In situ production of active vitamin B12 in cereal matrices using Propionibacterium freudenreichii

The in situ production of active vitamin B12 was investigated in aqueous cereal-based matrices with three strains of food-grade Propionibacterium freudenreichii. Matrices prepared from malted barley flour (33% w/v; BM), barley flour (6%; BF), and wheat aleurone (15%; AM) were fermented. The effect of cobalt and the lower ligand 5,6-dimethylbenzimidazole (DMBI) or its natural precursors (riboflavin and nicotinamide) on active B12 production was evaluated. Active B12 production was confirmed by UHPLC-UV-MS analysis. A B12 content of 12-37 mu g.kg(-1) was produced in BM; this content increased 10-fold with cobalt and reached 940-1,480 mu g.kg(-1) with both cobalt and DMBI. With riboflavin and nicotinamide, B12 production in cobalt-supplemented BM increased to 712 mu g.kg(-1). Approximately, 10 mu g.kg(-1) was achieved in BF and AM and was increased to 80 mu g.kg(-1) in BF and 260 mu g.kg(-1) in AM with cobalt and DMBI. The UHPLC and microbiological assay (MBA) results agreed when both cobalt and DMBI or riboflavin and nicotinamide were supplemented. However, MBA gave ca. 20%-40% higher results in BM and AM supplemented with cobalt, indicating the presence of human inactive analogues, such as pseudovitamin B12. This study demonstrates that cereal products can be naturally fortified with active B12 to a nutritionally relevant level by fermenting with P. freudenreichii.Peer reviewe

Characterization of Quorum Sensing and Quorum Quenching Soil Bacteria Isolated from Malaysian Tropical Montane Forest

We report the production and degradation of quorum sensing N-acyl-homoserine lactones by bacteria isolated from Malaysian montane forest soil. Phylogenetic analysis indicated that these isolates clustered closely to the genera of Arthrobacter, Bacillus and Pseudomonas. Quorum quenching activity was detected in six isolates of these three genera by using a series of bioassays and rapid resolution liquid chromatography analysis. Biosensor screening and high resolution liquid chromatography-mass spectrometry analysis revealed the production of N-dodecanoyl-L-homoserine lactone (C12-HSL) by Pseudomonas frederiksbergensis (isolate BT9). In addition to degradation of a wide range of N-acyl-homoserine lactones, Arthrobacter and Pseudomonas spp. also degraded p-coumaroyl-homoserine lactone. To the best of our knowledge, this is the first documentation of Arthrobacter and Pseudomonas spp. capable of degrading p-coumaroyl-homoserine lactone and the production of C12-HSL by P. frederiksbergensis

Science, institutions, and values

This paper articulates and defends three interconnected claims: firstly, that the debate on the role of values for science misses a crucial dimension, the institutional one; secondly, that institutions occupy the intermediate level between scientific activities and values and that they are to be systematically integrated into the analysis; thirdly, that the appraisal of the institutions of science with respect to values should be undertaken within the premises of a comparative approach rather than an ideal approach. Hence, I defend the view that the issue be framed in reference to the following question: “What kind of institutional rules should be in place in order for the scientific process to unfold in such a way that the values that we deem more important come to the fore?” Addressing this concern is equivalent to conducting a debate on institutions and their role for science