Deproteinization and demineralization efficiencies are reported in Fig. 1 which indicates that all the strains were able to demineralize crab waste. The highest demineralization rate (83%) was obtained with B. licheniformis NH1, followed by B. pumilus A1 (80%). However, the lowest DM value was observed with B. cereus BG1 (58.5%). It must be noted that all used strains were able to deproteinize crab shells (more than 75% DP). The highest DP rate was obtained with B. pumilus A1 strain (94%), which exhibited the highest level of protease activity (1100 U/ml) (Table 1). High deproteinization rates were also obtained with Bacillus strains, despite the low levels of proteases produced under the same conditions. However, B. cereus BG1, which produced the lowest level (231 U/ml) of protease activity, showed a higher DP (80.9%) rate. The DP and DM rates obtained in this work were higher than those obtained by Jo et al. [26] who reported a DM and DP rates of 84% and 47%, respectively, after 7 days of fermentation of crab shells with Serratia marcescens FS-3. This proves the efficiency of the Bacillus strains used in our study.