General Microbiology Lab Briefing

Here’s a presentation (no voice) on the fungi we’re looking at in lab this week:

Exercise 3:  Kingdom Myceteae

Be sure to view the sort on-line lecture on the fungi in Vancko Hall Laboratory.  This will be a short introduction to the group since I won’t be getting to it in lecture before you have lab.

You will be examining fungi that are unicellular (yeasts) as well as those that are filamentous (molds).

Filamentous Fungi — Three representative genera are Penicillium, Rhizopus, and Aspergillus.

• View and draw these as they appear in an agar plate of Sabauroud Dextrose Agar.  Do not open the petri dishes — spores will escape and contaminate everything for the rest of the semester!!!!!
• View and draw them from a prepared slide that contains all three genera.  They are located on the slide in the order they are listed on the label.  View:
  • Aspergillus and Rhizopus at 100x
  • Penicillium at 400x
• The spores you see are asexual spores — either conidiospores or sporangiospores depending upon the genus.

Yeast:

• View yeast of two genera — make wet mounts — Candida (opportunistic pathogen) and Saccharomyces (bread and brewing yeast).
• Make a wet mount of my sourdough “sponge”.
  • A sponge is a culture of yeast (and in this case bacteria).
  • You will see abundant yeast and small rod-shaped bacteria between the cells of yeast.  The yeast breakdown carbohydrates and produce alcohol and the bacteria (Lactobacillus ) produce acid from the alcohol.  Hence the sour taste of sourdough bread!
• Try to culture some yeast from your tongue.  Follow directions in your lab book.  We’ll incubate them at 37 degrees C and you’ll check them on Thursday and maybe into next week.

Exercise 4:  Helminths (Multicellular Parasites)

Be sure to view the online lecture on Helminths in Vancko Hall — lecture section.

You will be looking at and drawing the following:

Here is the table from Microbiology Perspectives by Wistreich.  [Note this book will be very handy this week so if you have it, bring it to lab.]

• Cestodes (tape worms)
  • Slides:
    • Scolex and immature proglottids
    • Gravid proglottids
  • Whole or part tapeworms in bioplastic
• Trematodes (flukes):
  • Slides:
    • Chinese liver fluke (Clinorchis senensis) [I took invertebrate zoology with my fiance and we were going to name our first son Clinorchis -- good thing we never had kids, huh?]
      • Whole mount (w.m.)
      • Ova (eggs)
  • Sheep liver fluke (Fasciola hepatica)
    • These you do not need to look at because they are in the pictures on the diagram above.  They include:
      • cercarium
      • metacercarium
      • miracidium
  • Blood fluke (Schistosoma japonicum)
    • male
    • female
    • eggs
  • Also various whole flukes in bioplastic or other preservative.
• Nematodes (roundworms)
  • Trichinella spiralis slides:
    • muscle section
    • isolated larvae

This week we’re doing Exercise 2:  The Kingdom Protista

• Be sure to read the introductory portion of the lab book for this lab before you come to lab.  It is also a good idea to review the lecture information that we have gone over.  [NOTE that the Protista lecture (with pictures) is posted in the lecture portion of Vancko Hall.]
• The Protista consists of two subkingdoms:  Algae and Protozoa
• Be sure to draw and label your drawings.  Also include a brief description of what you see.

Here is what you’ll be looking at of the Protozoa

• Live Cultures of the following — all can be easily viewed at 100x and 400x (draw them at either magnification):
  • Paramecium — these are kind of speedy you may want to slow them down with some Protoslo solution — a drop of it on your slide then some of the culture.
  • Amoeba — your instructor may need to fish these out for you — they are a bit hard to capture with a pipet because they are kind of sparse in the culture.
  • Vorticella – a stalked ciliated protozoan that looks like a wine goblet!  The cilia create a vortex or mini-whorlpool that draws the bacteria in the water toward the gullet.
  • NOTE:  be sure to view the live protozoans in your first lab — they probably will not live to Wednesday or Thursday!
• Prepared slides of
  • Trichomonas vaginalis — causes an STD.  These are small and are stained pink or lavender. [400x]
  • Trypanosoma – are hemoparasites causing sleeping sickness.  So this is a blood slide — best viewed at 1,000x.  The parasites look kind of like worms between the red blood cells. Why are they wavy on one side? What is that called?
    • Be sure to listen to the podcast on Trypanosoma available in Vancko Hall lecture section.
  • Paramecium – 100x or 400x.
  • Amoeba – 100x or 400x — the colors are due to stains that have been used in the preparation of the slides.
  • For all of these make a note about what group of Protozoa they belong to — Mastigophora, Sarcodina, Ciliata, or Apicomplexa!

Algae:

• Live cultures of (mostly can be viewed at 100x but for some you may need 400x):
  • Closterium – a green alga that looks like a green cigar or new moon (some will have a curve to them).
  • Spirogyra - a filamenouts green alga with a spiral-shaped chloroplast.
  • Variety of live algae from various habitats.  I’ll let you know where from after I collect them!
• Prepared slides of (100x and 400x):
  • Volvox
  • Various diatoms — these are slides I prepared for my master’s degree work on a small stream.  I’ll include my thesis so you can look at the pictures of these as well.
    • What you are looking for are regular shapes — round or lancet shaped usually.  These have been “cleaned” so all you are seeing is their silica cell walls.

Cyanobacteria:

• I include the Cyanobacteria here because they are metabolically similar to the algae because they generate oxygen during the light reactions of photosynthesis.  In addition they are found in aquatic habitats like the algae.  They also tend to be green(ish) — actually they are sometimes called “Bluegreen Algae”.  They contain chlorophyll a and a red pigment (phycoerythrin) and a blue pigment (phycocyanin).  Note that they do not have any internal structure (no chloroplasts).  For this reason they are classified with the bacteria.
• Live cultures of
  • Oscillatoria (400x)
  • There may be some Cyanobacteria in the mixed cultures from streams or ponds.
• Prepared slides of
  • Oscillatoria (400x)

  For more information on Cyanobacteria see this website:  http://www.ucmp.berkeley.edu/bacteria/cyanolh.html

This is a lab briefing blog.

• I publish the blog each week, usually on Friday.
• It contains information for the next week’s lab.
• It is sort of a “heads up” on what we are going to be  doing.
• It is NOT a substitute for reading the lab book.

Why a blog?

• Because you can enable a RSS Feed for the blog which means that as I post to it, you can get a message showing I have done so.
• Because I like it!

About Micro Lab

1. First of all Microbiology lab meets twice a week:  for two hours early in the week, and for one hour later in the week.  This is so you can set up experiments one day and let them incubate so you can check the results during the “come-back” lab.
2. Yes, lab does meet the first week of the semester.
3. Be sure that you have a lab coat (or scrubs or lab apron), a NEW lab notebook, and a lab kit which contains slides, cover slips, lens paper, a wax pencil, and a depression slide.
4. You should have these by the comeback lab this week or at the latest by the start of the second week’s lab.

Week One’s Lab:

• This week is important because we’re going over the basics of lab procedures and lab safety.
• We’re also doing exercise 1:  Microscopy.
  • This includes the proper use and care of the most important tool in Microbiology, the microscope.
  • You’ll use the microscope to look at a prepared slide of blood.
    • Draw what you see at all 4 magnifications (40x, 100x, 400x, and 1,000x).
    • Note that after this you only need to draw what you see at the best magnification to view the specimen (for bacteria that is 1,000x, for protozoa it is usually 400x).
    • Label your drawings.
    • AND be sure to describe in words what you see.  This is an important practice to do because you are seeing things you have not seen before and will be expected to do a number of reports that include your detailed observations!
• For the comeback lab you’ll be looking at hanging drop preparations of a Hay Infusion.
  • Be sure to look at your lab book for how to make a hanging drop preparation.
  • A hay infusion contains dried grass (hay) plus water from a pond or stream that has been allowed to sit at room temperature for at least a week.
  • It will contain a number of kinds of organisms including bacteria and protozoans.  (Some may also contain fungal filaments).
    • Be sure you take note of the relative sizes of the organism that you see.