ABSTRACT
There are two roads to obtain bacterial strains potentially useful for biotechnically important transformations: genetic engineering and the classical enrichment culture approach. The present state of the art in the knowledge of the extremely thermophilic archaebacteria distinguishes the acidophilic aerobic sulfide and sulfur oxidizers, comprised in the order Sulfolobales and Thermoproteales, from the anaerobic methanogens falling into the orders Methanobacteriales, Methanococcales, and Methanomicrobiales. Thermophilic sulfate- and thiosulfate-reducing bacteria have been isolated and described by Schink and Zeikus and Zeikus et al. Work on thermophilic bacteria receives a strong impetus from biotechnological goals. The production of proteins, the fermentation of starch and cellulose, and possible conversion of lignites are the predominant areas of emphasis. An isolate, NS—E, is unique by its eubacterial characteristics despite certain similarities to extremely thermophilic archaebacteria: namely, the reduction of elemental sulfur, neutrophily, heterotrophy, and oxygen sensitivity.
