EBIO 3400 1st Edition Lecture 20 Outline of Last Lecture I. The Human MicrobiomeII. Early ObservationsIII. The Human Microbiome Cont..IV. SkinV. MouthVI. Stomach Outline of Current Lecture VII. Small Intestine v. Large IntestineVIII. Bacterial prevalence IX. Germ-free or gnotobiotic mice X. Intestine’s microbial population XI. ProteobacteriaCurrent LectureI. Small Intestine v. Large Intestine Small intestine: Some bacteria reside that have low pH, short transit time, antimicrobial compounds A. Large Intestine: long transit time (10 – 100 hours), anaerobic, 1-2 kg of microbes, >1000 bacterial and archaeal species (most uncultivable, undescribed), 60% of fecal mass = microbial cells (1010 cells per g feces), 1000 anaerobes (e.g. Bacteroides thetaiotaomicron) : 1 aerobe (e.g. Escherichia coli), Mostly obligate (oxygen kills it, lethal) anaerobic as seen in the Firmicutes and BacteroidetesB. More efficient through microbes to break down energy C. E. Coli plays a role in recycling the products and materials that we naturally produce These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.II. Bacterial prevalence A. Only 13% of palm bacterial species are shared between any two individualsB. Identify keyboards by their owners, Bacteria helps with forensic tools, Can get different communities of microbes from touching a keyboardC. Natural vaginal birth or C-section delivery: Depending on the delivery of the infant, natural or c-section- Infants in the womb are sterile/no associated microbiome, first inoculum comesfrom the mother (first source of microbial community) -Skin and vaginal microbiomes are very different- Infants delivered more naturally inherent are inoculated with large component microbiome of the vaginal canal- Infants from C-section are devoid of those types of microbes and have more skin microbiome - Very different microbiome when an infant than when an adult - Lack of microbiome that usually come from natural delivery effect how the microbiome are formed later in life - Help with healthy immune, nervous health - Breast milk also contains bacteria and babies that don’t get those from breast milk or vaginal microbiome are exposed to more infections III. Germ-free or gnotobiotic mice Gnotobiotic mice: Abilities to raise and maintain these mice in completely sterile conditions (no bacteria) - Every optimal things that they might require in their environment: food, vitamins, oxygen, comfort without their microbiome do show diminished functioning Characteristics: lower metabolic rate, higher susceptibility to pathogens, vitamin deficiencies, less efficient digestion, limited intestinal cell growthA. Study: Obesity alters gut microbial ecology What is it driven by? Selected genetically different types of mice that are characterized by the lean phenotype and ones that are exposed to the obese phenotype and introduced microbial human microbiomes that came from lean phenotypes. The genetics had an important aspect on microbial community, started with same microbes and food type eventually the obese mice modified through the genetics of their microbial communities that they were a significant increase of firmicutes microbes and less bacteriodetes. These microbes in firmicutes are the ones that have the better capability of extracting more energy from the food rather than under normal circumstances. Can be the obese phenotype that was delivered as genetic basics but works through the modification of the microbial community B. Study: Effect of diet on the human gut microbiome: Exposed them to different diet. A lean diet low fat protein vs. the westernized diet high in fat and high insugars. Inoculated with just the lean microbiome for both instances. Obese phenotype is generated disregarded of the genetic influence just by the diet. Results: increase level of firmicutes and decreased suppression of bacteriodetes IV. Intestine’s microbial population - Complex but balanced - Antibiotic therapy disrupts this balance and may lead to poor digestion or disease.- Example: Pseudomembranous colitis, which is caused by Clostridium difficile- Fecal transplants restore health V. ProteobacteriaConsists of five major classes and have diverse metabolisms - All share a common structure—their triple-layered Gram-negative cell envelope =Outer membrane, cell wall (periplasm), and cell membrane- Largest cultured group of bacteria - 380 genera & at least 1500 species- 5 classes: Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria, Deltaproteobacteria,
View Full Document
Unlocking...