Related Experiment Video
Updated: Apr 1, 2026
07:35
Preparation, Imaging, and Quantification of Bacterial Surface Motility Assays
Published on: April 7, 2015
25.4K
A Phase-Variable Surface Layer from the Gut Symbiont Bacteroides thetaiotaomicron
Mao Taketani1, Mohamed S Donia2, Amy N Jacobson2
1Department of Bioengineering and Therapeutic Sciences and California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, California, USA Graduate Group in Infectious Diseases and Immunity, School of Public Health, University of California, Berkeley, Berkeley, California, USA.
Mbio
|October 1, 2015
Summary
Researchers discovered a new protein layer on Bacteroides thetaiotaomicron, a common gut bacteria. This structure helps bacteria resist immune attack, suggesting greater surface variation aids gut colonization.
Area of Science:
- Microbiology
- Immunology
- Host-Microbe Interactions
Background:
- Bacteroides species are common gut symbionts with phase-variable polysaccharide capsules.
- These capsules mediate host-symbiont interactions and immune system modulation.
- Previous understanding suggested limited structural variation within Bacteroides populations.
Purpose of the Study:
- To report the discovery of a novel protein-based surface structure in Bacteroides thetaiotaomicron.
- To investigate the function and characteristics of this previously unknown surface layer.
- To understand the role of structural variation in Bacteroides gut colonization and immune evasion.
Main Methods:
- Characterization of a novel protein, BT1927, in Bacteroides thetaiotaomicron.
- Analysis of phase-variable expression of BT1927 in wild-type cultures.
- Assessment of resistance to complement-mediated killing and C3b deposition in BT1927-expressing subpopulations.
Main Results:
- Discovery of a previously unknown protein surface layer (BT1927) in Bacteroides thetaiotaomicron.
- BT1927 is expressed in a phase-variable manner by a small subpopulation (~1:1,000 cells).
- The BT1927 layer confers resistance to complement-mediated killing by blocking C3b deposition.
Conclusions:
- Bacteroides exhibits greater surface structure variability than previously recognized.
- The novel protein surface layer plays a role in immune evasion and bacterial survival.
- Increased structural variation within Bacteroides species is crucial for effective gut colonization and host immune modulation.
Related Concept Videos
01:26Bacterial Phylum Bacteroidota
861
The phylum Bacteroidota includes over 700 species classified into four primary orders: Bacteroidales, Cytophagales, Flavobacteriales, and Sphingobacteriales. These gram-negative, non-sporulating rods exhibit saccharolytic capabilities and can be aerobic or fermentative, encompassing obligate aerobes, facultative aerobes, and obligate anaerobes. Many species display gliding motility, though some are nonmotile or use flagella. The genus Bacteroides is well-studied due to its significant role in...
861
01:26Bacterial Phylum Planctomycetes
534
Planctomycetes are a group of morphologically distinct bacteria predominantly classified into two orders: Planctomycetales and Brocadiales. These gram-negative bacteria exhibit unique features, including division by budding and the presence of stalks or appendages. Their cells are often found in rosette arrangements, and they are notable for possessing an S-layer in their cell envelope, which is relatively uncommon among bacteria. Additionally, Planctomycetes frequently exhibit intracellular...
534
01:18Surface Membrane Barriers
3.3K
The skin and mucous membranes serve as the primary line of defense against pathogens by providing both physical and chemical protection. These barriers are essential in preventing the entry and establishment of microbes, thereby maintaining the integrity of the host.
The outer layer of the skin, the epidermis, is a robust barrier comprising layers of closely packed keratinized cells. This dense arrangement prevents microbes from penetrating the body. The periodic shedding of epidermal cells...
The outer layer of the skin, the epidermis, is a robust barrier comprising layers of closely packed keratinized cells. This dense arrangement prevents microbes from penetrating the body. The periodic shedding of epidermal cells...
3.3K
01:28Regulation of Bacterial Virulence
36
Pathogenic bacteria employ a range of regulatory mechanisms to modulate the expression of virulence genes in response to environmental and host-derived signals. These mechanisms ensure that virulence factors are expressed only under favorable conditions, thereby optimizing infection and survival strategies.Mechanisms of Virulence RegulationKey regulatory strategies include:Two-Component Systems: These consist of a membrane-bound sensor kinase and a cytoplasmic response regulator. Environmental...
36
01:24Bacterial Phylum Tenericutes
586
The phylum Tenericutes, which includes the single class Mollicutes, comprises bacteria that lack cell walls. The term "Mollicutes" derives from the Latin word mollis, meaning "soft." These organisms are among the smallest known and are commonly referred to as mycoplasmas due to the prominence of the genus Mycoplasma, which includes well-known human pathogens. Despite their inability to stain gram-positively (a result of their lack of cell walls), mycoplasmas are phylogenetically related to the...
586
01:25Microbial Mats
45
Microbial communities forming biofilms and mats represent complex, spatially structured ecosystems where metabolic processes are stratified according to light, oxygen, and nutrient gradients. Biofilms are initial colonization stages, only a few millimeters thick, while mature microbial mats can reach centimeter-scale thickness and display intricate vertical organization. Their structural and functional heterogeneity allows microorganisms to occupy distinct ecological niches within a few...
45