MIC 102 Lecture Notes - Lecture 23: Biogeochemical Cycle, Cyanobacteria, Proteobacteria
Document Summary
Microbes catalyze many important conversions on earth. Most elemental conversion processes boil down to redox reactions. Potential use of microbes in recycling man made materials. Carbon is 50% of a cells weight. Carbon in multiple forms: co2, methane, organic, inorganic. Cycling of organic c: respiration, fermentations. Microbial o2 synthesis in oceans accounts for half or more of o2 production on earth: cyanobacteria, diatoms. Carbon and oxygen cycling are closely linked. Communities of archaea and bacteria combing sulfate reducing and methane oxidizing. Nitrogen fixation critical to life on earth. Soil would be depleted in a week if nitrogen fixation stopped. Ammonification is only in the marine environment not in the farmland enviornment. Assimilation used as a nutrient for biosynthesis: reduced and incorporated into cell material. Dissimilation used as an energy source: can be reduction or oxidation, oxidation of ammonia to nitrate, reduction of oxidized nitrogen compound in anaerobic respiration. The same nitrogen can be used in both processes.
