Bacterial growth.docx

Bacteria replicate via binary fission= all clones of each other. Cells rapidly increase in number in favourable conditions e.g. in labs. There can be 2 scales on a microbial growth curve. Logarithmic= produces a straight line Arithmetic= produces a curve. Population growth curve The rate of cell div...

Bacteria replicate via binary fission= all clones of each other. Cells rapidly increase in number in favourable conditions e.g. in labs. There can be 2 scales on a microbial growth curve. Logarithmic= produces a straight line Arithmetic= produces a curve. Population growth curve The rate of cell division changes Lag phase= metabolically active, used nutrients. No change in population Log phase= exponential growth/replication of bacteria. Ideal conditions with lots of nutrients. Stationary phase= used all the resources nutrients. No more replication- plateau. No net change and number of alive= number of dead. Death phase= bacteria start to die due to no nutrients being left. The waste products accumulate and leads to toxic environment. Spectrometer= used to monitor the growing population of bacteria. Chemostatic bacterial growth= regulation of growth environment e.g. controlling pH, nutrients, and temperature. Useful for biotechnology when mass produced. Energy sources Chemotrophs= use chemical sources to produce energy Phototrophs= uses light to fix CO2. Autotrophs= requires only CO2 as a carbon source to photosynthesise. Can synthesesis organic molecules from inorganic molecules. Heterotrophs= require organic forms of carbon therefore cannot synthesise organic molecules form inorganic molecules. Factors that affect growth Environment Essential, minor and micronutrients Ph- has an ideal range of ph for optimum activity. There are some pH extremophiles bacteria such as neutrophiles, acidophiles and alkalinophiles. Temperature must be optimum as well as it effects the growth. Has extremophiles such as hyperthermophiles, mesophiles etc. As the temperature goes up, lag phase decreases and more growth. Water activity= water available for metabolism. Higher water availability supports more microorganism. Oxygen availability- Obligate anaerobe= no oxygen should be present to grow. Obligate aerobe= = must have oxygen present to grow Facultative anaerobe= grow in absence or in presence of oxygen.