Invisibe life in the water
Who lives in the pond?
After the rain, we can notice small ponds all around us. Depending on the season, some last for several months, while some evaporate with the first sun. Ponds are stagnant waters that are much smaller than a lake. Natural ponds usually arise in floodplains or along rivers. They may contain shallow water and aquatic plants and many animals live in them. Various microorganisms can also be found in the ponds. In addition to bacteria and viruses, there are heterotrophic protists that, like bacteria, cannot be seen with the naked eye. Paramecium and amoebae, as representatives of heterotrophic protists, are one of the main inhabitants of all ponds.
Paramecium
Back in 1675, naturalist scientist Antoni van Leeuwenhoek noticed under his microscope tiny organisms that moved vividly. One of the organisms was a 0.25 mm slipper animalcule. It was named after its shape which looked like a foot - a slipper. It belongs to the group of migratory animals, a class of ciliates, which are very widespread in freshwater terrestrial and marine environments. We call them protozoans because they appeared long ago in the evolutionary past and because probably all modern animals have evolved from their ancestors.
A is covered by a stick elastic structure called the pellicle, on which surface the cilia are used for moving and feeding. The pellicle also has a groove called the vestibulum. The vestibulum, i.e. oral groove, directs food into the cell mouth (cytostome) by which Paramecium feeds itself. The cell mouth is followed by a slightly more advanced digestive system, which includes the cell pharynx (cytopharynx) and the anal pore, or cytoproct, through which the undigested contents are expelled. When food enters the paramecium, a food bubble is created in which the lysosomes are poured and the food is digested by enzymes.
The Paramecium breaths by the exchange of gases that take place through the cell surface. Also, the paramecium has contractile vacuoles that serve as a mechanism for regulating the amount of water. The paramecium has a large nucleus called a macronucleus and a small nucleus called a micronucleus. The large nucleus controls feeding, gas exchange, and osmoregulation, and the small nucleus controls reproduction.
Find out in video file how Paramecium feeds.
Source - author: youtube.com - Craig Smith
Amoebae
Amoeba is also a protozoa belonging to the group of . Its characteristic is that it moves using false feet (pseudopods), i.e., it changes its body shape when moving. Amoeba is enclosed by the cell membrane, has a single nucleus, and feeds throughout the entire body surface.
As with the Paramecium, when the food enters, a food bubble is created around it, which associates with the lysosome and digests the food. The amoeba can survive adverse conditions (such as drought or cold) by forming a cyst. In the form of a cyst, the amoeba does not feed, move or reproduce, and waits for favorable conditions to return to a vegetative form. Amoeba feeds on bacteria, algae and slipper animalcules.
View more about Amoeba in video file.
Source - author: youtube.com - Dr. Ralf Wagner
The surface of the amoeba body is covered by a cell membrane. Amoeba doesn’t contain any additional structures on the cell membrane. The shape of an amoeba’s body is variable. It takes in food through the body surface by capturing its prey with false feet or pseudopods. When food enters the body, a food bubble forms around it. The food bubble associates with a lysosome that contains nutrient degradation enzymes. The undigested food is ejected out of the body of the amoeba. As with the paramecium, the amoeba gets oxygen by diffusion and uses contractile vacuoles for osmoregulation. The amoebae reproduce by binary fission, that is, by dividing the parent cell into two smaller ones, whereby the parent cell disappears.
View more how Amoeba feeds.
Source - author: youtube.com - 7activestudio
Some amoeba species live as parasites in the organs of different animals and humans. The most common pathogenic amoebae are and Acanthamoeba.
Do you want to know more?
Amoebae as “Trojan horses” of the microbial world
Should we watch out for amoebae and slipper animalcules carrying pathogenic bacteria?
Heterotrophic protists, such as amoebae and slipper animalcules, are found in almost every aquatic ecosystem on Earth. They mainly eat bacteria, and as their predators they can eat tens to hundreds of bacteria in just one hour. However, some bacteria have been able to develop certain traits that prevent the protist from digesting them after eating them, which allows them to survive within their host. Inside the protists, the bacteria find a safe shelter and protection from environmental hazards such as chlorination or, in some cases, antibiotics that could harm them.
Examples of such bacteria are , , , and many other bacteria. In this way, amoebae and slipper animalcules become "microbial Trojan horses" with a potential role in human and animal infection.
Illustration of Legionella pneumophila within Achantamoeba castellanii amoeba after 48 hours of cocultivation. The bacteria can be seen as dark blue sticks inside the amoeba.
Do not consume water found in the environment that doesn’t meet health safety standards as it may contain bacteria and amoebae!
Entamoeba histolytica
Profession: A pathogenic amoeba.
Specialization: Causes amoebic dysentery in humans.
Skills: I am a pathogenic amoeba that moves gently on the substrate using pseudopods or filaments. Under unfavorable conditions, I curl up in a cyst and, in this way, I can survive in water, soil and food for a long time. A person becomes infected when he or she drinks or eats me, and the symptoms only appear when I emerge from the cyst into an active form called the trophozoite. I can cause prolonged diarrhea in people, and I like poor hygiene conditions. If you do not want me, I advise you to keep a high level of hygiene, wash your hands frequently and of course drink only drinking water.
Legionella pneumophila
Profession: An opportunistic pathogen in drinking water supply systems.
Specialization: An amoeba parasite, which can survive in small droplets of water (aerosols).
Skills: I love hidden spaces where there is water, such as the water supply and air conditioning systems. Usually, I live in an aquatic microbial community, i.e. a biofilm. I am relatively resistant to chlorine and heat, and if necessary, I can hide and grow in amoebas. Through small droplets in the air (aerosols), I can enter the lungs of humans and cause infection, that is, legionellosis. This disease is not contagious. I can travel up to 10 km by air from the source in which I live.
Mycobacterium avium komplex
Profession: An opportunistic pathogens in drinking water supply systems.
Specialization: Resistance to acids and infections in patients with a weakened immune system.
Skills: We are two nontuberculous mycobacteria: Mycobacterium avium and Mycobacterium intracellulare and together we make a perfect couple. We generally do not cause disease unless the immune system is severely weakened. You can find us in soil, water and dust. Unlike other bacteria in the group, it is difficult to grow us on nutrient media. In addition to being picky about food, we reproduce slowly, and we create colonies on Lowenstein-Jensen agar after 10 to 21 days. We are visible under the microscope only if you paint us with special Ziehl-Nielsen staining since we have a waxy cell wall, through which the color hardly passes.
Salmonella spp.
Profession: A pathogenic bacteria.
Specialization: I cause diseases in humans and animals.
Skills: I can survive on foods and other surfaces for a long time. Unfortunately, I do not tolerate temperatures above 70 ° C.
Campyilobacter spp.
Profession: I inhabit the digestive system of most warm-blooded animals such as wild birds, poultry, cattle, pigs, sheep, dogs and cats, but also oysters and other shellfish.
Specialization: I love it when the meat is not thermally treated because then I can enter a human’s body and cause the disease called campylobacteriosis.
Paramecium
Profession: A model organism for the study of biological processes.
Specialization: Fast swimming and symbiosis with algae.
Skills: I am a scientist amongst microorganisms and I help people to understand the biological processes in protozoa. I am called "slipper animalcules" because of my slipper-like shape. I do not cause disease, and I am not a bacterium. I was discovered by Antoni van Leeuwenhoek in 1675 under the light microscope that was invented by him. You can find me in the seas, inland and brackish water, and in moist soil.
