Lecture notes in Microbiology

Difference between Bacterial Endotoxin and Exotoxin – Comparison Table


Compare Exotoxin and Endotoxin

Endotoxins vs Exotoxins
(Difference between Bacterial Endotoxin and Exotoxin)

Microbial toxins are noxious substances produced by the microorganisms such as bacteria and fungi in order to promote their pathogenicity and disease-causing process. The microbial toxins usually destroy the host tissue and they facilitate the infection by disabling the host immune system. A disease that results from a specific toxin is denoted as ‘Intoxication’. A toxin is a substance that alters the normal metabolism of host cells with deleterious effects. The term ‘Toxemia’ refers to the condition caused by the toxins that have entered the bloodstream of the host.

The toxins produced by bacteria are categorized into two main categories: (1) Endotoxins and (2) Exotoxins.

More in Microbiology: Lecture Notes, PPTs, MCQs

(1). Endotoxins: They are also called as Lipopolysaccharides or LPS. LPS are present on the outer membrane of the cell wall of Gram-negative bacteria that, under certain circumstances, become toxic to specific hosts. Lipopolysaccharides are called endotoxins because they are bound to the bacterium and they are released only when the bacterial cells lyse.

Lipopolysaccharides Toxin

Continue reading

Lecture notes in Microbiology

Difference between Sterilization and Disinfection – Comparison Table


Compare sterilization and Disinfection

Sterilization vs Disinfection
(Similarities and Differences between Sterilization and Disinfection in Microbiology)

Microbes are present in almost all types of habitats. They are so ubiquitous that the presence of many microbes causes undesirable consequences such as food spoilage and diseases. Thus in many situations, it is mandatory to kill the microbes or inhibit their growth to minimize or completely nullify their destructive activities. Sterilization and Disinfection are the two commonly used methods to kill or inhibit the growth of microbes to avoid their undesirable consequences.

More in Microbiology: Lecture Notes, PPTs, MCQs

Sterilization is a process by which an article, surface or medium is freed of all living microorganisms either in vegetative or in spore state. The materials that have been subjected to the process is said to be Sterile. Usually, the sterilization process is done by physical agents such as heat, steam or radiation.

Disinfection is the use of chemical agents that destroy pathogenic microorganisms. Disinfection reduces the number of microbes to a minimal level so that it is no longer harmful. Disinfection destroys only vegetative cells, not the spores (endospores and fungal spores)

The present post discusses the Similarities and Differences between Sterilization and Disinfection with a Comparison Table.

Continue reading

Lecture notes in Microbiology

Difference between the Cell Wall of Gram Positive and Gram Negative Bacteria


Compare Cell wall Gram Positive and negative

Difference between the Cell Wall of Gram Positive and Gram Negative Bacteria

Most of the bacterial cells are surrounded by a thick rigid cell wall. The cell wall provides shape to the cell and protects the bacteria from changes in the osmotic pressure. Peptidoglycan (murein) is the principal component of the bacterial cell wall and it is responsible for the shape and extreme tough nature of the cell wall.

Based on the characteristics of the cell wall, the bacterial cells are classified into Gram Positive and Gram Negative, primarily based on the classical staining reaction called Gram Staining. In the previous post we have discussed about the Similarities and Differences between Gram Positive and Gram Negative Bacteria. Both Gram positive and Gram negative bacterial possess cell wall, however, their structural organization, chemical and physical properties varies. In general, the cell wall of Gram positive bacteria has simpler chemical structures compared to the Gram negative bacteria. The present post discusses the Differences between the Cell Wall of Gram positive and Gram negative bacteria with a comparison table.

OSC Microbio 03 03 CellWalls

Comparison of the Cell Wall of Gram Positive and Gram Negative Bacteria


Continue reading

Biotechnology Lecture Notes

Batch Fermentation vs Continuous Fermentation Process: Similarities and Differences – A Comparison Table


Difference continuous and batch fermentation

Batch Fermentation vs Continuous Fermentation Process
(Similarities and difference between Batch Fermentation and Continuous Fermentation Process)

Batch Fermentation and Continuous Fermentation are the two commonly adopted Industrial Fermentation methods for the scale production of microbial biomass or metabolites.

Batch Fermentation: Here the fermenter is first filled with the raw material (carbon source). Then the microbes are added and allowed to ferment the raw material under optimum pH and aeration. The products remain in the fermenter until the completion of fermentation. After fermentation, the products are extracted and the fermenter is cleaned and sterilized before next round. Thus here the fermentation is done as separate batches.

Continuous Fermentation: Here the exponential growth rate of the microbes is maintained in the fermenter for prolonged periods of time in by the addition of fresh media are regular intervals. The metabolite or the product of fermentation is extracted for the overflow from the fermenter. Thus unlike batch fermentation, in continuous fermentation, the fermentation process never stops in between and it continues to run for a long period of time with the addition of nutrients and harvesting the metabolites at regular intervals.

The present post describes the Similarities and Differences between Batch Fermentation and Continuous Fermentation Process as a Comparison Table.

Similarities between Batch Culture and Continuous Culture Fermentation Methods

Ø  Both are industrial fermentation methods for the large scale production.

Ø  Both methods can be used for the production of microbial biomass or products.

Ø  Both run under controlled environmental conditions

Ø  The mechanical components of fermenter is almost similar in both types




Difference between Batch Fermentation and Continuous Fermentation Process

Continue reading

Lecture notes in Microbiology

Compare Archaebacteria, Bacteria and Eukaryotes: Similarities and Differences (Table)


comparison chart archaebacteria bacteria and eukaryotes

The Three Domain System of Classification by Carl Woese (1977) based on variations in 16S rRNA sequence, divided the entire living organism in the biosphere into three major groups called Domains namely (1). Archaea, (2). Eubacteria (Bacteria) and (3). Eukarya or Eukaryota. In the earlier systems of classifications, Archaea were treated as a unique type of bacteria called Archaebacteria and they were included in the Kingdom Monera along with true bacteria and Cyanobacteria (blue green algae).  Now we are certain that Archaea possess distinct difference from true bacteria in their cellular structures and metabolic activities, and also they have a unique and separate evolutionary ancestry. Archaea shows some characters similar to true bacteria where as some unique sets of characters they share between eukaryotes. Due to these peculiarities, the group Archaea is now recognized as a distinct domain of life. The present post article describe what all are the similarities and difference between Archaea, Bacteria (eubacteria) and Eukarya (eukaryote) with a comparison table for easy understanding.

Similarities and Differences Between Bacteria, Archaebacteria and Eukaryotes: Comparison Table

Continue reading