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Nutrición,Condiciones de
Cultivo y Fases de
Crecimiento
 Temperatura:
 Psicrófilas: crecen óptimamente en temperaturas
bajas < 20 grados C.
 Mesófilas: crecen óptimamente a temperatura
ambiente > 20- 40 grados C
 Flora normal del cuerpo= comensales
 Termófilas: Crecen a temperaturas altas
pH
 Mayoría Bacterias patógenas: crecen en
ambientes de Ph 6.5- 7.5.
 Algunas toleran ambientes ácidos: flora
gastrointestinal
 Otras como Vibrio cholerae crece en pH
alcalinos.
Requisitos de oxígeno
 Aeróbicos
 Anaeróbicos facultativos
 Microaerofílicos capneicosrequieren
más CO2 que O2
 Anaeróbicos estrictos: oxígeno es letal
Gas Pak System
 GasPak Plus® Hydrogen + CO2 with Safety-
Shielded Integral Palladium Catalyst Strip
For CO2-enriched anaerobic environment.
Enlace
 http://www.microbiologytext.com/index.php
?module=Book&func=displayarticle&art_id=7
5
http://www.monografias.com/trabajos27/cre
cimiento-bacteriano/crecimientobacteriano.shtml#ciclo
http://www.javierhuertas.co
m/PTMA-04-05.html
Phases of Growth
 4 Phases
 1. Lag Phase
 2. Log Phase
 3. Stationary Phase
 4. Death Phase
1. Lag Phase
 Bacteria are first introduced into an




environment or media
Bacteria are “checking out” their
surroundings
cells are very active metabolically
# of cells changes very little
1 hour to several days
2. Log Phase
 Rapid cell growth (exponential growth)
 population doubles every generation
 microbes are sensitive to adverse conditions
 antibiotics
 anti-microbial agents
3. Stationary Phase
 Death rate = rate of reproduction
 cells begin to encounter environmental stress
 lack of nutrients
 lack of water
 not enough space
 metabolic wastes
 oxygen
 pH
Endospores would form now
3. Stationary Phase
 Death rate = rate of reproduction
 cells begin to encounter environmental stress
 lack of nutrients
 lack of water
 not enough space
 metabolic wastes
 oxygen
 pH
Endospores would form now
4. Death Phase
 Death rate > rate of reproduction
 Due to limiting factors in the environment
Curva de Crecimiento
Tiempo de Generación
 G= (t min) (log 2)/ log Bt – log B0
Ejemplo:
t= 135 min
Log 2=
Bt= 4.5 X 10 8
B0= 2.83X 10 7
G= 135 min X o.301/ 8.65- 7.45
G= 33. 8 min
Calcular factor de dilución
 Factor de dilución= ct + cb/ ct X cs
Ejemplo:
Si transfieres o.1 ml en 99.9 ml de agua y
siembras 0.1ml, el factor de dilución es:
0.1ml + 99.9 ml/ 0.1 ml X 0.1 ml
100/.01 =
FD= 10,000
Metabolismo
 Autótrofos: producen su propio alimento
 Fotosintéticos
 CO2+ 2H2A CH2O + 2A
Ejs:
CO2 + 2 H2S  CH2O + H2O + 2S
CO2 + 2S + 5 H2O  3 CH2O + 2 H2SO4
CO2 + 2H2  CH2O + H2O
Autótrofos NO fotosintéticos
 Thiobacillus: ( Oxida azufre)
2S + 3O2 + 2 H2O  2 H2SO4
 Nitrosomonas: ( Oxida amonio)
2NH4Cl + 3O2  2 HNO2 + 2 HCl + 2 H2O
 Nitrobacter ( oxida nitritos)
2 NaNO2 + O2  2 NaNO3
Metabolismo Heterótrofo
 Atacan materia preformada.
 Catabolizan moléculas
 Veamos el metabolismo de glucosa
GLUCOLISIS= EMBDEN MEYERHOFF
PATHWAY
Figure 9.9 A closer look at glycolysis: energy investment phase (Layer 2)
Figure 9.9 A closer look at glycolysis: energy payoff phase (Layer 3)
Figure 9.9 A closer look at glycolysis: energy payoff phase (Layer 4)
Figure 9.8 The energy input and output of glycolysis