Effect of pH and Recombinant Barley (Hordeum vulgare L.) Endoprotease B2 on Degradation of Proteins in Soaked Barley

Nonfermented
soaking of barley feedstuff has been established as
an in vitro procedure prior to the feeding of pigs as it can increase
protein digestibility. In the current study, two feed cultivars of
barley (Finlissa and Zephyr) were soaked in vitro either nonbuffered
or buffered at pH 3.6 and 4.3. Solubilized and degraded proteins evaluated
by biuret, SDS-PAGE, and differential proteomics revealed that pH
4.3 had the greatest impact on both solubilization and degradation.
In order to boost proteolysis, the recombinant barley endoprotease
B2 (rec-HvEP-B2) was included after 8 h using the pH 4.3 regime. Proteolysis
evaluated by SDS-PAGE and differential proteomics confirmed a powerful
effect of adding rec-HvEP-B2 to the soaked barley, regardless of the
genotype. Our study addresses the use of rec-HvEP-B2 as an effective
feed enzyme protease. HvEP-B2 has the potential to increase the digestibility
of protein in the pig, either supplied as recombinant additive or
as possible new selection criterion in barley breeding.