NOVELTY - Isolated Chlorella ohadii composition (C1), where the isolated Chlorella ohadii genome comprises at least one nucleic acid sequence of SEQ ID NO: 1, SEQ ID NO: 2 (Sequences not defined here may be found at ftp://ftp.wipo.int/pub/published_pct_sequences/publication) or their complements, is claimed.    USE - The composition is useful: in substantially pure culture; in edible composition that is formulated as a food or food supplement for at least one of aquaculture animals, poultry and mammals, in a form of a capsule, dragee, pill, tablet, gel, liquid, suspension, slurry, powder, pellets, cubes and flakes; in a composition for reducing the amount of at least one undesired substance present in waste, where the waste is one of wastewater, partially purified wastewater and contaminated soil; for producing algal biomass and/or its products, where the product produced by the microalgae cells is one of lipids, carbohydrates, proteins, vitamins and pigments, and is a metabolite useful in controlling the growth of toxic cyanobacteria naturally present in the microalgae cells, and the algal biomass is used as a food or a food supplement for an aquaculture animal, mammal or poultry (all claimed); and in production of biofuels, fertilizers, dietary nutrients, pharmaceuticals and polymers. No biological data given.    ADVANTAGE - The composition contains Chlorella ohadii that can rapidly and efficiently grow under optimized as well as harsh environmental conditions while maintaining their normal metabolism and high biomass production.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for: (1) a substantially pure culture comprising the composition (C1), and a growth medium; (2) a method (M1) for producing algal biomass and/or its products, comprising culturing Chlorella ohadii microalgae under conditions suitable for the Chlorella ohadii proliferation and photosynthetic activity; (3) a biomass of Chlorella ohadii produced by the method (M1); (4) an edible composition (C2) comprising the composition (C1), and an excipient, diluent or carrier suitable for oral consumption; (5) a method (M2) for reducing the amount of at least one undesired substance present in waste, comprising culturing Chlorella ohadii microalgae in a culture medium comprising waste, where the culturing conditions are suitable for the Chlorella ohadii proliferation and for photosynthetic activity for at least 8 hours/day; and (6) a composition (C3) for reducing the amount of at least one undesired substance present in wastewater or contaminated soil, comprising isolated Chlorella ohadii and at least one type of aerobic microorganism capable of reducing the amount of the undesired compound.