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2021-05-16

What happens in the lag phase?

What happens in the lag phase?

During lag phase, bacteria adapt themselves to growth conditions. During the lag phase of the bacterial growth cycle, synthesis of RNA, enzymes and other molecules occurs. During the lag phase cells change very little because the cells do not immediately reproduce in a new medium.

Under what conditions would a lag phase not occur?

Lag Phase – In the lag phase, the number of cells doesn’t increase. However, considerable metabolic activity is occurring as the cells prepare to grow. (This phase may not occur, if the cells used to inoculate a new culture are in the log phase & provided conditions are the same).

Which of the following is a reason for the occurrence of a lag phase in a bacterial growth curve?

Which of the following is a reason for the occurrence of a lag phase in a bacterial growth curve? A. The cells may be old and depleted of ATP, essential cofactors, and ribosomes that must be synthesized before growth can begin. During the lag phase of microbial growth, the cells are metabolically inactive.

Which phase of bacterial growth involves more cells dying than reproducing?

Key Takeaways: Bacterial Growth Curve The exponential or log phase is a time of exponential growth. In the stationary phase, growth reaches a plateau as the number of dying cells equals the number of dividing cells. The death phase is characterized by an exponential decrease in the number of living cells.

Why do bacterial colonies reach a certain size and then stop growing?

Why do bacterial colonies reach a certain size and then stop growing? They deplete the accessible nutrients from the agar that is immediately around the colony. However, there are some species that spread out faster than the agar is depleted of nutrients. These species will overgrow the entire surface of the agar.

What does size of a colony indicate about the bacteria?

Size of the bacterial colony: The size of the colony can be a useful characteristic for identification. The diameter of a representative colony may be measured in millimeters or described in relative terms such as pinpoint, small, medium, large. Colonies larger than about 5 mm are likely to be motile organisms.

What is the advantage of solid medium vs liquid?

Solid media are used for isolating bacteria or for determining the colony characteristics of the microorganisms. Liquid media are used for various purposes such as propagation of a large number of organisms, fermentation studies, and various other tests.

Which bacteria is on a solid medium?

These agar plates provide a solid medium on which microbes may be cultured. They remain solid, as very few bacteria are able to decompose agar (the exception being some species in the genera: Cytophaga, Flavobacterium, Bacillus, Pseudomonas, and Alcaligenes).

What is difference between broth and agar?

The only difference between broth and agar media is that broths do not contain an agar component. We use broth tubes primarily for specific assays, or (rarely) for bacteria that will not form colonies on a solid surface. Unlike preparation of agar plates, tubes are prepared with media already in the incubation vessel.

What are the advantages and disadvantages of liquid media?

What are the advantages and disadvantages of liquid media? Liquid media is any material that is in liquid form, created by adding a liquid to a pigment. An advantage is that it tends to be durable. The disadvantages to using liquid media are that it can be costly and difficult to work with.

How can you tell if bacteria is growing in nutrient broth?

Bacterial growth in broths is indicated by the development of a cloudy appearance. If the newly inoculated broth looks cloudy at the start, you will have no way to determine if this is due to bacterial growth during the incubation period.

What are the advantages of liquid media?

Nutrient broth is a liquid bacterial growth medium made of powdered beef extract and short chains of amino acids that have been dissolved in water. Liquid medium is convenient to use for growing bacteria in test tubes, and can reveal information about the oxygen requirements of bacteria growing within.

What Bacteria grows on nutrient?

What Grows on Nutrient Agar? Microorganisms need food, water and a suitable environment in order to survive and grow. Nutrient agar provides these resources for many types of microbes, from fungi like yeast and mold to common bacteria such as Streptococcus and Staphylococcus.

What Bacteria grows red on nutrient agar?

Due to this, and because S. marcescens produces a reddish-orange tripyrrole pigment called prodigiosin, it may cause staining of the teeth. The biochemical pathway for the production of prodigiosin by S….

Serratia marcescens
S. marcescens on an agar plate
Scientific classification
Domain: Bacteria
Phylum: Proteobacteria

Does Lactobacillus grow on nutrient agar?

Nutrient agar with added glucose can be used but grows better on special medium, as for Lactobacillus.

What is MRS agar used for?

Remel MRS Agar (Man, Rogosa, Sharpe) is a solid medium recommended for use in qualitative procedures for isolation of Lactobacillus species and gram-positive cocci. Gelatin peptone and beef extract provide essential nutrients and amino acids necessary for bacterial growth.

Why does Lactobacillus grow slowly?

Therefore, when resources are limiting, less energy becomes available for growth-associated processes, resulting in slow or no growth. These conditions are not only commonly encountered in natural environments, but also in engineered cultivation systems, such as fed-batch fermentations.

At what temperature does Lactobacillus die?

While Lactobacillus can comfortably thrive between 115° and 120° F, Clostridium dies at temperature above 112° F.