Adsorption and Biodegradation of Aromatic Chemicals by Bacteria Encapsulated in a Hydrophobic Silica Gel

Abstract

An adsorbent silica biogel material was developed via silica gel encapsulation of Pseudomonas sp. NCIB 9816-4, a bacterium that degrades a broad spectrum of aromatic pollutants. The adsorbent matrix was synthesized using silica precursors methyltrimethoxysilane and tetramethoxysilane to maximize the adsorption capacity of the matrix while maintaining a highly networked and porous microstructure. The encapsulated bacteria enhanced the removal rate and capacity of the matrix for an aromatic chemical mixture. Repeated use of the material over four cycles was conducted to demonstrate that the removal capacity could be maintained with combined adsorption and biodegradation. The silica biogel can thus be used extensively without the need for disposal, as a result of continuous biodegradation by the encapsulated bacteria. However, an inverse trend was observed with the ratio of biodegradation to adsorption as a function of log K, suggesting increasing mass-transport limitation for the most hydrophobic chemicals used (log K > 4).

Signal Disruption Leads to Changes in Bacterial Community Population

“…Silica encapsulation is a method of choice for entrapping enzymes or cells due to their compatibility with biological molecules, mechanical properties, durability, stability, cost, and easy synthesis. Silica gels have been previously used to encapsulate bioreactive bacteria for bioremediation (Reátegui et al, 2012; Aukema et al, 2014; Sakkos et al, 2016, 2017). While most encapsulated bacteria may remain viable through the process of making the gels (Benson et al, 2018), it is likely to be unnecessary in this study, since the lactonase Sso Pox is a metalloenzyme that only requires a water molecule as the nucleophile for the hydrolytic reaction (Elias et al, 2008).…”

“…In order to determine the effects of AHL degradation in the context of a complex microbial community, we used a silica gel, bead-based, bioencapsulation technique. Silica is a cytocompatible material in which bacteria or their enzymes can be physically confined, retained within the matrix, and protected from the environment (Reátegui et al, 2012; Mutlu et al, 2013, 2015; Aukema et al, 2014; Sakkos et al, 2016, 2017). Here, we used encapsulated Escherichia coli cells overexpressing the lactonase Sso Pox W263I to produce enzymatically active beads.…”

Enhancement of biocatalyst activity and protection against stressors using a microbial exoskeleton

“…porosity, pore size, and surface functionality) 39,41,42 . These materials can further be functionalized to enhance reactivity 43 , adsorb excess substrate 44 , and even respond to stimuli (pH, temperature, etc.) 45 .…”

Rapid and selective recognition of Vibrio parahaemolyticus assisted by perfluorinated alkoxysilane modified molecularly imprinted polymer film

“…The adsorption capacity of the imprinted PDMS lm with bacteria was based on the superhydrophobic effect. 35 The lm modied with POTS can increase surface roughness due to the Si-CH 3 groups are replaced by CF 3 by uorination, which can reduce the hydrophobic interaction between the imprinted PDMS lm and non-target bacteria leading to the inhibition of the non-specic adsorption effect. To verify the effect of POTS modication, static contact angle data were measured to characterize the hydrophobic properties (Fig.…”