Abstract: Olive leaves were fermented by Aspergillus niger, Geotrichum candidum, Aspergillus oryzae, Candida utilis, Candida tropicalis, and Trichoderma viride. The effects of the single and the combination of two strains on the cellulase activity(β-glucosidase, CMCase and filter paper activity), protein content, and total tannins content were investigated. The results indicated that the best fermented efficiency for single strain of olive leaves fermented feedstuff was A.niger, with a result of β-glucosidase activity 10.53 U/mL, CMCase activity 10.61 U/mL and filter paper activity 4.02 U/mL when they were fermented for 3 days. The highest protein content 14.61% for 5 days and the highest tannins degradation 84.14% for 7 days were achieved. The best fermented efficiency by mixed strains of olive leaves fermented feedstuff was the combination of A. niger and C. utilis with a ratio of 1:1(v/v). The highest cellucase activity(β-glucosidase activity 12.45 U/mL, CMCase activity 12.59 U/mL, filter paper activity 5.51 U/mL) was obtained by the mixed strains(1:1) in need of 5 days. When the fermented time reached 7 days, the protein content reached 18.63% and total tannic degradation was 86.49% in the fermented product.

Key words: strains, olive leaves, solid state fermentation, cellulase activity, protein content, total tannins content