Two new gene clusters involved in the degradation of plant cell wall from the fecal microbiota of Tunisian dromedary

Abstract

Dromedaries are capable of digesting plant cell wall with high content of lignocellulose of poor digestibility. Consequently, their intestinal microbiota can be a source of novel carbohydrate-active enzymes (CAZymes). To the best of our knowledge, no data are available describing the biochemical analysis of enzymes in dromedary intestinal microbiota. To investigate new hydrolytic enzymes from the dromedary gut, a fosmid library was constructed using metagenomic DNA from feces of non-domestic adult dromedary camels living in the Tunisian desert. High-throughput functional screening of 13756 clones resulted in 47 hit clones active on a panel of various chromogenic and non-chromogenic glycan substrates. Two of them, harboring multiple activities, were retained for further analysis. Clone 26H3 displayed activity on AZO-CM-cellulose, AZCL Carob galactomannan and Tween 20, while clone 36A23 was active on AZCL carob galactomannan and AZCL barley β-glucan. The functional annotation of their sequences highlighted original metagenomic loci originating from bacteria of the Bacteroidetes/Chlorobi group, involved in the metabolization of mannosides and β-glucans thanks to a complete battery of endo- and exo-acting glycoside hydrolases, esterases, phosphorylases and transporters.

Lignocelluloytic activities and composition of bacterial community in the camel rumen

“…This could explain the ability of camels to survive in desert harsh conditions with low-quality forages. Also, this result highlights the camel rumen as a good source of fibrolytic enzymes and productive bacteria [9] , [10] , [53] .…”

“…Therefore, the camel rumen microbiota could be a rich source of cellulase and xylanase enzymes that could be used in a wide range of biotechnological and industrial applications [10] . Bacteria dominate the microbial community in the rumen and make the greatest contribution to rumen fermentation [11] .…”

“…Many rumen bacterial isolates are involved in the production of cellulolytic enzymes commercially such as Rumminococcus [15] , Bacillus [16] , [17] , Clostridium [18] . Therefore, the camel rumen has received great interest for mining for enzymes with biotechnological and industrial applications [9] , [10] , [19] , [20] . Cellulases and xylanases have a key role in the bioconversion of lignocellulosic biomass to animal feed or fermentable sugars for bioethanol production [21] .…”

“…Furthermore, these enzymes have many industrial and biotechnological applications such as in textiles and detergent industry, and food and pharmaceutical applications [17] , [23] . Therefore, the demand for cheap, high-active, and stable enzymes are growing rapidly [10] , [21] .…”

Effect of barley straw and Egyptian clover hay on the rumen fermentation and structure and fibrolytic activities of rumen bacteria in dromedary camel

“…The rapid expansion of molecular techniques such as next-generation sequencing has enabled determining the changes in rumen microbiota under various treatment conditions, which offer the possibility to improve the digestibility of plant fiber and improve animal productivity [7]. A previous study suggested that the microbial community in camel can degrade poor-quality plant biomass [20][21][22]. Thus, the camel rumen microbiome could be a promising source of carbohydrate-active enzymes used in different biotechnological and industrial applications [21].…”