EBIO 3400 1st Edition Lecture 19 Outline of Last Lecture I. Review for Exam 2Outline of Current Lecture II. The Human Microbiome III. Early Observations IV. The Human Microbiome cont..V. SkinVI. MouthVII. StomachCurrent LectureI. The Human Microbiome- Our world is a microbial worldA. Multicellular lineages (eucarya) are rare, not diverse as measured by the SSU rRNA so basically: Extract the DNA amplify that part marker, sequence it [don’t have to culture every sample] just sequence them and get the bases of the DNA to get a better idea of what is going on out thereB. Most molecular diversity can be found in microbesC. Most (99%+) microbes can’t be cultured: known only from sequencesD. Microbes are ubiquitous and are important for playing a driving role in many servicesin ecosystems processes - Regulation the outbreaks of diseases, or regulation of climate, carbon cycles, water quality, etc - Loss of ecosystem processes will lose some diversity of microbial communities II. Early Observations: body crowded with life A. E. Coli is thought of as a classic gut microbe and that is because is it easy to grow in captivity i.e cultured in the lab unlike other microbes B. Surprisingly, any two humans you pick have 99.9% identical genomes meaning you are not a unique snowflake however your microbial symbionts are in other 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.words they become unique when we have compare the microbes genes in our bodies III. The Human Microbiome Cont.. A. The normal microbiota: live on or within humans, typically are non-pathogenic, commensals or mutualists (derive benefit from the host but do not harm the host), vary with type of tissue, condition, can cause disease if reach abnormal location or are thrown off “balance” - If thrown on balance: too much sugar consumption, wrong diet and sacrifice their function that they provide for us B. Different body habitats are very different from one another: A microbial community from mouth of two individuals is more similar in other words yours and my mouth community is very similar but my mouth and gut community are very different- Tight communities in mouth and gut (more more specific compared to skin community (variable) - So your skin community and my skin community are very different - Takes about 6 months to a year to restore our ecosystem after antibiotic treatment C. Main reservoirs in human body: mouth, GI tract and skin D. More bacteria in our gut than all of our cells in our body!E. Skin microbes: Not all microbes can function in certain areas of the skin, Production of salt and sweat glands, draw water away from microbes: subcutaneous, anti-microbial compounds like lysosomes that dissolve some microbes, Moisture loving microbes cant live in subcutaneous, Very selective for very specific microbes IV. SkinA. The skin is difficult to colonize.- Dry, salty, acidic, protective oilsB. Most microbes in moist areas- Scalp, ears, armpits, genital and anal areasC. Mostly Gram-positive bacteria- More resistant to salt and dryness- Staphylococcus epidermidis- Propionibacterium acnesC. Skin is not uniform meaning that there are many variables that vary among organisms and conditions: pH, moisture availability, temperature, UV exposure, O2/CO2* These variables Regulate potential lifestyles of some microbes - Skin pH averages 5.5 (in adults), 7.0 (in children)- Acidity due to sebum (fatty acids and triglycerides) production and fermentation (to short fatty acids and priopionic acid) by Priopionibacterium acnes - Excessive production of oils in adolescence leads to excessive production of fatty acids that may block the sebum channels. An increased bacterial abundance may trigger inflammation (immune system response process) Note: Hand washing removes: - 90% of transient bacteria- 40% of resident bacteria- Presence of skin microbiome inhibits infection by Staphylococcus aureusV. Mouth 1010 bacterial cells500 – 1000 bacterial ‘species’ per mouthHuman’s infant mouth is colonized with nonpathogenic:A. Dominant ones -Neisseria (G-negative cocci)-Streptococcus and Lactobacillus (G-positive rods)B. As teeth emerge (anaerobic space), other bacteria grow-Prevotella and Fusabacterium: between gums and teeth-Streptococcus mutans: attached to tooth enamelC. Organisms must survive: -Mechanical removal by adhering to gums and teeth-Chemistry of saliva (1 – 100 mL/hr) that contains lysozymes, lactoferrin, antimicrobial compoundsVI. Stomach Few bacteria (low pH, swift passage)- Exception: Helicobacter pylori -Found in >60% of adults-Gram-negative microaerophile-Grows best at pH 6 but survives at pH 1-Burrows into gastric epithelium* The causing agent of ulcers and potentially stomach cancers: Heliobacter pylori under certain circumstances can become seriously negative Note: Most bacteria cannot survive passage through stomach (low pH)This is because: In the 1950’s, U.S. Army tested cholera vaccinesPathogenic V. cholerae was administered to healthy volunteers, few contracted choleraCholera can be very high among malnourished individuals..Why?Healthy diet then produces a lot of hydrochloric acid so pH is really low so cannot let the vibrio survive so this is called - achlorhydria (loss of stomach acid) due to poor