Methanogens promoters

Analysis of the sequences located upstream of archaeal rRNA genes has shown that archaeal rRNA promoters consist of the sequence TTTA(A/T)A located 20-30 nucleotides upstream of the transcription initiation site and a weakly conserved sequence, (A/T)TG(A/C) around the transcription initiation site [40]. Transcription of the rRNA genes terminates within pyrimidine-rich regions in the extreme thermophiles [30,41], in pyrimidine-rich regions followed by a short hairpin loop in the methanogens [27,34] and in AT-rich regions preceded by a GC-rich region in the extreme... 

Promoter structure is the one feature of methanogen gene organization that is conspicuously different from its bacterial counterpart. Methanogens, in common with all archaea, have complex, multi-subunit DNA-dependent RNA-polymerases (RNAP) [31,32,41,42] which recognize and bind to sequences which have very little in common with the canonical -10 and -35 promoter sequences established in bacteria (see Chapter 12... 

Chiu et al. (53) reported that lowering of soil redox potential increased the ratio of As(III) and promoted arsenic methylation. Methylation of arsenic compounds by yeast and bacteria under oxic conditions plays a significant role, whereas methanogenic bacteria are important under anoxic conditions in releasing volatile arsenic from the soil to the atmosphere (39,41). Woolson and Kearney... 

These conditions are the same as those that may be anticipated to promote maximum rates of waste stabilisation and to therefore reduce the long tenn pollution potential of landfilled waste. The use of highly engineered and specified containment landfills will create the opportunity to optimise (within Hnancial constraints) the limits of the above conditions to more effectively and safely codispose different waste streams, especially as Knox (1990a) was able to demonstrate the robusmess of the methanogenic waste degradation process under adverse conditions of co-disposal. 

---