Microbiology 101 Week 8 Lecture Notes
Microbiology 101 Week 8 Lecture Notes 101.0
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This 5 page Class Notes was uploaded by Isabel Markowski on Friday November 6, 2015. The Class Notes belongs to 101.0 at University of Wisconsin - Madison taught by a professor in Fall 2015. Since its upload, it has received 40 views. For similar materials see General Microbiology in Microbiology at University of Wisconsin - Madison.
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Date Created: 11/06/15
Microbiology 101 Week 8 Notes Molecular Mechanisms of Antibiotic Resistance to BLactams review 0 Mutation in o Porin gene reduced permeability o Transpeptidase gene reduced binding 0 Mutation increase production of efflux pump gene regulation 0 Gene Acquisition get new 0 Gene encoding degradative enzyme Blactamase destroy antibiotic I Blactamase breaks bond of Blactam ring of penicillin disable I Narrow spectrum broad spectrum and extended spectrum I Penicillin resistance 0 Gene encoding new transpeptidase MecA aren t inhibited by antibiotics Start of this 0 Gene encoding efflux pump acquires from horizontal gene transfer week39s 0 BetaLactamase inhibitors materia 39 o Clavulanate sulbactam tazobatam o Bind to enzyme that destroys Blactam antibiotics and inhibits function 0 Are NOT antibacterial themselves 0 Combination drugs I inhibitor antibiotic ex Augmentin clavulanate amoxicillin 0 Target replacement 0 Transpeptidases natural target of Blactams aka Penicillin Binding Proteins o MecA protein backup transpeptidase enzyme I Does NOT bind to Blactam drugs 0 Cells containing MecA may be resistant to Blactams Protein can continue to function despite antibiotic presence 0 S Aureus with MecA is MRSA methicillin resistant staphylococcus aureus I Not easily treatable because microbe now has new MecA gene 0 Quinolones o Mutation porin gene gyrasetopoisomerase genes increased production efflux pump 0 Gene acquisition I Gene encoding protective protein binds to gyrasetopoisomerase prevents antibiotic binding I Gene encoding degradative enzyme I Gene encoding efflux pump Combating Antibiotic Resistance 0 New Drugs 0 Will still have limited useful life 0 Focus on narrow spectrum specific species antibiotics 0 Less antibiotic use 0 Decreased selective pressure for resistance 0 Combination therapy 0 Surveillance to limit spread 0 Take extra measure when dealing with resistant strains 0 Infection prevention 0 Infection control by other methods vaccines bacteriophage bacterial viruses Microbial Interactions Terminology o Symobiosis intimate association of 2more different species original term does NOT imply benefit or detriment Mutualism Commensalism Amensalism Benefits both benefits one partner benefits one partner Other unaffected Other harmed Synergism Parasitism Cooperation Predation Pathogenesis MicrobeMicrobe Interactions o Lichens o Symbiotic organisms 0 Neither partner alone can colonizegrow without other I Allows growth of partners in environments where neither would succeed usually 0 Fungus typically filamentous fungal hyphae and phototroph agla or cyanobacterium o Symbiotic functions I Mycobiont heterotroph provides protection from desiccation and access to minerals N P I Photobiont photoautotroph provides fixed carbon PlantMicrobe Interactions o All exposed parts of plants colonized by microbes 0 Plants actively manipulate these surfaces to promote beneficial microbial interactions 0 Ex rhizosphere the root zone I Plants secrete 10 of total photosynthate in soil 0 NitrogenFixingInteractions o quotRhizobiaquot and legumes greater legume growth with quotRhizobiaquot I Nodules symbiotic organs filled with Nfixing bacteria home I New organs induced by plantmicrobe relationship 39 N2 gt 2NH3 Nodule Formation Legumes gt Secrete flavonoids Rhizobia secrete nod factors gt Rhizobia invade gt Nodule formation plant roots amp Nfixation Nod factors are lipochitinoligosaccharides Different flavonoids different species Variety structures Send signals back and forth Flavonoids released by root hairs attract Rhizobia o Bacteroids Leela 0 Nodule forms from rapidly dividing cortex cells o Rhizobia inside root hair cause infection thread to form 0 Infection thread grows buds off releases Rhizobia inside cortex cells I Bacteria differentiate into bacteroids capable of Nfixation provide N to plants I Intracellular but compartmentalized I Nitrogen metabolism I Reductive process so need ATP source and electron source 0 Bacteria need to acquire sources 0 O O O 0 Carbon metabolism Plant provides carbon to bacteroid usually acids Electrons either go through citric acid cycle ATP or straight to Nreduction Need electron acceptor aerobic respiration Obligate Aerobes Need organic acids from plants and oxygen source 0 Problem oxygen toxic to nitrogenase enzymes of Nfixation o Mychorrhizallnteractions O 0 Energy metabolism Plant solution produce Leghemoglobin Lb bind to O deliver to electron transport chain and keep away from nitrogenase enzymes Nodules contain Lb Mutualistic relationship 0 Fungi associate with plant roots mutualistic beneficial 0 Most terrestrial plants have mycorrhizal infection o 2 categories Ectomvcorrhizae Endomycorrhizae 0 outside coating over surface of 0 inside invade plant tissue to expand root surface area of interaction 0 Colonize the rhizoplane 0 Send hyphae into plant root cells 0 Ex truffles branching growths to form arbuscles 0 Function NutrientMetabolic exchange I Fungi can t fix N only bacteriaarchaea Fixed N exchanged for N and Phosphorus I Fungus takes N from soil gt plant I Plant provides carbon I All fungi heterotrophs can t fix carbon by themselves 0 Greatly extends available soil volume for plant I Longextending fungal hyphaemycelia AnimalMicrobe Interactions Autotrophs provide carbon source to their animal hosts Heterotrophs degrade plant materials for host quotto eat Microbes affect animal behavior fertility appearance reproduction etc 0 Some use biosynthetic capacity provide amino acidsvitamins 0 Some fix N for hosts 0 Some produce antibiotics Heterotrophic Microbes 0 Feed herbivore hosts 0 Carnivores minimal accommodations for microbes meat less work 0 Herbivores extensive accommodations larger cecum longer large intestine plant material hard to digest for animals lack degradative enzymes I Digesting hemicellulose cellulose lignin by microbes o Herbivores outsource food degradation to microbes Foregut Fermentation chamber 0r Hindgut Fermentation chamber ex ruminants monkeys ex cecal primates rodents Microbial Metabolism in Herbivores o Cellulose Degradation 0 Actual nutrients short chain fatty acids waste products of fermentation o Cellulolytic microbes abundant in nature some fungi bacteria and protists o Freeliving cellulose degraders soil sewage compost 0 Form animal partnerships 0 Systems Aerobic Secrete extracellular enzymes to degrade cellulose Glucanases chew from ends Endoglucanases cut in internal amorphous regions to create more ends for glucanases o Bglucosidases degrade oligosaccharides Anaerobic Produce cell surface associated structure cellulosomes to degrade cellulose Very efficient Scaffoldin protein attaches to own cell wallcellulose Cellulose degrading enzymes attach to scaffoldin within dockerin domains o Fermentation 0 Primary fermentation ferm Products include SCFA succinate short chain alcohols lactase methane Hgas C02 formate 0 Secondary fermentation Acetogens and Methanogens convert H2 and C02 to acetate and methane I 2quot l step bacteriaconversion after fermentation o Ruminants o Rumen microbial fermentation vat I Microbes bacteria archaea fungi protists viruses I Anaerobic I Neutral pH 0 Key ferm end products actetae propionate butyrate animal gets nutrients from these 0 Other ferm end products C02 and Methane released to environment 0 Changes in rumen microbiota can affect animal health I Abrupt change from forage cellulose diet to grain starch diet I Streptococcus bovis can use starch rapidly produce large amounts of lactic acid I Acidification of rumen acidosis may occur 0 Can lead to rumen inflammation acidification of blood and death