Enhanced vitamin B12 production in an innovative lupin tempeh is due to synergic effects of Rhizopus and Propionibacterium in cofermentation

© 2017 Informa UK Limited, trading as Taylor & Francis Group Fermentation represents a valuable and cost-effective approach for food stabilisation and nutritional improvement. Tempeh is an example of soybean solid-state fermentation. In this work, we investigated the possibility of producing a tempeh analogue containing high amounts of vitamin B12 using seeds of three different species of the legume lupin, namely Lupinus albus, L. angustifolius and L. mutabilis, with Rhizopus oligosporus and Propionibacterium freudenreichii cofermentation. Synergic effects of Rhizopus and Propionibacterium in increasing vitamin B12 up to 1230?ng/g dw was observed. These findings indicate that this cofermentation can improve lupin nutritional quality and safety to provide a tempeh analogue with added value for vegan and vegetarian communities and low-income populations. The level of potentially toxic lupin alkaloids was also monitored during the tempeh preparation

Structure and Molecular Mechanism of a Nucleobase-Cation-Symport-1 Family Transporter

The nucleobase–cation–symport-1 (NCS1) transporters are essential components of salvage pathways for nucleobases and related metabolites. Here, we report the 2.85-angstrom resolution structure of the NCS1 benzyl-hydantoin transporter, Mhp1, from Microbacterium liquefaciens. Mhp1 contains 12 transmembrane helices, 10 of which are arranged in two inverted repeats of five helices. The structures of the outward-facing open and substrate-bound occluded conformations were solved, showing how the outward-facing cavity closes upon binding of substrate. Comparisons with the leucine transporter LeuTAa and the galactose transporter vSGLT reveal that the outward- and inward-facing cavities are symmetrically arranged on opposite sides of the membrane. The reciprocal opening and closing of these cavities is synchronized by the inverted repeat helices 3 and 8, providing the structural basis of the alternating access model for membrane transport