EBIO 3400 1st Edition Lecture 21Outline of Last Lecture I. Small Intestine v. Large IntestineII. Bacterial prevalence III. Germ-free or gnotobiotic mice IV. Intestine’s microbial population V. ProteobacteriaOutline of Current Lecture II. AlphaproteobacteriaIII. GammaproteobacteriaIV. BetaproteobacteriaCurrent LectureI. AlphaproteobacteriaA. Rickettsias: intracellular pathogens, clade includes mitochondria, very reduced genomes, obligate parasites and pathogens- Rickettsia rickettsii - Rocky Mountain spotted fever- 4 main genera: Rickettsia, Orienta, EhrlichiaandAnaplasma- Ehrlichiachaffeensis and Ehrlichiaequi - emerging diseases in the USAB. Endosymbionts: Nitrogen fixers inside plant root nodules, Rhizobium and Sinorhizobium- Very important in agriculture world wide - Any plant in legume family in wild have nodules on the rootsbut here the nodules are getting fed amino acids and feeding the plant organic compounds so they help each other- Living cells with bacteria inside of them: nodules C. Rhizobia are Alphaproteobactria - symbionts in root nodules of plants; fix nitrogen- Genera:Rhizobium spp. symbionts of pea, beans, clover etc..Sinorhizobium spp.symbionts of alfalfa etc..Bradyrhizobium spp.symbionts of soybeans etc..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.- Each species of bacterium is specific to a species of plants- Related to: Agrobacterium – but Agrobacteriumdoes not stimulate root nodule formation or fix nitrogen. Instead, these bacteria invade plant tissues and cause tumors - crown gall disease.D. Photoheterotrophs: generally unicellular, Rhodobacter sphaeroidesE. Oligotrophs: adapted to very low nutrient content ex: CaulobactercrescentusF. The Rhodospirillales: Anoxygenic photosynthesis. Can use sulfide for photosynthesis, but inhibited by high concentrations, can be chemoheterotrophs photoautotrophs or photoheterotrophs under the right conditionsII. Gammaproteobacteria (Disease causing group closely related to beta: monophyletic)- Incredibly diverse, largest group of Proteobacteria- Many familiar genera - Escherichia, Salmonella, Pseudomonas, Vibrio, YersiniaA. Enterobacteriaceae: Rods, grow singly, in chains, or in biofilms, use aerobic or anaerobic respiration and fermentation- Like Escherichia coli: can switch from aerobic,anaerobic, to fermentation depending on where it is- Some strains grow normally in the intestine.- Others, such as E. coli O157:H7, cause serious illness, especially in childrenB. Aerobic rods: Pseudomonas species have polar flagella and are vigorous swimmers-May give up motility and develop biofilms-Legionella pneumophila-Grows intracellularly within macrophages and freshwater amoeba’sC. Vibrios: are very common inhabitants of ocean and estuary waters. Many are symbiotic with fish and squid and some cause diseases:Vibrio cholerae– cholera: facultative aerobe (can ferment sugars) and it is often found attached to plankton (including copepods) in the ocean..Thus, it leads a double life (as do many vibrios and enterobacteria) and is endemic in most of S. America, India, SE Asia, Africa and even the gulf coast of the USA..Grows best at high pHs and is killed in stomach of healthy people – malnurished people have higher stomach pH and thus are more suseptible...Most often spread to humans via contaminated water or shellfishVibrio parahaemolyticus - similar to cholera - caused by eating contaminated shellfishD. Sulfur lithotrophs: Beggiatoa Oxidize H2S to sulfur, which collects as periplasmic granulesE. Enterobacteriaceae:Proteus species are heavily flagellated. Display a remarkable swarming behavior: aids in moving up urethra. Involved in bladder and kidney infectionsIII. BetaproteobacteriaA. Nitrifiers oxidize ammonia to nitrite- Nitrosomonas: used in wastewater treatment- Sulfur and iron oxidizers like: - ThiobacillusB. Pathogens- Neisseria gonorrhoeae(humans)- Burkholderiacepacia(animals and plants)C. Burkholderiales: Burkholderiacepacia (also called B. cenocepacia) very metabolically diverse - very large genome (8 Mb), opportunistic pathogen in hospitals (nosocomial infections) especially in Cystic Fibrosis patients, very similar in capabilities toPseudomonas aeruginosa-OtherBurkholderiasppSeveral disease causing species, esp. in the tropics- Burkholderiapseudomallei - causes Melioidosis - fever, pneumonia usually in immuno-suppressed patients - biggest risk factor is diabetes and in those who work with tropical soils (farmers)D. Bordetella pertussis - whooping cough, small aerobic gram negative rods, primarily affects children, very common worldwide (60 million cases and 500,000deaths per year), > 20,000 cases per year in USA, recent increase in cases in the U.S. due to lapses in vaccination, about 1000 cases per year in Colorado (several recent deaths..…) - Highly contagious (infects 90% of exposed
View Full Document