In vitro removal of ochratoxin A by wine lactic acid bacteria

A study was carried out to determine the in vitro interaction between ochratoxin A (OTA) and wine lactic acid bacteria (LAB). Fifteen strains belonging to five relevant oenological LAB species were grown in liquid synthetic culture medium containing OTA. The portion of OTA removed during the bacterial growth was 8 to 28%. The OTA removed from the supernatants was partially recovered (31 to 57%) from the bacterial pellet. Cell-free extracts of three representative strains were produced by disrupting cells in a French pressure cell. The ability of crude cell-free extracts to degrade OTA was studied. OTA was not degraded by cell-free extracts of wine LAB strains, and no degradation products of OTA were detected in the high-performance liquid chromatograms of the methanol extract of the bacterial pellet. On the basis of these results, we conclude that OTA removal by wine LAB is a cell-binding phenomenon. The chemistry and the molecular basis of OTA binding to wine LAB remains unknown.     

Production of butanol (a biofuel) from agricultural residues: Part I – Use of barley straw hydrolysate

Fermentation of dilute sulfuric acid barley straw hydrolysate (BSH; undiluted/untreated) by Clostridium beijerinckii P260 resulted in the production of 7.09 gL^?1 ABE (acetone butanol ethanol), an ABE yield of 0.33, and productivity of 0.10 gL^?1 h^?1. This level of ABE is much less than that observed in a control experiment (21.06 gL^?1) where glucose (initial concentration 60 gL^?1) was used as a substrate. In the control experiment, an ABE yield of 0.41 and productivity of 0.31 gL^?1 h^?1 were observed. This comparison suggested that BSH is toxic to the culture. To reduce this potential toxicity effect, BSH was treated with lime [Ca(OH)₂] followed by fermentation. The treated BSH resulted in a successful fermentation and ABE concentration of 26.64 gL^?1 was achieved. This was superior to both glucose and untreated BSH (initial sugar 60 gL^?1) fermentations. In this fermentation, an ABE yield of 0.43 and productivity of 0.39 gL^?1 h^?1 (390% of untreated/undiluted BSH) was obtained. It should be noted that using lime treated BSH, a specific productivity of 0.55 h^?1 was obtained as compared to 0.12 h^?1 in the control fermentation suggesting that more carbon was directed to product formation.     

Advances in analysis of microbial metabolic fluxes via 13C isotopic labeling

Metabolic flux analysis via ¹³C labeling (¹³C MFA) quantitatively tracks metabolic pathway activity and determines overall enzymatic function in cells. Three core techniques are necessary for ¹³C MFA: (1) a steady state cell culture in a defined medium with labeled‐carbon substrates; (2) precise measurements of the labeling pattern of targeted metabolites; and (3) evaluation of the data sets obtained from mass spectrometry measurements with a computer model to calculate the metabolic fluxes. In this review, we summarize recent advances in the ¹³C‐flux analysis technologies, including mini‐bioreactor usage for tracer experiments, isotopomer analysis of metabolites via high resolution mass spectrometry (such as GC‐MS, LC‐MS, or FT‐ICR), high performance and large‐scale isotopomer modeling programs for flux analysis, and the integration of fluxomics with other functional genomics studies. It will be shown that there is a significant value for ¹³C‐based metabolic flux analysis in many biological research fields. © 2009 Wiley Periodicals, Inc., Mass Spec Rev 28:362–375, 2009     

Cohesive zone simulations of crack growth along a rough interface between two elastic-plastic solids

It has been known for many years that crack propagation along interfaces is influenced by interface topography or roughness profile. This has given rise to a small body of literature in which interface toughening with stochastic surface finishes, produced by grinding, rolling, or grit blasting, has been the primary focus. However, there is very little information currently available on the effect of patterned interfaces that are characterized by a minimal number of geometric parameters. In the present article, roughness-enhanced toughening of a cohesive interface between two identical materials is explored with a pure sinusoidal interface morphology that is characterized by its aspect ratio or ratio of amplitude to wavelength. Sixteen finite element meshes, each with a different aspect ratio, were constructed to study initiation and growth of a semi-infinite interface crack due to remote mode-I loading. The cohesive interface was modeled with a viscosity-modified Xu-Needleman cohesive zone law, and the solids were characterized with continuum elastic and elastic-plastic constitutive models. Predicted relationships between the aspect ratio and the macroscopic toughness point to key differences in the material models. A set of critical parameters which include the aspect ratio, material and cohesive properties is predicted such that catastrophic crack growth is inhibited due to crack blunting. A clear boundary between brittle and ductile fracture behavior is thus identified. The results suggest some guidelines for practical design of failure resistant interfaces through appropriate choice of geometric, material, and cohesive parameters.     

Starch Policy in the European Community

Within the framework of the EC-policy measures on starch, the European starch industry has developed successfully, also as a partner on the world market. Starch production in the European Union continues to increase by about 3 % per year. This growth is attributable almost entirely to wheat starch. Production of potato starch has reached a ceiling. The amount of maize starch remains at roughly the same volume and is thus declining in relative terms but maize continues to be the most important raw material. The European Community is easily self-sufficient with respect to starch and does not import any. The EC′s most important trading partner, the United States, produces four times as much starch especially for utilisation in the sugar and the biofuel sector. Starch exports are vital to the EC industry and account for ca. 17 % of total production, for which export refunds are granted. The subsidy granted within the Community, to compensate for the price difference on the world market and destined for the non-food sector which is not protected against imports, covers about 45 % of total starch production. Starch producers, processors and users in the Community work with this EC system which is generally well received and accepted. It is acknowledged that the refund policies provide fair indemnity with little risk of over- or undercompensation. In the context of Agenda 2000, the planned price cut should normally result in all refunds being discontinued, a major simplification and relief for business and authorities. However, if a significant price difference persists, the refunds would continue to apply, but subject to the restrictions operating within the World Trade Organisation (WTO). A strong pressure will be brought at the WTO negotiations in favour of greater market liberalisation. As regards the future enlargement of the Community, the applicant eastern countries will gradually have to adopt EC′s policies; production of starch and derivatives is still limited in these countries and they are generally not self-sufficient.     

Stabilization of α‐amylase by chemical modification with carboxymethylcellulose

Carboxymethylcellulose activated by periodate oxidation was covalently linked to porcine pancreatic α‐amylase (EC 3.2.1.1). The specific activity of the conjugate prepared was 54% of the native enzyme. The carbohydrate content was estimated to be 62% by weight as a result of the modification of 67% of the amino groups from the protein. In comparison with the native enzyme, the thermostability and pH stability were improved for α‐amylase by this modification. The conjugate was also more resistant to the action of denaturant agents such as urea and sodium dodecylsulfate. We conclude that modification of enzymes by the anionic polysaccharide carboxymethylcellulose might be a useful method for improving enzyme stability under various denaturing conditions. © 1999 Society of Chemical Industry     

Alterations in Metabolome and Microbiome Associated with an Early Stress Stage in Male Wistar Rats: A Multi-Omics Approach

Stress disorders have dramatically increased in recent decades becoming the most prevalent psychiatric disorder in the United States and Europe. However, the diagnosis of stress disorders is currently based on symptom checklist and psychological questionnaires, thus making the identification of candidate biomarkers necessary to gain better insights into this pathology and its related metabolic alterations. Regarding the identification of potential biomarkers, omic profiling and metabolic footprint arise as promising approaches to recognize early biochemical changes in such disease and provide opportunities for the development of integrative candidate biomarkers. Here, we studied plasma and urine metabolites together with metagenomics in a 3 days Chronic Unpredictable Mild Stress (3d CUMS) animal approach that aims to focus on the early stress period of a well-established depression model. The multi-omics integration showed a profile composed by a signature of eight plasma metabolites, six urine metabolites and five microbes. Specifically, threonic acid, malic acid, alpha-ketoglutarate, succinic acid and cholesterol were proposed as key metabolites that could serve as key potential biomarkers in plasma metabolome of early stages of stress. Such findings targeted the threonic acid metabolism and the tricarboxylic acid (TCA) cycle as important pathways in early stress. Additionally, an increase in opportunistic microbes as virus of the Herpesvirales was observed in the microbiota as an effect of the primary stress stages. Our results provide an experimental biochemical characterization of the early stage of CUMS accompanied by a subsequent omic profiling and a metabolic footprinting that provide potential candidate biomarkers.     

Imbalances in TCA,Short Fatty Acids and One-Carbon Metabolisms as Important Features of Homeostatic Disruption Evidenced by a Multi-Omics Integrative Approach of LPS-Induced Chronic Inflammation in Male Wistar Rats

Chronic inflammation is an important risk factor in a broad variety of physical and mental disorders leading to highly prevalent non-communicable diseases (NCDs). However, there is a need for a deeper understanding of this condition and its progression to the disease state. For this reason, it is important to define metabolic pathways and complementary biomarkers associated with homeostatic disruption in chronic inflammation. To achieve that, male Wistar rats were subjected to intraperitoneal and intermittent injections with saline solution or increasing lipopolysaccharide (LPS) concentrations (0.5, 5 and 7.5 mg/kg) thrice a week for 31 days. Biochemical and inflammatory parameters were measured at the end of the study. To assess the omics profile, GC-qTOF and UHPLC-qTOF were performed to evaluate plasma metabolome; ¹H-NMR was used to evaluate urine metabolome; additionally, shotgun metagenomics sequencing was carried out to characterize the cecum microbiome. The chronicity of inflammation in the study was evaluated by the monitoring of monocyte chemoattractant protein-1 (MCP-1) during the different weeks of the experimental process. At the end of the study, together with the increased levels of MCP-1, levels of interleukin-6 (IL-6), tumour necrosis factor alpha (TNF-α) and prostaglandin E2 (PGE2) along with 8-isoprostanes (an indicative of oxidative stress) were significantly increased (p-value < 0.05). The leading features implicated in the current model were tricarboxylic acid (TCA) cycle intermediates (i.e., alpha-ketoglutarate, aconitic acid, malic acid, fumaric acid and succinic acid); lipids such as specific cholesterol esters (ChoEs), lysophospholipids (LPCs) and phosphatidylcholines (PCs); and glycine, as well as N, N-dimethylglycine, which are related to one-carbon (1C) metabolism. These metabolites point towards mitochondrial metabolism through TCA cycle, β-oxidation of fatty acids and 1C metabolism as interconnected pathways that could reveal the metabolic effects of chronic inflammation induced by LPS administration. These results provide deeper knowledge concerning the impact of chronic inflammation on the disruption of metabolic homeostasis.