Lab 1 (1-4, 1-5, 1-6, 2-11)

broth medium

0% agar high cell yield but only viable for 3 days

solid

1.5-1.8% agar solid slant: hold culture for 2 weeks but low cell yield

bacterial spores

121 degrees c, 15 min, 15 psi highly resistant to chemical and physical means of control autoclave kills spores (works properly) autoclave not kill spores (autoclave not working properly)

4 quadrant streak

1: most 4: least (isolated)

semi solid

<1% agar

How could you verify the purity of a colony? How could you purify it?

Examine the isolated culture under microscope. Observe size, shape, and color of colonies to see if they are the same. If not pure, perform a 4QS or serial dilutions to isolate the colonies

Did you notice a difference in turbidity of growth in NB tubes inoculated from NB and NA slants?

From broth to broth transfer the turbidity was higher than the slant to broth transfer.

What will happen if the cell density exceeds 300 cells?

If cell density greater than 300, would not get isolated colonies

Critique of isolation technique

Isolation was obtained All of agar was used and was not damaged by the loop 4 quadrant streak method was a success

Did you get growth on/in the sterile NB and NA slant tubes you practiced with?

No we did not see growth in sterile NB and NA

Was the zigzag streak method appropriate to the cell density in that sample?

No, the zigzag method resulted in a lower cell density than the 4QS method

Did you notice a difference in density of growth on NA slants inoculated from NA slants and NB?

The NA slant inoculated from the NB had a higher density of growth compared to NA slant inoculated from NA slant

Which medium was most difficult for you to transfer from? Which medium was most difficult for you to inoculate?

The agar slants was the most difficult to transfer from and to inoculate. It was difficult b/c you had to make sure not to damage the agar & the agar is easy to damage especially when heating up the loop constantly

Describe differences in appearance of growth. In which medium was this the most difficult to determine? What made this difficult?

The broth medium was the most difficult to determine the appearance of growth b/c the growth was only visible at the bottom of tube (sediment)

Organism A is 1000x more abundant than organism B. Will you be able to isolate B using spread plate technique?

Would be difficult to isolate since A is 1000x more concentrated than B

What is the consequence of not spreading the inoculum adequately over the agar surface?

Would not result in isolation, would be clumped together

Did you achieve isolation using 4QS?

Yea I did achieve isolation in quadrants 3 & 4

How many different microbial types should you expect to see in/on each medium?

You should expect to see only one microbial type at a time due to using proper aseptic techniques

sterile

absence of living organisms

[1-5: Streak Plate Methods of Isolation] CFU

colony forming unit

[1-6: Spread Plate Method of Isolation] Spread plate technique

diluted sample deposited on agar and spread uniformly across surface

[2-11: Steam Sterilization]

increase pressure and increase temperature

agar

polysaccharide from seaweed 1) solidifying agent 2) substrate (hard surface) 3) no nutritional value 4) stable at wide range of temps

pure culture

single isolate

biological indicator

spores, carbohydrate, pH indicator -pH indicator goes from purple to yellow as spores metabolize carbohydrate (autoclave not working properly)

[1-4: Common Aseptic Transfers & Inoculation Methods] aseptic

without contamination