A rapid screening method for the isolation of metal-accumulating microorganisms

Summary An agar plate screening method was developed for the rapid isolation of heavy metal-accumulating microorganisms and preliminary estimation of their biosorption capacity. The test is based on the visulaization and interpretation of the metal distribution between agar and colonies by chemical preciptitation with hydrogen sulphide or ammonium sulphide. The heavy metals silver, thallium, lead, copper, nickel and cadmium have been tested successfully. The efficiency of the method is demonstrated for isolating silver-accumulating bacterian and estimating silver biosorption capacity.     

The free-living inland aquatic nematodes of Africa — a review

During the past three decades, much attention has been given to free-living nematodes and, in particular, to the species of the African continent. Despite the current absence of evidence for the existence of planktonic species, several conditions are suggested that could lead to intrusion of the planktonic habitat, e.g. turbulent shallow waters, high food densities and preadaptations such as swimming ability and negative geotaxis. A new and more practical ecological classification of the inland free-living nematodes is proposed to avoid further incoherency in this regard. All the free-living inland aquatic species described in Africa are presented here in a checklist, including notes on their ecology and distribution. Many of the cosmopolitan species, included in the checklist, are now increasingly being recognized as conglomerates of species, each species of which occupies a restricted area. Finally the distribution of free-living inland aquatic species in Africa is discussed and some preliminary notes are presented.