Investigation of the potential effect of encapsulated metal nanoparticles on enhancement of thermophilic anaerobic digestion

peer reviewedThe present work investigates the enhancement effect of seven different catalysts made of Cu/SiO2, Pd/SiO2, Pt/SiO2, Ni/SiO2, Co/SiO2, Ag/SiO2 and Fe/SiO2 nanoparticles (NPs) on methane production during thermophilic anaerobic digestion. The tested NPs were synthesized by the sol-gel process and encapsulated in porous silica (SiO2) to prevent their coagulation and agglomeration. Transmission electron microscopy (TEM) pictures confirmed the specific morphologies of all seven catalysts. Then, these 7 NPs were tested first in batch experiments with acetate as a carbon substrate for biomethane production. Ni/SiO2 and Co/SiO2 showed the best enhancement of methane production from acetate. From this part, both NPs were tested for bio-methane production on two different substrates: starch and glucose. With the starch substrate, the improvements of methane production were equal to 47% and 22%, respectively, for Ni-and Co/SiO2 compared to control sample. In the last part of this work, the influences of NP concentration and thermal pre-treatment applied to the NPs on bio-methane production from glucose were investigated. The results showed that all forms of nickel and cobalt NPs enhance the methane production, and their effect increased with the increase of their concentrations. The best sample was the calcined nickel NPs at a concentration of 10-4 mol L-1 , leading to a methane production rate of 72.5% compared to the control

AN APPROACH TO DESICCATION-TOLERANT BACTERIA IN STARTER CULTURE PRODUCTION

peer reviewe

Utilization of methyloleate in production of microbial lipase.

In this article, we report the development and optimization of an industrial culture medium for the production of extracellular lipase in the yeast Yarrowia lipolytica. Until now olive oil in combination with glucose was used as the carbon source and inducer for the production of lipase. Our results demonstrate that methyloleate, a cheap hydrophobic compound, could efficiently substitute olive oil as the inducer and carbon source for lipase production. A new process of lipase production was developed yielding a twofold increase in the level of production compared with the levels in previous reports.Comparative StudyJournal Articleinfo:eu-repo/semantics/publishe

Production and down-stream processing of an extracellular lipase from the yeast Yarrowia lipolytica

info:eu-repo/semantics/publishe

Effect of encapsulated nanoparticles on thermophillic anaerobic digestion

Recently, enormous interest has been focused on biological applications of metal nanoparticles NPs due to their small size, high specified surface and their great potential in application to many science fields. The most studied process concerns zero valent palladium and iron NPs improving anaerobic biodegradation of chlorinated hydrocarbons (Windt et al., 2005). Moreover, investigation carried out in our lab showed that iron NPs encapsulated in silicate matrix may enhance hydrogen production by Clostridium butyricum (Beckers et al., 2013). Nevertheless the influences of metal NPs on methane producing anaerobic digestion have seldom been investigated. The present work investigates the enhancement effect of seven different metal NPs on methane production during the thermophilic anaerobic digestion. NPs of Cu, Pd, Pt, Ni, Co, Ag and Fe encapsulated in porous silica (SiO2) to prevent their coagulation and agglomeration, were added at concentration of 10-5mol/L in batch test (125ml serum bottles containing 70mL culture medium with 5g/L acetate monohydrate as the sole carbon substrate). Nickel, cobalt and iron NPs improved methane production from acetate. To confirm the previous results, the NPs were tested at different concentrations (10-4, 10-5, and 10-6 mol/L) with starch and glucose substrates. The results show that the impact increases with the increase of NPs concentrations up to 10-4 mol/L. The modified Gompertz equation was applied to describe the effect of NPs on anaerobic digestion. According to this model, the kinetic of methane production was particularly affected by nanoparticles addition. The values of the maximum methane production rate MPR (ml/day) was significantly higher 72.5% with nickel NPs at a concentration of 10-4 mol/L than the control without NPs

Effect of iron nanoparticles synthesized by a sol-gel process on Rhodococcus erythropolis T902.1 for biphenyl degradation

peer reviewedNanoparticles (NPS) are considered as a new generation of compounds to improve environmental remediation and biological processes. The aim of this study is to investigate the effect of iron NPS encapsulated in porous silica (SiO2) on the biphenyl biodegradation by Rhodococcus erythropolis T902.1 (RT902.1). The iron NPS (major iron oxide FexOy form) were dispersed in the porosity of a SiO2 support synthesized by sol-gel process. These Fe/SiO2 NPS offer a stimulating effect on the biodegradation rate of biphenyl, an organic pollutant that is very stable and water-insoluble. This positive impact of NPS on the microbial biodegradation was found to be dependent on the NPS concentration ranging from 10−6 M to 10−4 M. After 18 days of incubation the cultures containing NPS at a concentration of 10−4 M of iron improved RT902.1 growth and degraded 35% more biphenyl than those without NPS (positive control) or with the sole SiO2 particles. Though the microorganism could not interact directly with the insoluble iron NPS, the results show that about 10% and 35% of the initial 10−4 M iron NPS encapsulated in the SiO2 matrix would be incorporated inside or adsorbed on the cell surface respectively and 35% would be released in the supernatant. These results suggest that RT902.1 would produce siderophore-like molecules to attract iron from the porous silica matrix.NANOMICRO : nanoparticles for hydrocarbons (PAH) bioremediatio

Amélioration de la biodégradation du biphényle par Rhodococcus erythropolis t902.1 en présence de Fe2O3 et de nanoparticules de fer encapsulées dans un xérogel de silice

Dans ce travail, l’effet de particules d’oxyde de fer Fe2O3 et de nanoparticules de fer encapsulées dans des particules poreuses de silice (xérogel Fe/SiO2) a été étudié sur la biodégradation du biphényle par la souche Rhodococcus erythropolis T902.1. Les pourcentages de biodégradation après 18 jours d’incubation en présence du xérogel Fe/SiO2 à 10-5 M en fer atteignent 75 % et 85 % respectivement pour les conditions sans ou après autoclavage ; c’est-à-dire 42 et 60 % de dégradation supplémentaire par rapport aux conditions standards sans xérogel Fe/SiO2. L’impact dû à l’autoclavage serait directement associé à la libération d’une certaine quantité de fer moins bien ancré dans la matrice de silice. Cette étude a jeté la lumière sur la liaison entre la sécrétion de sidérophores par Rhodococcus erythropolis T902.1 et la présence de nanoparticules de fer dans le milieu de culture. Elle suggère une diminution de la sécrétion de sidérophores avec l’augmentation de la quantité d’ions ferriques mobilisés à partir du xérogel Fe/SiO2. Finalement, la majorité des surfactants glycolipidiques contenant du trehalose (hexose) produits par Rhodococcus erythropolis T902.1 sont liés à la surface de la cellule et ne sont pas excrétés dans le milieu de culture ; leur concentration a augmenté de 85 % enprésence de nanoparticules de fer.In this work, the effect of iron oxide particles Fe2O3 and iron nanoparticles encapsulated in a porous silica matrix (xerogel Fe/SiO2) was investigated on biphenyl biodegradation by the strain Rhodococcus erythropolis T902.1. After 18 days of incubation biodegradation yields of 75% and 85% were achieved respectively in presence of non-autoclaved or autoclaved xerogel Fe/SiO2 at 10-5 M iron. These results are 42 and 60 % higher than in standard conditions without nanoparticles. They suggest that the autoclave procedure lead to the release of some iron less anchored in the silica matrix. This study highlights that siderophore production by Rhodococcus erythropolis T902.1 would be related to the presence of iron nanoparticles in the culture. It suggests that the production of these strong chelating compounds decreases with increase of iron release from xerogel Fe/SiO2. Moreover, most of the surfactants synthesized by Rhodococcus erythropolis T902.1 which are glycolipids containing trehalose (hexose), would be linked to cell surface and not excreted in the culture medium; the biomass hexose content also increased by 85% in presence of iron nanoparticles.NANOMICRO : nanoparticles for hydrocarbons (PAH) bioremediatio

Effect of Temperature on Growth of Psychrophilic and Psychrotrophic Members of Rhodotorula Aurantiaca

[en] The thermo-dependence of growth kinetic parameters was investigated for the Antarctic psychrophilic strain Rhodotorula aurantiaca and a psychrotrophic strain of the same species isolated in Belgium (Ardennes area). Cell production, maximum growth rate (mu max), and half-saturation constant for glucose uptake (Ks) of both yeasts were temperature dependent. For the two yeasts, a maximum cell production was observed at about 0 degree C, and cell production decreased when temperature increased. The mu max values for both strains increased with temperature up to a maximum of 10 degrees C for the psychrophilic strain and 17 degrees C for the psychrotrophic strain. For both yeasts, Ks for glucose was relatively constant at low temperatures. It increased at temperatures above 10 degrees C for the psychrophilic strain and 17 degrees C for the psychrotrophic strain. Although its glucose affinity was lower, the psychrotrophic strain grew more rapidly than the psychrophilic one. The difference in growth rate and substrate affinity was related to the origin of the strain and the adaptation strategy of R. aurantiaca to environmental conditions.info:eu-repo/semantics/publishe

Conidies aériennes et résistantes de souches de champignons filamenteux et leur procédé d'obtention

publication date: 2016-02-22; filing date: 201

Projet NANOMICRO dans le Pôle GREENWIN (01/01/2013-30/09/2017) (n° 6917, Plan MARSHALL)

L’Europe dans son ensemble et particulièrement la Région wallonne sont des régions caractérisées par un lourd passif environnemental. En effet, si l’époque industrielle a fait prospérer ces régions, elle a aussi induit de nombreuses pollutions au niveau des sols. Depuis quelques années, la réglementation européenne impose progressivement la décontamination des sites pollués. Des technologies diverses ont donc été développées mais impliquent souvent l’excavation du sol à traiter. Toutefois, des technologies propres de type biologique sont disponibles ; elles sont basées sur l’utilisation de différents types de microorganismes pour décontaminer les lieux