Bacteria's life

Before we meet every different bacteria, we have to know their life.

‧Reproduction

Unlike multicellular organisms, increases in the size of bacteria (cell growth) and their reproduction by cell division are tightly linked in unicellular organisms. Bacteria grow to a fixed size and then reproduce through binary fission, a form of asexual reproduction.

The following is the process of bacteria' s cell divide:

1. Cell elongates and DNA is replicated
2. Cell wall and plasma membrane begin to divide
3. Cross-wall forms completely around divided DNA
4. Cells separate

picture from:http://www.uic.edu/classes/bios/bios100/lecturesf04am/binfission.jpg

There is also a video, this is about the bacteria growth. Show you how bacteria divide. http://tw.youtube.com/watch?v=gEwzDydciWc

‧Phases of growth

According to the life of bacteria, we can plot a bacterial growth curve to show the change in over time. There are four bacis phases of growth: the lag, log, stationary, and death phases.

-Lag phase: production of new enzymes needed for growth
-Log phase: maximum growth
-Stationary phase: growth = death; nutrients or waste products limiting growth
-Death phase: death > growth; lack of nutrients or accumulation of waste products killing cells

picture from:http://microvet.arizona.edu/Courses/MIC205/Exams/05Exams/06-14_BacteriaGrowth_1.jpg

Who live in the small world？

In this small world, there are three main cultures live in. So, who are they?

‧Bacteria
It belong to prokaryotic species. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods to spirals. Bacteria could live in many place, for instance, acidic hot spring, sea water, and soil. Every bacteria have their own growth range. Bacteria are vital in recycling nutrients, and many important steps in nutrient cycles depend on bacteria, such as the fixation of nitrogen from the atmosphere.



This is a video about the characterization and classification of bacteria
cited from: http://tw.youtube.com/watch?v=RrTjOrzva3I





‧Molds 　
It belong to eukaryotic species and in the kingdom fungi. The normal fungi that we know just like champignon and mushroom. Some molds cause disease or food spoilage, others are useful for their role in biodegradation or in the production of various foods, beverages, antibiotics and enzymes.




‧Yeast 　
It belong to eukaryotic species and also in the kigdom fungi. Just like molds, yeasts will make food spoliage or be pathogenic yeasts. On the other hands, in food industry, it is a very useful cultures to ferment sugars to make many different food. Baker's yeast in bread production, brewer's yeast in beer fermentation.