Enhanced biodegradation of atrazine by bacteria encapsulated in organically modified silica gels

Benson, Joey J.; Sakkos, Jonathan K.; Radian, Adi; Wackett, Lawrence P.

doi:10.1016/j.jcis.2017.09.044

Cited by 23 publications

(14 citation statements)

References 61 publications

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“…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). Therefore, cells can be viewed as “bags of enzymes” that disrupt the AHL signaling molecules produced by bacteria.…”

Section: Resultsmentioning

confidence: 99%

Signal Disruption Leads to Changes in Bacterial Community Population

et al. 2019

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The disruption of bacterial signaling (quorum quenching) has been proven to be an innovative approach to influence the behavior of bacteria. In particular, lactonase enzymes that are capable of hydrolyzing the N- acyl homoserine lactone (AHL) molecules used by numerous bacteria, were reported to inhibit biofilm formation, including those of freshwater microbial communities. However, insights and tools are currently lacking to characterize, understand and explain the effects of signal disruption on complex microbial communities. Here, we produced silica capsules containing an engineered lactonase that exhibits quorum quenching activity. Capsules were used to design a filtration cartridge to selectively degrade AHLs from a recirculating bioreactor. The growth of a complex microbial community in the bioreactor, in the presence or absence of lactonase, was monitored over a 3-week period. Dynamic population analysis revealed that signal disruption using a quorum quenching lactonase can effectively reduce biofilm formation in the recirculating bioreactor system and that biofilm inhibition is concomitant to drastic changes in the composition, diversity and abundance of soil bacterial communities within these biofilms. Effects of the quorum quenching lactonase on the suspension community also affected the microbial composition, suggesting that effects of signal disruption are not limited to biofilm populations. This unexpected finding is evidence for the importance of signaling in the competition between bacteria within communities. This study provides foundational tools and data for the investigation of the importance of AHL-based signaling in the context of complex microbial communities.

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Section: Resultsmentioning

confidence: 99%

Signal Disruption Leads to Changes in Bacterial Community Population

et al. 2019

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“…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 .…”

Section: Introductionmentioning

confidence: 99%

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

Sakkos

Wackett

Aksan

2019

Sci Rep

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Whole cell biocatalysts can perform numerous industrially-relevant chemical reactions. While they are less expensive than purified enzymes, whole cells suffer from inherent reaction rate limitations due to transport resistance imposed by the cell membrane. Furthermore, it is desirable to immobilize the biocatalysts to enable ease of separation from the reaction mixture. In this study, we used a layer-by-layer (LbL) self-assembly process to create a microbial exoskeleton which, simultaneously immobilized, protected, and enhanced the reactivity of a whole cell biocatalyst. As a proof of concept, we used Escherichia coli expressing homoprotocatechuate 2,3-dioxygenase (HPCD) as a model biocatalyst and coated it with up to ten alternating layers of poly(diallyldimethylammonium chloride) (PDADMAC) and silica. The microbial exoskeleton also protected the biocatalyst against a variety of external stressors including: desiccation, freeze/thaw, exposure to high temperatures, osmotic shock, as well as against enzymatic attack by lysozyme, and predation by protozoa. While we observed increased permeability of the outer membrane after exoskeleton deposition, this had a moderate effect on the reaction rate (up to two-fold enhancement). When the exoskeleton construction was followed by detergent treatment to permeabilize the cytoplasmic membrane, up to 15-fold enhancement in the reaction rate was reached. With the exoskeleton, we increased in the reaction rate constants as much as 21-fold by running the biocatalyst at elevated temperatures ranging from 40 °C to 60 °C, a supraphysiologic temperature range not accessible by unprotected bacteria.

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“…TEOS was hydrolyzed by adding water and 1 M hydrochloric acid at a 1:5.3:0.0013 molar ratio of TEOS:water:HCl and stirring vigorously. Under these conditions, hydrolysis is complete after 80 mins 16 .…”

Section: Methodsmentioning

confidence: 99%

“…True ELMs have been created by engineering E. coli to produce an extracellular matrix from curli fibers [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] . Other types of extracellular matrices for ELM fabrication were created from secreted bacterial cellulose to embed microbial cells 26,27 or from elastin-like polypeptides to attach Caulobacter cells via their protein S-layers 28 .…”

Section: Introductionmentioning

confidence: 99%

Engineering Bacillus subtilis for the formation of a durable living biocomposite material

Kang

Pokhrel

Bratsch

et al. 2021

Preprint

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Engineered living materials (ELMs) are a fast-growing area of research that combine approaches in synthetic biology and material science. Here, we engineer B. subtilis to become a living component of a silica material composed of self-assembling protein scaffolds for functionalization and cross-linking of cells. B. subtilis was engineered to display SpyTags on polar flagella for cell attachment and cross-linking of SpyCatcher modified secreted scaffolds. Through deletion of the autolysis LytC, endospore limited B. subtilis cells become a structural component of the material with spores for long-term storage of genetic programming. Known silica biomineralization peptides were screened and scaffolds designed for silica polymerization to fabricate biocomposite materials with enhanced mechanical properties. We show that the resulting ELM can be regenerated from a piece of silica material and that new functions can be readily incorporated by co-cultivation of engineered B. subtilis strains. We believe that this work will serve as a framework for the future design of resilient ELMs as functional, self-healing materials for use as responsive coatings and plasters.

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Enhanced biodegradation of atrazine by bacteria encapsulated in organically modified silica gels

Cited by 23 publications

References 61 publications

Signal Disruption Leads to Changes in Bacterial Community Population

Signal Disruption Leads to Changes in Bacterial Community Population

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

Engineering Bacillus subtilis for the formation of a durable living biocomposite material

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