incorporate information on bacterial pathogenicity?

Bergey's Manual includes information on bacterial pathogenicity as part of species descriptions. It provides details on virulence factors, host ranges, and disease associations for pathogenic bacteria. While pathogenicity is not a primary classification criterion, this information is valuable for understanding the clinical significance of different bacterial species and can aid in their identification in medical settings.

30. How does Bergey's Manual address the classification of photosynthetic bacteria?

Bergey's Manual includes specific sections for photosynthetic bacteria, detailing their unique metabolic capabilities, pigment compositions, and genetic characteristics. The classification of these bacteria considers their photosynthetic apparatus, light-harvesting complexes, and carbon fixation mechanisms. This specialized information helps in accurately identifying and classifying various groups of photosynthetic bacteria, including cyanobacteria and purple bacteria.

31. How does Bergey's Manual handle the classification of bacteria with complex life cycles?

Bergey's Manual addresses bacteria with complex life cycles by providing detailed descriptions of their various life stages and morphological changes. This includes information on processes like sporulation, fruiting body formation, and dimorphic growth. The manual considers these complex life cycles in the classification process, ensuring that all stages of a bacterium's life are accounted for in its taxonomic placement.

32. How does Bergey's Manual incorporate information on bacterial biofilms?

While biofilm formation is not a primary classification criterion, Bergey's Manual includes information on bacterial biofilms as part of species descriptions. It provides details on the ability of different species to form biofilms, the characteristics of these biofilms, and their ecological or clinical significance. This information is valuable for understanding the behavior of bacterial species in natural and clinical environments.

33. How does Bergey's Manual address the classification of bacteria with unusual metabolic capabilities?

Bergey's Manual includes specific sections for bacteria with unusual metabolic capabilities, such as extremophiles, chemolithotrophs, and bacteria with unique degradation abilities. The manual provides detailed information on their metabolic pathways, energy sources, and biochemical reactions. This specialized information is crucial for accurately classifying these unique organisms and understanding their ecological roles.

34. How does Bergey's Manual handle the classification of bacteria with horizontal gene transfer?

Bergey's Manual acknowledges the impact of horizontal gene transfer on bacterial classification. It includes information on known instances of gene transfer between species and its effects on bacterial characteristics. The manual emphasizes the importance of using multiple criteria for classification, as horizontal gene transfer can sometimes lead to misleading results if only a single gene or characteristic is considered.

35. What is the significance of bacterial quorum sensing in Bergey's classification?

While quorum sensing is not a primary classification criterion, Bergey's Manual includes information on this phenomenon as part of species descriptions. It provides details on the quorum sensing systems of different bacterial species, their signaling molecules, and the behaviors regulated by these systems. This information contributes to understanding the ecological and pathogenic potential of different bacterial species.

36. How does Bergey's Manual address the classification of bacteria with unusual reproductive methods?

Bergey's Manual includes information on bacteria with unusual reproductive methods, such as budding bacteria or those that reproduce through multiple fission. The manual provides detailed descriptions of these unique reproductive processes and considers them in the overall classification scheme. This information is crucial for accurately identifying and classifying bacteria that deviate from typical binary fission.

37. What is the role of bacterial antibiotic resistance in Bergey's classification system?

Antibiotic resistance patterns are included in Bergey's Manual as part of species descriptions, although they are not primary classification criteria. The manual provides information on known antibiotic resistance profiles of different bacterial species, which can be valuable for clinical identification. However, due to the potential for rapid evolution of antibiotic resistance, this information is used cautiously in classification.

38. How does Bergey's Manual incorporate information on bacterial symbiotic relationships?

Bergey's Manual includes information on bacterial symbiotic relationships as part of species descriptions. It provides details on known symbiotic associations, including mutualistic, commensal, and parasitic relationships. This information is particularly important for understanding the ecological roles of different bacterial species and can provide insights into their evolutionary history and metabolic capabilities.

39. What is the significance of bacterial toxins in Bergey's classification system?

Bacterial toxins are included in Bergey's Manual as part of species descriptions, particularly for pathogenic bacteria. The manual provides information on the types of toxins produced, their mechanisms of action, and their clinical significance. While not a primary classification criterion, toxin production can be an important characteristic for identifying certain bacterial groups, especially in clinical settings.

40. How does Bergey's Manual address the classification of bacteria with unusual nutrient requirements?

Bergey's Manual includes detailed information on bacteria with unusual nutrient requirements, such as auxotrophs or bacteria requiring specific growth factors. The manual provides data on their unique nutritional needs, metabolic pathways, and cultivation requirements. This information is crucial for accurately identifying and classifying these specialized bacteria and understanding their ecological niches.

41. What is the significance of bacterial capsules and slime layers in Bergey's classification?

Bacterial capsules and slime layers are important characteristics in Bergey's classification system. The manual provides information on the presence, composition, and properties of these extracellular structures. These features can be crucial for identifying certain bacterial groups, understanding their virulence potential, and determining their ability to survive in various environments.

42. How does Bergey's Manual address the classification of bacteria with unusual temperature requirements?

Bergey's Manual includes specific sections for bacteria with unusual temperature requirements, such as psychrophiles, thermophiles, and hyperthermophiles. The manual provides detailed information on their temperature ranges for growth, metabolic adaptations, and unique cellular components that allow survival in extreme temperatures. This information is crucial for accurately classifying these specialized bacteria and understanding their ecological roles.

43. What is the role of bacterial fermentation patterns in Bergey's classification system?

Fermentation patterns are important characteristics in Bergey's classification system, particularly for identifying and differentiating among certain bacterial groups. The manual provides detailed information on the fermentation capabilities of different species, including the types of substrates utilized and the end products produced. This information is especially useful for classifying and identifying bacteria in clinical and food microbiology settings.

44. How does Bergey's Manual incorporate information on bacterial magnetotaxis?

Bergey's Manual includes information on magnetotactic bacteria as part of species descriptions. It provides details on the presence and characteristics of magnetosomes, the genes involved in their formation, and the ecological significance of magnetotaxis. While not a primary classification criterion, this unique characteristic is important for identifying and classifying certain bacterial groups, particularly in aquatic environments.

45. How does Bergey's Manual address the classification of bacteria with unusual cell division mechanisms?

Bergey's Manual includes information on bacteria with unusual cell division mechanisms, such as those that divide asymmetrically or through budding. The manual provides detailed descriptions of these unique division processes and considers them in the overall classification scheme. This information is important for accurately identifying and classifying bacteria that deviate from typical binary fission patterns.

46. What is the role of bacterial secondary metabolites in Bergey's classification system?

While secondary metabolites are not primary classification criteria, Bergey's Manual includes information on these compounds as part of species descriptions. The manual provides