3 research outputs found
Role of a family 11 carbohydrate-binding module in the function of a recombinant cellulase used to supplement a barley based diet for broiler chickens
Cellulases and xylanases display a modular architecture that comprises a catalytic
module linked to one or more non-catalytic carbohydrate-binding modules (CBMs). CBMs have been
classified into 52 different families, based on primary structure similarity. These non-catalytic modules
mediate a prolonged and intimate contact of the enzyme with the target substrate eliciting efficient
hydrolysis of the target polysaccharides.
2. A study was undertaken to investigate the importance of a family 11 CBM, displaying high affinities
for barley -glucans, in the function of recombinant derivatives of cellulase CtLic26A-Cel5E of
Clostridium thermocellum used to supplement a barley-based diet for broiler chicken.
3. The results showed that birds fed on diets containing the recombinant CtLic26A-Cel5E modular
derivatives or the commercial enzyme mixture RovabioTM Excel AP displayed improved performance
when compared with birds fed on diets not supplemented with exogenous enzymes.
4. It is suggested that the enzyme dosage used in this study (30 U/kg of basal diet), was probably too
high for the efficacy of the family 11 CBM to be noticed. It remains to be established if the targeting
effect resulting from the incorporation of CBMs in plant cell wall hydrolases may be effective at lower
exogenous enzyme dosages
Crop -glucanase activity limits the effectiveness of a recombinant cellulase used to supplement a barley-based feed for free-range broilers
1. The supplementation of diets rich in soluble polysaccharides with microbial cellulases
and hemicellulases decreases digesta viscosity and promotes broiler performance.
2. In contrast, recent experiments suggest that polysaccharidases are ineffective for improving the
nutritive value of pasture biomass used by free-range broilers. However, the feasibility of using cellulases
and hemicellulases to improve the utilisation of cereal-based feeds by pastured poultry remains to be
established.
3. A study was undertaken to investigate the capacity of a recombinant cellulase from Clostridium
thermocellum to improve the nutritive value of a barley-based feed for free-range pastured broilers of the
RedBro Cou Nu RedBro M genotype.
4. The results show that supplementation of a barley-based diet with a recombinant -glucanase had
no effect on the performance of free-range broilers, foraging in legume-based diets from d 28 to 56.
In addition, the results confirm that the lack of effect of the recombinant enzyme in improving the
nutritive value of the barley-based feed does not result from enzyme proteolysis or inhibition in the
gastrointestinal tract.
5. Significantly, -glucanase activity was identified in the crop of non-supplemented animals. The data
suggest that endogenous cellulases originated both from the barley-based feed and from the crop
microflora.
6. The results presented here suggest that in older birds of slow-growing genotypes associated with
free-range production systems, previously unknown sources of -glucanases, such as the feed and
microbial symbiotic microflora, can affect the effectiveness of exogenous enzymes added to the feed
A family 11 carbohydrate binding module (CBM) improves the efficacy of a recombinant cellulase used to supplement barley-based diets for broilers at lower dosage rates
1. Exogenous microbial -1,3-1,4-glucanases and hemicellulases contribute to improving
the nutritive value of cereals rich in soluble non-starch polysaccharides for poultry.
2. In general, plant cell wall hydrolases display a modular structure comprising a catalytic module
linked to one or more non-catalytic carbohydrate-binding modules (CBMs). Based on primary structure
similarity, CBMs have been classified in 50 different families. CBMs anchor cellulases and hemicellulases
into their target substrates, therefore eliciting efficient hydrolysis of recalcitrant polysaccharides.
3. A study was undertaken to investigate the effects of a family 11 -glucan-binding domain in the
function of recombinant derivatives of cellulase CtLic26A-Cel5E of Clostridium thermocellum that were
used to supplement a barley-based diet at lower dosage rates.
4. The results showed that birds fed on diets supplemented with the recombinant CtLic26A-Cel5E
modular derivative containing the family 11 CBM or the commercial enzyme mixture RovabioTM Excel
AP tended to display improved performance when compared to birds fed diets not supplemented with
exogenous enzymes.
5. It is suggested that at lower than previously reported enzyme dosage (10 U/kg vs 30 U/kg of basal
diet), the -glucan-binding domain also elicits the function of the recombinant CtLic26A-Cel5E
derivatives.
6. Finally, the data suggest that exogenous enzymes added to barley-based diets act primarily in the
proximal section of the gastrointestinal tract