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I have cultured Cyanobacteria (in a media) in a beaker. I want that bacteria to attach to a cloth (e.g. Carbon). My current method is using a syringe to slowly push the bacteria to one side of a cylindric tube and exist through the other end. The cloth is placed stationary inside that tube throughout the process.
Is there a way to get more bacteria to attach to the cloth? (e.g.maybe adding something to the cloth)
You're thinking in terms of making them attach to your cloth, but they want to be attached - there are more nutrients and it is safer. Make sure they have enough light, but not too much, and their nutrients. They may be attaching and growing, but just not as fast as you expect.
It is also possible that your strain of Cyanobacteria has lost the ability to attach. If it has been maintained in liquid culture for many generations, any bacteria attached to the wall of the container were selected against.
1. Working in pairs, label each slide and draw a circle on the center of the slide with a wax pencil which is provided at your table, DO NOT use a sharpie, this will keep the bacteria concentrated in one area on the slide.
2. Prepare an emulsion on each slide:
- If you are taking a bacteria from a plate, place a small drop of water on a slide and aseptically add bacteria.
- If you are taking a bacteria from a broth, place 3-6 loopfuls of bacteria onto a slide with no water added.
3. You and your lab partner will need to prepare the following slides:
- 3 slides of Staphylococcus epidermidis (one for simple stain, one for gram stain, one as back-up)
- 3 slides of Pseudomonas aeruginosa (one for simple stain, one for gram stain, one as back-up)
- 2 slides of S. epidermidis and P. aeruginosa mixed together (one for gram stain, one as back-up)
4. Mix gently until you get an even cloudy mixture (should look like skim milk)
If you mix too aggressively, you will lose the bacterial morphology.
5. Allow the slide(s) to air dry on the slide warmer. While the slides are drying, start your negative stain.
6. Once the liquid has completely evaporated, heat fix by passing the slide through a flame three times.
If you heat fix too little, the bacteria will wash off the slide. If you heat fix too much, you will cook the bacteria and denature them.
7. Allow the slide to cool and then continue with your staining protocol.
Beginning from the innermost structure and moving outward, bacteria have some or all of the following structures:
Plasma Membrane: This is a lipid bilayer much like the cytoplasmic (plasma) membrane of other cells. There are numerous proteins moving within or upon this layer that are primarily responsible for transport of ions, nutrients and waste across the membrane.
Periplasmic Space: This cellular compartment is found only in those bacteria that have both an outer membrane and plasma membrane (e.g. Gram negative bacteria). In the space are enzymes and other proteins that help digest and move nutrients into the cell.
Cell Wall: Composed of peptidoglycan (polysaccharides + protein), the cell wall maintains the overall shape of a bacterial cell. The three primary shapes in bacteria are coccus (spherical), bacillus (rod-shaped) and spirillum (spiral). Mycoplasma are bacteria that have no cell wall and therefore have no definite shape.
Outer Membrane: This lipid bilayer is found in Gram negative bacteria and is the location of lipopolysaccharide (LPS) in these bacteria. Gram positive bacteria lack this layer. LPS can be toxic to a host and can stimulate the host's immune system.
Capsule: This layer of polysaccharide (sometimes proteins) protects the bacterial cell and is often associated with pathogenic bacteria because it serves as a barrier against phagocytosis by white blood cells. Capsules can be seen by viewing bacteria in India ink.
Slide Mount Instructions
Before you start building your slides, make sure you have everything you will need, including slides, cover slips, droppers or pipets and any chemicals or stains you plan to use.
You will be using two main types of slides, 1) the common flat glass slide, and 2) the depression or well slides. Well slides have a small well, or indentation, in the center to hold a drop of water or liquid substance. They are more expensive and usually used without a cover slip.
Standard slides can be either plastic or glass and are 1 x 3 inches (25 x 75 mm) in size and 1 to 1.2 mm thick.
Wet slides will use a cover slip or cover glass, a very thin square piece of glass (or plastic) that is placed over the sample drop. Without the cover in place, surface tension would cause the droplet to bunch up in a dome. The cover breaks this tension, flattening the sample and allowing very close inspection with minimal focusing. The cover also serves to protect the objective lens from interfering with the sample drop.
There are four common ways to mount a microscope slide as described below:
In a dry mount, the specimen is placed directly on the slide. A cover slip may be used to keep the specimen in place and to help protect the objective lens. Dry mounts are suitable for specimens such as samples of pollen, hair, feathers or plant materials.
In a wet mount, a drop of water is used to suspend the specimen between the slide and cover slip. Place a sample on the slide. Using a pipette, place a drop of water on the specimen. Then place on edge of the cover slip over the sample and carefully lower the cover slip into place using a toothpick or equivalent. This method will help prevent air bubbles from being trapped under the cover slip.
Your objective is to have sufficient water to fill the space between cover slip and slide. If there is too much water, the cover slip will slide around. Take a piece of paper towel and hold it close to one edge of the cover slip. This will draw out some water. If too dry, add a drop of water beside the cover slip. Practice this until you get used to it.
Wet mounts are suitable for studying water-bound organisms such as paramecium or bodily fluids such as saliva, blood and urine.
In a section mount, an extremely thin cross-section of a specimen is used. Using a microtome, cut a thin slice of your selected specimen such as an onion, and carefully set it on your slide. Then follow the instructions for a dry or wet mount. A stain can often be applied directly to the specimen before covering with a cover slip.
Section mounts are suitable for useful for a wide variety of samples such as fruit, vegetables and other solids that can be cut into small slices.
A smear is made by carefully smearing a thin layer of the specimen across a slide and then applying a cover slip. Typically, a smear should be allowed to air dry before applying a stain.
Stains are used to help identify different types of cells using light microscopes. They give the image more contrast and allow cells to be classified according to their shape (morphology). By using a variety of different stains, you can selectively stain different areas such as a cell wall, nucleus, or the entire cell. Stains can also help differentiate between living or dead cells.
Stains tend to be grouped as neutral, acidic or basic, depending upon their chemical makeup and will attract or repel different organisms accordingly. For example, scientists and health professionals use Methylene Blue, a slightly alkaline stain, to reveal the presence of deoxyribonucleic acid, more commonly known as DNA.
Iodine is one of the more commonly available stains and is used to identify starch in a variety of samples. It will stain carbohydrates in plants and animal specimens brown or blue-black. Glycogen will show as red.
Methylene Blue is an alkaline stain useful in identifying acidic cell nuclei and DNA in animal, bacteria or blood samples. It&rsquos also useful in aquariums to prevent the spread of fungal infections in fish. See more details >
Eosin Y is an acidic stain which stains pink for alkaline cells (cytoplasm, for example). It colors red for blood cells, cytoplasm and cell membranes. Eosin's most important medical uses are in blood and bone-marrow testing, including the PAP smear. See more details >
Gram's Stain is one of the most frequently used processes in identifying bacteria &ndash used daily in hospitals. It is a primary test that quickly and cost effectively divides bacteria into one of two types: Gram positive or Gram negative. See more details >
Reproduction of Bacteria
Even though they are single-celled microorganisms, bacteria can reproduce prolifically, if the conditions are right. Like most of the other single-celled organisms, bacteria too undergo reproduction through binary fission, which is a type of asexual reproduction. In this case, identical generations are formed, because the daughter cells are identical clone cells only. Budding is another form of asexual reproduction in bacteria. Even genetic recombination occurs in different types of bacteria, through transduction, transformation, and conjugation.
This is a form of asexual reproduction, which is common among bacteria. In this type of reproduction, a single parent cell divides into two, and forms two daughter cells, which will be replicas of the parent. In order to undergo binary fission, the bacterial cells must grow to a fixed size. Once they reach that size, each cell produces a replica of the genetic material, and form two DNA molecules that attach to the cell membrane in different locations. The cell membrane starts growing inwards in such a fashion that the two daughter clone cells are formed with the two DNA molecules. It has been observed that, if the conditions are right, bacteria can double in number through binary fission, within a short time of about ten minutes!
This is another form of asexual reproduction in bacteria. Some types of bacteria reproduce through budding, which is otherwise known as fragmentation. In this case, the mother cell forms a bud at one end, and also makes a nucleus for the bud, through the process of mitosis. The bud grows to the same size as that of the mother cell, that remains constant in size. The bud separates from the mother, and forms a different organism. Even though the nucleus of the bud is formed through mitosis, it has been observed that sometimes the characteristics of the offspring may differ from that of the mother.
Though sexual reproduction is rare in bacteria, in some cases, genetic recombination is facilitated through conjugation, transformation, or transduction. One of the reasons is that bacteria formed through asexual reproduction have the same genetic material, and can get affected by the same antibiotics. So genetic recombination helps them in creating bacteria with variations in genetic material. The latter category may be resistant to the particular antibiotics, or may be adapted to the changing environment.
In case of conjugation, the genetic material will be transferred between bacteria, as one bacteria connects to the other through a tube called pilus. In case of transformation, DNA is collected from the remnants of dead bacterial cells. In this case, the bacterial cells get attached to the DNA of the dead bacteria, and this DNA is transported through the cell membrane and incorporated to the genetic material of the live bacteria. In case of transduction, genetic material is transferred through bacteriophages (viruses that attack bacterial cells). As a bacteriophages attach to the bacterial cell, it inserts its genetic material into the bacterial cell. This results in the formation of replicated bacteriophages inside the bacterial cell, which opens up to release the former. The genetic material of this host bacterial cell can attach to the DNA of any other bacterial cell, that is attacked by these new bacteriophages.
To summarize, bacteria reproduce both sexually and asexually. Asexual method of reproduction, especially binary fission, is commonly found in bacteria. Some types of bacteria may resort to budding too. Sexual reproduction, though rare, happens in bacteria in some special circumstances.
Sexual and asexual reproduction are the two means of producing offspring. Read this article to gain more information about asexual reproduction in the animal kingdom.
Aerobic bacteria require oxygen to perform cellular respiration and derive energy to survive. In short, aerobic bacteria grows and multiplies only in the presence of oxygen. To know more about&hellip
Gram-negative bacteria refers to a broad category of bacteria that are unable to retain the crystal violet dye owing to their distinct cell wall structure. Know more about such bacteria&hellip
Analytical Lab Balance
What it Does
An analytical lab balance weighs samples and substances between .01 and 500 milligrams. The measuring pans are generally enclosed inside a glass box to prevent dust from settling in the pan since they can disrupt testing.
How to Use it in a Biology Lab
Never place chemicals directly on the balance pan unless they are at room temperature and unreactive. Instead, place the sample in a container before measuring. Containers, glassware, and pieces of metal can be placed on the pan. Measure it, weighing the container first to adjust for its weight. Return the weights back to zero.
- Mettler Toledo
- Thermo Fisher Scientific
- Adam Equipment USA
- Sartorius, Ohaus
When your mom tells you to wash your hands before dinner, she is thinking about all the germs you might have on your hands from touching the world around you. Germs are everywhere! Germs, or microorganisms, that cause illness and disease can grow on many surfaces called fomites. Here is a good description of fomites and how they harbor germs from the American Society for Microbiology:
"Fomites? What are fomites? This is a term for any inanimate object that can carry disease-causing organisms. Your cutting board, kitchen sink, the change in your pocket and even that pen you keep putting in your mouth are all fomites. Very few things we encounter in our everyday activities are sterile, or microbe-free, including us. At birth, microbes immediately begin colonizing our bodies as they do most every object in the world. They float around until they come in contact with a surface that offers food and shelter. You are most likely to find microbes in and on dark, moist objects that frequently come into contact with food, dirt or vegetation. Bathroom surfaces, hairbrushes, refrigerators, kitchen sinks and cutting boards often have lots of microbes on them. But doorknobs and walls have fewer because they are nutrient-poor and dry.
"Most of the microbes on our bodies and other surfaces are harmless, but some are pathogenic or disease-causing. For this reason, we want to control the number of microbes around us. The odds of becoming infected increase with the number of microbes on surrounding objects. But what can we do to affect the number of microbes on surfaces around us?
"In this activity, you will test a chosen fomite for the presence of microbes and the effects of a disinfectant by growing colonies of bacteria in a medium on petri plates. A medium has food, vitamins and salts that help microbes grow. You usually don't see bacterial colonies like those that form on petri plates on everyday surfaces. That's because there is rarely such a perfect concentration of nutrients on fomites in nature." (ASM, 2001)
An agar plate showing colonies of microorganisms that have been isolated from a deep-water sponge. (Wikipedia contributors, 2006 original source of image from NOAA Ocean Explorer)
How well do disinfectants work to clean surface bacteria? In this experiment you will use a cutting board as a fomite and test the use of different types of disinfectants. By culturing bacteria from the surface after you have cleaned it, you will find out how well the disinfectant worked. Which disinfectant types will work the best? Consider doing some background research first to understand how the different types of disinfectants affect microbes.
Show/hide words to know
Airborne transmission: passing pathogens from one person to another through the air.
Bacteria: one-celled, microscopic organisms that grow and multiply everywhere on Earth. They can be either useful or harmful to animals. more
Direct transmission: passing pathogens by the direct contact (touching) of two people.
Fungus: an organism that is part of the kingdom called fungi which includes yeasts, molds, and mushrooms. Fungi mainly feed on decaying organic matter. more
Indirect transmission: passing pathogens from one person to another by way of an intermediate object, like a doorknob.
Organism: a living thing that can be small like bacteria or large like an elephant.
Pathogen: a virus, bacterium, fungus or parasite that infects and harms a living host.
Protozoa: a group of single-celled organisms that live in water. more
Virus: a super tiny germ that you can only see with a microscope. Viruses need a host in order to reproduce. more
Have you ever wondered why you get sick? The answer is germs. Germs are tiny organisms that make you feel sick and cause disease. We come in contact with millions of germs every day. There are different kinds of germs: bacteria, fungi, viruses, and protozoa.
Germs are parasitic, which means they gobble up nutrients and energy from other organisms (like us). This process causes someone who has trouble fighting off the germs to show symptoms of common infections like fevers, sniffles, rashes, coughing, vomiting, and diarrhea, just to name a few.
Now that we know germs cause sickness, how do you think germs are spread? Germs can be spread many ways, including three types of transmission (or passing of germs): direct, indirect, and airborne. Direct transmission means person-to-person contact occurs, and the germs are passed that way. Indirect means that someone spread germs onto an object and when the next person touched that object, the germs spread. Germs can also travel through the air to move from one person to another.
With all these different ways for germs to be passed around, you might wonder if there's a way to avoid germs from getting to you. While we can’t really avoid germs altogether, we can take care of ourselves by washing our hands and covering our mouths when sneezing, among other things. This helps reduce the spread of germs.
During this activity you will illustrate the steps germs take during transmission. You will learn about the different types of bacteria, how they are spread, and discuss ways to keep from getting sick.
What You Need
- Sheet of paper
- Cups of water
Welcome to the beginning of a four-day festival of germs! Each day you will learn or do something new and germy.
Read the Puzzling Pathogens story and discuss it with the rest of your class.
Listen to a short presentation and do three activities that will teach you how those jolly germs jump from one person to another (this is called transmission).
- Direct transmission. Get a cup of water from where your teacher has set them up (don't drink it!). One will have a special chemical in it. You are going to see how just one person with a cold can spread it to many people. You will pour a little bit of your water into three other students' cups. Make sure to write down whose cup you put water into. Your teacher will then tell you who started out infected and from there, you will try to figure out who all should be infected. At the end of the activity, your teacher will come around and put one drop of another chemical into each cup. Those "infected" will end up with red water.
- Indirect transmission. This is a surprise activity that you will have to wait to learn about from your teacher.
- Airborne transmission. One student in class will get to use the spray bottle. They will point it in one direction and spray. Everyone else should stand around, trying to feel whether water from the spray bottle reached them. If you feel water land on you, raise your hand. Those that didn't get sprayed will use a meter stick to measure the furthest distance the water traveled.
Work on making a tree map. This will be a chart with bacteria, viruses, fungi, and protozoans listed at the top. Your teacher will prompt you with three or four questions related to these organisms. Then, you will watch a PowerPoint presentation and fill out your charts so they contain the answers to the questions in the appropriate columns.
Discuss ways to prevent the spread of germs with the rest of your class. You will split into groups and come up with skits that show how you can protect yourself and your classroom from germs. At the end of the day, you will take a quiz to show how much you've learned.
Cardboard, wood and cloth: safety in pores
The kind of surface matters. A recent review of the scientific literature found that the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes COVID-19, can survive on different surfaces for different amounts of time.
Food and mail deliveries are unlikely sources of COVID-19 infection. Image adapted from: Kristina Bratko/Unsplash CC0
On cardboard, it can survive for up to 24 hours. “I don't think that's likely to be a major source of infection,” said Australian immunologist Professor Peter Doherty in a recent interview, “but it's something you just might keep in mind when you're taking hold of the pizza box.”
The Australian Government Department of Health agrees. Its advice for cargo and mail workers (PDF) is that the risk of catching the virus from handling goods is low.
Microorganisms like viruses might disappear into a porous surface. Not to scale. Image by the Australian Academy of Science.
Surface porosity might be the key. Viruses are some of the tiniest biological organisms known. Like a golf ball rolling into a field of holes, they might sink into porous materials—like cardboard, wood or cloth—seldom to be seen again.
This might come as a surprise. Common advice for your kitchen is to avoid wooden chopping boards. Because liquids get sucked into the wood’s pores, these boards are more difficult to clean and disinfect.
Although non-porous surfaces are easier to disinfect, porous surfaces might result in less transmission. Not to scale. Image by the Australian Academy of Science.
However, a 2016 review of the microbial safety of wood concluded that these pores actually benefit wood as a safe food preparation surface. “In fact,” wrote the authors, “its rough or porous surface often generates unfavourable conditions for microorganisms.” In another 2016 study, food that was dropped on a carpet—also a porous surface—was less contaminated with bacteria than food that fell on stainless steel or tile.
It’s all about what is available on the surface. If pathogens get sucked into a porous surface like wood, they might not be able to transfer to anything you place on the surface. Moisture is also drawn away from the surface, which makes it less friendly to pathogens.
Foods like raw meat, poultry and seafood have a high risk of cross contamination—transferring harmful bacteria like salmonella via surfaces to other food items. To be on the safe side, the Australian Food Safety Information Council recommends that you use plastic or glass chopping boards for these foods. Running chopping boards through a dishwasher at high temperatures helps disinfect them.
Old chopping boards of any material should be replaced. Knife grooves and worn areas on plastic chopping boards can become a breeding ground for microorganisms. Pores in old wooden chopping boards can become clogged and lose their food safety benefits.
In a 2016 study, food that was dropped on carpet was much less likely to be contaminated than food that fell on tile or stainless steel. Image adapted from: Egor Lyfar/Unsplash CC0
Doctors treat bacterial meningitis with a number of antibiotics. It is important to start treatment as soon as possible.
Vaccines are the most effective way to protect against certain types of bacterial meningitis. There are vaccines for 3 types of bacteria that can cause meningitis:
- Meningococcal vaccines help protect against N. meningitidis
- Pneumococcal vaccines help protect against S. pneumoniae
- Hib vaccines help protect against Hib
Make sure you and your child are vaccinated on schedule.
Like with any vaccine, the vaccines that protect against these bacteria are not 100% effective. The vaccines also do not protect against all the types (strains) of each bacteria. For these reasons, there is still a chance vaccinated people can develop bacterial meningitis.
Pregnant women should talk to their doctor or midwife about getting tested for group B Streptococcus. Women receive the test when they are 36 through 37 weeks pregnant. Doctors give antibiotics (during labor) to women who test positive in order to prevent passing group B strep to their newborns.
Pregnant women can also reduce their risk of meningitis caused by L. monocytogenes. Women should avoid certain foods during pregnancy and safely prepare others.
If someone has bacterial meningitis, a doctor may recommend antibiotics to help prevent other people from getting sick. Doctors call this prophylaxis. CDC recommends prophylaxis for:
- Close contacts of someone with meningitis caused by N. meningitidis
- Family members, especially if they are at increased risk, of someone with a serious Hib infection
Doctors or local health departments recommend who should get prophylaxis.
You can also help protect yourself and others from bacterial meningitis by maintaining healthy habits:
- Don&rsquot smoke and avoid cigarette smoke
- Get plenty of rest
- Avoid close contact with people who are sick
This is especially important for people at increased risk for disease, including: