Related Experiment Video
Updated: Jun 19, 2026
09:25
Implementation of a Permeable Membrane Insert-based Infection System to Study the Effects of Secreted Bacterial Toxins on Mammalian Host Cells
Published on: August 19, 2016
BIOLOGICAL AND PHYSICAL PROPERTIES OF THE HEMOTOXIN OF STREPTOCOCCI
1Department of Bacteriology of the School of Hygiene and Public Health, the Johns Hopkins University, Baltimore.
The Journal of Experimental Medicine
|October 30, 2009
Summary
Streptococcus hemotoxin is a fragile substance released into the culture medium, requiring specific nutrients like phosphorus and an unknown component for its production.
Area of Science:
- Microbiology
- Biochemistry
Background:
- Streptococcus produces a hemotoxin affecting red blood cells.
- The nature and production requirements of this hemotoxin are not fully understood.
Purpose of the Study:
- To investigate the characteristics and production conditions of Streptococcus hemotoxin.
- To identify essential components for hemotoxin elaboration.
Main Methods:
- Assessing hemotoxin stability through physical manipulation (centrifugation, shaking).
- Investigating adsorption properties with various substances.
- Determining optimal hydrogen ion concentration for production.
- Analyzing medium components essential for hemotoxin elaboration.
- Characterizing the unknown essential component through solubility and heat/filter stability tests.
Main Results:
- Hemotoxin is a labile substance, sensitive to physical stress.
- It is released extracellularly into the culture medium.
- Production occurs over a broad pH range.
- Phosphorus and an unidentified, water-soluble substance are crucial for hemotoxin formation.
- The unknown component is heat-labile and can be partially removed by diatomaceous filtration.
Conclusions:
- Streptococcus hemotoxin is an extracellular, labile substance.
- Its production is dependent on specific medium components, including phosphorus and a novel, heat-sensitive factor.
- Further characterization of the unknown component is warranted.
Related Concept Videos
01:20Determinants of Bacterial Pathogenicity and Virulence
Pathogenic bacteria employ a variety of strategies to establish infections, including the secretion of extracellular enzymes that act as potent virulence factors. These enzymes facilitate bacterial colonization of host tissues and help evade immune surveillance. By targeting structural components of host tissues and interfering with immune mechanisms, these enzymes play a pivotal role in disease progression.Extracellular Enzymes Facilitating Tissue Invasion: Several bacterial pathogens secrete...
01:12Bacterial Toxins
Bacterial toxins are sophisticated virulence factors that enable pathogenic bacteria to interact with, invade, and damage host tissues. These toxins fall broadly into two types: protein exotoxins, which are secreted into the environment and target specific host receptors, and lipopolysaccharide endotoxins, which are structural components of the bacterial outer membrane released primarily during bacterial lysis or membrane shedding. Exotoxins generally act more selectively, binding to cell...
01:25Inhibitors of Bacterial Protein Synthesis
Aminoglycosides constitute a highly potent class of bactericidal antibiotics that exert their antimicrobial effects by targeting the bacterial ribosome, specifically disrupting protein synthesis. These polycationic molecules consist of amino-modified sugars linked via glycosidic bonds to an aminocyclitol core such as 2-deoxystreptamine or streptamine. Their strong positive charges facilitate tight binding to the negatively charged phosphate backbone of ribosomal RNA (rRNA), primarily at the 16S...
01:13Special Staining Techniques
Specialized staining techniques play a vital role in microbiology by enabling the visualization of specific bacterial structures that remain undetectable with standard microscopy methods. These techniques not only enhance the structural visualization of bacterial cells but also provide critical insights into their pathogenicity and classification. Additionally, they support diagnostic and research endeavors in microbiology by identifying key bacterial features.Capsule Staining for Virulence...
01:29Staphylococcal Skin Infections
Staphylococcus aureus is a Gram-positive coccus that resides harmlessly on the skin and mucous membranes of healthy individuals. When the skin barrier is breached, it can shift from a commensal to an opportunistic pathogen. This transition is facilitated by surface adhesins, such as clumping factor B and S. aureus surface protein G (SasG), which bind to structural proteins, including loricrin and cytokeratin, in the damaged epidermis. Protein A, another key factor, binds the Fc region of...
01:18Bacterial Gastroenteritis
Bacterial gastroenteritis, characterized by diarrhea, abdominal cramps, and vomiting, is often caused by ingestion of contaminated food or water and is frequently associated with pathogenic Escherichia coli strains. These microbes exploit two principal mechanisms to inflict disease.Shiga toxin–producing E. coli, also referred to as STEC—notably O157:H7—release Shiga toxins that target ribosomes, blocking protein synthesis. The B subunit of the toxin binds the host glycolipid receptor...