Actinomycetes are the most economically and biotechnologically valuable prokaryotes. They are responsible for the production of about half of the discovered bioactive secondary metabolites, notably antibiotics, antitumor agents, immunosuppressive agents and enzymes. Because of the excellent track record of Actinomycetes in this regard, a significant amount of effort has been focused on the successful isolation of novel actinomycetes from terrestrial sources for drug screening programs in the past fifty years. Recently, the rate of discovery of new compounds from terrestrial Actinomycetes has decreased, whereas the rate of re-isolation of known compounds has increased. Thus, it is crucial that new groups of Actinomycetes from unexplored or underexploited habitats be pursued as sources of novel bioactive secondary metabolites.
The Streptomycetes are members of the bacterial order Actinomycetales, bacteria which resemble fungi in their branching filamentous structure. However, they are true bacteria - prokaryotic cells - unlike eukaryotic fungal cells. As Actinomycetes grow, they form branching filaments of cells which become a network of strands called as mycelium, similar in appearance to the mycelium of some fungi. Actinomycetes are also unique in the way they form spores and in the production of numerous antibiotics. By far the most successful genus in this group is Streptomyces with over 500 species. Few species of Streptomyces are pathogenic for animals, although a few species cause plant diseases.
The biochemistry of Streptomycetes is truly remarkable, considering their production of secondary metabolites, many of which account for almost half of all known Antibiotics (Berdy, 1964). Many of these compounds have important applications in human medicine as antibacterial, antitumour and antifungal agents. Also, in agriculture these compounds act as growth promoters, agents for plant protection, antiparasitic agents and herbicides (Hopwood, 1995). The onset of antibiotic production of Streptomyces cultures grown on agar usually coincides with the early stages of morphological differentiation.
Applications of Streptomyces
Streptomyces are metabolically diverse and can "eat" almost anything, including sugars, alcohols, amino acids, organic acids, and aromatic compounds. This is achieved by producing extracellular hydrolytic enzymes. There is considerable interest in these organisms as agents for bioremediation. Their metabolic diversity is due to their extremely large genome which has hundreds of transcription factors that control gene expression, allowing them to respond to specific needs.
Several species of Streptomyces are involved in a symbiotic relationship with species of ants in the genus Attini. Attine ants cultivate fungus in, what are termed fungal gardens. They perform all the motions of human farmers, weeding, and nurturing their gardens. The small bacterium in the Streptomyces genus inhabits the cuticles of the ants, and aids in weeding their fungal gardens. Streptomycetes produce toxins that keep the main weed in ant fungal gardens, another fungus, Escovopsis, at bay (Donia et al., 2003).
IN BIOTECHNOLOGY FIELD
In recent years, biotechnology researchers have begun to use Streptomyces spp. for production of recombinant human proteins. Traditionally, Escherichia coli were the species of choice to host eukaryotic genes since it was well understood and easy to work with. However, Escherichia coli introduces problems such as incorrect (or lack of) glycosylation and incorrect protein folding, resulting in insolubility and loss of bioactivity of the product. Streptomyces species. on the other hand has the ability to secrete correctly folded recombinant proteins into the medium after production simplifying the subsequent purification steps. These properties among others make Streptomyces species. an attractive alternative to other bacteria such as Escherichia coli and Bacillus subtilis.
Streptomyces are also of medical and industrial importance because they synthesize antibiotics. There are several theories to may explain antibiotic production, the most widely accepted one being that antibiotics help the organism compete with other organisms in the relatively nutrient-depleted environment of the soil by reducing competition. Over 50 different antibiotics have been isolated from Streptomycetes species, including streptomycin, neomycin, chloramphenicol and tetracyclines. Bleomycin is an antibiotic drug with anticancer properties produced by Streptomyces verticillus. It was isolated and its mechanism of action is breaking the DNA double helix by the production of free radicals (Umezawa et al., 1966). It is used for malignant tumors, specifically germ cell tumors, lymphomas, head and neck and Kaposi's sarcomas (Bull et al., 2005).
Thus the present study is focussed on evaluating the efficacy of three compounds from Streptomyces species namely Actinogan, Lactonamycin and Fredericamycin which have activities to induce apoptosis strongly on cancer cells by treating with cell lines.
The present study is focussed on evaluating the efficacy of three compounds from Streptomyces species namely Actinogan, Lactonamycin and Fredericamycin which have activities to induce apoptosis strongly on cancer cells by treating with cell lines. The following are to be done to find the efficacy of the three anti- tumor compounds:
1.) Growth Kinetics of the source should be found by plotting a graph between time and O.D at 600nm in order to find the time at which the secondary metabolites are produced.
2.) The optimized pH of Lactonamycin, Actinogan and Fredericamycin. Has to be calibrated.
3.) Isolation of the protein should be performed.
4.) SDS PAGE should be done which serves as a conformation test for, Lactonamycin, Actinogan and Fredericamycin.
5.) The three anti-tumor compounds should be treated with normal Vero cell lines and cancerous HeP2 cell lines.
The Life Cycle of Streptomyces sertoni
The life cycle of Streptomyces begins with the germination of a single spore. This spore produces one or more multi-nucleoid filaments. This will elongate and branch on the surface and into the culture medium to form a vegetative mycelium. Hyphal growth is by quasi-exponential growth kinetics. This complex network of filaments will continue penetrating the medium, utilising the available organic molecules with the use of extracellular hydrolytic enzymes. This motility of the Streptomyces vegetative filaments gives it a big advantage to other less motile bacteria when it comes to colonizing solid substrates in the soil. In response to appropriate signals, believed to include the exhaust of nutrient supplies in the surrounding environment, the substrate mycelium will break the surface barrier and aerial hyphae are formed.
Aerial growth coincides with the onset of secondary metabolism in cultures grown on solid media. The continuation of the aerial growth is supported by the utilization of the vegetative mycelium. When the extension of the aerial hyphae stops; their multigenomic tips undergo synchronous, multiple septation to give rise to unigenomic prespore compartments. Mature spores are held together in chains of about 50 and they develop a characteristic grey pigment as they mature. Unlike the endospores of other Gram-positive bacteria, such as Bacillus and Clostridium, Streptomyces exospores are not resistant to extreme heat or pH and are less dormant; however, they are fairly resistant to desiccation.
Highlights of the Project
The high demands for the drugs that have the ability to cure many types of cancer have long been met by Chemotheraphy. However, some of the side effects reverting from such treatments have been undesirable. For this reason, the production of drugs having anti tumor activity microbial sources has been the focus of the extensive research. Among the different marine organisms, Streptomyces speices were isolated. This organism been the major producer of certain proteins effective against cancer, is an important and commercially viable organism.
Over 50 different antibiotics have been isolated from Streptomycetes species, including streptomycin, neomycin, chloramphenicol and tetracyclines. Fredericamycin, Lactonamycin and Actinogan are antibiotic drugs with anticancer properties produced by Streptomyces species. Their mode of action happens through inhibition of RNA and protein bio systhesis and inhibition of cell cycle in the G2/M phase. It is used for malignant tumors, specifically germ cell tumors, lymphomas, head and neck and Kaposi's sarcomas.