A plate assay for simultaneous screening of polysaccharide‐ and protein‐degrading micro‐organisms

Aims: To develop a plate assay for simultaneous screening of polysaccharide‐degrading and protein‐degrading micro‐organisms. Methods and Results: A plate assay, based on the visible solubilization of small substrate particles and the formation of haloes on Petri dishes, containing a mixture of diversely coloured insoluble polysaccharides and dye‐labelled collagen as chromogenic substrates, was developed. This method was successfully applied for isolating the diverse polysaccharide‐ and/or protein‐degrading bacteria from soil and sludge samples. Selected strains were identified using 16S rDNA partial sequencing; most of them belong to the genera Bacillus, Cellulomonas and Cellulosimicrobium. Conclusions: This novel approach provides unique and valuable information for direct primary screening when the target of selection is micro‐organisms exhibiting protein‐degrading activity, polysaccharide‐degrading activity or a specific combination of them. Significance and Impact of the Study: This plate assay is convenient and easy to perform, rapid, and more adaptable for screening of a large number of samples, compared with other existing methods in the literature.