Algae Introduction and industrial important

Algae

1. Vivekanandha arts and science College for women , Sankagiri. PG DEPARTMENT OF MICROBIOLOGY ALGAE Presented by S.Menakagandhi II- M.Sc Microbiology VIAAS

2. Introduction Algae is an informal term for a large and diverse group of photosynthetic, eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular microalgae, such as Chlorella, Prototheca and the diatoms, to multicellular forms, such as the giant kelp, a large brown alga which may grow up to 50 meters (160 ft ) in length. Most are aquatic and lack many of the distinct cell and tissue types, such as stomata, xylem and phloem that are found in land plants. The largest and most complex marine algae are called seaweeds, while the most complex freshwater forms are the Charophyta, a division of green algae which includes, for example, Spirogyra and stoneworts . Algae that are carried by water are plankton, specifically phytoplankton.

3. General characteristics of algae Algae are photosynthetic organisms
Algae can be either unicellular or multicellular organisms
Algae lack a well-defined body, so, structures like roots, stems or leaves are absent
Algae are found where there is adequate moisture.
Reproduction in algae occurs in both asexual and sexual forms. Asexual reproduction occurs by spore formation.
Algae are free-living, although some can form a symbiotic relationship with other organisms.

4. Classification of algae Algae possess diverse characters in their pigments nature of reserve food, nature of cilia etc. According to these morphological and physiological differences they are classified by many people. Fritsch (1935) classified the whole of the algae into eleven classes on the basis of type of pigments, nature of reserve food material, mode of reproduction etc. They are Chlorophyceae , Xanthophyceae,Chrysophyceae , Bacillariophyceae , Cryptophyceae,Dinophyceae , Chloromonodineae , Euglinineae,Phaeophyceae , Rhodophyceae and Myxophyceae ( Cyanophyceae ). The classification is published in his book titled “The structure and Reproduction of Algae”.

5. 1. Class: Chlorophyceae (Green Algae) Occurrence: Most forms are fresh water and a few are marine.• Pigments: Chief pigments are chlorophyll a an b and carotenoids(yellow pigments)• Reserve food: Starch Structure: Unicellular motile to heterotrichous filaments. Cell wallconsists of Cellulose. Pyrenoids are commonly surrounded by starch sheath. Motile cells have equal flagella(24). Reproduction: Sexual reproduction ranges froisogamous to advanced oogamoustype . Example: Chlamydomonas , Volvox , Chlorella, Scenedesmus,Pediastrum

6. 2. Class: Xanthophyceae (Yellow green algae) Occurrence: Most forms are fresh water but a few are marine. Pigments: Yellow xanthophyll is found abundantly. Reserve food: oil Structure: Unicellular motile to simple filamentous. Cell wall rich in pectic compounds and composed of two equal pieces overlapping at their edges. Motile cells have two very unequal flagella. Pyrenoids absent. Reproduction: Sexual reproduction is rare and alwaysisogamous. Example: Vaucheria

7. 3. Class: Chrysophyceae Occurrence: Most forms occur in cold Fresh water but a few are marine. Pigments:Chromatophores are brown or Orange colored. Phycochrysin serves as chief accessory pigments. Reserve food: Fat and leucosin. Structure: Plants are unicellular motile to branched filamentous. Flagella are Unequal attached at front end. Cells Commonly contain one or two parietal Chromatophores. Reproduction: Sexual reproduction Seldom occurs but is of isogamous type. Example: Chrysodendron,Phaeothamnion

8. 4. Class: Bacillariophyceae (Diatoms) Occurrence: In all kind of fresh water, sea, soil and terrestrial habitats Pigments: Chromatophores are yellow or Golden brown. Nature of accessory pigments is not very definite. Reserve food: Fat and volutin. Structure: All the members are unicellular or Colonial. Cell wall is partly composed of silica Add partly of pectic substances. It consists of Two halves and each has two or more pieces.
Cell wall is richly ornamental. Reproduction: Forms are diploid. Sexual reproduction is special type, occurs by fusion of protoplasts of the ordinary individuals. Example: Pinnularia

9. 6. Class: Dinophyceae Occurrence: Plants occur widel Ass sea water planktons. A few way be fresh water forms. Pigments:Chromatophores are dark yellow, brown , etc., and Contain a number of special Pigments. Reserve food: Starch and oil. Structure: plants are unicellular Motile to branched filamentous. Reproduction: Sexual reproduction is of isogamous Type. It is rare and not very definite. Example: Dinoflagellate ,Ceratium.

10. 7. Class: Chloromonadineae Occurrence: All plants are fresh Water forms.
pigments: Chromatophores are Brightt green in colour andContain an excess of Xanthophyll.
Reserve food: Oil
Structure: The plants are motile, Flagellate with two almost equal flagella. Reproduction: Sexual reproduction absent, cells Divide by longitudinal division. Example: Trentonia

11. 8. Class: Euglenineae Occurrence: Only fresh water form area known
Pigments: Chromatophores are pure green. Each cell has several chromatophores.
Reserve food: Polysaccharide and Paramylon. Structure: Motile flagellates, flagella may be one or two arising from the base of canal like invagination at the front end. Complex vacuolar system and a large and prominent nucleus. Reproduction: Sexual reproduction is stiallybstantially known. It is Isogamous type. Example: Eugle

12. 9. Class: Phaeophyceae (Brown algae) Occurrence: Mostly marine Pigments: chl a, c,carotenes,xanthophylls , not chl b Reserve food: Mannitol as well as laminar in and fats
Structure: The plants may be Simple filamentous to bulk Parenchymatouss forms. Several plants attain giant size, external and internal differentiation.
Reproduction: Sexual reproduction ranges isogamous to oogamous. Motile gametes have two laterall attachedd flagella. Varied types of Alternation of generation. Example: Ectocarpus , Sargassum

13. 10. Class: Rhodophyceae (Red algae) Occurrence: Few forms are fresh waterand others are marine. Pigments: Chromatophores are res blue containing pigments like re phycoerythrin and blue phycocyanin , Chl - a,d , carotenes.
Reserve food: Floridean starch
Structure: Simple filamentous to attainingconsiderable complexity of structure.
Motile structures are not known.
Reproduction: Sexual reproduction is advanced oogamous type. The maleorgan produces non motile gametes andthe female organ has a long receptiveneck . After sexual reproduction special spores (carpospores) are produced
Example: Batrachospermum,Polysiphonia

14. 11. Class: Myxophyceae ( Cyanophyceae or Blue green algae) Occurrence: Found in sea and freshwater. Pigments: Chlorophyll, carotenes, xanthophylls, and phycocyain and phycoerythrin. The ratio of last two pigments exhibits colour variation, commonly blue green. Reserve food: Sugars and Glycogen.
Structure: Simple type of cell filamentousentous , some of the filamentous forms show false or true branching,
very rudimentary nucleus, no proper chromatophores, the photosynthetic pigments being diffused throughout the peripheral position.
No motile Stages.
Reproduction: There is no sexual reproduction.
Example: Oscillatoria , Nostoc

15. Classification of algae

16. Reproduction In algae

17. Reproduction of algae The algae reproduce by three different methods, namely, vegetative reproduction, asexual reproduction and sexual reproduction. Vegetative Reproduction in Algae: Any vegetative part of the thallus grows into a fresh new organism in this form. This does not entail the development of spores or the alternation of generations. This is the most typical method for algae to reproduce.
The modes of vegetative reproduction in algae are as follows: Cell Division or Fission: It is the most basic type of reproduction. Synechococcus , Chlamydomonas, diatoms, and other unicellular algae generally reproduce through this simple mechanism, known as binary fission. The vegetative cell undergoes mitotic division and results in two daughter cells, which then function as new individuals in this process.

18. Reproduction in Algae Bulbils :
Food is processed at the peak of rhizoids as well as on the basal part of Chara , resulting in tuber-like outgrowths known as bulbils. Bulbils expand into new plants until detaching from the plant body. Fragmentation :
The multicellular filamentous thallus is broken into many-celled fragments in this process, all of which produces a new organism. Fragmentation in algae may occur by chance, as a result of the formation of separation discs, or as a result of another mechanical force or injury. Spirogyra, Zygnema , Oedogonium , Ulothrix , Cylindrospermum , and other plants contain it.

19. Reproduction in Algae Hormogonia :
Blue-green algae use this form of vegetative reproduction. The trichomes of blue-green algae part ways and get divided into many-celled segments termed as hormogonia or hormones inside the sheath. The development of separation discs, or necridia , heterocysts , as well as the death and decay of trichome intercalary cells, keep them delim­ited. Hormogonia can be found in Nostoc , Oscillatoria , and other places. Budding :
Bud-like structures are defined in Protosiphon as a result of the proliferation of vesicles that are separated from the parental body by a septum and develop into a fresh new plant following detachment.

20. Reproduction in Algae Formation of Adventitious Branches: Various big thalloid algae create adventitious branches, that when detached from the body of the plant grow into new individuals (for instance, Fucus , Dictyota). Stolons of Cladophora glomerata , Internodes of Chara , and other stolons form protonema -like adventitious branches. Amylum Stars: On the basal part of Chara , a star-shaped accumulation of starch-containing cells forms. Amylum stars are indeed the name given to these structures. They evolve into new plants once they are separated from the plant body.

21. Reproduction in Algae Asexual Reproduction in Algae: The creation of some types of spores — whether naked or freshly walled spores — is needed for asexual reproduction. It is a mechanism of protoplast rejuvenation that does not involve sexual fusion. Every single spore develops into a plant. There occurs no alternation of generations in this process.
Asexual reproduction in algae can come in a variety of forms: Zoospores :
Zoospores are motile exposed spores containing two, four, or several flagella, and are respectively referred to as bi-, quadri -, or multi flagellated zoospores. Ulothrix , Chlamydomonas, Ectocarpus , and other bacteria produce biflagellate zoospores; Ulothrix produces quadriflagellate zoospores, and Oedogonium produces multiflagellate zoospores.

22. Reproduction in Algae Aplanospores : Aplanospores are spores that are not mobile. Under unfavourable conditions, such as drought, such spores can develop singly or their protoplast can split to form several aplanospores within the sporangium (e.g., Ulothrix , Microspora ). Some algae in semi-aquatic habitats may also produce aplanospores . Autospores are cells that tend to be similar to their parent cell (for example, Scenedesmus , Chlorella etc.). Hypnospores are aplanospores possessing a thickened surface and a large food reserve (examples may include., Sphaerella , Pediastrum , etc.).

23. Reproduction in Algae Tetraspores Tetraspores are haploid aplanospores produced by diploid algae (– for example, Polysiphonia). Tetraspores are produced inside tetrasporangia . A tetrasporangium’s diploid nucleus undergoes meiotic division and leads to the creation of four haploid nuclei, each of which grows into four tetraspores with just a minor fraction of protoplasm. Tetraspores germinate to produce male and female gametophytes upon libe­ration. Akinetes :
Some filamentous algae’s vegetative cells grow into akinetes , which are lengthened thick-walled spore-like formations with ample food reserves (for example., Gloeotrichia ). They have the ability to weather the storm. They germinate into new individuals as ideal conditions arise.

24. Reproduction in Algae Akinetes :
Some filamentous algae’s vegetative cells grow into akinetes , which are lengthened thick-walled spore-like formations with ample food reserves (for example., Gloeotrichia ). They have the ability to weather the storm. They germinate into new individuals as ideal conditions arise. Exospores :
Exospores are spores that are chopped off at the uncovered distal end of the protoplast throughout the basipetal succession of certain algae. Such spores clump together and form new colonies, including Chamaesiphon . Endospores :
These are tiny spores produced by the mother protoplast’s divisions. Conidia and gonidia are other names for them. After the breakdown of mother wail, they were set free. The spores germinate immediately and grow into a new plant, such as Dermocarpa , without having to rest.

25. Reproduction in Algae Sexual Reproduction in Algae: Except for individuals of the Cyanophyceae class, almost all algae undergo sexual reproduction. Gametes unite to produce zygotes while sexual reproduction. The combination of gametes from different parents will result in a new genetic establishment.
Sexual reproduction in algae are divided into five groups based on the structure, physiological activity, and complexity of sex organs: Autogamy :
Fusing gametes are formed from the very same mother cell throughout this process, and then after fusion, these produce a zygote. For the reasons mentioned above, autogamous plants do not display the emergence of any new characteristics, such as Diatoms (Amphora normani

26. Reproduction in Algae Hologamy :
Vegetative cells of various strains (+ and -) act as gametes in certain unicellular members, and then after fusion, they result in the formation of a zygote. This seems to be an inefficient method in terms of multiplication, however, it does result in the creation of new genetic varieties, such as Chlamydomonas. Isogamy :
It is the merger of two gametes that are physiologically and morphologically identical, resulting in the formation of a zygote. Isogametes are a form of gamete. These are typically flagellates, such as Chlamydomonas Eugametos , Ulothrix , and others.

27. Reproduction in Algae Anisogamy :
The uniting gametes are physiologically and morphologically distinct during this phase. The microgamete (male) is small and more aggressive, while the macrogamete (female) is bigger and less active, such as Chlamydomonas braunii . Physiological anisogamy differs from traditional anisogamy in that the uniting gametes share morphological similarities but vary physiologically. Zygnema , Spiro­gyra, can be some examples. Oogamy :
It is a complex process in which a small motile (non-motile in Rhodophyceae ) male gamete (sperm or antherozoids ) is fertilised by a large non-motile female gamete (egg or ovum). Male gametes grow in antheridium, while female gametes grow in oogonium , such as Polysiphonia, Oedogonium , Chara , Batrachospermum, Vaucheria, Sargassum , Laminaria , and so on.

28. Life cycle in algae LIFE CYCLES IN ALGAE The sequence of events through which one generation passes into the next generation is called life cycle. Sexual reproduction involves alternation between haploid and diploid generation which we call alternation of generation. In algae, there are five main types of Life cycles or alternation of generation. These are as follows Haplontic Life Cycle- In this type of life cycle the main plant body is gametophytic (haploid) that produces mitospore during growing season that develops
into gametophytic plant. Towards the end of the growing season gametophyte produces gametes (haploid). Zygote/ zydospore (diploid) is formed after gametic fusion, which is the only diploid phase in the life cycle. Soon after their formation zygospores /zygote divides by meiosis to form meiospores that germinates into gametophytic thallus . Such a life cycle is called haplontic life cycle and the most primitive one in which zygotic
meiosis takes place and there is no formation of sporophytic thallus (diploid). This type
of life cycle is shown by majority of green algae, Charophytes and Bangia of red algae

29. Life cycle in algae Diplontic Life Cycle - The dominant plant thallus is diploid. The thallus reproduces sexually by gametes that are formed by meiosis in sex organs. Thesegametes represent the haploid phase in the life cycle. These gametes fuse to for zygotee / zygospore that ultimately forms the diploid plant body. No true alternationof generation as in the first case (haplontic) occurs. This type of life cycle is calleddiplontic life cycle. This life cycle is shown by diatoms ( Bacillariophyceae ), some members of Siphonales , Siphonocladiales and Dasycladiales of green algae an Fucaless of Brown algae. Diplohaplontic Life Cycle - This type of life cycle is exhibited by Ulvales ndd Cladophorales of Chlorophyceae and some brown algae ( Ectocarpus,Dictyota ). In this type of life cycle two different generations alternate each other. True alternation of generation occurs. This type of life cycle that consists of two different vegetative individuals alternating with each other is called diplohaplontic . There are two types of diplohaplontic life cycles- isomorphic and heteromorphic. ( i ) Isomorphic- In isomorphic diplohaplontic life cycle, alternating sporophyte and gametophyte are morphologically similar. Zygote produces sporophytic thallus that produces meiospores in sporangium by reduction division. Meiospores germinate Too form a gametophytic thallus that forms gamtes in sex organs. Syngamy betweengametes yields zygote that produces diploid thallus . E.g., Ulvales , Cladophoraleet ectocarpales , Dictyotales and red algae. ii) Heteromorphic- In heteromorphic diplohaplontic life cycle, alternating generations are morphologically dissimilar. Sporophyte has elaborate development as compared to the gametophyte. E.g., Laminarials , Desmarestiales etc.

30. Life cycle in algae Haplobiontic Life Cycle- This is either diphasic or triphasic life cycle. In Nemalion a red alga exhibits two haploid phases and a diploid zygote. Hence, this type of haplobiontic is diphasic as it consists of two haploid thallus . It is also be called as haplo -haplontic. In Nemalion dominant phase is a gametophyte that produces gametes. Zygote is formed after gametic union that develops into carposporophyte after meiosis. Carposporophyte produces carpospores that Ultimately germinate into main gametophytic plant body.
Batrachospermum (red alga) do exhibit haplobiontic life cycle but it is triphasic as it consists of three prominent haploid phases (main gametophyte, carposporophyte ndd chatransia phase). Therefore, this life cycle may be called as haplo - haplo -haplontic life cycle. Zygote is the only diploid phase. The main plant body which is gametophyte produces gametes. These gametes fuse to form zygote that undergoes meiosis and develops into carposporophyte. Carpospores of carrposporophyte germinates to form chatransia stage. Chatransia stage then develops into normal gametophytee .

31. Life cycle in algae Diplobiontic Life Cycle- It is also a triphasic life cycle also called as diplodiplohaplontic life cycle. This life cycle consists three phases of which two phases are diploid and one is haploid. The main plant body is gametophyte thatproduces gametes. Zygote is formed by syngamy . In this life cycle, zygot differentiatess into diploid carposporophyte. Diploid carposporangia develops in carposporophyte and diploid carpospores are produced within carposporangia . On liberationn , carpospores develops into diploid tetrasporophyte . Tetraspores are produced after meiosis inside tetrasporangia . Tetraspores eventually develops into mainn gametophytic plant thallus . This type of life cycle is exhibited by somemembers of red algae such as Polysiphonia.

32. Life cycle in algae

33. Economic importance Of algae Algae are important to human life in various aspects. These plants have been used for centuries. Although algae are beneficial to us but there are some harmful aspects too. In this section we will come to know about the role of algae in various fields like industry, agriculture etc. 1-Agricultural importance- Blue green soil algae are very important in agriculture as they are capable of nitrogen fixation in the soil.In Rajasthan, blue green algae Spirulina and Anabaena are cultured commercially in Sambhar Lake and are used as manure by local farmers. Concentrated liquid extracts of sea weeds are sold as fertilizers and insecticides also. The grinded form of Lithothamnion , Lichophyllum and Chara are used in place of lime in some countries. 2-Role of Algae as food and fodder- Algae synthesize organic food stuffs and are an important food source of fishes and other aquatic animals. As the flesh of the land is dependent upon the activities of the green leaf, so the fish and other aquatic forms of animal life are dependent, directly or indirectly, upon algae.

34. Economic importance of algae 3-Algae and space travel- Chorella (space algae) Scenedesmus and Synchococcu aree used as food source for space travelers. These algae are very rich in proteins (single cell protein) and multiplies rapidly and thus synthesize a rich harvest of food utilizing carbon dioxide and liberating sufficient oxygen as a byproduct for use. 4-Role of algae in medicine- Algae has been used for medicinal purposes since time immemorial. Ancient literature of China revealed the use of Laminaria sp. For the treatment of goiter. Brown algae being rich source of iodine are employed in the preparation of medicines for goiter. Members of Laminariales have lon Chorella used as a surgical tool and also during child birth to expand the cervix. An antibiotic chlorellin is obtained from Chorella . 5-Algae as the origin of petroleum and gases - It is an accepted fact the environment fuels such as petroleum and gases have their origin in the organic mat marine environment.

35. Economic importance of algae