EFFECT OF SOLID STATE FERMENTATION ON NUTRITIONAL CONTENT AND EVALUATION OF DEGRADABILITY IN CACTUS PEAR

The process of protein enrichment of cactus pear (Nopalea cochenillifera (L.) Salm Dyck) by solid state fermentation with the use of Aspergillus niger and Rhyzopus sp. was studied for improving the nutritional value of this cactus species for use as animal feed. The experiments were conducted in the Agroindustrial Waste Laboratory of State University of Southwest Bahia (Brazil). To this end, we have evaluated the effects of biotransformation on the levels of protein, cellulose, hemicellulose, and lignin, as well as the potential degradability. Bioconversion was carried out using cactus pear as the only substrate, without supplementation with nitrogen, mineral and vitamin sources. The fermentation with Aspergillus niger promoted a 78% increase in/of protein content and reductions of cellulose, hemicellulose, and lignin of 40%, 36%, and 28%, respectively. Degradability, in turn, was observed to have increased by 66 % after 240 h. On the other hand, the fermentation with Rhyzopus sp. was less efficient, with a 69% increase in protein content, and reductions in cellulose, hemicellulose, and lignin contents of 30%, 28%, and 18%. In turn, degradability was seen to have increased by 51%. The fermentation of cactus pear by Aspergillus niger and Rhyzopus sp. exhibited the protein enrichment and increased protein degradability of this Cactaceae. Moreover, this is the most ever efficient micro-organism used in bioconversion. Based on the results, bioconversion of cactus is an excellent alternative to ruminant feeding in arid or semi-arid land

PRODUCTION AND CHARACTERIZATION OF CELLULOLYTIC ENZYMES BY ASPERGILLUS NIGER AND RHIZOPUS SP . BY SOLID STATE FERMENTATION OF PRICKLY PEAR

Prickly palm cactus husk was used as a solid - state fermentation support substrate for the production of cellulolytic enzymes using Aspergillus niger and Rhizopus sp. A Box - Behnken design was used to evaluate the effects of water activity, fermentation time and temperature on endoglucanase and total cellulase production. Response Surface Methodology showed that optimum conditions for endoglucanase production were achieved at after 70.35 h of fermentation at 29.56°C and a water activity of 0.875 for Aspergillus niger and after 68.12 h at 30.41°C for Rhizopus sp. Optimum conditions for total cellulase production were achieved after 74.27 h of fermentation at 31.22°C for Aspergillus niger and after 72.48 h and 27.86°C for Rhizopus sp . Water activity had a significant effect on Aspergillus niger endoglucanase production only. In industrial applications, enzymatic characterization is important for optimizing variables such as temperature and pH. In this study we showed that endoglucanase and total cellulase had a high level of thermostability and pH stability in all the enzymatic extracts. Enzymatic deactivation kinetic experiments indicated that the enzymes remained active after the freezing of the crude extract. Based on the results, bioconversion of cactus is an excellent alternative for the production of thermostable enzymes