Metabolic Responses of Bacterial Cells to Immobilization

Abstract

In recent years immobilized cells have commonly been used for various biotechnological applications, e.g., antibiotic production, soil bioremediation, biodegradation and biotransformation of xenobiotics in wastewater treatment plants. Although the literature data on the physiological changes and behaviour of cells in the immobilized state remain fragmentary, it is well documented that in natural settings microorganisms are mainly found in association with surfaces, which results in biofilm formation. Biofilms are characterized by genetic and physiological heterogeneity and the occurrence of altered microenvironments within the matrix. Microbial cells in communities display a variety of metabolic differences as compared to their free-living counterparts. Immobilization of bacteria can occur either as a natural phenomenon or as an artificial process. The majority of changes observed in immobilized cells result from protection provided by the supports. Knowledge about the main physiological responses occurring in immobilized cells may contribute to improving the efficiency of immobilization techniques. This paper reviews the main metabolic changes exhibited by immobilized bacterial cells, including growth rate, biodegradation capabilities, biocatalytic efficiency and plasmid stability.

BIOSORPTION OF CADMIUM AND LEAD USING SUSPENDED AND IMMOBILIZED Enterobacter cloacae AT DIFFERENT PH

“…The higher biomass production in the immobilized cultures observed in the growth experiments coincides with the results obtained by several authors with different bacterial cultures (Garzón-Jiménez and Barragán-Huerta 2008, Martins et al 2012, Zur et al 2016, and is probably explained by the higher availability of dissolved and particulate nutrients adsorbed on the film of extracellular organic compounds used for adhesion by bacterial cells (Cohen 2001, Garrett et al 2008. This organic film might also participate in metal resistance and retention, through immobilization on its active sites (Lau et al 2005).…”

“…These microorganisms possess detoxification mechanisms based on the energy-dependent elimination of toxic metals (Silver 1996, Castrillón-Rivera andPalma-Ramos 2012), or they may tolerate the presence of several metals because of their immobilization within or outside their cell wall (Zur et al 2016).…”

Phototrophic marine benthic microbiomes: the ecophysiology of these biological entities

“…In their natural habitat, the majority of microorganisms are associated with surfaces (Żur et al ., ), either attached to a substratum, as part of an aggregate and on and in sediments (Whitman et al ., ). These surfaces include the exterior of plants and animals, where they form part of the microbiome of these organisms, together with microorganisms living inside these (macro)organisms.…”

Valorization of Lignin as an Immobilizing Agent for Bioinoculant Production using Azospirillum brasilense as a Model Bacteria

“…Immobilization presents many advantages over free-cell systems; it makes cells more tolerant to changing environmental conditions and less vulnerable to toxic substances, and adsorption is one of the most used techniques for cell immobilization. Furthermore, it has been reported that adhesion to surfaces makes bacterial communities more active than their free-living counterparts; adhesion frequently increases in the exponential growth phase given the increment in the cell wall hydrophobicity [18]. In this study, we took advantage of the ability of A. brasilense to form biofilms and its consequent adherence to prepare a bioinoculant with organosolv-recovered lignin.…”