Abstract
Canola meal (CM), the protein-rich by-product of canola oil extraction, has shown promise as an alternative feedstuff and protein supplement in poultry diets, yet its use has been limited due to the abundance of plant cell wall fibre, specifically non-starch polysaccharides (NSP) and lignin. The addition of exogenous enzymes to promote the digestion of CM NSP in chickens has potential to increase the metabolizable energy of CM. We isolated chicken cecal bacteria from a continuous-flow mini-bioreactor system and selected for those with the ability to metabolize CM NSP. Of 100 isolates identified, Bacteroides spp. and Enterococcus spp. were the most common species with these capabilities. To identify enzymes specifically for the digestion of CM NSP, we used a combination of glycomics techniques, including enzyme-linked immunosorbent assay characterization of the plant cell wall fractions, glycosidic linkage analysis (methylation-GC-MS analysis) of CM NSP and their fractions, bacterial growth profiles using minimal media supplemented with CM NSP, and the sequencing and de novo annotation of bacterial genomes of high-efficiency CM NSP utilizing bacteria. The SACCHARIS pipeline was used to select plant cell wall active enzymes for recombinant production and characterization. This approach represents a multidisciplinary innovation platform to bioprospect endogenous CAZymes from the intestinal microbiota of herbivorous and omnivorous animals which is adaptable to a variety of applications and dietary polysaccharides.
Highlights
Canola meal (CM) is the protein rich by-product generated by oil extraction from the seeds of several registered rapeseed (Brassica napus L.) canola cultivars developed by Canadian plant breeders for the production of high-quality oil [1]
Enzyme discovery for targeted biomass deconstruction is quite difficult without knowledge of the structure of CM non-starch polysaccharides (NSP)
MAb based techniques such as enzyme-linked immunosorbent assay (ELISA) and Micro Array Polymer Profiling (MAPP) are only semi-quantitative, they are based on the extraction of largely intact polysaccharides
Summary
Canola meal (CM) is the protein rich by-product generated by oil extraction from the seeds of several registered rapeseed (Brassica napus L.) canola cultivars developed by Canadian plant breeders for the production of high-quality oil [1]. The use of CM in poultry diets has been limited due to its correlation with weaker performance outcomes when compared to other protein sources, such as soybean meal (SBM), despite containing similar levels of protein (37% CM: 46% SBM) [7,8] This outcome has been attributed to the higher abundance of plant cell wall-derived non-starch polysaccharides (NSP) (32% CM: 22% SBM) and lignin (10% CM: 3% SBM) in CM [8,9,10]. Previous work reported that the carbohydrate active enzyme (CAZyme) content within the chicken cecal microbiome is enriched in select families of core enzymes (e.g., GH5 cellulase; GH10 xylanases) and devoid of others that possess complementary activities (e.g., GH6, GH7, GH45, and GH48 cellulases; GH11 xylanase; and GH12 xyloglucanase) This suggests that the chicken intestinal microbiome is tuned towards the digestion of specific dietary polysaccharides (e.g., starch), and that the metabolism of more complex substrates may be less efficient. Introducing enzymes from other biological sources, such as the digestive organs of ruminants or other herbivorous species, or enriching the abundance of limiting enzyme activities found within the chicken microbiota may have utility for improving the digestion of alternative feedstuffs, such as CM
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