A phylogenetic analysis of Wadi el Natrun soda lake cellulase enrichment cultures and identification of cellulase genes from these cultures

Samples of sediments and surrounding soda soils (SS) from the extremely saline and alkaline lakes of the Wadi el Natrun in the Libyan Desert, Egypt, were obtained in October 2000. Anaerobic enrichment cultures were grown from these samples, DNA isolated, and the bacterial diversity assessed by 16S rRNA gene clone analysis. Clones derived from lake sediments (LS) most closely matched Clostridium spp., Natronoincola histidinovorans, Halocella cellulolytica, Bacillus spp. and the Cytophage-Flexibacter-Bacteroides group. Similar clones were identified in the SS, but Bacillus spp. predominated. Many of the clones were most closely related to organisms already identified in alkaline or saline environments. Two genomic DNA libraries were made from the pooled LS enrichments and a single SS-enrichment sample. A novel cellulase activity was identified and characterized in each. The lake cellulase ORF encoded a protein of 1,118 amino acids; BLASTP analysis showed it was most closely related to an endoglucanase from Xanthomonas campestris. The soil-cellulase ORF encoded a protein of 634 amino acids that was most closely related to an endoglucanase from Fibrobacter succinogenes.