La microflore de boues aérobies acclimatées à des teneurs élevées en graisse

Le travail présenté dans cet article a pour but d'isoler les principaux micro-organismes impliqués dans la biodégradation des lipides concentrés dans des réacteurs spécifiques de stations d'épuration des eaux et d'étudier leur action sur ce type de substrat.La microflore d'une boue activée « classique » est comparée à celle de boues acclimatées à des teneurs élevées en lipides selon un nouveau procédé « BIOMASTER® G ». Cela montre un enrichissement en bactéries fortement lipolytiques dans le système à l'équilibre. En effet, la boue activée « classique » ne contient aucun microorganisme fortement lipolytique alors qu'à partir de la boue acclimatée du même site on a pu en isoler, Acinetobacter calcoaceticus et Pseudomonas putida étant les constituants les plus actifs. L'utilisation de bioadditifs du commerce pour l'ensemencement des pilotes au lancement du système ne semble pas apporter d'avantages décisifs puisqu'on ne retrouve pas à l'équilibre les micro-organismes contenus dans ces bioadditifs. Par contre, d'autres microorganismes à pouvoir lipolytique élevé sont détectés tels que Pseudomonas sp., Aeromonas hydrophila et Staphylococcus sp . Le genre Pseudomonas est par ailleurs presque toujours rencontré quelle que soit la boue acclimatée examinée. De même, on peut noter la quasi absence de bactéries Gram positif.Tous les isolats Gram négatif dégradent plus ou moins les acides gras de longueur de chaîne variée. Le seul isolat Gram positif est inhibé ou même tué par les acides gras à chaîne moyenne ou courte et cela peut contribuer à la pauvreté en bactéries Gram positif dans les boues acclimatées. Les genres principaux que nous avons rencontrés, Pseudomonas, Acinetobacter et Aeromonas, sont capables d'assurer à la fois la lipolyse (libération des acides gras) et l'oxydation subséquente des acides gras. L'enrichissement naturel de la microflore lipolytique des boues activées dans le procédé aboutit à une microflore acclimatée capable d'assurer la biodégradation complète des lipides.In this study, the main microorganisms involved in lipid biodegradation in activated sludge sewage treatment plants were isolated and their action on triglycerides and on fatty acids was investigated.Six different sludge samples were studied. An activated sludge of the usual type (A) was used as reference. At the same site, activated sludge was adapted to higher lipid levels, through separation of fats reaching the sewage treatment plant, followed by their addition in higher proportion to activated sludge. In experiment B, adaptation took place in a « BIOMASTER® G » reactor, which is a new process for the elimination of fats by an aerobic treatment. Experiments C and D used the same original sludge plus lipid mixture, but with the addition of commercial bioadditives containing lipolytic bacteria. Finally, microorganisms isolated from two other systems, located at two other sites, were also studied (experiments E and F).The control activated sludge, A, did not contain any strongly lipolytic microorganisms. On the other hand, in the new system at equilibrium, after adaptation, bacteria with a strong lipolytic potential such as Acinetobacter calcoaceticus and, Pseudomonas putida were isolated. The use of bioadditives at the start of the incubation did not afford any notable advantage, since at equilibrium microorganisms contained in these additives were not reisolated. However, other microorganisms with high lipolytic power (activity higher than 0.1 µmole acid liberated per minute and per ml of culture broth) were isolated, such as Pseudomorns sp., Aeromonas hydrophila and Staphylococcus sp. The genus Pseudomozas was almost always detected, regardless of the acclimated sludge studied. Conversely, Gram positive bacteria were virtually absent.All Gram negative isolates were more or less capable of degrading fatty acids with various chain lengths. The only Gram positive isolate was inhibited, even killed, by short and medium chain fatty acids. In the present study, this might contribute to the paucity of Gram positive bacteria in the adapted sludges. The main genera encountered, Pseudomonas, Acinetobacter and Aeromonas, were able to perform both lipolysis (liberation of fatty acids) and the subsequent oxidation of the liberated fatty acids. The natural enrichment of the lipolltic microflora of activated sludges in the process leads to an acclimated microflora, able to completely biodegrade lipids

Like a Cold Glass of Water on a Hot Summer Day: Essays Expoloring Differential Sensitivity to Nonconscious Cues in Consumer Contexts.

The value of an ice-cold glass of water is a function of an individual’s thirst, whether he finds himself in the middle of the Sahara or the North Pole, and an interaction of the two. At some level marketers are aware that value is a dynamic construct, but in spite of this, little to no research has been conducted exploring the interactions between the internal states of consumers, their context, and the interaction of the two, particularly in the domain of nonconscious processing. Despite the fact that individuals’ sensitivity to nonconscious cues has been shown to vary, no one has yet considered how the interaction of one’s internal milieu and his context might influence his sensitivity to such nonconscious cues. In this dissertation three essays explore how sensitivity to subtle cues varies as a function of an individuals’ internal state and his context, revealing implications for consumer behavior. Essay 1 focuses on how sensitivity to relationships, whether by cultural default or situated by priming a mindset, influences consumer response to the common situation in which a chosen set of products cannot be obtained in its entirety. Essay 2 explores how threats to social connection motivate individuals to be more sensitive to humanlike cues in consumer contexts and subsequently decreases the likelihood of engaging in genuine interpersonal interactions and prosocial behaviors after exposure to humanlike cues in products. Essay 3 discusses how a more general threat to an individual’s internal milieu – putting one in a conflicted state of mind – leads to greater sensitivity to relevant cues in his context, which has subsequent effects on choices and behaviors including spending or saving money, choosing an apartment, and eating healthily or indulgently. Taken together, the essays provide different examples of how individuals can be more or less sensitive to the cues in their context based on an interaction between their internal states and the contexts in which they find themselves. Implications for marketing practice and consumer research are discussed including ideas for future research employing emerging technologies that allow for more proximal, real-time measures of both self and context.PHDBusiness AdministrationUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/97936/1/alvarezj_1.pd

Density-functional studies of tungsten trioxide, tungsten bronzes, and related systems

Tungsten trioxide adopts a variety of structures which can be intercalated with charged species to alter the electronic properties, thus forming `tungsten bronzes'. Similar optical effects are observed upon removing oxygen from WO_3, although the electronic properties are slightly different. Here we present a computational study of cubic and hexagonal alkali bronzes and examine the effects on cell size and band structure as the size of the intercalated ion is increased. With the exception of hydrogen (which is predicted to be unstable as an intercalate), the behaviour of the bronzes are relatively consistent. NaWO_3 is the most stable of the cubic systems, although in the hexagonal system the larger ions are more stable. The band structures are identical, with the intercalated atom donating its single electron to the tungsten 5d valence band. Next, this was extended to a study of fractional doping in the Na_xWO_3 system (0 < x < 1). A linear variation in cell parameter, and a systematic change in the position of the Fermi level up into the valence band was observed with increasing x. In the underdoped WO_3-x system however, the Fermi level undergoes a sudden jump into the conduction band at around x = 0.2. Lastly, three compounds of a layered WO_4&#215;a,wdiaminoalkane hybrid series were studied and found to be insulating, with features in the band structure similar to those of the parent WO_3 compound which relate well to experimental UV-visible spectroscopy results.Comment: 12 pages, 16 figure

Distinction between Pore Assembly by Staphylococcal α-Toxin versus Leukotoxins

The staphylococcal bipartite leukotoxins and the homoheptameric α-toxin belong to the same family of β-barrel pore-forming toxins despite slight differences. In the α-toxin pore, the N-terminal extremity of each protomer interacts as a deployed latch with two consecutive protomers in the vicinity of the pore lumen. N-terminal extremities of leukotoxins as seen in their three-dimensional structures are heterogeneous in length and take part in the β-sandwich core of soluble monomers. Hence, the interaction of these N-terminal extremities within structures of adjacent monomers is questionable. We show here that modifications of their N-termini by two different processes, using fusion with glutathione S-transferase (GST) and bridging of the N-terminal extremity to the adjacent β-sheet via disulphide bridges, are not deleterious for biological activity. Therefore, bipartite leukotoxins do not need a large extension of their N-terminal extremities to form functional pores, thus illustrating a microheterogeneity of the structural organizations between bipartite leukotoxins and α-toxin

Does Observation of Postural Imbalance Induce a Postural Reaction?

Import JabRef | WosArea Life Sciences and Biomedicine - Other TopicsInternational audienceBackground: Several studies bring evidence that action observation elicits contagious responses during social interactions. However automatic imitative tendencies are generally inhibited and it remains unclear in which conditions mere action observation triggers motor behaviours. In this study, we addressed the question of contagious postural responses when observing human imbalance. Methodology/Principal Findings: We recorded participants' body sway while they observed a fixation cross (control condition), an upright point-light display of a gymnast balancing on a rope, and the same point-light display presented upside down. Our results showed that, when the upright stimulus was displayed prior to the inverted one, centre of pressure area and antero-posterior path length were significantly greater in the upright condition compared to the control and upside down conditions. Conclusions/Significance: These results demonstrate a contagious postural reaction suggesting a partial inefficiency of inhibitory processes. Further, kinematic information was sufficient to trigger this reaction. The difference recorded between the upright and upside down conditions indicates that the contagion effect was dependent on the integration of gravity constraints by body kinematics. Interestingly, the postural response was sensitive to habituation, and seemed to disappear when the observer was previously shown an inverted display. The motor contagion recorded here is consistent with previous work showing vegetative output during observation of an effortful movement and could indicate that lower level control facilitates contagion effects

Hypericum sp.: essential oil composition and biological activities

Phytochemical composition of Hypericum genus has been investigated for many years. In the recent past, studies on the essential oils (EO) of this genus have been progressing and many of them have reported interesting biological activities. Variations in the EO composition of Hypericum species influenced by seasonal variation, geographic distribution, phenological cycle and type of the organ in which EO are produced and/or accumulated have also been reported. Although many reviews attributed to the characterization as well as biological activities of H. perforatum crude extracts have been published, no review has been published on the EO composition and biological activities of Hypericum species until recently (Crockett in Nat Prod Commun 5(9):1493–1506, 2010; Bertoli et al. in Global Sci Books 5:29–47, 2011). In this article, we summarize and update information regarding the composition and biological activities of Hypericum species EO. Based on experimental work carried out in our laboratory we also mention possible biotechnology approaches envisaging EO improvement of some species of the genus.Fundação para a Ciência e a Tecnologia (FCT) - project PTDC/AGR AAM/70418/2006, SFRH/BD/ 13283/2003