How would you be able to tell if your S marcescens agar plate was contaminated by E coli?

How would you be able to tell if your S marcescens agar plate was contaminated by E coli?

coli, it would be hard to tell if your results were contaminated as many common environmental bacteria are also white/colorless. If you see any results on your slant that are NOT yellow, you can easily tell it’s been contaminated.

How do you determine whether a colony was a contaminant?

1. Perform Gram staining and look at the morphology of the bacterial cells, if contaminated more than one cell type shall be visible. 2. Streak the culture on a suitable agar based medium and observe color and type of cfus.

How do you know if something is contaminated in microbiology?

So, although the threat of contamination from these microorganisms is ever-present, you can easily spot their presence by the turbidity of the growth medium or the floating, branching mycelia. Bacterial contamination can often be confirmed under a 10x microscope within a few days of contamination.

How could your streak plate end up being contaminated?

How can a streak plate become contaminated? If the loop is not sterilized. If you drop the plate.

Why must you Flame the loop between streaks?

You want to spread only a tiny fraction of the bacteria in one quadrant to the next, so it’s important to flame and cool the loop between each streaking step. This ensures thinning of the bacteria with each streak, which ultimately produces isolated colonies after incubation.

Why is it important to sterilize the inoculating loop?

Flame-sterilize the inoculating loop (Figure 6) in order to prevent contamination of the bench surface and as a consideration to others in the lab who may later use the inoculating loops. Figure 6: Inoculating loop turning red hot while being sterilized with a Bunsen burner.

Why is it important to sterilize your inoculating loop before and after each use?

The most important tool for transferring cultures is the wire inoculating needle or loop. It can be quickly sterilized by heating it to red hot in a Bunsen burner flame. Always flame the loop immediately before and after use! Allow it to cool before picking up an inoculum of bacteria (or you will kill the bacteria).

Why do you flame sterilize the loop again after transferring the bacteria to the slide?

Flaming the loop between streaks ensures that the loop starts clean and that only this small amount of bacteria is used to inoculate the next quadrant. streak d must draw inoculum from streak c.

What happens once all the nutrients are used up in bacterial growth medium?

Organisms in a tube of culture medium can maintain log growth for only a limited time, as nutrients are used up, metabolic wastes accumulate, microbes suffer from oxygen depletion.

What are the phases of growth?

There are three phases of growth – meristematic, elongation and maturation.

What are the 3 phases of growth?

The three phases of cell growth are cell division, cell enlargement and cell differentiation. The first two stages increase the size of the plant cell while the 3rd stage brings maturity to the cells.

What are the 5 phases of growth in plant?

The major stages of the flower life cycle are the seed, germination, growth, reproduction, pollination, and seed spreading stages.

  • Seed Stage. The plant life cycle starts with a seed; every seed holds a miniature plant called the embryo.
  • Germination.
  • Growth.
  • Reproduction.
  • Pollination.
  • Spreading Seeds.

What are 3 pieces of evidence suggesting gibberellins are required for plant development?

Three major points that are involved in the GA signaling mechanism are 1) the stamen is the essential site of GA synthesis, other sites cannot replace the stamen; 2) GA20ox and GA3ox are key regulators of GA biosynthesis in the stamen and 3) short-distance movement of bioactive GA (but not of its biosynthetic …

How does cytokinins affect plant growth?

Cytokinins are essential plant hormones. By stimulating cell division, they regulate shoot meristem size, leaf primordia number, and leaf and shoot growth. They can stimulate both the differentiation and the outgrowth of axillary buds. In roots, unlike auxin, cytokinins inhibit lateral root formation.

Where are gibberellins found?


What is the difference between auxins and gibberellins?

The main difference between auxin and gibberellin is that the auxin promotes the growth of the shoot system whereas gibberellin promotes stem elongation, germination, and flowering. Furthermore, auxin plays a role in apical dominance whereas gibberellin has no role in apical dominance.

What is the source of gibberellins?

Gibberellin, any of a group of plant hormones that occur in seeds, young leaves, and roots. The name is derived from Gibberella fujikuroi, a hormone-producing fungus in the phylum Ascomycota that causes excessive growth and poor yield in rice plants.

Where are gibberellins used?

Gibberellins are a group of plant hormones responsible for growth and development. They are important for initiating seed germination . Low concentrations can be used to increase the speed of germination, and they stimulate cell elongation so plants grow taller. They are naturally produced by barley and other seeds.