Fig. 7
From: New keratinolytic bacteria in valorization of chicken feather waste
Response contour plots for the accumulation of soluble proteins (a–c) and amino acids (d) representing interaction effects of tested independent variables. Accumulation of soluble proteins as a function of feathers concentration vs MgSO4 (a), feathers vs KH2PO4 (b), MgSO4 vs KH2PO4 (c). Accumulation of free amino acids as a function of feathers concentration vs MgSO4 (d)