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Microorganisms for you
Environmental Science: Definition, principles and scope. Medicinal Plants of the Month
Research Methodology— Antimicrobial testing
Facts: Plant Taxonomy
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Arthrobacter nicotianae It is an aerobic gram positive bacterium. The appropriate growth media are nutrient agar and nutrient broth. It is a calcite forming bacteria and has been evaluated for cement crack remediation. It produces restriction endonuclease. The preferred temperature for growth is 26ยบC.
Anabaena It is a genus of filamentous cyanobacteria that exist as plankton. The species are well known for their nitrogen fixing abilities and they form symbiotic relationships with certain plants like mosquito ferns. It produces neurotoxins which is responsible for symbiotic association and is responsible for protection of plants from grazing pressure under nitrogen limiting conditions. Vegetative cells differentiate into heterocysts at semiregular intervals along the filaments. These heterocysts are specialized for nitrogen fixation and convert nitrogen into ammonia. The interior of heterocysts are microxic as a result of increased respiration inactivation of oxygen producing photosystem II occurs resulting in the formation of a thickened envelope outside the cell walls. Nitrogenase, sequestrated within these cells transforms dinitrogen into ammonium at the expense of ATP and reductant both generated by carbohydrate metabolism. Carbohydrates generated in the form of glucose in vegetative cells move into heterocysts which inturn supply fixed nitrogen to the vegetative cells and thus a symbiotic relationship is established.
Arthrobacter arilaitensis MICRO ORGANISMS FOR YOU
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It is found on the surface of cheeses especially on that of smear ripened cheese and is responsible for the typical colour, texture and flavour of the final product. It is well equipped with enzymes required for the catabolism of major carbon substrate present at the surface of the cheese such as fatty acids, aminoacids and lactic acid.
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Arthrobacter bergerei It is an aerobic gram positive bacterium isolated from the surface of the smear ripened cheese. It is non motile and non spore forming species and exhibit catalase positive activity. The preferred carbon sources are D-glucose, fructose, D-galactose, sucrose, maltose, lactose, ribose, L-arabinose, D-xylose, D-glycerol, D-gluconate, quinate, protocatechuate, lactate, aspartate and glutamate.
Arthrobacter globiformis The genus name in Greek means ‘Jointed Small Sticks’. All the species of Arthrobacter are rods during growth and cocci in their stationary phase. A.globiformis is a gram negative, non motile bacterium present in the soil and is widely distributed in the environment. The colonies formed on nutrient agar are smooth, circular, convex elevation with entire margin. The preferred temperature for growth is 20º30ºC and grows well in neutral to slightly alkaline pH. It utilizes ammonium salt or nitrate as the nitrogen source and glucose is used as a carbon and energy source. It has the ability to oxidize ammonia to nitrate, nitrite and hydrylamine. This provides reliable nitrogen source for the growth of the plant. It has the ability to reduce pesticides and other harmful chemicals found in the soil. A lot of plants don’t have the ability to grow in the presence of hexavalent or trivalent chromium but A.globiformis can grow and can even help to reduce the amount of trivalent chromium.
Arthrobacter variabilis It is a gram positive, slightly aerobia, non motile, rod shaped bacterium. The cells are irregular (club shaped or tapered) and occur singly, in pairs with typical V forms or clumps. In older cultures, older forms are visible. Colonies are small, circular and convex and are grey white in colour with a dry appearance. The optimum temperature for growth is 25-30ºC. The preferred carbon sources are acetate, propionate, succinate, malate and levulinate. The cell wall contains an arabinogalactan polymer.
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INDIGOFERA TRIFOLIATA L. Family : Fabaceae Medicinal properties: Seeds– astringent, antileucorrhoeic, antirheumatic, restorative. Phytochemicals reported from the plant: Crude protein, pentosan, water and soluble gum. According to H.H.Thomas (1936), the Facts angiosperms of the past replaced many of the older Gymnosperms in asturine and marshy waters. Theophrastus (370—285 B.C.) classified plants on the basis of form and texture. He considered trees to be the highest evolved and herbs as primitive. Dioscorides (64 AD) of Christian era prepared a ‘Materia Medica’ and described many plants of medicinal value. William Turner (1512) who is regarded as the ‘Father of English Botany’ was the author of several botanical works. He wrote the English Herbal.
Medicinal plants of
the Month
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MELILOTUS ALBA Desr Family : Fabaceae Medicinal properties: Plant– astringent, discutient, emollient. Used as poultice or plaster for swellings. Phytochemicals reported from the plant: Coumarine, fraxidin, heniarin, umbelliferone and scopoletin.
The most important of the British Herbals was written Facts by John Gerard (1545– 1612) entitled ‘Herbal or General Historie of plants.’ G. Bauhin, a Swiss Botanist wrote ‘An Introduction to Botany’ in which he described about 6000 species of plants. He described many plants with generic and specific names. His great work ‘Phytopinax’ of 1596 ins great contribution of Botany. M. de Lobelius differentiated between monocotyledons and dicotyledons chiefly on the basis of leaves. His great work ‘Kruydtboeck’ was published in 1581. John Ray (1628– 1705), an English botanist contributed much and the foundation of modern Botany was laid. His most important work was the ‘Historia Plantarum’ which was published in three volumes between 1686 and 1704.
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ORMOCARPUM COCHINCHINENSE (Lour).Merr. Family : Fabaceae Medicinal properties: The plant is extremely efficacious in mending bone fractures. Phytochemicals reported from the plant: Alkaloids, anthocyanin, betacyanin, cardiac glycosides, coumarine, flavonoids, phenols, quinines, saponins, steroids, tannins, terpenoids.
Facts
Carolus Linnaeus (1707– 1778), a great Swedish Botanist who is regarded as the father of Modern Botany published a
number of important works (Genera Plantarum, Species Plantarum, Flora Lapponica) in which he described hundreds of plants he known that time. The outline of the classes of system was published in Systema Nature in 1735 and gain in Genera Plantarum in 1737.
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PHASEOLUS TRILOBUS AIT Family : Fabaceae Medicinal properties: Whole plant– febrifuge. Leaves– sedative, cooling, antibilious. A decoction is used in intermittent fever. Phytochemicals reported from the plant: Friedelin, epifriedelin, stigmasterol, tannins, methionine, tryptophan, tyrosine, strepogenin, uridine, diphosphate galacturonic acid, lysine, valine, leucine and phenyl alanine. Bentham and Hooker, the well known English sysFacts tematists, established an important system of classification. They published a joint system of classification, containing 202 orders in a monumental work ‘Genera Plantarum.’ Michel Adanson published ‘Families des plantes’ in Paris in 1763 with an arrangement of genera in 58 families. A.P.de Candolle, a French Botanist proposed a very reasonable natural system of classification. His great work ‘theorie elementaire de la botanique’ was published in 1813.
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Environmental Science: Definition, principles and scope Environment literally denotes the surrounding around us. Environment includes all the biotic and abiotic components on which we depend either directly or indirectly. Environmental science is the study of all the components or factors that make or influence our life supporting biophysical environment. The processes in the environment (ecological systems, biodiversity, natural resource, climate change, various types of pollutions) are guided by the complex interaction of the physical, chemical and biological processes along with significant human intervention. Environmental science integrates information from a number of other disciplines like biology, physics, chemistry, geology, geography, sociology, economics etc., and is thus a multidisciplinary course. According to Environmental protection Act, 1986: “Environment is the sum total of water, air and land, their interrelationships among themselves and with the human beings, other living beings and property. � There are certain subdivisions of environmental studies. They are environmental engineering,
environmental
economics,
environmental
ethics,
environmental
management, environmental sociology, environmental biotechnology etc., Scope: Environmental studies has a vast scope as it covers a wide range of subject matters or issues related to our complex life supporting system. The scope of Environmental studies are as follows:
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It deals with energy flow and the cycle of materials in the environment.
It deals with the study of nature and its function
Biogeochemical cycles– the cycling of materials or nutrients between the biotic and abiotic components of the environment.
To create awareness about the environmental problems among people.
To impart basic knowledge about the environment and its allied problems.
To motivate public to participate in environmental protection and environmental improvement.
To encourage research opportunities in this study area to study different types of pollution and pollutants and their causes and effects.
The study guides us to know how our development and day to day activities affect environment.
It encourages us to create a pollution free environment.
To teach the proper utilization of natural resources.
Principles: According to UNESCO, the guiding principles of the environmental education should be as follows:
Environmental education should have an interdisciplinary approach by including physical, chemical, biological as well as socio cultural aspects of the environment. It should build a bridge between biology and technology.
Environmental education should take into account the historical prospective, the current and potential historical issues.
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Environmental education should emphasize the
importance of sustainable
development.
It should emphasize the necessity of seeking international
cooperation in
environmental planning.
Environmental education should lay more stress on practical activities and first hand experiences.
Importance of environmental studies:
To conserve biodiversity.
To create sustainable development.
To use natural resources effectively.
To know the behavior of organism under natural conditions.
To know the interrelationship between organisms in population and communities.
To educate and create awareness among the people regarding environmental issues and problems at local, national and international levels.
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Facts
Robert Brown was the first keeper of the Botani-
cal department of the British Musseum. In 1810 Brown published his Prodromus Florae Noval Hollandiae,
containing the descriptions of Australian plants collected by Banks and Solander. In 1827, Brown published a paper entitled ‘The female flower in Cycadaceae and Coniferae’ and in this he announced the important discovery of the distinction between Angiosperms and Gymnosperms.
John Lindley proposed a system of classification and published ‘Introduction to the Natural order of plants.’
In 1851, Hofmeister carried out many researches and established the existence of alternation of generations in lower as well as higher plants.
In 1883, a system of classifying the flowering plants was proposed by A.W. Eichler is also remarkable because of its resemblance with the widely accepted Englerian system.
Adolf Engler and Eugen Prantl ‘s Phylogenetic system of classification was first published as a guide to the botanical garden of Breslau in 1892. most of the prominent herbaria of the world are arranged according to this system. According to this system, the families were arranged in accord to the increasing complexity of flower, fruit and seed development.
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C.E. Bessey, an American Botanist proposed a system Facts of classification based on Bentham and Hooker’s system. According to him, the Ranales were the primitive Angiosperms from which two branches were given out which gave birth to Monocots and Dicots. Hans hallier, a German Botanist proposed a system based on the phylogenetic relationships parallel to Besseyan system with minor alternations. He considered dicots to be the older and more primitive than monocots. John Hutchinson, an English botanist has given the latest information about the phylogentic classification of Angiosperms which has been published in his famous work ‘families of Flowering Plants’ in 1959. Armen Takhtajan, an academician of Leningard, Russia, presented a system of classification of Angiosperms for the first time in 1942. according to himthe angiosperms are of monophyletic origin and evolved from some ancient group of gymnosperms. Arthur Cronquist of USA presented a comprehensive system of classification in 1968 and his system is parallel to that of the Takhtajan’s system. Rolf Dahlgren, Denmark botanist, published a system of classification of Angiosperms in 1975 in which he used chemical characters of plants for classification. According to Turril, the physiological aspects, to some extent, lead the taxonomist towards the determination of phylogeny. Mc Nair showed the distribution of certain chemical substances in the families of Angiosperms and its relation to climate.
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Alston and turner (19963) in their work Facts ‘biochemical Systematics’; hegnauer (1965) in his ‘Chemotaxonomical der pflanzen’; Leone (1964) in his ‘Taxonomic Biochemistry and serology’; Swain (1963) in his ‘Chemical Plant Taxonomy’ and Harborne (1967) have given a review of phytotaxonomical chemistry and emphasized on the role of various chemicals in Plant Taxonomy. Serotaxonomical test and consequent phylogenetic relationships between the taxa of angiosperms were established in germany by professor K.C.Mez in 1926. Heywood I n 1967 defined numerical taxonomy as ‚the numerical evaluation of the similarity between groups of organisms and the ordering of these groups into higher ranking taxa on the basis of these similarities. According to Sneath and Sokal (1973)‛numerical taxonomy aims to develop methods that are objective, explicit and repeatable, both in evaluation of taxonomic relationships and in the erection of taxa.‛ The necessity of mathematical applications in taxonomy has been realized by J.P.M. Brenon (1968) in Royal Botanical Garden, Kew, Engloand. He has given the example of Kew herbarium with nearly 40 to 50 million specimens. J.Cullen (1968) has precisely revised the botanical problems of numerical taxonomy and has compared the numerical taxonomical methods with the orthodox taxonomical methods. The possibility of using embryological features in Taxonomy was suggested for the first time by Hofmeister and Strasburger.
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Antimicrobial Testing Antimicrobial susceptibility testing can be used for epidemiology, drug discovery. Agar disk diffusion method: It is the official method used in many clinical laboratories for routine antimicrobial susceptibility testing. Agar plates are inoculated with a standardized inoculum of test micro organism. Then filter paper discs (about 6mm in diameter), containing the test compound at a desired concentration, are placed on the agar surface. Petri dishes are incubated under suitable conditions. The antimicrobial agent diffuses into the agar and inhibits germination and growth of the Research methodology
test microorganisms. Antimicrobial gradient method (E test): This method combines the principle of dilution methods with that of diffusion methods in order to determine MIC value. It is based on the possibility of creating a concentration gradient of the antimicrobial agent tested in the agar medium. The E test is a commercial version of this technique. In this, a strip impregnated with an increasing concentration of the antimicrobial agent from one end to the
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Other is deposited on the agar surface previously inoculated with the microorganisms tested. This technique can also be used to investigate the antimicrobial interaction between two drugs. Agar well diffusion method: It is widely used to evaluate the antimicrobial activity of plant extracts. The agar plate is inoculated by spreading a volume of the microbial inoculum over the entire agar surface. Then a hole (6 to 8 mm in diameter) is made aseptically with a sterile cork borer and a volume (20 to 100Âľl) of antimicrobial agent or extract solution at desired concentration is introduced into the well. Then agar plates are inoculated under suitable conditions depending upon the test microorganism. The antimicrobial agent diffuses in the agar medium and inhibits the growth of the microbial strain tested. Agar plug diffusion method: This is used to show the antagonism among microorganisms. It involves making an agar culture of the strain of interest on its appropriate culture medium by streaks on the plate surface. During their growth, microbial cells secrete molecules which diffuse in the agar medium. After incubation, an agar plot or cylinder is cut aseptically with a sterile cork borer and deposited on the agar surface of another plate previously inoculated by the test microorganism. Substances diffuses from the plug to the agar medium. The antimicrobial activity of the microbial secreted molecules is detected by the appearance of the inhibition zone around the agar plug.
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Cross streak method: It is used to rapidly screen microbes for antagonism. The microbial strain is seeded by a single streak in the centre of the agar plate. After incubation period the plate is seeded with the microorganism tested by single streak perpendicular to the central streak. After further incubation, the observations are made. Poisoned food method: Mostly to evaluate antifungal activity. The extract is incorporated into the molten agar at a desired final concentration and mixed well. Then, the medium is poured into petri dish. After over night pre-incubation, the inoculation can be done by a mycelia disc ranging from 2 to 5 mm, which is deposited in the centre of the plate. After further incubation, suitable observations are made. Thin layer chromatography (TLC): Agar diffusion: It involves the transfer by diffusion of the antimicrobial agent from the chromatogram (paper chromatography or TLC) to an agar plate previously inoculated with the micro organism tested. After some minutes or hours to allow diffusion, the chromatogram is removed and agar plate is incubated. The growth inhibition zones appear in places, where the antimicrobial compounds contact with the agar layer. Direct bioautography: The developed TLC plate is dipped into or sprayed with microbial suspension. Then bioautogram is incubated at 25ยบC for 48 hours under humid condition. For visualization of the microbial growth, tetrazolium salts
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are frequently used. These salts undergo a conversation to corresponding intensely colored formazan by dehydrogenase of living cells. Agar overlay bioassay: It is the hybrid of both the previous methods. TLC is covered with a molten seeded agar medium. Inorder to allow a good diffusion of the tested compounds into agar medium, the plates can be placed at low temperature for few hours before incubation. After incubation under suitable conditions depending upon the test microorganism, staining can be done with tetrazolium dye.
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Darani Vasudevan daraniauthor.ga
Hi readers, I am a Botanist and writer. This magazine is an outcome of the topics that interested me a lot while doing my research works. I chose this magazine as a platform for sharing many interesting facts related to plant Science and microorganisms.