Microbial diversity and biogeochemical cycling in soda lakes

Soda lakes contain high concentrations of sodium carbonates resulting in a stable elevated pH, which provide a unique habitat to a rich diversity of haloalkaliphilic bacteria and archaea. Both cultivation-dependent and -independent methods have aided the identification of key processes and genes in the microbially mediated carbon, nitrogen, and sulfur biogeochemical cycles in soda lakes. In order to survive in this extreme environment, haloalkaliphiles have developed various bioenergetic and structural adaptations to maintain pH homeostasis and intracellular osmotic pressure. The cultivation of a handful of strains has led to the isolation of a number of extremozymes, which allow the cell to perform enzymatic reactions at these extreme conditions. These enzymes potentially contribute to biotechnological applications. In addition, microbial species active in the sulfur cycle can be used for sulfur remediation purposes. Future research should combine both innovative culture methods and state-of-the-art ‘meta-omic’ techniques to gain a comprehensive understanding of the microbes that flourish in these extreme environments and the processes they mediate. Coupling the biogeochemical C, N, and S cycles and identifying where each process takes place on a spatial and temporal scale could unravel the interspecies relationships and thereby reveal more about the ecosystem dynamics of these enigmatic extreme environments

HOT-ISOSTATIC PRESSING OF Mn-Zn FERRITES FOR MAGNETIC RECORDING HEADS

On produit des ferrites magnétiques denses par frittage normal et pressage isostatique à chaud. Les matériaux de départ sont des ferrites frittes normalement avec des pores fermés. La dimension des grains du matériau fini pressé à chaud peut être ajustée dans une large gamme de valeurs, de 15 à 1 000 µm.Dense magnetic ferrites are produced by normal sintering and isostatic hot pressing. The starting materials are normally sintered ferrites with closed porosity. The grain size in the final hot-pressed material can be adjusted in a broad range between 15 µm and 1 000 µm