An understanding of what and how microbes do things depends upon our ability to grow the organisms in the laboratory. In order to culture them, we must provide them with proper food and environmental conditions, isolate them and maintain them in pure culture clone.
Tweet cell temperature carbon oxygen Bacteria are mostly unicellular organisms that lack chlorophyll and are among Bacterial growth requirements smallest living things on earth—only viruses are smaller. Multiplying rapidly under favorable conditions, bacteria can aggregate into colonies of millions or even billions of organisms within a space as small as a drop of water.
The Dutch merchant and amateur scientist Anton van Leeuwenhoek was the first to observe bacteria and other microorganisms. Using single-lens microscopes of his own design, he described bacteria and other microorganisms calling them "animacules" in a series of letters to the Royal Society of London between and Bacteria are classified as prokaryotes.
Broadly, this taxonomic ranking reflects the fact that the genetic material of bacteria is contained in a single, circular chain of deoxyribonucleic acid DNA that is not enclosed within a nuclear membrane. The word prokaryote is derived from Greek meaning "prenucleus.
In addition, prokaryotic cells lack other membrane-bounded organelles, such as mitochondria. Prokaryotes belong to the kingdom Monera. Some scientists have proposed splitting this designation into the kingdoms Eubacteria and Archaebacteria. Eubacteria, or true bacteria, consist of more common specieswhile Archaebacteria with the prefix archae—meaning ancient represent strange bacteria that inhabit very hostile environments.
Scientists believe these bacteria are most closely related to the bacteria which lived when the earth was very young. Examples of archaebacteria are those bacteria which currently live in extremely salty environments or extremely hot environments, like geothermal vents of the ocean floor.
Stages of bacterial growth Under ideal conditions, the growth of a population of bacteria occurs in several stages termed lag, log, stationary, and death. During the lag phase, active metabolic activity occurs involving synthesis of DNA and enzymes, but no growth.
Geometric population growth occurs during the log, or exponential phase, when metabolic activity is most intense and cell reproduction exceeds cell death. Following the log phase, the growth rate slows and the production of new cells equals the rate of cell death.
This period, known as the stationary phase, involves the establishment of an equilibrium in population numbers and a slowing of the metabolic activities of individual cells. When the rate of cell deaths exceeds the number of new cells formed, the population equilibrium shifts to a net reduction in numbers and the population enters the death phase, or logarithmic decline phase.
The population may diminish until only a few cells remain, or the population may die out entirely. Temperature and bacteria The lowest temperature at which a particular species will grow is the minimum growth temperature, while the maximum growth temperature is the highest temperature at which they will grow.
The temperature at which their growth is optimal is called the optimum growth temperature. Most bacteria thrive at temperatures at or around that of the human body Mesophiles have adapted to thrive in temperatures close to that of their host.
Psychrophiles, which prefer cold temperatures, are divided into two groups. These organisms live in ocean depths or Arctic regions. These organisms, sometimes called psychrotrophs, are often those associated with food spoilage under refrigeration.
Most commonly, bacteria grow optimally within a narrow range of pH between 6. Acidophiles, however, prefer acidic conditions. For example, Thiobacillus ferrooxidans, which occurs in drainage water from coal mines, can survive at pH 1.
Other bacteria, such as Vibrio cholera, the cause of choleracan thrive at a pH as high as 9. Osmotic pressure and bacteria Osmotic pressure is another limiting factor in the growth of bacteria.
Cell walls protect prokaryotes against changes in osmotic pressure over a wide range. Fluid leaves the bacteria causing the cell to contract, which, in turn, causes the cell membrane to separate from the overlying cell wall. This process of cell shrinkage is called plasmolysis.
Because plasmolysis inhibits bacterial cell growth, the addition of salts or other solutes to a solution inhibits food spoilage by bacteria, as occurs when meats or fish is salted.Temperature and bacteria.
The lowest temperature at which a particular species will grow is the minimum growth temperature, while the maximum growth temperature is the highest temperature at which they will grow. Although bacteria are good at adapting to their environments, certain conditions promote bacterial growth more than others.
These conditions include temperature, moisture, pH and environmental oxygen. Understanding the optimal conditions for bacterial growth can potentially help you reduce your risk for bacterial infections and food initiativeblog.comd: Jun 17, Bacterial Growth Requirements Bacteria are single celled organisms that can only be seen with a microscope.
They are so small that scientists measure them in micrometers. Microbes have a variety of physical requirements for growth, including temperature, pH, and water stress.
Temperature Microbes can be separated into groups based . 2 Food Spoilage Temperatures Requirements for Growth Physical Requirements initiativeblog.com: 4Most bacteria prefer neutral pH ( ).
4Molds and yeastgrow in wider pH range, but prefer pH between 5 and 6. 4Acidity inhibits most microbial growth and is used frequently for food preservation (e.g.: pickling). Growth Requirements for Microorganisms One of the results of microbial metabolism is an increase in the size of the cell.
The many requirements for successful growth include those both chemical and physical.