Selection of culturable environmental microbial strains for cellular immobilization: Association of phenotypic adhesive characteristics and quantitative cellular retention

Abstract

Environmental pollution by organic compounds is a global problem. Biological treatment methods are used to restore polluted environments. Microbial immobilization on abiotic surfaces is a recent strategy to improve the efficiency of these processes. In this technique, cell adhesion is a fundamental step for subsequent colonization and biofilm formation. Therefore, the use of strains with adhesive properties is a critical factor for successful immobilization. In this work, culturable environmental microbial strains were phenotypically characterized regarding their hydrophobicity, adhesion to polystyrene and production of exopolysaccharides and amyloid fibers. The cell retention was quantified by counting viable cells using polyurethane foam as material support. The degree of hydrophobicity varied from moderately hydrophobic to hydrophilic, while the adhesion to polystyrene and production of exopolysaccharides and amyloid fibers ranged from strong to negative. The results of qualitative tests were transformed into scores and a direct relationship between the qualitative characteristics and number of adhered cells on polyurethane foam was observed. The Gram-negative bacterium Serratia marcescens and the yeast Candida rugosa showed the best results and were selected for further immobilization tests.

Key words: Hydrophobicity, cell adhesion, cell immobilization, Serratia marcescens, Candida rugosa.