Microbial GrowthF08

Microbial GrowthF08

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Unformatted text preview: - u nabl e to use O2 – L ack detoxi fyi ng enzymes • AEROT OLOERAN T AN AEROBE - d oes not use O2 but can gr ow i n i t’s pr esence (1 – 2% O2) • M I CROAEROPH I LE - r equi r es l ess O2 – Needs 5-10% CO2 t o i ni ti ate gr owth T he Effect of Oxygen (O2) on Gr owth Table 6.1 Table 6.1 T oxi c For ms of Oxygen • Si ngl et oxygen: O2 boosted to a hi gher -ener gy state − • Super oxi de fr ee r adi cal s: O2 Per oxi de: O22− O 2 : G ood or Ba d? • Rea cti ve a nd T oxi c bypr oducts – H i ghl y unstabl e al l owi ng them to steal el ectr ons fr om n ear by mol ecul es – Si ngl et Oxygen .– Super oxi de fr ee r adi cal (O2 ) Per oxi de (O2-2) – – H ydr oxyl • D etoxi fyi ng enzymes – SOD: Super oxi de di smutase .Conver ts 2 O2 + 2H + O2 + H 2O2 • – Catal ase • Conver ts H 2O2 O2 + 2 H 2O – Per oxi dase + B I OFI LM S • I n natur e most mi cr obes l i ve i n communi ti es of bi ofi l ms. • These bi ofi l ms l i ve i n a hyr ogel of pol ysaccahr i des, pr otei ns, and DNA • The communi cati on between the cel l s, quor um sensi ng, al l ows them to coor di nate for a mor e benfi ci al envi r onment for thei r sur vi val • Wi thi n thi s communi ty the var i ous bacter i a shar e n utr i ents, avoi d desi ccati on, r esi st anti bi oti cs and i mmune system Bi ofi l ms • M i cr obi al communi ti es • For m sl i me or h ydr ogel s – Bacter i a attr acted by chemi cal s vi a quor um sensi ng Figure 6.5 Bi ofi l ms • Shar e nutr i ents • Shel ter ed fr om h ar mful factor s Applications of Microbiology, p. 57 B I OFI LM S • Thi s bi ofi l m star ts as a si ngl e pl anktoni c or gani sms attaches to a sol i d sur face • They gr ow i n pi l l ar l i ke str uctur es wi th channel s between t hem for better sur vi val • They wor k i n cooper ati on to car r y out compl ex tasks • These bi ofi l ms ar e ver y i mpor tant i n di sease pathogenesi s because they ar e 100ox mor e r esi stant to anti bi oti cs and m i cr obi ci des • Nosocomi al i nfecti ons, catheter s, contact l enses, pl aque etc… • Pr eventi on of bi ofi l ms needs: i ntr oduci ng anti bi oti cs i nto t he sur face, i nhi bi ti ng quor um sensi ng, or l actofer r i n that bi nds i r on and i nhi bi ts aggr egati on i n a bi ofi l m. B ACT ERI AL GROWT H & D I VI SI ON ...
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This note was uploaded on 01/30/2011 for the course BIOL 246 taught by Professor Kocache during the Spring '10 term at George Mason.

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