Form IC sequences were affiliated to Alpha-, Beta- and Gammaproteobacteria for which chemolithotrophy and/or sulphur metabolism is a major mode of energy generation. In the composite tree, molecular phylogenetic analysis of cbbL clone libraries demonstrated the presence of six different novel monophyletic lineages of cbbL harbouring chemolithoautotrophic VX 809 bacteria residing in the agroecosystem and saline soil clone libraries (Figure 2). These cbbL genes had a low sequence similarity with cbbL-types from known organisms, which

indicates the sources of these cbbL genes may be yet unknown and uncultured autotrophic bacteria. The cbbL sequences fall into 15 clusters; one cluster AS site specific, five clusters SS1 & SS2 site specific and nine clusters having cbbL-gene sequences obtained from all three sampling sites. The ubiquitous distribution of majority of the phylotypes (nine mix clades) in the agroecosystem and saline soil clone libraries suggest a possible large scale distribution of several closely related chemolithotrophs. However, the possibility of high degree of sequence conservation and horizontal gene transfer in RuBisCO gene has limited the inference about taxonomic identity

of closely related clones [19]. The saline soils phylotypes were assigned to some recognized genera like Nitrosospira, Paracoccus, Rhodobacter Salinisphaera, and many uncultured clones from differently managed XL184 purchase agricultural systems, contaminated aquifers and deltaic mobile sediments. These sequences from saline soil clone libraries mostly belong to Alpha- and Betaproteobacteria. The other important members of chemolithoautotrophic community in saline soils were Gammaproteobacterial autotrophs which were found predominantly in saline soil. The Gammaproteobacteria Sulfite dehydrogenase are previously known to be dominated by obligate haloalkaliphiles, for example, cluster 15 has sequences related to the genus Salinisphaera which are halophilic, aerobic, facultatively chemolithoautotrophic bacteria oxidizing CO and thiosulphate [42]. Some sequences from saline soil were related to

nitrifying photoautotrophic purple non sulphur bacterium Rhodobacter and denitrifying bacterium Paracoccus. One phylotype was related to the Aurantimonas bacterium which is facultative lithotrophic marine manganese oxidizing bacteria. The agricultural clone library phylotypes tightly clustered with different genera of Alphaproteobacteria and Betaproteobacteria like Rhizobium, Bradyrhizobium, Xanthobacter, Beijerinckia, Sulfobacillus, Oligotropha and uncultured bacterial clones from grassland soils [26] and arid soils. Bradyrhizobium japonicum is a facultative chemolithoautotroph and utilizes thiosulphate and H2 as an electron donor and CO2 as a carbon source [43]. In cluster 10 three phylotypes from AS and one from SS1 clone libraries were related to Sulfobacillus acidophilus (sulphide oxidizing bacteria) and Mycobacterium of phylum Actinobacteria.