USEFULNESS OF ALGAE AS FOOD AND MEDCINE TO OUR SOCIETY

USEFULNESS OF ALGAE AS FOOD AND MEDCINE TO OUR SOCIETY

CHAPTER ONE

• INTRODUCTION

Algae are photosynthetic organisms which constitute a total of about twenty-five to thirty thousand species with a great diversity of forms and sizes ranging from unicellular microscopic organisms (microalgae) to multicellular organisms of great sizes (macroalgae) (Arun et al., 2012). There are three phyla or division of algae and they include: Red algae (Rhodophyta) green algae (Chlorophyta), and Brown algae (Phaeophyta) (Gamal, 2010).

Microalgae exhibit notable biodiversity they can be found as individual cells, as colonies or as extended filaments. They account for the basic of food chain in aquatic ecosystems. They have the capacity to take up water and carbon (IV) oxide that with the aid of solar energy are used to synthesize complex organic compounds which are subsequently accumulated and/or secreted as primary or secondary metabolites (Arun et al., 2012). They are uniformly distributed throughout the biosphere where they have adapted to survival under a large spectrum of environmental stress which includes heat, cold drought, salinity, photooxidation, anaerobiosis, osmotic pressure and ultra violet exposure (Tandeau-de-marsac, 1993). They may equally grow under all environmental condition ranging from fresh water to extreme salinity.

Algae can double every few hours during their exponential growth period (Matting, 1996). During the peak growth phase, some icroalgae can double their growth even 3.5hrs (Christi, 2007). Marine organisms are a rich soruce of structurally novel and biological active metabolites (Borowitzka et.al., 1992; Ely et al., 2004). Secondary metabolites produced by algae may be potential bioactive compounds of interest in the pharmaceutical industries (Febles et al., 1995). Marine algae are also widely exploit as industrial raw materials. The chemicals composition of marine algae varies and it is also affected by the species of algae involved, the geographic area the algae is found, season of the year and as well as temperature f the water body where they are found. Marine algae are an important cash crop in different countries. They are used as food stuff in many countries such as Asian and china for centuries because they contain some phytonutriets such as carotenoids, dietary fibres, protein, essential fatty acids, vitamins, mineral and carbohydrates (Norziah and Ching, 2000). Many chemically unique compounds have been isolated form marine origin with various biologically activities and some of them are still under investigation and are equally been used to develop new pharmaceutical (Febles et al., 1995; Lima-Filho et al., 2002). The cell extract and active component of various algae have been reported to have antibacterial activities in vitro against Gram-positive and Gram-negative bacteria (Borowitzka et al., 1992). Green algae extract from diatoms and dinoflagelate have been reported to have antifungi activities by Borowitzka et al., (1992) and Morean (1988). The search for similar antimicrobial activity in other algae species has gained importance in recent years due to growing worldwide concern about antibiotic resistant microorganisms. Efforts are been made to extract substances with antibacterial, antiviral, antifungi enzymes inhibitory, immunosuppressive and cytotoxic and algicidal properties from low cost algal biomass (Knubel et al.,1990) and (Jaki et al., 1999). Some algal species such as SpirIulina has been reported to hinder oxidative damage by scavenging free radicals and active oxygen and therefore can indirectly reduce cancer formation in human (Halliwel, 1989; and Kok, 1990).

Microalgae have meanwhile been found to produce antibiotic. A large number of microalgae extract and/or extracellular products have been proven to have antibacterial, antifungi, anti protozoal and antiplasmodial activities (Kellan, 2004) and (Ghasemi, 2004). The antimicrobial activity of microalgae has attributed to compounds belonging to several chemical classes including indole, terpenes, actogenins, phenols, fatty acids and volatile halogenated hydrocarbons (Mayer, 2001-2002) and (Cardozo, 2007). Microalgae cell-free extracts are already being tested as additives for food formulation in attempts to replace antimicrobial compounds of synthetic origin currently in use, these includes sub-therapentical dose of antibiotics employed as prophylactic measure in animal breeding (Tramper, 2003).

Bacteria are microorganisms too small to be seen with naked eyes but they exist in virtually all environments in the world, even in foods we eat. They exists in dirty water, caves and hot spring organic materials like fallen trees, dead animals and inside the bodies of almost every living organisms on earth. Bacterial infection causes high rate of mortality in human population and aquaculture organisms. For an example, Bacillus subtilis is responsible for causing food borne gastroenteritis (Kramer, 1982). Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa cause diseases like mastitis, abortion, respiratory complications including some life threatening illness (Boyed, 1995), while Salmonella sp. causes diarrhea and typhoid fever (Leven, 1987), (Jaweltz et al., 1995).

Some fungi are opportunistic while others are pathogenic, causing disease if the immune system is not healthy (Eddy, 1982). Preventing disease outbreaks or treating the diseases with drugs or chemicals alone may not be sufficient to tackles these problems as the microorganisms develop resistance against the applied chemical drugs (Walsh, 2003). It becomes a greater problem of giving treatment against resistant pathogenic bacteria (Sieradzki, 1999).

• OBJECTIVES OF THE WORK

The covers the following:

1. Assessment of the phytochemicals presents to in algae Oscillatoira curviceps.
2. Assessment of antibacterial activities of Oscillatoira curviceps.