Micromasters of the Earth

Micromasters of the Earth Anna WĘGRZYN – the Department of Environmental Biotechnology at the Faculty of Energy and Environmental Engineering at the Silesian University of Technology, Gliwice Please cite as: CHEMIK 2011, 65, 11, 1182-1189 Introduction membrane constitutes about 25% of the whole bacterium mass. It is estimated that our planet was formed about 4.6 billion Peptidoglycan (murein) is a fundamental substance of the bacterial cell years ago. At the very beginning, it was just a lifeless ball of melted wall. In their cell walls, bacteria can contain different quantities of murein magma. The Earth surface was gradually getting cool until reaching which is connected with a diversified sensitivity to dyes. Depending the temperature at which water and other chemical compounds on the number of peptidoglycan layers, the applied dyes (e.g. crystal could have been created. First traces of life are being discovered in violet) are retained inside the cell wall or leached from it. This is the rocks formed about 3.85 billion years ago. Stromatolites - biogenic basis for classifying bacteria into a group of Gram-positive or Gram- rocks dated at about 3.4 billion years which formation was connected negative bacteria (originating from the name of the Danish scientist with activities of cyanobacteria – autotrophic organisms being able to Gram who was the first person to perform the complex staining with XII Conference Environmental produce oxygen in the process of photosynthesis, constitute the fossil crystal violet in 1884). The cells of Gram-negative bacteria contain trace of the prokaryotic structure1 of primitive forms. The creation of lower quantities of murein than in case of Gram-positive bacteria. eukaryotic cells (containing nucleus), i.e. cells making inter alia human They also contain an additional outer membrane consisting of proteins, body, was the next stage of the biological evolution. The creation phospholipids and lipopolysaccharides (LPS) making up its inner tissue. of eukaryotic cells is explained by the endosymbiotic theory2: The space between the outer membrane and peptidoglycan is called a primitive prokaryotic cell lost its cell wall and its membrane became the periplasmic space [1, 4]. folded. Membranous inner vesicles appeared inside this form, and The ultrastructure of the inner part of bacterial cells can be the cell increased its size; the cell nucleus was isolated. The aerobic examined due to the studies on these cells with different types prokaryotic forms – precursors of mitochondria3 – and photosynthetic of microscopes. As previously mentioned, the prokaryotic cell does prokaryotes – precursors of chloroplasts4 – entered into a newly not contain a nucleus. And its function is possessed by nucleoid, also formed structure by endosymbiosis [1, 2]. known as bacterial chromosome. Plasmids5 are additional elements The theory explaining the life evolution on our planet shows of the genetic material present in the bacterial cell [1, 4]. that microorganisms dominated on the Earth much earlier than we, Bacteria usually move by means of cilia or mucous coats. Moreover, human beings, and our worlds are very strongly linked at the cellular their cells include formations known as pilii or fimbriae. They are thin level. However, until the 17th century A.D., the world of scientists and long appendages present at the cell surface. The process of cellular was not aware of the existence of microorganisms. Just Antonie van respiration takes place in invaginations of cellular membrane, known Leeuwenhoek, a Dutch tradesman, discovered small creatures waving as mesosomes [1, 4]. their legs and tails in a raindrop under a microscope constructed by himself. It was the world that no one had ever expected to exist. The Bacterial lilliputians and giants world in which “small creatures”, namely bacteria, can assume the The diameter of a “standard” bacterial cell is estimated to be about oddest shapes, perform various processes, proliferate at a phenomenal 1 μm (i.e. 10-6 m) and its length does not exceed 5 μm. In the kingdom rate, and they very often rule both our life and death. This paper Bacteria, there are present both much smaller and bigger forms. presents the most interesting examples of micromasters of the Earth. The representatives of Mycoplasma genus [1] belong to the smallest type of bacteria. The size of these cocci corresponds to the size What are common features of the micromasters of biggest viruses, and their diameter is up to about 0.3 μm. Mycoplasma of the Earth? pneumoniae is hazardous to human health; it causes atypical bacterial The feature of microorganisms, as their name indicates, is their pneumonia in young children [5]. A group of ultramicrobacteria with microscopic size. The size of bacterial cell ranges from 0.5 to several a diameter smaller than 0.3 μm was also identified. However, these micrometers, depending on their taxonomical classification. This feature microorganisms have not been examined in details so far [6]. was decisive in isolating this group from Plantae and Animalia kingdoms The bacterial giants include such species as, inter alia, Epulopiscium as well as their specific structure, activity, diversity and variability fishelsoni or Thiomargarita namibiensis. The length of microorganisms of their metabolism and ecological distribution [1]. belonging to the first of mentioned species ranges from 200 to Shapes of bacterial cells can be observed through an optical 700 μm and their diameter is about 80 μm. Despite their size making microscope. Eubacteria exist in spherical (cocci and their combinations), them visible to the naked eye, it is quite improbable to spot them as cylindrical (e.g. cocobacilli and bacilli) and helical shapes. The bacterial they are present inside intestines of tropical fish of the Acanthuridae cell is surrounded with a flexible cell wall, which along with the cell family and have a symbiotic relationship with their host [7]. They were 1 Prokaryotic organisms – usually unicellular microorganisms whose cell lacks the biggest known bacteria in science until 1999. That year, when the cell nucleus (spherical DNA molecule, known as nucleoid acts as the Thiomargarita namibiensis species, isolated from the bottom sediment nucleus) and other cell organelles typical for eukaryotic cells (e.g. human cells). at Namibia coast, was described. Thiomargarita means “sulphur pearl” 2 Endosymbiosis – a specific type of symbiosis (a phenomenon of close in- – it was named due to its distinctive picture of sulphur globules in cells teraction between at least two species which is favourable for one side and observed under a microscope. The length of bacterial cells reaches up does not make any harm to the second one), in which cells of one organisms to 1000 μm, i.e. 1 mm. So, they are visible to the naked eye [8]. live within cells or tissues of the other. 3 Mitochondrion – an energetic centre in the eukaryotic cell. 5 4 Chloroplast – a cell organelle present at plants and eukaryotic algae contain- Plasmid – a small, usually circular DNA molecule which usually occurs in ing dyes – chlorophylls absorbing light energy used in the photosynthesis bacterial cells, it encodes, among other things, resistance genes to antibiot- process. ics and heavy metals, has an ability to independent replication. 1186 • nr 11/2011 • tom 65 Bacterial toughies Regarding the utilitarian issues, enzymes produced by cells of The bacteria are the most common organisms on the Earth. They extremophiles draw the greatest interest [13]. Enzymes are mainly are growing not only in a moderate environment, but also under protein catalysts which accelerate specific biochemical reactions extreme conditions – in cold environments (permanently frozen even by a few thousand times by reducing their activation reaction ground, sea and polar ice) and in hot environments (geysers with [14]. Enzymes application in the industrial catalysis is attracting boiling water, rock-core), in strongly acidic environments (areas more and more followers. However, some industrial processes rich in sulphur and pyrites), in alkaline environments (sodium lakes), supported by enzymes require high temperature and/or pressure, in saline environments (brines), environments which are under high concentration of salts or acidic pH of the environment. continuous influence of high hydrostatic pressure (ocean deeps) In such cases, the application of enzymes isolated from or in extremely dry environments (hot and cold deserts) with a high extremophilic microorganisms seems to be reasonable because content of heavy metals and other toxic substances, contaminated these protein molecules demonstrate the highest activity under with radioactive substances [9]. Table 1 presents the examples of conditions similar to the ones in which the organism producing such extremophilic microorganisms. enzymes exists. And having the knowledge of the structure and properties of enzymes acting in extreme environments, it would Table 1 be possible to construct new or modify the “standard” enzymes Types of extremophilic microorganisms, their scientific classification by means of genetic engineering methods and use them in various and examples [9] biotechnological processes [15]. Conditions All enzymes which were isolated from the thermophile bacteria, Group Places for growth Microorganisms namely, the bacteria which grow and proliferate at high temperatures, name: of presence XII Conference Environmental and proliferation are stable even above 100°C. It is interesting that the

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