ANAEROBIC RESPIRATION OF BACILLUS-MACERANS WITH FUMARATE, TMAO, NITRATE AND NITRITE AND REGULATION OF THE PATHWAYS BY OXYGEN AND NITRATE

In Bacillus macerans, anaerobic respiratory pathways and the regulatio n of facultatively anaerobic catabolism by electron accepters were ana lysed. In addition to fermentative growth, B. macerans was able to gro w anaerobically by fumarate, trimethylamine N-oxide, nitrate, and nitr ite respiration with glycerol as donor. During growth by fumarate resp iration, a membrane-bound fumarate reductase was present that was diff erent from succinate dehydrogenase. The end product of nitrate and nit rite respiration was ammonia. No N-2 or NO and only traces of N2O coul d be detected. O-2 repressed the activity of nitrate ad fumarate reduc tases and the fermentation of glucose, presumably at the transcription al level. Nitrate repressed fumarate reductase activity and partially glucose fermentation. Thus energy metabolism and the regulatory hierar chy with respect to the use of electron accepters were very similar to that known from E. coli; B. macerans can be regarded as a truly facul tative anaerobic bacterium. In addition, the anaerobic growth capabili ties of some other Bacillus strains are described.