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1.
Enzyme Microb Technol ; 180: 110485, 2024 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-39059288

RESUMO

Gram-positive Bacillus subtilis is a model organism for the biotechnology industry and has recently been characterized as weakly electroactive in both planktonic cultures and biofilms. Increasing the extracellular electron transfer (EET) rate in B. subtilis biofilms will help to develop an efficient microbial electrochemical technology (MET) and improve the bioproduction of high-value metabolites under electrofermentative conditions. In our previous work, we have shown that the addition of compatible solute precursors such as choline chloride (ChCl) to the growth medium formulation increases current output and biofilm formation in B. subtilis. In this work, we utilized a low-carbon tryptone yeast extract medium with added salts to further expose B. subtilis to salt stress and observe the osmoregulatory and/or nutritional effects of a D-sorbitol/choline chloride (ChCl) (1:1 mol mol-1) deep eutectic solvents (DESs) on the electroactivity of the formed biofilm. The results show that ChCl and D-sorbitol alleviate the osmotic stress induced by the addition of NaH2PO4 and KH2PO4 salts and boost biofilm production. This is probably due to the osmoprotective effect of ChCl, a precursor of the osmoprotectant glycine betaine, and the induction of electroactive exopolymeric substances within the B. subtilis biofilm. Since high ionic strength media are commonly used in microbial biotechnology, the combination of ChCl-containing DESs and salt stress could enhance biofilm-based electrofermentation processes that bring significant benefits for biotechnological applications.


Assuntos
Bacillus subtilis , Biofilmes , Colina , Solventes Eutéticos Profundos , Osmorregulação , Bacillus subtilis/efeitos dos fármacos , Bacillus subtilis/fisiologia , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Colina/farmacologia , Colina/metabolismo , Solventes Eutéticos Profundos/metabolismo , Solventes Eutéticos Profundos/farmacologia , Sorbitol/farmacologia , Sorbitol/metabolismo , Meios de Cultura/química , Pressão Osmótica , Fontes de Energia Bioelétrica
2.
Microb Biotechnol ; 17(3): e14426, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38497275

RESUMO

Fluctuations in redox conditions in bioprocesses can alter the end-products, reduce their concentration, and lengthen the process time. Electrofermentation enables rapid metabolic modulation of biosynthesis and allows control of redox imbalances in biofilm-based fermentation processes. In this study, electrofermentation is used to boost the production of the bacterial biopolymer poly-γ-glutamic acid (γ-PGA) from Bacillus subtilis ATCC 6051. When compared to control experiments (3.3 ± 0.99 g L-1 ), the application of an electrode potential E = 0.4 V versus Ag/AgCl results in a more than two-fold increase in the production of γ-PGA (9.13 ± 1.4 g L-1 ). Using an engineered B. subtilis strain, in which γ-PGA production is driven by isopropyl ß-d-1-thiogalactopyranoside, electrofermentation improves polymer concentrations from 15.4 ± 1.5 to 23.1 ± 1.6 versus g L-1 . These results confirm that electrofermentation conditions can be adopted to increase the concentration of γ-PGA and perhaps other extracellular biopolymers in industrial strains.


Assuntos
Bacillus subtilis , Ácido Glutâmico , Ácido Poliglutâmico/análogos & derivados , Bacillus subtilis/genética , Bacillus subtilis/metabolismo , Ácido Glutâmico/metabolismo , Fermentação , Biofilmes
3.
Enzyme Microb Technol ; 163: 110156, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36423432

RESUMO

Drug-eluting stents (DES) are mostly used in percutaneous coronary intervention, which is the main treatment for coronary artery occlusion. This procedure aims to restore the natural lumen, while minimizing the risk of restenosis. However, stent insertion increases the risk for infections, due to contamination of the device or insertion hub with normal skin flora. While coronary stent infection is a rare complication, it can be fatal. Currently, there is little information on biofilm formation on everolimus-eluting stents. Although everolimus is not designed as an antimicrobial agent, its antimicrobial activity should be investigated. In this study, biofilm formation on everolimus-eluting and bare metal stents (BMS) is characterized through biochemical and electrochemical methods. DES and BMS are inoculated with Pseudomonas aeruginosa and Staphylococcus epidermidis, both independently and in co-culture. Biofilms formed on DES were 49.6 %, 12.9 % and 47.5 % higher than on BMS for P. aeruginosa, S. epidermidis and their co-culture, respectively. Further, the charge output for DES was 18.9 % and 59.7 % higher than BMS for P. aeruginosa and its co-culture with S. epidermidis, respectively. This observation is most likely due to higher surface roughness of DES, which favors biofilm formation. This work shows that bioelectrochemical methods can be used for rapid detection of biofilms on drug-eluting and bare metal stents, which may find application in quality assessment of stents and in characterization of stents removed after polymicrobial infections.


Assuntos
Fármacos Cardiovasculares , Reestenose Coronária , Stents Farmacológicos , Humanos , Everolimo/farmacologia , Stents Farmacológicos/efeitos adversos , Reestenose Coronária/diagnóstico , Reestenose Coronária/etiologia , Reestenose Coronária/terapia , Sirolimo , Metais , Desenho de Prótese , Resultado do Tratamento , Stents/efeitos adversos , Biofilmes
4.
Biosensors (Basel) ; 12(7)2022 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-35884284

RESUMO

Bacterial biofilms are one of the most important challenges that modern medicine faces due to the difficulties of diagnosis, antibiotic resistance, and protective mechanisms against aggressive environments. For these reasons, methods that ensure the inexpensive and rapid or real-time detection of biofilm formation on medical devices are needed. This study examines the possibilities of using optical- and fiber-based biosensors to detect and analyze early bacterial biofilms. In this study, the biofilm-forming model organism Pseudomonas aeruginosa was inoculated on the surface of the optical sensor and allowed to attach for 2 h. The biosensors were made by a fiber-tip ball resonator, fabricated through a CO2 laser splicer on a single-mode fiber, forming a weak reflective spectrum. An optical backscatter reflectometer was used to measure the refractive index detected by the sensors during different growth periods. The early biofilm concentration was determined by crystal violet (CV) binding assay; however, such a concentration was lower than the detection limit of this assay. This work presents a new approach of biofilm sensing in the early attachment stage with a low limit of detection up to 10-4 RIU (refractive index units) or 35 ± 20 × 103 CFU/mL (colony formed units).


Assuntos
Técnicas Biossensoriais , Fibras Ópticas , Bactérias , Biofilmes , Pseudomonas aeruginosa , Refratometria
5.
Sci Rep ; 12(1): 11701, 2022 07 09.
Artigo em Inglês | MEDLINE | ID: mdl-35810245

RESUMO

Acinetobacter baumannii is an infectious agent of global proportion and concern, partly due to its proficiency in development of antibiotic resistance phenotypes and biofilm formation. Dithiocarbamates (DTC) have been identified as possible alternatives to the current antimicrobials. We report here the evaluation of several DTC-metal complexes against A. baumannii planktonic cells and biofilms. Among the DTC-metal complexes and DTCs tested, ZnL1 (N-methyl-1-phenyldithiocarbamato-S,S' Zn(II)), originally designed as an antitumor agent, is effective against biofilm forming A. baumannii. A MIC value of 12.5 µM, comparable to that of Gentamicin (5 µM) was measured for planktonic cells in tryptic soy broth. Spectroscopy, microscopy and biochemical analyses reveal cell membrane degradation and leakage after treatment with ZnL1. Bioelectrochemical analyses show that ZnL1 reduces biofilm formation and decreases extracellular respiration of pre-formed biofilms, as corroborated by microscopic analyses. Due to the affinity of Zn to cells and the metal chelating nature of L1 ligand, we hypothesize ZnL1 could alter metalloprotein functions in the membranes of A. baumannii cells, leading to altered redox balance. Results indicate that the DTC-Zn metal complex is an effective antimicrobial agent against early A. baumannii biofilms under laboratory conditions.


Assuntos
Acinetobacter baumannii , Anti-Infecciosos , Complexos de Coordenação , Antibacterianos/farmacologia , Anti-Infecciosos/farmacologia , Biofilmes , Complexos de Coordenação/farmacologia , Testes de Sensibilidade Microbiana , Plâncton , Zinco/farmacologia
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