User:Student 60/Notebook/Biology 210 at AU
Identifying and Studying Bacteria - February 11, 2016
PURPOSE
MATERIALS AND METHODS
- Latex gloves
- Lab Coat
- Bunsen Burner
- Agar plates (with incubated bacteria cultures from the previous week's serial dilutions)
- Microscope
- Glass slide and cover slips
- Metal transfer loop
- 95% alcohol
- Graham's iodine
- Safranin Stain
- Distilled water (in wash bottle)
- Kimwipes
To begin, one final observation of group #2's Hay Infusion Culture was made, noting any changes in smell and/or appearance. Our culture in particular remained orderless, but in terms of what used to be three distinct layers (top, middle, and bottom), now only consisted of a top and bottom layer with the surface of the culture being uncharacteristically clear and free of any notable organisms (i.e. algae or mold). I suspect that this may be due to a stark decrease in available nutrients. As a result, the organisms that thrived on the dried milk added to the culture died off or the habitat became uncondusive to life. It is for this reason that Archaea species would thrive if grown on agar plates since they require a steady source of nutrients, which the plates proved. Beyond this, about 50% of the water volume remained. It likely evaporated as a result of direct exposure to sunlight.
Procedure I: Quantifying and Observing Bacteria and Bacterial Colonies
Procedure II: Testing for Antibiotic Resistance
Procedure II: Observing Bacteria Cell Morphology
DATA AND OBSERVATIONS
Table 1. 100-fold Serial Dilutions Results
From this data, there is a stark difference between the agar plates containing tetracycline, a broad-spectrum antibiotic, and those without it. Many of the bacteria cultures, 10^-5, 10^-7, 10^-9 nutrient + tet plates, did not show signs of antibiotic resistance. Absolutely no bacteria grew on these plates. The 10^-3 nutrient + tet plate, however, did show signs of antibiotic resistance and grew approximately 230 colonies.
CONCLUSIONS AND FUTURE DIRECTIONS
Source: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC99026/
Hay Infusion Culture: Taking a Microscopic Look - January 21, 2016
PURPOSE
The purpose of this experiment is to identify microorganisms growing on the surface, middle, and bottom of Group #2's Hay Infusion Culture, while considering the biotic and abiotic factors residing in each level of the culture. If the presence of photosynthetic microorganisms, such as algae, are present in the culture, then it is likely that algae will exist closest to its surface for maximum exposure to the sun. Also, if protists reside within Group #2's Hay Infusion Culture, then it is likely that they will be found near its top layer layer as well since protists, such as Paramecium, eat plankton which is found in the layers closest to the surface of the water.
MATERIALS AND METHODS
- Hay Infusion Culture (*prepared previous week)
- Latex Gloves
- Microscope
- (6) Slides and slide covers
- Transfer pipettes
- Dichotomous Key (*aid in identifying microorganisms)
DATA AND OBSERVATIONS
(Group #2, upon opening its Hay Infusion culture,
found it to have a very slight "earthy/eggy", but
overall odorless smell)
(Characteristics - brown-yellow in color, non-motile,
photosynthesizing form of algae. This microorganism
meets all the needs of life as described on page 2
of the Freeman text in that it 1. is comprised of
cells, or more specifically, it's unicellular 2. with cell
walls 3. use chlorophyll to harvest energy from the sun
(photosynthesis) 4. able to adapt to their environment
(i.e. forming stalks to attach to water surface) 5. Can
grow by forming larger colonies 6. has an
oogamous sexual reproduction cycle)
(Paramecium: (left) Characteristics - greenish-brown in
color, covered in cilia which allow it to collect food
and be motile unicellular, Eukaryota, protozoa)
CONCLUSIONS AND FUTURE DIRECTIONS
The niche where most of Group #2's organisms were found was the top layer of the Hay Infusion Culture. This makes sense considering the top layer would have had the most direct exposure to sunlight, attracting photosynthesizing organisms such as diatoms. Paramecium would also be drawn to the surface of the culture to be near one of its primary food sources: photosynthetic algae.
If the Hay Infusion Culture had been allowed to grow for an additional two months, it may be that the microorganisms growing within it would reproduce, gradually approaching their respective carrying capacities. This would lead to an increased competition for resources and a lab-friendly window into a microscopic survival of the fittest scenario.
SERIAL DILUTIONS DIAGRAM: (In Preparation for Next Week's Bacteria Quantification Lab)
VW
Examining Biological Life at AU - January 7, 2016
PURPOSE
The purpose of this experiment is to observe and describe the topograhic, biotic, and abiotic characteristics of a 20 by 20 foot transect on American University's Main Campus by creating a Hay Infusion Culture, or lab-friendly ecosystem. This makes it possible to examine the breadth of biodiversity (or lack thereof) within a finite plot of land on campus. Considering one of the features of the transect observed in this experiment, just North of the AU campus Amphitheater and Southwest of Leonard Hall, is a small creek with flowing water, boulders and tiny pebbles covered in moss and algae, and fresh, saturated soil, it is likely that a more thorough analysis of the samples taken from Group#2's transect will show there to be more biotic than anbiotic components overall.
MATERIALS AND METHODS
- 1 Gallon Ziplock Bag
- Latex Gloves
- Flashlight (*transect observed after dark)
- Camera/camera phone
- Glass Jar (w/ 1L capacity) with lid
- 500ml of purified water
- 0.1 gram of dried milk (*sustenance for living organisms in hay infusion culture)
- Sharpie
- Painter's tape or labels
Group #2 collected roughly 10-12 grams worth of samples from its transect which consisted of a sloping bank leading down to a small creak with gently flowing water. The biotic components collected included moss, algae, and reeds. The anbiotic components included water (not including the micro-organisms within it), soil, dead leaves, drift wood, and small pebbles. The living organisms were collected from the creek; the nonliving organisms were taken from the bank leading down to the creek. These samples were then added to a gallon-sized ziplock bag and 10 grams worth of samples were added to a 1 liter glass jar along with 500 ml of purified Deer Park water and 0.1 grams of dried milk. A lid was placed over the glass jar and the contents were gently shaken to evenly distribute the dried milk.
DATA AND OBSERVATIONS
Biotic Organisms:
- Mold - surface level of creek
- Algae - surface level of creek
- Water reeds - near edge of soil bank leading down to creek
- Moss - surface of surrounding trees
Abiotic Organisms:
- Water (not including the organisms living within it) - within creek
- Soil - near bank of creek
- Detached leaves/foliage -found covering entire transect
- Driftwood - near bank of creek
- Boulders - atop bank of creek (north and south)
- Small pebbles - within the creek
CONCLUSIONS AND FUTURE DIRECTIONS
Group #2's transect contained a great deal of water, soil, moss, and algae. Where there is water, there is life. As a result, moving forward, I predict that there will be either a great diversity of microorganisms to classify in our next lab, or there will be a larger groups of only a few types of microorganisms.
VW
