One-step formation of three-dimensional macroporous bacterial sponges as a novel approach for the preparation of bioreactors for bioremediation and green treatment of water

Abstract

A novel method of crosslinking live bacteria into a stable 3D porous structure and its subsequent use in phenol degradation is reported.

Polymeric Materials Used for Immobilisation of Bacteria for the Bioremediation of Contaminants in Water

“…These advantages make biofilm attractive viable catalysts for organic syntheses, which may find wide technological applications [7]. In Figure 1c, macroporous hydrogel formation takes place via direct covalent linkage of bacteria cells' membranes' into 3D biofilm(advantages: one step, rapid biofilm formation due to cryoconcentration phenomenon leading to generation of high cells density with respect to polymer weight) [23,28,29]. Pseudomonas fluorescens(S3X), Microbacterium oxydans (EC29) and Cupriavidus spp.…”

“…The principal difference between cryogels and other porous materials(perlite, vermiculite, Grow plant or glass aerogel) of similar pore size is that the former exhibit tissue-like elasticity and flexibility and are able to withstand deformation without being destroyed or damaged. Preparation at low temperatures allows sufficient preservation of enzymes or cells (Figure 1c) [23,28,29].…”

“…A streptavidin modified cryogel was designed to enable single-step capture of chemically biotinylated Moloney Murine Leukaemia Virus from crude, unclarified cell culture supernatant [66]. Scanning electron microscopy indicated that the bound cells were distributed uniformly throughout the mesh of pores without physical entrapment of the cells (Figure 1c) [23]. The high density of the cell suspensions did not block the pores of the cryogel, thus not impeding the flow permeability rates [19,27].…”

“…An alternative approach developed by Kirsebom et al [78] is to form cryogels from the actual bacteria by crosslinking the bacterial cells using glutaraldehyde. A drawback is that GA may adversely affect the growth and viability of the bacterial cells since the GA molecule is small enough to enter the cell and disrupt cellular metabolism [23,28,79]. Consequently, the concentration of GA (and other low-molecular-weight aldehydes employed as cross-linkers) requires careful calibration to achieve a balance between cryogel morphology and strength and the viability of the bacterial cells.…”

“…Within the author's lab aldehyde activated poly(vinyl alcohol)-PVA-al and poly ethyleneimine-PEI-al cryogels cross-linked with different phenol-degrading bacteria strains have been developed to remove phenol, cresol, nitrophenols, and 4-chlorophenol (p-chlorophenol or 4-hydroxy-chlorobenzene) from wastewater [23,29]. For the first time, the toxicity of novel polymers for different bacterial strains and the effect of freezing of cells during cryogel preparation were evaluated using spectrophotometric methods i.e., the MTT(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay [29].…”