Morphological and cultural characterization of some strains of unicellular algae of the genus Prototheca sampled from mastitic cow milk

Abstract

Prototheca is a unicellular, achlorophillous, ubiquitary and saprophytic alga spread in the surrounding environment mostly in vastly damp locations in the presence of the organic matters. This is deemed to be pathogenic to a low degree, taking immediate advantage of the environment and triggering diseases at a time when the immunological capability of defense of the organisms is low or, when favorable factors come about. Prototheca is capable to induce disease in man as well as in several other animal species. Twenty strains of Prototheca sp, were sampled from cows with mastitis. The strains are characterized morphologically and developmentally on various culture media: glucose media (broth and agar), blood agar, potato medium, glucose medium of various pH values, medium containing antibiotics, Mac Conkey agar, Smith Baskerville medium (without antibiotics), and engine-oil medium. Growth took place within conditions of aerobic at 37°C and the culture became visible within 36-48 hours. On liquid media there has been noticed that the medium keeps settled and the tube bottom shelters granular drags, that lend to slight homogenization. On solid media the colonies become visible within 36-48 hours. By continuing to maintain them at room temperature, they increase in size. First, they are small, irregular in shape resembling ice crystals reflecting shiny irisations. With lapse of time, they increase in size reaching 3-5 mm, displaying pale-white colour. They also increase in height and the surface takes a mulberry or cauliflower shape. Morphological assessment was carried out on wet smear in Lügol solution or in thinned staining solutions (methylene blue, malachite green, Congo red or fuchsine), allowing for good differentiation in the inner structures. The prevailig shape of Prototheca is that of an egg, seldom round or, that of a kidney with variation in size between 9.5/10.5μm up to 27.5/30.4μm. With some cells 6 to 8 endospores were noticed. Based on morphological and cultural characters there was set down that the strains under surveillance belonged to the species of Prototheca zopfii.