Production of biohydrogen from brewery wastewater using Klebsiella pneumoniae isolated from the environment

The use of wastewater for the biological production of H₂ (biohydrogen) by dark fermentation has been studied for a variety of waste substrates and mixed or isolated inocula. However, for brewery wastewater (BW), which is generated in large volumes and has characteristics that are highly suitable for acidogenic fermentation, the available studies describe the use of mixed cultures, especially pretreated methanogenic inocula. The aim of this work was to isolate an enterobacterium from aviary litter that was capable of fermenting BW and generating biogas rich in H₂. The biochemical characterization and species confirmation confirmation revealed the isolation of Klebsiella peneumoniae, which provided efficient production of biogas rich in H₂ (30–40%) in batch assays performed for up to 72 h, with the inoculum in suspension, at a small scale (in serum bottles) and using a mechanically-stirred anaerobic reactor (AnBBR), employing crude BW without any supplementation. The hydrogen yield and molar hydrogen flow rate were 0.80–1.67 mol H₂ mol^?1 glucose and 0.2–2.2 mmol H₂ h^?1, respectively, indicating good performance of the inoculum in metabolizing this substrate and the possibility of optimizing the process by varying the duration of the batch.     

Characterization of different promoters for designing a new expression vector in Saccharomyces cerevisiae

The widely used pESC vector series (Stratagene, La Jolla, CA, USA) with the bidirectional GAL1/GAL10 promoter provides the possibility of simultaneously expressing two different genes from a single vector in Saccharomyces cerevisiae. This system can be induced by galactose and is repressed by glucose. Since S. cerevisiae prefers glucose as a carbon source, and since its growth rate is higher in glucose than in galactose‐containing media, we compared and evaluated seven different promoters expressed during growth on glucose (pTEF1, pADH1, pTPI1, pHXT7, pTDH3, pPGK1 and pPYK1) with two strong galactose‐induced promoters (pGAL1 and pGAL10), using lacZ as a reporter gene and measuring LacZ activity in batch and continuous cultivation. TEF1 and PGK1 promoters showed the most constant activity pattern at different glucose concentrations. Based on these results, we designed and constructed two new expression vectors which contain the two constitutive promoters, TEF1 and PGK1, in opposite orientation to each other. These new vectors retain all the features from the pESC–URA plasmid except that gene expression is mediated by constitutive promoters. Copyright © 2010 John Wiley & Sons, Ltd.     

Untersuchungen zur Maillard-reaktion 18. Mitteilung. radikalische inhibierung der br?unung durch schwefelverbindungen

Zusammenfassung ESR spektroskopische Untersuchungen zum Mechanismus der Maillard-Reaktion am Modelld-Glucose/Glycin belegen den radikalischen Verlauf einiger Reaktionsschritte, möglicherweise in Konkurrenz zu ionischen Mechanismen. Die Bildung von Radikalen ist abhängig von der Konzentration der Reaktanten und durchläuft in thermisch-induzierten Bräunungsreaktionen ein Maximum. Der Zusatz vonl-Cystein bewirkt eine 60%ige Reduzierung der Konzentration an Radikalen und beweist somit indirekt deren Beteiligung bei der Bildung von Bräunungsprodukten. Die Analyse der Hyperfein-struktur der ESR-Spektren läßt Pyrazinkationradikale vermuten.

---

Investigation on the Maillard-reaction. Part 18. Radical inhibition of browning by sulphur compounds

Summary ESR spectroscopic investigations on the mechanism of Maillard-reactions using the modeld-glucose/glycin show radical formation in some of the reaction steps. These are possibly due to competitive reactions against ionic mechanism. The formation of radicals depends on the concentration of reactants and reaches a maximum in thermically induced browning reactions. The addition ofl-cysteine leads to a decrease in the radical concentration to about 60%. It can be indirectly proven that the radicals are involved in the formation of browning products. The hyperfine structures of ESR spectra are supposed to be similar to pyrazine cation radicals.

     

Combining selected immunomodulatory Propionibacterium freudenreichii and Lactobacillus delbrueckii strains: Reverse engineering development of an anti‐inflammatory cheese

Scope : Inflammatory bowel disease (IBD) constitutes a growing public health concern in western countries. Bacteria with anti‐inflammatory properties are lacking in the dysbiosis accompanying IBD. Selected strains of probiotic bacteria with anti‐inflammatory properties accordingly alleviate symptoms and enhance treatment of ulcerative colitis in clinical trials. Such properties are also found in selected strains of dairy starters such as Propionibacterium freudenreichii and Lactobacillus delbrueckii (Ld). We thus investigated the possibility to develop a fermented dairy product, combining both starter and probiotic abilities of both lactic acid and propionic acid bacteria, designed to extend remissions in IBD patients. Methods and results : We developed a single‐strain Ld‐fermented milk and a two‐strain P. freudenreichii and Ld‐fermented experimental pressed cheese using strains previously selected for their anti‐inflammatory properties. Consumption of these experimental fermented dairy products protected mice against trinitrobenzenesulfonic acid induced colitis, alleviating severity of symptoms, modulating local and systemic inflammation, as well as colonic oxidative stress and epithelial cell damages. As a control, the corresponding sterile dairy matrix failed to afford such protection. Conclusion : This work reveals the probiotic potential of this bacterial mixture, in the context of fermented dairy products. It opens new perspectives for the reverse engineering development of anti‐inflammatory fermented foods designed for target populations with IBD, and has provided evidences leading to an ongoing pilot clinical study in ulcerative colitis patients.     

Characterisation of the technological behaviour of mixtures of mesophilic lactic acid bacteria isolated from traditional cheeses made of raw milk without added starters

In this work, the technological behaviour in milk of a set of Lactococcus lactis strains, alone or in combination with strains of Leuconostoc spp. and Lactobacillus spp. isolated from traditional, raw milk cheeses made without commercial starters, was investigated. Small, mixture‐specific differences during milk fermentation were recorded for growth, milk acidification and production of organic acids, volatile compounds, free amino acids and biogenic amines. Four combinations appropriate for use as dairy starters were tested in pilot‐scale cheese trials. Two mixtures produced cheeses of high flavour and taste quality; these could be confidently used as starter cultures.     

Shiga‐Toxin Genes and Genetic Diversity of Escherichia coli Isolated from Pasteurized Cow Milk in Brazil

This study evaluated the genetic similarity and prevalence of the stx1, stx2, eae, and ehxA genes in Escherichia coli isolated from pasteurized cow milk. Eighty‐seven E. coli isolates from pasteurized cow milk from 22 dairies located in northwestern Paraná state, Brazil, were analyzed. Genetic similarity was evaluated using enterobacterial repetitive intergenic consensus sequence polymerase chain reaction (ERIC‐PCR) and repetitive extragenic palindromic sequence PCR (REP‐PCR). E. coli isolates were also analyzed by PCR to investigate the presence of the stx1, stx2, eae, and ehxA genes. ERIC‐PCR and REP‐PCR clustered 87 bacterial isolates in 76 and 81 genomic profiles, respectively. Both techniques revealed high genetic diversity among the E. coli isolates, confirming the possibility of their use in epidemiological studies. The stx1, stx2, eae, and ehxA virulence genes were not detected in E. coli isolates, indicating a low prevalence of Shiga toxin‐producing E. coli in milk produced in the region studied.     

Geothermal technology in Australia: Investigating social acceptance

Issues of social acceptance, such as lack of awareness and negative community perceptions and reactions, can affect low emission energy technology development, despite general support observed for reducing carbon emissions and mitigating climate change. Negative community reactions and lack of understanding have affected geothermal developments, as demonstrated by the fearful community reactions and negative media experienced in response to seismic disturbances caused by “hot rock” geothermal energy generation in Switzerland and Germany. Focusing on geothermal energy, this paper presents the results of using a participatory action research methodology to engage diverse groups within the Australian public. A key finding is that the majority of the Australian public report limited the knowledge or understanding of geothermal technology and have various concerns including water usage and seismic activity instigated by geothermal drilling. However, geothermal energy receives general support due to a common trend to champion renewable energy sources in preference to traditional forms of energy generation and controversial technologies. This paper also demonstrates the effectiveness of using an engagement process to explore public understanding of energy technologies in the context of climate change, and suggests a way forward for governments and industry to allocate resources for greatest impact when communicating about geothermal technology.