The Control Of Microbial Growth

• Fourthly, we kept the temperature at a constant 25°C using a water bath. At low temperatures, an increase in temperature causes an exponential increase in enzyme activity. This is because an increase in temperature provides more kinetic energy for the collisions of enzymes and substrates, so

Temperature controls the speed the enzymes work at. Higher temperatures increase the kinetic energy which increases the chance of collision therefore speeding up the rate of

7- what term refer to allowing food to remain for too ong a time in a temperature that allows the growth of germs

The water activity also plays a big role in the microbes ability to survive as most cannot grow in a water activity level less than 0.91. Based on observations and construction of a data table, it was shown that the 1% NaCl solution had a water activity level of 0.99, the 7% NaCl solution 0.96 and the 15% NaCl solution 0.91. Based on the table it was expected that there would be no growth in the 15% NaCl solution as most microbes cannot survive at a water activity level of 0.91.

The conditions needed for the growth of micro-organisms are: Micro - organisms need food to survive. They like high protein food to survive, eg. Poultry & fish. Most micro - organisms need warmth & grow best at 20-40c. They need moisture to multiply. They need air to multiply, though some can without. A single Micro-organism becomes two every twenty minutes.

These results show how temperature of extreme high, or low affects enzyme activity. The highest rate of enzyme activity occurred at 37 Cº. Anything that was hotter or cold than 37 Cº slowed the reaction rate. As I thought, 100 degrees would denature the enzyme, and that was the case. The data provided shows exactly what temperatures enzymes work best, and worst. The objective was achieved as we discovered the different reaction rates under different temperatures. The results are reliable, as we know enzymes do not work well when under extreme heat or denaturation occurs. What I learned in this experiment was that enzymes don’t work well under cold temperatures because they tend to move slower. My hypothesis did not quite match, because I thought they work best at lower temperatures.

Background information: In this lab you will be looking at the growth of bacteria under different conditions to see the how populations of bacteria grow. Read about cells in the text or e-text. For everyone, in your e-text read chapter 13, sections 13.3 and 13.4 to learn more about bacteria. Then answer the questions below.

this means that is the optimal temperature, but in bacterial occur in less time than in fungal

Finally there is the Hyperthermophiles. Found in very hot temperatures such as hydrothermal vents in deep oceans. With this said, the two microorganisms that I worked with would be known as Mesophiles. Both of these microorganisms grow on or in the human body. They prefer moist heat that is body temperature. I made an incubation box to help mimic the temperatures needed. Typically trying to maintain the temperature of thirty seven degrees Celsius.

During these experimental procedures, the implication of multiple different temperatures on fungal and bacterial amylase was studied. In order to conduct this experiment, there were four different temperatures used. The four temperatures used were the following: 0 degrees Celsius, 25 degrees Celsius, 55 degrees Celsius, and 80 degrees Celsius - Each temperature for one fungal and one bacterial amylase. Drops of iodine were then placed in order to measure the effectiveness of the enzyme. This method is produced as the starch test. The enzyme was tested over the course of ten minutes to determine if starch hydrolysis stemmed. An effective enzyme would indicate a color variation between blue/black to a more yellowish color towards the end of the time intervals, whereas a not so effective enzyme would produce little to no change in color variation. According to the experiment, both the fungal amylase and bacterial amylase exhibited a optimal temperature. This was discovered by observing during which temperature and time period produced a yellow-like color the quickest. Amylase shared a similar optimal temperature of 55 degrees Celsius. Most of the amylases underwent changes at different points, but some enzymes displayed no effectiveness at all. Both amylases displayed this inactivity at 0 degrees Celsius. At 80 Celsius both the enzymes became denatured due to the high temperatures. In culmination, both fungal and bacterial amylase presented a array of change during it’s

Bacterial amylases operate at higher temperatures than do fungal amylases. Fungal amylases react rapidly at lower temperatures; fungal amylases are used as an agent for alcohol fermentation for grain (Underkofler et al, 1958). Fungal amylases is said to be denatured – change shape (Alberte et al, 2012), at high temperatures above 60° C and bacterial amylases on the other hand are stable and show little denaturing at temperatures up to 85°C 3 The question answered by the experiment is if the temperature is not within the range of the enzymes (fungal and bacterial amylase) optimal temperature (higher temperature) then will the enzymes denature and if the enzymes are placed in lower temperature from optimal the activity then will it slow down enough to stop all reaction, meaning each enzyme will not be operating efficiently. Knowing about a bacterial amylases and fungal amylases optimal temperatures are important for knowing which food products and industrial products it can be used on to conserve the product because then the producer knows about which products it can be incorporated into depending on the temperature it is manufactured at.

A few different factors that affect bacterial growth are the availability of resources and nutrients, temperature and pH. (Act For Libraries) stated in the above paragraph, once the resources and nutrients are

The effects of temperature on fungal amylase Aspergillus oryzae, and bacterial amylase, Bacillus licheniformis ability to break down starch into maltose was studied. The study determined the optimal temperature the Aspergillus oryzae and Bacillus licheniformis was able to break down the fastest. The starch catalysis was monitored by an Iodine test, a substance that turns blue-black in the presence of starch. Amylase catabolizes starch polymers into smaller subunits. Most organisms use the saccharide as a food source and to store energy (Lab Manual, 51). The test tubes were labeled with a different temperature (0°C, 25°C, 55°C, 85°C). Each test tube was placed in its respective water baths for five minutes. After the equilibration process, starch was placed in the first row of the first row of the spot plate. Iodine was then added to the row revealing a blue black color. The starch was then added to the amylase. After every two minute section a pipette was used to transfer the starch-amylase solution to place three drops of the solution into the spot plate row under the corresponding temperature. Iodine drops was placed in the row. Color changes were noted and recorded. The results showed Aspergillus oryzae was found to have an optimal temperature between 25°C and 55°C and Bacillus licheniformis was found to have an

Being able to control bacterial growth is something that is important in our everyday lives. As shown in the previous labs, bacteria can grow and create colonies extremely quickly especially in the right environments. By acknowledging this, it is then important to get an understanding of how bacterial growth can be controlled by humans. To control microorganisms it means to inhibit their growth (static) and or kill them (cidal) (Kenneth Todar, 2015); therefore since focusing on bacteria the terms bactericidal and bacteriostatic are both extremely important for this lab. One broad method we will use to control bacterial growth is heat. The amount of heat needed to control bacterial growth is different for different species of bacteria (Kenneth Todar, 2015). Bacteria can also respond differently depending if moist heating method such as an autoclave with steam is used, or a dry heating method such as inoculating a loop over a fire is used (Kenneth Todar, 2015). UV works by damaging the cells DNA, without proper DNA, the cells will die and the object

These ranges are classed as cardinal temperatures and consist of minimum, optimum and maximum. The optimum is the temperature at which the bacteria will grow most rapidly, whilst temperatures below the minimum and above the maximum no growth will occur. (Prescott et al. 2008..) Growth rate decreases rapidly once temperatures exceed the optimal rate placing the maximum rate very close to it, whilst the minimum temperature is much further away from the optimum. (Ingraham et al..1990) The cardinal temperatures vary between each species of bacteria which places them into subcategories relevant to these experiments as shown below:-