[Example of a “poor” Report]

Bacterial Scavenger Hunt

Introduction

In this lab we are to gather different samples from the typical habitats of different organisms. [This is an important point. You need to expand on this to really “send it” to the reader. It is the first selective pressure in your isolation procedure.] The samples ranged from soils, muds, ponds, fish sauce, sea water, and sea weed. From these samples we carried out enrichments and selection procedures which would yield certain organisms. Then by continuing with experiments we can obtain pure cultures of the organisms. Even more experiments done on the pure cultures can confirm their identities. Through all of this we learn how to find and eventually isolate various microorganisms.

[This is ok it’s what you did. But you need to introduce the lab. What is the purpose? Tell me something about why organisms live in different environments.]

Materials and Methods

SEE MANUAL FOR INITIAL TESTS FOR ISOLATING PURE COLONIES

Then gram staining of Azobacter, Pseudomonads, Thermophiles, and Halophiles. Heat treatment to see if spores existed for Thermophiles and Halophiles.

RESULTS and DISCUSSION [You should not combine these sections. There is a distinct purpose to each section and it is easier for the reader to understand your work when presented separately.]

For the Escherichi coli [Underline or italicize genus and species names.] we were given pond water [Why?] in order to get cultures of the E. coli. I [Always use 3 ^rd person past tense in Scientific writing.] had tried to grow the E. coli in a tube of lactose-peptone broth. Nothing grew however. What may have happened is that there was not enough E. coli in the water where the sample was taken from. (The sample came from Mirror Lake.) The amount of fecal matter in the water was not great enough, probably because the Canadian geese had flown south for the winter and had not returned when the sample was taken [and water temp still very low so low bacterial numbers.] [So if this was the results section too....what was the gram stain? Cell morphology? Still report expected results.]

The next bacteria that I had grown was a Thermophile. I had gone through the experiments to the point where I had isolated pure cultures and streaked them on nutrient agar slants which were being refrigerated for the weekend. [so how did you isolate them. Tell me how you selected for these particular organisms, it wasn’t the agar, but instead the temp!] When I returned to the lab after the weekend I was not able to find the slants with my Thermophiles. I believe that they were either broken or stolen. To complete this organism I borrowed data from another student in the lab. [ok, but you need to cite him/her, initials are fine] He had received gram positive rods.

Picture of Gram positive Thermophiles that were colored red. There were no labels on the picture. [Gram positive is Red? Any endospores? Label pictures! What power 40x? 100x?]

And as can see there were no spores found among the rods. Therefore he did not have to do a heat treatment to confirm that the organism was a bacillus. Thermophiles can grow at temperatures of 55 degrees Celsius or higher, their growth minimum is usually around 45 degrees Celsius. This is why we place the thermophiles in an incubator so that we will be sure that thermophiles will grow while other bacteria will not. Thermophiles have heat-stable enzymes and protein synthesis systems able to function at higher temperatures. Their membranes lipids are very saturated and have higher melting points as their membranes will remain intact at higher temperatures. [ok, but this is the problem with combining the results and discussion sections. I was looking for this information earlier, but if the sections were separate I would not have.]

I had Actinomycetes isolated onto nutrient agar slants. [from where? Do they grow naturally on NA slants? Is this their natural habitat? NO! you must have started with soil at some point! Tell me about your isolation] Then I streaked a GLA plate with the actinomycetes. GLA medium possesses low concentration of a variety of compounds and Actinomycetes are able to grow in these low concentrations. GLA medium also inhibit fungal growth with an antibiotic. [is this part of your isolation procedure or are you now telling me about the testing?] After growth had occurred I smelled the plate. The odor coming form the plate could only be described as a strong smelling soil or dirt. Then by streaking Actinomycetes onto a plate of nutrient agar which had a layer of mixed lawn growth and soft agar on its surface. The Actinomycetes grew and produced many plaques [Typically this term is reserved for phage assay. Where a clearing zone is the result of bacterial cell death caused by bacteriophage infection. Also who told you to do the assay this way or provided you with the materials to do it. We (TA’s) instructed you to do this a different way in class we did a cross streak technique to look for inhibition. This other technique you describe was only used in years past?????] on the plate. [The organization of this paragraph is very poor. Are you testing the organism post isolation? If so how about telling me about the isolation!] The plaques proved that the Actinomycetes were producing some kind of antibiotics which were inhibiting the growth of the lawn organisms. After gram staining a colony of Actinomycetes I found that they are gram positive bacteria [cell morphology? Usually filaments not individual cells.] which contain spores. [Actinomycetes don’t contain endospores like Bacilluscereus; the spores develop at the end of the filaments] Actinomycetes are also aerobic bacteria. By observing the margins of the Actinomycete colonies they appear to be very filamentous. This is because Actinomycetes have branching filaments which contain spores. Most of the spores are not particularly heat-resistant but are very adaptive otherwise. [Reference? Or did you test them?]

For the next organism I received [isolated] gram negative Azobactor in the form of bacillus. [that was rod shaped.] Azobacter [italicize or underline genus names. When no particular species is isolated or further characterization is not done follow genus name with the abbreviation sp. for species ie: Azobacter sp.] colonies appear to look much like water droplets. Azobacter are nitrogen fixing bacteria. Only nitrogen fixing bacteria can survie on mannitol medium with [without – very important] nitrogen, this is how we can isolate Azobacter colonies. By observing the margins of these I could tell as to whether the colonies were Azobacter or Actinomycetes. The margins were undulate while the margins of the Actinomycetes are filamentous. [what was the color of it? and was it hard like actinomycetes or gummy?]

My isolated pure colonies of the Pseudomonads are gram negative rods. Pseudomonads can be isolated on media that contain carbon sources that can only be oxidized by a few organisms, this is why benzoate is used as the only source of carbon.

The agar slants that I had stored them on were poor in iron content so when the Pseudomonad colonies grew on the agar they produced a dark yellowish pigment. [Ahhh! We did not provide you with this medium so there is no way you could have done this. The lab manual does mention this so I’ll assume you just copied it out of there. Don’t ever report something you did not do.]

Pseudomonads can degrade an exceptionally wide variety of organic molecules making them important in the mineralization process in nature and in sewage treatment. [good]

The final organism I had grown was an Extreme Halophile. The halophiles grow in environments of high salt concentrations where other organisms cannot and this is how to isolate them. I had tried to grown halophiles from fish sauce and also from a salt water solution. On the halophile medium I received many dark shaded colonies. Upon gram staining I received gram negative cocci that did not produce spores. [Judging by the fact that none of the other 130 students were able to isolate this organism or get any thing out of their enrichment and that you don’t have it signed off, I highly doubt you did this isolation. Again, don’t ever report something you didn’t do] I did not have enough time to finish my experiments on the halophiles. But what I would have continued with would have been to streak the halophiles onto plates of varying salt concentration and observe whether the halophiles grew or not. The halophiles should have grown on plates with high salt concentrations but not on plates with concentrations of lower than 1.5M (or molar) salt. Halophiles accumulate great amounts of potassium in order to stay hypertonic to their environment. The enzymes, ribosomes, and transport proteins of Halophiles require high levels of potassium for stability and activity. I also would have use motility agar to tell whether the organism was motile, but halophiles are non-motile. [This is good.]

Finally, when I received what I now know as being the signing sheet. I thought that it was a check off list as in the unknown lab. I was not aware until the final lab period that I was supposed to have gotten the sheet signed whenever I had completed a step. I have included the sheet with my checks of each step with the lab. [If you were in the lab at all when other students were in there working on this lab during the four week period you would have known.....]

WORKS CITED

Terry, Thomas M. Fundamentals of Microbiology: Laboratory Manual University of Connecticut, Jan. 1999.

Prescott, Lansing M., Harley, John P., Klein, Donald A. Microbiology: Second Edition. McGraw-Hill, 1999.

[The combination of writing this lab the night before and doing very little work in the lab made for a report that was poorly organized, hard to read and littered with suspect data. Please make note of the comments for the next lab report. . .If you have any questions, please come see me.]