· Characteristics of lag phase· (1) Growth rate constant: R=O;· (2) Cells become larger or longer;· (3) RNA content elevated;: (4) Anabolism blossom;· (5)Sensitive to NaCl,high-temperature andantibiotics;
• Characteristics of lag phase • (1) Growth rate constant: R=0; • (2) Cells become larger or longer; • (3) RNA content elevated; • (4) Anabolism blossom; • (5) Sensitive to NaCl, high-temperature and antibiotics;
? Factors affecting the length of lagphase·(1) Cell age/菌龄.·（2)Inoculum size/接种量培养时间/h图6-2接种量对延滞期的影响1.大接种量，2.中等接种量，3.小接种量·（3）Mediumcomponent/培养基成分·（4)Degree of injury/损伤程度
• Factors affecting the length of lag phase • (1) Cell age/菌龄 • (2) Inoculum size/接种量 • (3) Medium component/培养基成分 • (4) Degree of injury/损伤程度
2.2.2 Exponential phase At this phase, microorganisms are growingand dividing at the maximal rate possiblegiven their genetic potential, the nature of themedium, and the environmental conditionsStationaryphaseExpbnential (log)ieaphateDeathphaseLagphaseTime
• 2.2.2 Exponential phase • At this phase, microorganisms are growing and dividing at the maximal rate possible given their genetic potential, the nature of the medium, and the environmental conditions
· Characteristics of the Exp. phase3.00(log phase)Exponential (log)ahase2.00(1)R=maximum;Generation time1.00Calculation ofthe growth rateconstantCalculation of generation (doubling) timeIfa population doubles, thenLet N, the initial population numberN,=2N,N, the population at timet0.50Substitute2N, into thegrowthrate Constant equation andnthe numberof generations in timetsolveforFor populations reproducing by binary fissionklog(2N)-logNe_log2+logNe-logNN,-NoX20.301g0.301gSovingfor n,thenumberofgenerations, whereallogarithmsk-are to the base 10,log N,=log No+n-log 2,andThe generation time Is the reciprocal of the growth rate con#logN.ogNa_logN.logNstantDR20301一是The growth rate constant (k) is the number of generations peLag phaseunittime(HThusnJogN,-logN0.1020· (2) Blanced growth;Time (hours)·(3)Exuberant metabolism/代谢旺盛;
• Characteristics of the Exp. phase (log phase) • (1) R=maximum; • Generation time • (2) Blanced growth; • (3) Exuberant metabolism/代谢旺盛;
. Three important parameters·（1)Generations/繁殖代数·(2)Growth rate constant(R)/生长速率常数·(3)Generation time/代时
• Three important parameters • (1) Generations/繁殖代数 • (2) Growth rate constant (R)/生长速率常数 • (3) Generation time/代时